Concentration-QTcF Modeling of Icenticaftor from a Randomized, Placebo- and Positive-Controlled Thorough QT Study in Healthy Participants

Icenticaftor (QBW251) is a potentiator of the cystic fibrosis transmembrane receptor. Based on its mechanism of action, icenticaftor is expected to provide benefits in patients with chronic obstructive pulmonary disease by restoring mucociliary clearance, which would eventually lead to a reduction of bacterial colonization and related inflammatory cascade. A placebo- and positive-controlled, 4-way crossover thorough QT study was conducted in 46 healthy participants with the objective to assess the effect of therapeutic (300 mg twice daily for 6 days) and supratherapeutic (750 mg twice daily for 6 days) oral doses of icenticaftor on electrocardiogram parameters, including concentration-corrected QT (QTc) analysis. Moxifloxacin (400 mg, oral) was used as a positive control. In the concentration-QTc analysis performed on pooled data from Day 1 and Day 6 (steady state), the estimated population slope was shallow and slightly negative: -0.0012 ms/ng/mL. The effect on the Fridericia corrected QT (QTcF) interval (∆ΔQTcF) was predicted to be -1.3 milliseconds at the icenticaftor 300-mg twice-daily peak concentration (geometric mean was 1094 ng/mL) and -5.5 milliseconds at the 750-mg twice-daily peak concentration (geometric mean Cmax was 4529 ng/mL) indicated a mild shortening effect of icenticaftor on QTcF interval length. The results of the by-time-point analysis indicated least squares placebo corrected mean ∆∆QTcF across time points ranged from -7.9 to 0.1 milliseconds at 1 and 24 hours after dosing both on Day 6 in the 750-mg dose group compared with -3.7 to 1.6 milliseconds at 1.5 and 24 hours after dosing on Day 1 in the 300-mg dose group. Assay sensitivity was demonstrated with moxifloxacin. The large accumulation of exposures, especially the 4.3-fold increase in peak plasma concentration observed at the icenticaftor 750-mg twice-daily dosage compared with Icenticaftor 300 mg twice daily (2.3-fold) on Day 6 provided a large concentration range (up to 9540 ng/mL) to evaluate the effect of icenticaftor on ΔΔQTcF. Based on the concentration-QTc analysis, an effect on ΔΔQTcF exceeding 10 milliseconds can be excluded within the full observed ranges of plasma concentrations on icenticaftor, up to approximately 9540 ng/mL. Icenticaftor at the studied doses demonstrated a mild shortening in QTcF, which is unlikely to be of clinical relevance in a therapeutic setting.

Gepirone-the latest antidepressant on market state-of-the-art or run-of-the-mill?

Gepirone was recently launched and FDA-approved for MDD. It belongs to azapirones group of psychotropics that is in popular use in Japan and China. Here, author wraps up current knowledge on gepirone contrasted with the older and cheaper anxiolytic buspirone.

Longitudinal ECG changes in tetralogy of Fallot and association with surgical repair

Background

ECG abnormalities have been linked to adverse changes in right ventricular (RV) morphology and poor clinical outcomes in repaired Tetralogy of Fallot (rTOF). Our aim was to describe how ECG changes progress in early and intermediate follow-up and whether types of surgical strategy at the time of primary repair affected these changes.

Methods

We studied patients with rTOF born 2000-2018 operated at our institution. Seven time points in relation to primary repair, follow-up, and pulmonary valve replacement (PVR) were identified. Patients correct with valve sparing repair (VSR), trans-annular patch (TAP) including with a monocusp valve (TAP + M) and with at least 3 ECGs were included. PQ interval, QRS duration, dispersion, and fragmentation, QTc duration and dispersion, JTc as well as presence of a right bundle branch block (RBBB) were analyzed. Medical records were reviewed for demographic and surgical data.

Results

Two hundred nineteen patients with 882 ECGs were analyzed with a median follow-up time of 12.3 years (8.4, 17) with 41 (19%) needing PVR during the study period. QRS duration increased at time of primary repair to discharge from 66 msec (IQR 12) to 129 msec (IQR 27) (p < 0.0001) and at 1- and 6- year follow-up but showed only a modest and temporary decrease after PVR. QTc increased at the time of primary repair as well as prior to PVR. PQ interval showed a small increase at the time of primary repair, was at its highest prior to PVR and decreased with PVR. Type of surgical repair affected mainly QTc and JTc and was consistently longer in the TAP + M group until PVR. In VSR, QTc and JTc were prolonged initially compared to TAP but were similar after 1 year. After PVR, there were no differences in adverse ECG changes between surgical groups.

Conclusions

PQ interval and QRS duration best correspond to the assumed volume load whereas the relationship with QTc and JTc is more complex, suggesting that these represent more complex remodeling of the myocardium. Before PVR, QTc and JTc are longer in the TAP + M group which may be due to a longer surgical incision.

The pharmacokinetics and pharmacodynamics of ibogaine in opioid use disorder patients

OBJECTIVE

Ibogaine is a hallucinogenic drug that may be used to treat opioid use disorder (OUD). The relationships between pharmacokinetics (PKs) of ibogaine and its metabolites and their clinical effects on side effects and opioid withdrawal severity are unknown. We aimed to study these relationships in patients with OUD undergoing detoxification supported by ibogaine.

METHODS

The study was performed in 14 subjects with OUD. They received a single dose of 10mg/kg ibogaine hydrochloride. Plasma PKs of ibogaine, noribogaine, and noribogaine glucuronide were obtained during 24 h. Cytochrome P450 isoenzyme 2D6 (CYP2D6) genotyping was performed. The PKs were analyzed by means of nonlinear mixed effects modeling and related with corrected QT interval (QTc) prolongation, cerebellar ataxia, and opioid withdrawal severity.

RESULTS

The PK of ibogaine were highly variable and significantly correlated to CYP2D6 genotype (p < 0.001). The basic clearance of ibogaine (at a CYP2D6 activity score (AS) of 0) was 0.82 L/h. This increased with 30.7 L/h for every point of AS. The relation between ibogaine plasma concentrations and QTc was best described by a sigmoid Emax model. Spearman correlations were significant (p < 0.03) for ibogaine but not noribogaine with QTc (p = 0.109) and cerebellar effects (p = 0.668); neither correlated with the severity of opioid withdrawal symptoms.

CONCLUSIONS

The clearance of ibogaine is strongly related to CYPD2D6 genotype. Ibogaine cardiac side effects (QTc time) and cerebellar effects are most likely more driven by ibogaine rather than noribogaine. Future studies should aim at exploring lower doses and/or applying individualized dosing based on CYP2D6 genotype.

Automated Quantification of QT-Intervals by an Algorithm: A Validation Study in Patients with Chronic Obstructive Pulmonary Disease

Study Objectives

To assess the diagnostic accuracy of a purpose-designed QTc-scoring algorithm versus the established hand-scoring in patients with chronic obstructive pulmonary disease (COPD) undergoing sleep studies.

Methods

We collected 62 overnight electrocardiogram (ECG) recordings in 28 COPD patients. QT-intervals corrected for heart rate (QTc, Bazett) were averaged over 1-min periods and quantified, both by the algorithm and by cursor-assisted hand-scoring. Hand-scoring was done blinded to the algorithm-derived results. Bland-Altman statistics and confusion matrixes for three thresholds (460, 480, and 500ms) were calculated.

Results

A total of 32944 1-min periods and corresponding mean QTc-intervals were analysed manually and by computer. Mean difference between manual and algorithm-based QTc-intervals was -1ms, with limits of agreement of -18 to 16ms. Overall, 2587 (8%), 357 (1%), and 0 QTc-intervals exceeding the threshold 460, 480, and 500ms, respectively, were identified by hand-scoring. Of these, 2516, 357, and 0 were consistently identified by the algorithm. This resulted in a diagnostic classification accuracy of 0.98 (95% CI 0.98/0.98), 1.00 (1.00/1.00), and 1.00 (1.00/1.00) for 460, 480, and 500ms, respectively. Sensitivity was 0.97, 1.00, and NA for 460, 480, and 500ms, respectively. Specificity was 0.98, 1.00, and 1.00 for 460, 480, and 500ms, respectively.

Conclusion

Overall, 8% of nocturnal 1-min periods showed clinically relevant QTc prolongations in patients with stable COPD. The automated QTc-algorithm accurately identified clinically relevant QTc-prolongations with a very high sensitivity and specificity. Using this tool, hospital sleep laboratories may identify asymptomatic patients with QTc-prolongations at risk for malignant arrhythmia, allowing them to consult a cardiologist before an eventual cardiac event.

Electrocardiographic proarrhythmic changes in pregnancy of women with CHD

OBJECTIVES

Pregnancy-related physiological adaptations result in increased heart rate as well as electrocardiographic changes such as a mean QTc prolongation of 27 ms. Pregnant women with CHD are at increased risk for cardiovascular complications. The aim of this study was to identify risk factors for abnormally prolonged QTc interval-a risk factor for ventricular arrhythmias-in pregnant women with CHD.

MATERIAL AND METHOD

Retrospective longitudinal single-centre study. Pre-pregnancy demographic and electrocardiographic risk factors for abnormal QTc duration during pregnancy of (a) > 460 ms and (b) >27 ms increase were analyzed.

RESULTS

Eighty-three pregnancies in 63 women were included, of which three had documented arrhythmias. All five Modified World Health Organization Classification of Maternal Cardiovascular Risk (mWHO) classes were represented, with 15 pregnancies (18.1%) in mWHO class I, 26 (31.3%) in mWHO II, 28 (33.7%) in mWHO II-III, 11 (13.3%) in mWHO III, and three pregnancies (3.6%) in mWHO class IV. Heart rate and QTc interval increased, while QRS duration and PR interval shortened during pregnancy. QTc duration of > 460 ms was associated with increased pre-pregnancy QTc interval, QRS duration, and weight, as well as body mass index. QTc increase of > 27 ms was associated with increased heart rate prior to pregnancy. No significant associations of electrocardiographic changes with mWHO class or CHD type were identified.

CONCLUSION

Increased QTc in pregnant women with CHD was associated with being overweight or having higher heart rate, QRS, or QTc duration prior to pregnancy. These patients should be monitored closely for arrhythmias during pregnancy.

Escitalopram-induced QTc prolongation and its relationship with KCNQ1, KCNE1, and KCNH2 gene polymorphisms

BACKGROUND

Escitalopram can cause prolongation of the QT interval on the electrocardiogram (ECG). However, only some patients get pathological QTc prolongation in clinic. We investigated the influence of KCNQ1, KCNE1, and KCNH2 gene polymorphisms along with clinical factors on escitalopram-induced QTc prolongation.

METHODS

A total of 713 patients prescribed escitalopram were identified and had at least one ECG recording in this retrospective study. 472 patients with two or more ECG data were divided into QTc prolongation (n = 119) and non-prolongation (n = 353) groups depending on the threshold change in QTc of 30 ms above baseline value (∆QTc ≥ 30 ms). 45 patients in the QTc prolongation group and 90 patients in the QTc non-prolongation group were genotyped for 43 single nucleotide polymorphisms (SNPs) of KCNQ1, KCNE1, and KCNH2 genes.

RESULTS

Patients with QTc prolongation (∆QTc ≥ 30 ms) got higher escitalopram dose (10.3 mg) than patients without QTc prolongation (9.4 mg), although no significant relationship was found between QTc interval and escitalopram dose in the linear mixed model. Patients who were older/coronary disease/hypertension or carried with KCNE1 rs1805127 C allele, KCNE1 rs4817668 C allele, KCNH2 rs3807372 AG/GG genotype were significantly at risk for QTc prolongation (∆QTc ≥ 30 ms). Concomitant antipsychotic treatment was associated with a longer QTc interval.

LIMITATIONS

A relatively small sample size and lack of the blood concentration of escitalopram restricted the accurate relationship between escitalopram dose and QTc interval.

CONCLUSION

Our study revealed that KCNQ1, KCNE1, and KCNH2 gene polymorphisms along with clinical factors provide a complementary effect in escitalopram-induced QTc prolongation.

Case report of a child with long QT syndrome type 14 caused by CALM1 gene mutation and literature review

OBJECTIVE

To analyze the clinical and genetic characteristics of a patient with long QT syndrome type 14 (long QT syndrome-14, LQT14, OMIM # 616247) caused by a de novo CALM1 mutation.

METHODS

The clinical data of the patient were collected, next-generation sequencing technology was used to determine the exome gene sequence of the patient, and the suspected pathogenic locus was verified by Sanger sequencing.

RESULTS

A 5-year and 9-month-old girl was admitted to the hospital due to a syncopal episode. During the attack, the main symptoms were loss of consciousness, cyanosis of the face and lips, and weakness of limbs. The child had multiple seizures in the past, all of which occurred after emotional excitement and activity. She was diagnosed with epilepsy for more than 3 years, but the effect of antiepileptic treatment was not satisfactory. The electrocardiogram was normal in the past. A month ago, convulsions occurred again after exercise, and the electrocardiogram showed QTc 496 ms. The treadmill test showed a significant prolongation of QTc after exercise, and the genetic results suggested a new heterozygous variant of CALM1, c.395A>G; p. (Asp132Gly). Consequently, she was diagnosed with LQT14 and treated with propranolol. During a follow-up of 15 months, there were no seizures or syncope.

CONCLUSIONS

This patient had multiple episodes of convulsions or syncope after emotional stimulation or activity, with intermittent prolongation of the QTc on routine ECG, marked prolongation of the QTc after exercise, and T-wave alternans, which differed from the LQT14 phenotype caused by the previous CALM1 mutation.

Clinical and Laboratory Correlates of QTc Duration in Adult and Pediatric Sickle Cell Disease

Background

Sickle cell disease, a common genetic disorder in African Americans, manifests an increased risk of sudden death, the basis of which is incompletely understood. Prolongation of heart rate-corrected QT (QTc) interval on the electrocardiogram, a standard clinical measure of cardiac repolarization, may contribute to sudden death by predisposing to torsades de pointes ventricular tachycardia.

Methods

We established a cohort study of 293 adult and 121 pediatric sickle cell disease patients drawn from the same geographic region as the Jackson Heart Study (JHS) cohort, in which significant correlates of QT duration have been characterized and quantitatively modeled. Herein, we establish clinical and laboratory correlates of QTc duration in our cohort using stepwise multivariate linear regression analysis. We then compared our adult sickle cell disease data to effect-size predictions from the published JHS statistical model of QT interval duration.

Results

In adult sickle cell disease, gender, diuretic use, QRS duration, serum ALT levels, anion gap, and diastolic blood pressure show positive correlation; hemoglobin levels show inverse correlation; in pediatric sickle cell disease, age, hemoglobin levels, and serum bicarbonate and creatinine levels show inverse correlation. The mean QTc in our adult sickle cell disease cohort is 7.8 milliseconds longer than in the JHS cohort, even though the JHS statistical model predicts that the mean QTc in our cohort should be > 11 milliseconds shorter than in the much older JHS cohort, a differential of > 18 milliseconds.

Conclusion

Sickle cell disease patients have substantial QTc prolongation relative to their age, driven by factors some overlapping, in adult and pediatric sickle cell disease, and distinct from those that have been defined in the general African American community.

What training should psychiatrists have to interpret six- and 12-lead electrocardiograms?

To monitor for drug-related cardiac arrhythmias, psychiatrists regularly perform and interpret 12-lead (12L) and, increasingly often, six-lead (6L) electrocardiograms (ECGs). It is not known how training on this complex skill is updated or how well psychiatrists can interpret relevant arrhythmias on either device.We conducted an online survey and ECG interpretation test of cardiac rhythms relevant to psychiatrists.A total of 183 prescribers took part; 75% did not regularly update their ECG interpretation skills, and only 22% felt confident in interpreting ECGs. Most participants were able to recognise normal ECGs. For both 6L and 12L ECGs, the majority of participants were able to recognise abnormal ECGs, but fewer than 50% were able to correctly identify relevant arrhythmias (complete heart block and long QTc). A small number prescribed in the presence of potentially fatal arrhythmias. These findings suggest a need for mandatory ECG interpretation training to improve safe prescribing practice.

The optimal QTc selection in patients of acute myocardial infarction with poor perioperative prognosis

BACKGROUND

The predictive utility of QTc values, calculated through various correction formulas for the incidence of postoperative major adverse cardiovascular and cerebrovascular events (MACCE) in patients experiencing acute myocardial infarction (AMI), warrants further exploration. This study endeavors to ascertain the predictive accuracy of disparate QTc values for MACCE occurrences in patients with perioperative AMI.

METHODS

A retrospective cohort of three hundred fourteen AMI patients, comprising 81 instances of in-hospital MACCE and 233 controls, was assembled, with comprehensive collection of baseline demographic and clinical data. QTc values were derived employing the correction formulas of Bazett, Fridericia, Hodges, Ashman, Framingham, Schlamowitz, Dmitrienko, Rautaharju, and Sarma. Analytical methods encompassed comparative statistics, Spearman correlation analysis, binary logistic regression models, receiver operating characteristic (ROC) curves, and decision curve analysis (DCA).

RESULTS

QTc values were significantly elevated in the MACCE cohort compared to controls (P < 0.05). Spearman's correlation analysis between heart rate and QTc revealed a modest positive correlation for the Sarma formula (QTcBaz) (ρ = 0.46, P < 0.001). Within the multifactorial binary logistic regression, each QTc variant emerged as an independent risk factor for MACCE, with the Sarma formula-derived QTc (QTcSar) presenting the highest hazard ratio (OR = 1.025). ROC curve analysis identified QTcSar with a threshold of 446 ms as yielding the superior predictive capacity (AUC = 0.734), demonstrating a sensitivity of 60.5% and a specificity of 82.8%. DCA indicated positive net benefits for QTcSar at high-risk thresholds ranging from 0 to 0.66 and 0.71-0.96, with QTcBaz, prevalent in clinical settings, showing positive net benefits at thresholds extending to 0-0.99.

CONCLUSION

For perioperative AMI patients, QTcSar proves more advantageous in monitoring QTc intervals compared to alternative QT correction formulas, offering enhanced predictive prowess for subsequent MACCE incidents.

Provocation testing in congenital long QT syndrome: A practical guide

Congenital long QT syndrome (LQTS) is a hereditary cardiac channelopathy with an estimated prevalence of 1 in 2500. A prolonged resting QT interval corrected for heart rate (QTc interval) remains a key diagnostic component; however, the QTc value may be normal in up to 40% of patients with genotype-positive LQTS and borderline in a further 30%. Provocation of QTc prolongation and T-wave changes may be pivotal to unmasking the diagnosis and useful in predicting genotype. LQTS provocation testing involves assessment of repolarization during and after exercise, in response to changes in heart rate or autonomic tone, with patients with LQTS exhibiting a maladaptive repolarization response. We review the utility and strengths and limitations of 4 forms of provocation testing-stand-up test, exercise stress test, epinephrine challenge, and mental stress test-in diagnosing LQTS and provide some practical guidance for performing provocation testing. Ultimately, exercise testing, when feasible, is the most useful form of provocation testing when considering diagnostic sensitivity and specificity.

Pronounced QT Prolongation During General Anesthesia in a Child with Left Ventricular Noncompaction Cardiomyopathy: A Case Report

We report the case of an 8-year-old boy with left ventricular noncompaction cardiomyopathy (LVNC) and QT prolongation who experienced further prolongation of the QTc during general anesthesia for extraction of a maxillary mesiodens. Pronounced prolongation of the QTc was observed after induction of general anesthesia with thiamylal and during emergence. No notable fluctuations in blood pressure, heart rate, and estimated continuous cardiac output were observed. We considered it likely that the QT prolongation was triggered by thiamylal and increased sympathetic nervous system activity. During general anesthesia for children with LVNC and QT prolongation, it is necessary to monitor intraoperative hemodynamic fluctuations and prepare for the possible occurrence of arrhythmias.

Comparing the sensitivity of cross-over and parallel study designs for QTc assessment: An analysis based on a single large study of moxifloxacin in 48 nonhuman primates

The cardiovascular safety pharmacology (SP) study conducted to satisfy ICH S7A and S7B has commonly used a cross-over study design where each animal receives all treatments. In an increasing number of cases, cross-over designs are not possible and parallel studies have to be used. These can seldom be as large as 8 animals/treatment to match an n = 8 cross-over. Animals in parallel designs receive only one treatment. Parallel studies will have a different sensitivity to detect changes. This sensitivity is a critical question in using nonclinical QTc evaluations to support an integrated proarrhythmic risk assessment under the newly released ICH E14/S7B Q&As. The current analysis used a study large enough (n = 48) to be analyzed both as a parallel and as a cross-over design to directly compare the performance of the two experimental designs coupled to different statistical models, while all other study conduct aspects were the same. A total of 48 nonhuman primates (NHP) received 2 different treatments twice: vehicle, moxifloxacin (80 mg/kg), vehicle, moxifloxacin (80 mg/kg). Post-dose QTc interval data were recorded for 48 h for each treatment. Data were analyzed using 12 animals randomly selected for each treatment in a parallel design or as an n = 48 animal cross-over study. Different statistical models were used. The primary endpoint was the residual deviation (sigma) from the models applied to hourly time intervals. The sigma was used to determine the minimal detectable difference (MDD) for the study design-statistical model combination. Two statistical models were applicable to either study design. They gave similar sigma and resulting MDD values. In cross-over designs, the individual animal identification (ID) can be used in the statistical model. This enabled the smallest MDD value. Simple statistical models for analysis were identified: Treatment + Baseline for parallel designs and Treatment + ID for cross-over designs. The statistical sensitivity of NHP parallel study designs is reasonable (MDD for n = 6 of 12.7 ms), and in combination with testing exposures higher than likely to be necessary in man could be used in an integrated risk assessment. Where sensitivity of the NHP in vivo QTc assessment is critical, the cross-over design enabled a higher sensitivity (MDD 12.2 ms for n = 4; 8 ms for n = 8).

Association of systemic immune inflammation index and system inflammation response index with clinical risk of acute myocardial infarction

Background

Systemic immune inflammatory index (SII) and systemic inflammatory response index (SIRI) are combinations of non-specific inflammatory and adaptive immune response impairments associated with cardiovascular disease. Yet little analysis has been done on SII, SIRI and acute myocardial infarction (AMI) prognosis. The purpose of this study was to investigate the correlation of SII and SIRI with clinical risk factors such as GRACE, Gensini, and QTc after acute myocardial infarction.

Methods

This study enrolled 310 patients with AMI from February 1, 2018, to December 31, 2022, at our institution. Routine blood items calculated SII and SIRI. Two groups were divided according to whether MACE occurred: the MACE group (81 cases) and the NMACE group (229 cases); each group was divided into three groups according to the SII and SIRI tertiles. The relationship between SII, SIRI and MACE was analyzed using multifactorial logistic regression analysis after adjusting for confounders; ROC curves were plotted to examine the predictive value of SII and SIRI for MACE. The correlation between SII and SIRI and potential risk factors such as Gensini, QTc and GRACE was further analyzed.

Results

The study enrolled 310 patients, comprising 248 men (80%, mean age 60.73 ± 13.695 years) and 62 women (20%, mean age 69.79 ± 11.555 years). In the regression model completely adjusted for confounders, the risk of MACE was higher in AMI patients with SII > 11.00 [OR = 1.061,95% CI (1.018,1.105)] than in SII < 5.98; the risk of MACE was 115.3% higher in AMI patients with SIRI (1.72-3.68) [OR = 2.153, 95% CI (1.251, 3.705)] was 115.3% higher in AMI patients with SIRI < 1.72 and the risk of MACE was 25.1% higher in AMI patients with SIRI > 3.68 [OR = 1.251, 95% CI (1.123, 1.394)] than in AMI patients with SIRI < 1.72. In addition, SII, SIRI, and potential post-infarction risk factors (Gensini, QTc, and GRACE) were also associated.

Conclusion

SII and SIRI have been significantly associated with post-myocardial infarction MACE and the predictive potential clinically integrated risk factors in AMI patients, for which more attention should be paid to targeted anti-inflammatory therapy in AMI patients to further reduce the incidence of prognostic MACE in AMI patients.

Manual vs. automatic assessment of the QT-interval and corrected QT

AIMS

Sudden cardiac death (SCD) is challenging to predict. Electrocardiogram (ECG)-derived heart rate-corrected QT-interval (QTc) is used for SCD-risk assessment. QTc is preferably determined manually, but vendor-provided automatic results from ECG recorders are convenient. Agreement between manual and automatic assessments is unclear for populations with aberrant QTc. We aimed to systematically assess pairwise agreement of automatic and manual QT-intervals and QTc.

METHODS AND RESULTS

A multi-centre cohort enriching aberrant QTc comprised ECGs of healthy controls and long-QT syndrome (LQTS) patients. Manual QT-intervals and QTc were determined by the tangent and threshold methods and compared to automatically generated, vendor-provided values. We assessed agreement globally by intra-class correlation coefficients and pairwise by Bland-Altman analyses and 95% limits of agreement (LoA). Further, manual results were compared to a novel automatic QT-interval algorithm. ECGs of 1263 participants (720 LQTS patients; 543 controls) were available [median age 34 (inter-quartile range 35) years, 55% women]. Comparing cohort means, automatic and manual QT-intervals and QTc were similar. However, pairwise Bland-Altman-based agreement was highly discrepant. For QT-interval, LoAs spanned 95 (tangent) and 92 ms (threshold), respectively. For QTc, the spread was 108 and 105 ms, respectively. LQTS patients exhibited more pronounced differences. For automatic QTc results from 440-540 ms (tangent) and 430-530 ms (threshold), misassessment risk was highest. Novel automatic QT-interval algorithms may narrow this range.

CONCLUSION

Pairwise vendor-provided automatic and manual QT-interval and QTc results can be highly discrepant. Novel automatic algorithms may improve agreement. Within the above ranges, automatic QT-interval and QTc results require manual confirmation, particularly if T-wave morphology is challenging.

The effect of dapagliflozin therapy on ventricular repolarization parameters in electrocardiography in patients with diabetic cardiovascular disease

BACKGROUND

Dapagliflozin is an agent that has both antihyperglycemic effects and is significantly associated with a lower risk of cardiovascular events in patients with diabetes mellitus (DM). However, there is insufficient data and information about the effect of dapagliflozin on electrocardiographic (ECG) parameters.

AIM

The effects of dapagliflozin on ventricular repolarization parameters have not been fully elucidated yet. This study aimed to investigate whether dapagliflozin has a positive effect on ventricular repolarization heterogeneity parameters in patients with type 2 DM.

METHOD

We retrospectively enrolled 140 patients with a known diagnosis of type 2 DM who were newly prescribed dapagliflozin in addition to standard anti-diabetic therapy. The patients were divided into two groups according to whether they had cardiovascular disease (CVD). The effect of dapagliflozin treatment on ventricular repolarization parameters (frontal plane QRST angle, Tp-e interval, Tp-e/QTc, QTc, and QTc dispersion) was investigated, patient groups were compared before and after treatment.

RESULTS

Among 140 patients, 70 (50 %) had CVD and 70 (50 %) did not have CVD. Dapagliflozin treatment resulted in significant reductions in ventricular repolarization parameters over the study period in the CVD group with diabetes. Mean fQRST angle, Tp-e interval, Tp-e/QTc, QTc, and QTc dispersion were significantly lower than baseline values at 6-month follow-up visits in the CVD group (61.61 ± 9.22° vs 52.55 ± 8.31°, 74.45 ± 16.06 msec vs 63.27 ± 13.99 msec, 0.19 ± 0.03 vs 0.16 ± 0.03, 384.12 ± 47.93 msec vs 356.15 ± 43.31 mesc, 55.28 ± 5.50 msec vs 48.08 ± 6.48 msec for all pairwise comparisons p < 0.001).

CONCLUSION

Similar antihyperglycemic effects were found with dapagliflozin treatment in patients with and without CVD. However, significant reductions in ventricular repolarization parameters were observed only in patients with CVD.

Methadone Maintenance and QT-Interval: Prevalence and Risk Factors-Is It Effective to Switch Therapy to Levomethadone?

Methadone is a chiral synthetic opioid primarily used to treat heroin and prescription-opioid addiction: the (R)-enantiomer (Levomethadone) activates the µ-opioid receptor more potently than the (S)-enantiomer, which is a more potent blocker of the hERG potassium channels, resulting in QTc prolongation. The purpose of this retrospective study was to assess the effect of methadone on the QTc interval and to investigate the benefits of Levomethadone. The electrocardiograms of 165 patients taking methadone at various dosages and for different periods of time were examined: the QTc value was manually measured and then adjusted using Bazett's formula. Data analysis revealed a linear association between the dosage of methadone and QTc length; no correlation was found between the QTc value and gender, age, or duration of therapy. In total, 14% of the sample (23 patients) showed a prolongation of the QTc interval (>470 ms in males and >480 ms in females); 10 of the 23 patients with QTc elongation underwent a change of therapy from Methadone to Levomethadone-in 90% of these patients, a normalization in the QTc length was established. This study confirmed the role of methadone, specifically its dosage, in QTc prolongation and the efficiency of Levomethadone as an adequate therapeutic substitute in these circumstances. This study validates the importance of careful electrocardiographic monitoring in methadone-treated patients.

Diagnostic Accuracy of the Standing Test in Adults Suspected for Congenital Long-QT Syndrome

Background An elegant bedside provocation test has been shown to aid the diagnosis of long-QT syndrome (LQTS) in a retrospective cohort by evaluation of QT intervals and T-wave morphology changes resulting from the brief tachycardia provoked by standing. We aimed to prospectively determine the potential diagnostic value of the standing test for LQTS. Methods and Results In adults suspected for LQTS who had a standing test, the QT interval was assessed manually and automated. In addition, T-wave morphology changes were determined. A total of 167 controls and 131 genetically confirmed patients with LQTS were included. A prolonged heart rate-corrected QT interval (QTc) (men ≥430 ms, women ≥450 ms) at baseline before standing yielded a sensitivity of 61% (95% CI, 47-74) in men and 54% (95% CI, 42-66) in women, with a specificity of 90% (95% CI, 80-96) and 89% (95% CI, 81-95), respectively. In both men and women, QTc≥460 ms after standing increased sensitivity (89% [95% CI, 83-94]) but decreased specificity (49% [95% CI, 41-57]). Sensitivity further increased (P<0.01) when a prolonged baseline QTc was accompanied by a QTc≥460 ms after standing in both men (93% [95% CI, 84-98]) and women (90% [95% CI, 81-96]). However, the area under the curve did not improve. T-wave abnormalities after standing did not further increase the sensitivity or the area under the curve significantly. Conclusions Despite earlier retrospective studies, a baseline ECG and the standing test in a prospective evaluation displayed a different diagnostic profile for congenital LQTS but no unequivocal synergism or advantage. This suggests that there is markedly reduced penetrance and incomplete expression in genetically confirmed LQTS with retention of repolarization reserve in response to the brief tachycardia provoked by standing.

Clinical and electrocardiographic factors associated with adverse cardiovascular events in bupropion exposures

INTRODUCTION

Bupropion toxicity can cause cardiogenic shock, ventricular dysrhythmias, and death. Clinical and electrocardiographic factors associated with adverse cardiovascular events in bupropion toxicity have not been well-studied. This study aimed to identify factors associated with adverse cardiovascular events in adult patients with isolated bupropion exposures.

METHODS

This retrospective cohort study queried the National Poison Data System from 2019 through 2020. We included patients 20 years or older with acute or acute-on-chronic single-agent bupropion exposures evaluated in a healthcare facility. Exclusion criteria were confirmed non-exposure, withdrawal as a reason for exposure, lack of follow-up, documentation that exposure was probably not responsible for the effects, and missing data. The primary outcome was adverse cardiovascular events, defined as the presence of any of the following: vasopressor use, ventricular dysrhythmia, myocardial injury, or cardiac arrest. Independent variables were age, the intentionality of exposure, seizures, tachycardia, QRS widening, and QTc prolongation. Multivariable logistic regression was performed to test for independent associations between independent variables and adverse cardiovascular events.

RESULTS

Of 4,640 patients included in the final analysis (56.7% female, 56.5% suspected suicidal intent), 68 (1.47%) experienced an adverse cardiovascular event. Age (odds ratio 1.03; 95% confidence intervals 1.02-1.05), single seizure (odds ratio 9.18; 95% confidence intervals 4.24-19.9) and complicated seizures (odds ratio 38.9; 95% confidence intervals 19.3-78.1), QRS widening (odds ratio 3.01; 95% confidence intervals 1.62-5.59), and QTc prolongation (odds ratio 1.76; 95% confidence intervals 1.00-3.10) were independently associated with adverse cardiovascular events. No patients with unintentional exposure experienced adverse cardiovascular events, prohibiting intentionality from inclusion in the regression model. In the post hoc subgroup analysis of intentional exposures, age, single and complicated seizures, and QRS widening remained independently associated with adverse cardiovascular events.

CONCLUSIONS

Increasing age, seizures, QRS widening, and QTc prolongation were associated with adverse cardiovascular events in bupropion exposures. Adverse cardiovascular events did not occur in unintentional exposures. Further research is needed to develop screening tools and treatments for bupropion cardiotoxicity.

Abnormal blood lipid and electrocardiogram characteristics in common mental disorders

BACKGROUND

At present, there is not enough evidence to prove the relationship between blood lipid and electrocardiogram (ECG) abnormalities in common mental disorders (CMD). This study aimed to explore the relationship between them, to detect and prevent arrhythmia or sudden death.

METHODS

We collected 272 CMD patients (maintained a fixed drug dose pattern for 1 year or more), including 95 schizophrenias (SC), 90 bipolar disorders (BD) and 87 major depressive disorders (MDD), and 78 healthy controls (HC) from the Third People's Hospital of Foshan, China. We analyzed and compared their blood lipid and ECG indicators, to clarify the relationship between them.

RESULTS

350 participants were included. There were no significant differences in age, gender, total cholesterol (TC), low density lipoprotein (LDL) and QTc (p > 0.05) among subjects. And there were significant differences in body mass index (BMI), triglyceride (TG), high density lipoprotein (HDL), heart rate, PR interval and QRS width (p < 0.05). Person correlation analysis showed that QRS width was positively correlated with BMI and TG. And negatively correlated with HDL. Meanwhile, QTc was positively correlated with BMI. Multiple linear regional analysis further proved that TG (B = 3.849, p = 0.007) and LDL (B = 11.764, p = 0.018) were the risk factors, and HDL (B = -9.935, p = 0.025) was the protective factor for QRS width increase.

CONCLUSION

Long term medication of CMD patients should strengthen weight management, and conduct regular blood lipid and ECG examinations to achieve early detection and intervention in order to promote their health.

Corrected QT interval in electrocardiogram recordings in patients treated with calcium channel blockers

Introduction

One of the most popular tests of the heart is the electrocardiogram (ECG). The physical basis of this study has been known for over 200 years. However, the way an ECG is performed and the interpretation of the obtained results have undergone considerable evolution over time.

Aim

To analyze the ECG recordings regarding the QTc interval in patients taking calcium channel blockers.

Material and methods

The publicly available PhysioNet signals database was used to analyze the effect of selected drugs on the heart rhythm and QTc interval. To automate the QTc assessment, the database was processed in MATLAB. First, QTc was assessed using four formulas; then the results were compared in terms of methodology and medications taken.

Results

In the group of patients taking dihydropyridine blockers, the QTc interval assessed by the Bazett formula (mean: 478.87 ms; SD: 73.10) is longer than in patients taking non-dihydropyridine blockers (mean: 446.54 ms, SD: 88.07, p = 0.2123) and in patients not taking calcium channel blockers (mean: 436.33 ms, SD: 49.94, p = 0.0319). The same significant differences were obtained regardless of the QTc assessment method used. However, the QTc result obtained with the Bazett formula is significantly lower than in the case of using the other three formulas used for the presented analysis.

Conclusions

Automatic ECG analysis is possible; however, it should be used carefully, considering the possibility of obtaining incorrect results. Taking calcium channel blockers may affect the QTc interval. QTc results significantly depend on the formula based on which we evaluate this parameter.

Electrocardiographic QTc as a Surrogate Measure of Cardiac Risk in Children, Adolescents, and Young Adults With Eating Disorders

The study goal was to investigate electrocardiographic findings, including corrected QT interval (QTc), in patients aged 8 to 23 with eating disorders (EDs) at presentation, compared with an age-and sex-matched control population. We retrospectively reviewed 200 ED patients, and 200 controls. Blinded electrocardiograms (ECGs) were interpreted by an expert reader, and QT intervals corrected using the Bazett formula. Eating disorder patients were 89.5% female, with mean age 16.4 years and median percent median body mass index (BMI)-for-age (%mBMI)a of 91.1%. In ED patients, QTc was significantly shorter than controls (399.6 vs 415.0msec, P < .001). After adjusting for height, %mBMI, sex, magnesium level, and bradycardia, mean QTc duration in patients with anorexia nervosa-restricting subtype (AN-R) was significantly shorter than other ED patients (P = .010). Higher %mBMI was associated with shorter QTc duration (P = .041) after adjusting for height, magnesium, bradycardia, and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnosis. Within the ED group, no significant association was identified between QTc and medications, electrolytes, or inpatient status.

QTc Interval of Healthcare Workers from India: Baseline and Effect of Hydroxychloroquine Prophylaxis during the COVID-19 Pandemic

Background

The aim of this study was to access the incidence of prolonged QTc interval and changes, if any, among Indian healthcare workers (HCWs) taking hydroxychloroquine (HCQ) prophylaxis while managing coronavirus disease 2019 (COVID-19) cases.

Methods

At the beginning of the COVID-19 pandemic, as per the Indian Council of Medical Research (ICMR) policy, HCWs were advised to take HCQ as prophylaxis after getting an electrocardiogram (ECG) while being posted to look after COVID-19 patients. A follow-up ECG was repeated for those who took HCQ. The normal upper limit for QTc interval of 460 milliseconds (ms) for females and 450 ms for males was considered.

Results

A baseline ECG was analyzed for 250 HCWs with a median age of 35 (30-43) years. The median QTc was 410 (395-421) ms with the prevalence of prolonged QTc of 1.8% in females and 0% in males. A follow-up ECG after HCQ intake for 43 HCWs was further analyzed. They had a median age of 35 (31-39) years and took an average dose of HCQ of 2372 ± 839 mg. Pre- and post-HCQ chemoprophylaxis QTc interval (ms) was as follows: 408 (386-419) and 405 (387-417), with P = 0.434, respectively.

Conclusion

Among Indian HCWs, the prevalence of prolonged QTc is 1.8% and 0% in females and males, respectively. HCQ intake as chemoprophylaxis for COVID-19 did not affect their QTc interval.

Characterization of rheumatic heart disease from electrocardiogram recordings

Objective. Rheumatic Heart Disease (RHD) is one of the highly prevalent heart diseases in developing countries that can affect the pericardium, myocardium, or endocardium. Rheumatic endocarditis is a common RHD variant that gradually deteriorates the normal function of the heart valves. RHD can be diagnosed using standard echocardiography or listened to as a heart murmur using a stethoscope. The electrocardiogram (ECG), on the other hand, is critical in the study and identification of heart rhythms and abnormalities. The effectiveness of ECG to identify distinguishing signs of rheumatic heart problems, however, has not been adequately examined. This study addressed the possible use of ECG recordings for the characterization of problems of the heart in RHD patients.Approach. To this end, an extensive ECG dataset was collected from patients suffering from RHD (PwRHD), and healthy control subjects (HC). Bandpass filtering was used at the preprocessing stage. Each data was then standardized by removing its mean and dividing by its standard deviation. Delineation of the onsets and offsets of waves was performed using KIT-IBT open ECG MATLAB toolbox. PR interval, QRS duration, RR intervals, QT intervals, and QTc intervals were computed for each heartbeat. The median values of the temporal parameters were used to eliminate possible outliers due to missed ECG waves. The data were clustered in different age groups and sex. Another categorization was done based on the time duration since the first RHD diagnosis.Main results. In 47.2% of the cases, a PR elongation was observed, and in 26.4% of the cases, the QRS duration was elongated. QTc was elongated in 44.3% of the cases. It was also observed that 62.2% of the cases had bradycardia.Significance. The end product of this research can lead to new medical devices and services that can screen RHD based on ECG which could somehow assist in the detection and diagnosis of the disease in low-resource settings and alleviate the burden of the disease.

Comparison of validity of standard nonclinical group size selection versus standard clinical group sizes for nonhuman primate QTc prolongation evaluation

The number of animals used in a nonhuman primate (NHP) in vivo QTc assessment conducted as part of the safety pharmacology (SP) studies on a potential new drug is relatively small (4-8 subjects). The number is much smaller than the number of healthy volunteers in a conventional thorough QT (TQT) study (40-60 volunteers). How is it possible that such small studies could offer an equivalent sensitivity in an integrated nonclinical and clinical cardiac repolarization risk assessment? This study provided the opportunity to empirically demonstrate in a large number of NHPs the performance of a nonclinical evaluation at a similar size to a TQT study. By contrasting an analysis mimicking the sampling and aggregation of QTc interval data in a manner which is TQT-like with a more conventional SP-like analysis it was demonstrated that the SP-like analysis was more sensitive. In prospective power calculations 80% power at p = 0.05 can be achieved for a 5 ms QTc change with only n = 8 NHPs using the SP-like analysis and in a group of only 4 NHPs 80% power to detect 10 ms could be achieved. By contrast groups of 24 NHPs would be required to achieve 80% power to detect 5 ms using the TQT-like sampling and aggregation approach. Overall, this study has demonstrated that smaller safety pharmacology in vivo QTc assessments using all the available data in larger data aggregates can achieve sensitivity comparable to a human TQT study.

Association between pre-operative prolonged corrected QT interval and all-cause mortality after non-cardiac surgery

BACKGROUND

Prolonged corrected QT interval (QTc) has been linked to risk of arrhythmias and mortality in the general population. Pre-operative electrocardiography is often obtained for patient-and procedural cardiovascular risk assessment. The aim of this study was to investigate the association of pre-operative QTc and all-cause mortality in a non-cardiac surgical cohort.

METHODS

A retrospective study of all patients over 18 years undergoing non-cardiac surgery at Landspitali-the National University Hospital in Iceland between 2 January 2005 to 31 December 2015, with follow-up through 20 May 2016. Patients were separated into five categories according to their pre-operative QTc interval ≤ 379, 380-439 (reference group), 440-479, 480-519 and ≥520 ms. Primary outcome was long-term mortality and secondary outcome was 30-day mortality.

RESULTS

A total of 10,209 surgeries for 10,209 individuals were included. The median follow-up for mortality was 2691 days (interquartile range [IQR] 1620-3705 days). Patients with longer QTc interval had a higher comorbidity burden, were more likely to undergo emergency surgery and were often prescribed cardiac medications. After adjustment for confounding variables, the hazard ratio (HR) for long-term mortality compared with reference (QTc 380-439 ms) was 0.85 [CI: 0.66-1.09] for QTc ≤379, 1.08 [CI: 0.99-1.17] for QTc 440-479 ms, 1.26 [CI: 1.10-1.43] for QTc between 480 and 519 ms and 0.97 [CI: 0.78-1.21] for QTc ≥520 ms. When compared with reference, only patients with QTc interval between 480 and 519 ms had higher odds ratio for 30-day mortality as odds ratio for other groups were following; 1.12 [CI: 0.18-3.8] for ≤379 ms, 1.03 [CI: 0.70-1.51] for QTc 440-479 ms, 1.64 [CI: 1.02-2.60] for QTc 480-519 ms and 0.98 [0.44-2.06] for QTc ≥520 ms.

CONCLUSION

Pre-operative QTc between 480 and 519 ms is associated with both higher long-term and 30-day mortality after non-cardiac surgery. The results suggest that this could reflect an underlying cardiovascular risk.

Effect of Futibatinib on Cardiac Repolarization: Results of a Randomized, Controlled, Double-Blind, QT/QTc, Phase 1 Study in Healthy Subjects

Futibatinib, a fibroblast growth factor receptor (FGFR) 1-4 inhibitor, is being investigated for FGFR-aberrant tumors. A 4-period, crossover, phase 1 thorough QT/QTc study compared effects on Fridericia heart rate-corrected QT (QTcF) interval of single doses of futibatinib 20 and 80 mg (therapeutic and supratherapeutic doses, respectively), placebo, and moxifloxacin (positive control) in healthy subjects. The study objective was to assess the time-matched difference in change from baseline in QTcF (ddQTcF) between futibatinib and placebo. In addition, changes from baseline in QTcF and other electrocardiogram (ECG) parameters, pharmacokinetics, ECG morphology, and safety were assessed. Forty-eight subjects were randomized. ddQTcF upper limits of 2-sided 90%CIs remained <10 milliseconds (clinical threshold) for both futibatinib doses at all time points (range, 2.0-4.5 milliseconds). Assay sensitivity was demonstrated by lower limits of 2-sided 97.5%CIs of the dQTcF difference between moxifloxacin and placebo of >5 milliseconds. Futibatinib exposure increased in a dose-dependent manner, and no significant relationship was detected between plasma futibatinib concentration and ddQTcF. There were no significant effects on heart rate, other ECG parameters, or ECG morphology. No serious adverse events occurred. Futibatinib did not prolong QTcF or affect other cardiac measures at therapeutic or supratherapeutic doses.

Erratum: Genotype-specific ECG-based risk stratification approaches in patients with long-QT syndrome

[This corrects the article DOI: 10.3389/fcvm.2022.916036.].

Association of QT interval-prolonging drugs with clinical trial eligibility in patients with advanced cancer

Introduction

Drug-induced prolongation of the heart rate-corrected QT interval (QTc) is associated with increased risk for the potentially fatal arrhythmia torsades de pointes. Due to arrhythmia risk, clinical trials with cancer therapeutics often exclude patients based on thresholds for QTc prolongation. Our objective was to assess associations between prescriptions for QT-prolonging drugs and the odds of meeting cancer trial exclusionary QTc thresholds in a cohort of adults with advanced cancer.

Methods

Electronic health records were retrospectively reviewed for 271 patients seen at our institutional molecular solid tumor clinic. Collected data included demographics, QTc measurements, ventricular arrhythmia-related diagnoses, and all inpatient and outpatient prescriptions. Potential associations were assessed between demographic and clinical variables, including prescriptions for QT-prolonging drugs, and QTc measurements.

Results

Women had longer median QTc measurements than men (p = 0.030) and were prescribed more QT-prolonging drugs during the study (p = 0.010). In all patients, prescriptions for QT-prolonging drugs were associated with longer median and maximum QTc measurements at multiple assessed time points (i.e., for QT-prolonging drugs prescribed within 10, 30, 60, and 90 days of QTc measurements). Similarly, the number of QT-prolonging drugs prescribed was correlated with longer median and maximum QTc measurements at multiple time points. Common QTc-related exclusionary criteria were collected from a review of ClinicalTrials.gov for recent cancer clinical trials. Based on common exclusion criteria, prescriptions for QT-prolonging drugs increased the odds of trial exclusion.

Conclusion

This study demonstrates that prescriptions for QT-prolonging drugs were associated with longer QTc measurements and increased odds of being excluded from cancer clinical trials.

QTc interval diurnal variations in patients treated with psychotropic medications: implications for the evaluation of drug induced QTc changes

Psychotropic drugs such as antipsychotics may prolong the QTc interval, increasing the risk of torsades de pointes (TdP) and sudden cardiac death. To assess QTc prolongation by psychotropic drugs, an electrocardiogram (EKG) is usually recorded before and after starting treatment. Circadian variations in the QTc interval have been described but have not been adequately studied in patients taking psychotropic drugs. In psychiatric clinical practice, EKGs before and after treatment initiation are often compared, without considering the time of day at which the two EKGs are recorded. To determine whether there is a circadian change in the QTc interval in patients treated with psychotropic drugs, we evaluated the EKGs of a group of patients treated with psychotropic drugs (85% on antipsychotics) and the EKGs of a group of patients that were not treated with medications. In each group, we compared the EKGs recorded before 11:00 am with those recorded after 5:00 pm. The QTc value was significantly longer in the group treated with psychotropic drugs than in the group without drugs at both morning and evening evaluations (p ≤ 0.001). In each group, a statistically significant difference was found between the EKGs recorded before 11:00 a.m. and the EKGs recorded after 5:00 p.m. In patients treated with medications, the mean QTc in the morning was 453.3 ± 25.4 while the mean QTc in the afternoon was 428.4 ± 24.7 (p < 0.0001). In patients who were not receiving any medication, the morning mean QTc was 422.4 ± 22.6 while the mean afternoon QTc was 409.4 ± 19.6 (p = 0.002). These results suggest that a circadian variation in QTc is observed both in patients taking psychotropic drugs and in patients not taking medication. We conclude that any comparison of EKGs to test the effect on QTc of a medication, should be referred to EKGs recorded at the same time of day.

The assessment of cardiac risk in patients taking lamotrigine; a systematic review

OBJECTIVE

The Food and Drug Administration (FDA) warned about lamotrigine's arrhythmogenicity based on in vitro data. This systematic review investigates lamotrigine's effect on cardiac conduction and risk of sudden cardiac death (SCD) in individuals with and without cardiovascular disease.

METHODS

We searched Web of Science and PubMed from inception through August 2021. We included studies measuring electrocardiogram (ECG) changes, laboratory abnormalities, or SCD among patients taking lamotrigine. Studies examining sudden unexpected death in epilepsy were excluded for scope. Two reviewers assessed articles and extracted data. We used the Effective Public Healthcare Panacea Project tool to evaluate confidence in evidence.

RESULTS

Eight randomized controlled trials, 9 nonrandomized observational studies, and 24 case reports were identified, with >3054 total participants, >1606 of whom used lamotrigine. One randomized trial of older patients found an average QRS increase of 3.5 +/- 13.1 ms. Fifteen studies reported no changes in ECG parameters. Case reports documented QRS widening (13), Brugada syndrome (6), QTc prolongation (1) and SCD (2), though many ingested toxic quantities of lamotrigine and/or other medications.

CONCLUSIONS

Evidence is insufficient to support the breadth of the FDA warning concerning lamotrigine's cardiac risk. Lamotrigine at therapeutic doses may be associated with modest, non-dangerous QRS widening.

QT Ratio: A simple solution to individual QT correction

Preclinical risk assessment of drug-induced arrhythmias is critical for drug development and relies on heart rate corrected QT interval (QT) prolongation as a biomarker for arrhythmia risk. However, the methods used to correct QT vary in complexity and don't account for all changes in the QT-rate relationship. Thus, we developed the novel Ratio QT correction method which characterizes that relationship at each timepoint using the ratio between QT, adjusted for a species-specific constant, and rate (RR interval). This ratio represents the slope between the intercept and the datapoint being corrected, which is then used in a linear equation like individual methods. A unique correction coefficient for each datapoint avoids assuming static relationships. We hypothesize that the simple and dynamic nature of the Ratio method will provide more consistent rate correction and error reduction compared to Bazett's and individual regression methods. Comparisons were made using ECG data from non-human primates (NHPs) treated with dofetilide or moxifloxacin, separated into small groups (n = 4). The methods were compared based on corrected QT vs RR slopes, standard error, and minimal detectable difference (MDD) for each method. The Ratio method resulted in smaller corrected QT-rate relationship slopes than Bazett's, more closely matching those of individual methods. It produced similar or lower MDDs compared to individual and Bazett's correction, respectively, with more consistent reduction in standard error. This simple and effective method has the potential for easy translatability across species.

Early Alterations of QTc in Patients with COVID-19 Treated with Hydroxychloroquine or Chloroquine in Libreville, Gabon

The objective of this study was to analyze the effect of hydroxychloroquine or chloroquine associated with azithromycin on the QTc interval in Gabonese patients treated for COVID-19.

METHODS

This was an observational study conducted from April to June 2020, at the Libreville University Hospital Center in Gabon. Patients admitted for COVID-19 and treated with hydroxychloroquine or chloroquine, each combined with azithromycin were included. The QTc interval was measured upon admission and 48 h after starting treatment. The primary endpoint was QTc prolongation exceeding 60 ms and/or a QTc value exceeding 500 ms at 48 h.

RESULTS

Data from 224 patients, 102 (45.5%) who received hydroxychloroquine and 122 treated with chloroquine, were analyzed. The median baseline QTc was 396 (369-419) ms. After 48 h of treatment, 50 (22.3%) patients had a significant prolongation of QTc. This tended to be more frequent in patients treated with chloroquine (n = 33; 27.0%) than in those treated with hydroxychloroquine (n = 17; 16.7%) (p = 0.06). QTc prolongation exceeding 60 ms was found in 48 (21.3%) patients, while 11 patients had a (4.9%) QTc exceeding 60 ms at admission and exceeding 500 ms after 48 h.

CONCLUSION

Early QTc prolongation is frequent in COVID-19 patients treated with hydroxychloroquine or chloroquine in association with azithromycin.

Possible Lurasidone-Associated Dose-Dependent QTc Prolongation in First-Episode Psychosis

This case is one of the earliest to report on lurasidone-related QTc prolongation in a dose-dependent fashion in CAP population at therapeutic doses. Although these reports remain scarce, it behoves prescribers to be vigilant and mindful of these unusual but serious side effects especially in setting of cumulative risks.

QTc prolongation is associated with severe desaturations in stroke patients with sleep apnea

Background

Obstructive sleep apnea (OSA) is associated with vascular diseases from which stroke and sudden cardiac death are the most significant ones. It is known that disturbances of the autonomic nervous system and electrocardiographic changes are seen in patients with a previous cerebrovascular event. However, the pathophysiological cascade between breathing cessations, autonomic regulation, and cardiovascular events is not fully understood.

Methods

We aimed to investigate the acute effect of desaturation on repolarisation in OSA patients with a previous stroke. We retrospectively analysed heart-rate corrected QT (QTc) intervals before, within, and after 975 desaturations in OSA patients with a stroke history and at least moderate sleep apnea (apnea–hypopnea index ≥ 15 events/h, n = 18). For the control population (n = 18), QTc intervals related to 1070 desaturation were analysed. Desaturations were assigned to groups according to their length and duration. Groupwise comparisons and regression analyses were further executed to investigate the influence of desaturation features on repolarization.

Results

In the stroke population the QTc prolonged at least 11 ms during 27.1% of desaturations, and over 20 ms during 12.2% of desaturations. QTc was significantly prolonged during longer (> 30 s, p < 0.04) and deeper (> 7%, p < 0.03) desaturations. Less severe desaturations didn't influence QTc. In median, QTc prolonged 7.5 ms during > 45 s desaturations and 7.4 ms during > 9% deep desaturations. In the control population, QTc prolongation was observed but to a significantly lesser extent than in stroke patients. In addition, desaturation duration was found to be an independent predictor of QTc prolongation (β = 0.08, p < 0.001) among all study patients.

Conclusions

We demonstrated that longer (> 30 s) and deeper (> 7%) desaturations prolong QTc in patients with stroke history. A significant proportion of desaturations produced clinically relevant QTc prolongation. As it is known that a long QTc interval is associated with lethal arrhythmias, this finding might in part explain the pathophysiological sequelae of cardiovascular mortality in OSA patients with a history of stroke.

Effect of hyperglycaemia in combination with moxifloxacin on cardiac repolarization in male and female patients with type I diabetes

Background

Patients with Type 1 diabetes mellitus have been shown to be at a two to ten-fold higher risk of sudden cardiac death (SCD) (Svane et al., Curr Cardiol 2020; 22:112) than the general population, but the underlying mechanism is unclear. Hyperglycaemia is a recognised cause of QTc prolongation; a state patients with type 1 diabetes are more prone to, potentially increasing their risk of ventricular arrhythmia. Understanding the QTc prolongation effect of both hyperglycaemia and the concomitant additive risk of commonly prescribed QTc-prolonging drugs such as Moxifloxacin may help to elucidate the mechanism of sudden cardiac death in this cohort. This single-blinded, placebo-controlled study investigated the extent to which hyperglycaemia prolongs the QTc in controlled conditions, and the potential additive risk of QTc-prolonging medications.

Methods

21 patients with type 1 diabetes mellitus were enrolled to a placebo-controlled crossover study at a single clinical trials unit. Patients underwent thorough QTc assessment throughout the study. A ‘hyperglycaemic clamp’ of oral and intravenous glucose was administered with a target blood glucose of > 25 mM and maintained for 2 h on day 1 and day 3, alongside placebo on day 1 and moxifloxacin on day 3. Day 2 served as a control day between the two active treatment days.

Thorough QTc assessment was conducted at matched time points over 3 days, and regular blood sampling was undertaken at matched time intervals for glucose levels and moxifloxacin exposure.

Results

Concentration-effect modelling showed that acute hyperglycaemia prolonged the QTc interval in female and male volunteers with type 1 diabetes by a peak mean increase of 13 ms at 2 h. Peak mean QTc intervals after the administration of intravenous Moxifloxacin during the hyperglycaemic state were increased by a further 9 ms at 2 h, to 22 ms across the entire study population. Regression analysis suggested this additional increase was additive, not exponential.

Hyperglycaemia was associated with a significantly greater mean QTc-prolonging effect in females, but the mean peak increase with the addition of moxifloxacin was the same for males and females. This apparent sex difference was likely due to the exclusive use of basal insulin in the male patients, which provided a low level of exogenous insulin during the study assessments thereby mitigating the effects of hyperglycaemia on QTc. This effect was partially overcome by Moxifloxacin administration, suggesting both hyperglycaemia and moxifloxacin prolong QTc by different mechanisms, based on subinterval analysis.

Conclusions

Hyperglycaemia was found to be a significant cause of QTc prolongation and the additional effect of a QTc-prolonging positive control (moxifloxacin) was found to be additive. Given the high risk of sudden cardiac death in type 1 diabetes mellitus, extra caution should be exercised when prescribing any medication in this cohort for QTc effects, and further research needs to be undertaken to elucidate the exact mechanism underlying this finding and explore the potential prescribing risk in diabetes.

Trial Registration

NCT number: NCT01984827.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00392-022-02037-8.

Temporal Changes in Electrolytes, Acid-Base, QTc Duration, and Point-of-Care Ultrasound during Inpatient Hemodialysis Sessions

Background

Of the more than 550,000 patients receiving maintenance hemodialysis (HD) in the United States, each has an average of 1.6 admissions annually (>880,000 inpatient HD sessions). Little is known about the temporal changes in laboratory values, ECGs, and intravascular and extravascular volume during inpatient HD sessions.

Methods

In this prospective cohort study of hospitalized HD patients, we assessed intradialytic laboratory values (metabolic panels, blood gases, ionized calcium levels), ECGs, and sonographic measures of volume status.

Results

Among 30 participants undergoing HD (mean age 62 years; 53% men, 43% Black) laboratory values had the largest changes in the first hour of HD. There was no significant change in ionized calcium levels pre- to post-HD (change: -0.01±0.07, P=0.24); 12 of 30 and 17 of 30 patients had levels below the lower reference limit at the beginning and end of HD, respectively. The mean pH increased pre- to post-HD (change: 0.06±0.04, P<0.001); 21 of 30 had a pH above the upper reference limit post-HD. There was a trend toward longer median QTc duration from pre- to post-HD (change: 7.5 msec [-5 msec, 19 msec], P=0.07). The sum of B lines on lung ultrasound decreased from pre- to post-HD (median decrease: 3 [1, 7], P<0.01). The collapsibility index of the inferior vena cava increased pre- to post-HD (median increase: 4.8% [1.5%, 13.4%], P=0.01), whereas internal jugular vein diameter did not change (P=0.24).

Conclusions

Among hospitalized patients undergoing HD, we found dynamic changes in laboratory values, QTc duration, and volume status. Further research is required to assess whether HD prescriptions can be tailored to alter these variations to potentially improve patient outcomes.

Does the use of proton pump inhibitors in children affect ventricular repolarisation parameters?

Proton pump inhibitors are widely used agents in the treatment of dyspepsia, and their effects on ventricular repolarisation through ion channels are well-known. Our aim is to evaluate the change in ventricular repolarisation parameters on electrocardiogram before and after proton pump inhibitor treatment. This study included 69 patients who had symptoms such as burning stomach pain, bloating, nausea, and heartburn for at least 3 months. Electrolyte levels of the patients were measured before and after treatment, and 12-lead electrocardiograms were taken at the initial and 1st month follow-up visit. Heart rate, QT interval, corrected QT (QTc), QT dispersion (QTd), QTc dispersion (QTcd), Tp-e measurements, and Tp-e/QT ratio were calculated and compared. Thirty-nine of the patients were girls, 30 were boys, and the mean age was 13.16 ± 3.02 years. Electrolyte levels of the patients before and after treatment were within the normal range. There was no statistically significant difference in the QTc, the Tp-e duration, or the Tp-e/QT ratio of the patients before and after treatment. We did not find a significant prolongation in the QTc duration or any other ventricular repolarisation parameters after proton pump inhibitor treatment in children with dyspepsia. We did not observe ventricular arrhythmia in our patients during follow-up. However, different results might be obtained with a larger sample and a longer follow-up period. These patients may have an increased risk of developing ventricular arrhythmias. Therefore, precaution should be taken when using drugs that prolong the QT period, and follow-up with serial electrocardiograms should be planned.

Medium-Term Outcomes in COVID-19

COVID-19 causes severe illness that results in morbidity and mortality. Electrocardiographic features, including QT prolongation, have been associated with poor acute outcomes; data on the medium-term outcomes remain scarce. This study evaluated the 1-year outcomes of patients who survived the acute COVID-19 infection. Methods and Materials: Data of the 159 patients who survived the COVID-19 illness during the first wave (1 March 2020−18 May 2020) were collected. Patient demographics, laboratory findings and electrocardiography data were evaluated. Patients who subsequently died within 1-year of the index illness were compared to those who remained well. Results: Of the 159 patients who had survived the index illness, 28 (17.6%) subsequently perished within 1-year. In comparison to the patients that were alive after 1-year, the deceased were older (68 vs. 83 years, p < 0.01) and equally male (60.4% vs. 53.6%, p = 0.68), with a similar proportion of hypertension (59.5% vs. 57.1%, p = 0.68), diabetes (25.2% vs. 39.2%, p = 0.096) and ischaemic heart disease (11.5% vs. 7.1%, p = 0.54). The QTc interval for the alive and deceased patients shortened by a similar degree from the illness to post-COVID (−26 ± 33.5 vs. −20.6 ± 30.04 milliseconds, p = 0.5); the post-COVID R-R interval was longer in the alive patients compared to the deceased (818.9 ± 169.3 vs. 761.1 ± 61.2 ms, p = 0.02). A multivariate Cox regression analysis revealed that age (HR1.098 [1.045−1.153], p < 0.01), diabetes (HR3.972 [1.47−10.8], p < 0.01) and the post-COVID R-R interval (HR0.993 [0.989−0.996], p < 0.01) were associated with 1-year mortality. Conclusions: The COVID-19-associated mortality risk extends to the post-COVID period. The QTc does recover following the acute illness and is not associated with outcomes; the R-R interval is a predictor of 1-year mortality.

Multicenter Observational/Exploratory Study Addressed to the Evaluation of the Effectiveness and Safety of Pharmacological Therapy in Opioid-Dependent Patients in Maintenance Therapy in Southern Italy

A multicenter-observational study was performed to assess the effectiveness of rac-methadone, levomethadone, and buprenorphine in opioid-dependent patients in polytherapy in Southern Italy. The primary endpoint was the reduction of urinary positivity to the substances and the maintaining doses. Patients (N = 266, age = 44.80 ± 5.65, male = 79.70%, female = 20.30%) have been recruited. At recruitment, 75% of them were on treatment with rac-methadone, levomethadone, and buprenorphine/naloxone. The patients were grouped into three clusters. The levomethadone patients of Cluster A (N patients = 211), after 180 days, showed stability in urinary methadone positivity, with a marked decrease in heroin −53 ± 4%, cannabinol’s −48 ± 2%, and cocaine −37 ± 6% positivity, with no differences between treatments. A lower QTcF value of 426 ± 8.4 ms was recorded in the levomethadone patients (delta = −19 ms) vs. rac-methadone, at significantly lower doses of levomethadone (−34%, −50.2% in males) (p < 0.05). The Cluster B data were collected from 37 patients, with a high prevalence of comorbidity infections (HIV/HCV/HPV), monitored for 21 months during COVID-19. High doses of levomethadone (58.33 ± 31.58 mg/day) were needed to stabilize those that were negative for opioids and cannabinoids, in contrast to the rac-methadone and buprenorphine/naloxone patients that showed positive toxicology. Eighteen patients of the Cluster C in double diagnosis (major depressive 38.90%, bipolar 27.78%, and schizophrenia 16.67%) were stabilized with high doses of racemate 97.5 ± 8 mg/day, 51.8 ± 5 mg/day of levomethadone (−46.8% vs. rac-methadone; −71% in men), and 2.5 ± 1 mg/day of buprenorphine/naloxone. Three patients in remission were treated with tapering doses of levomethadone. Significantly reduced QTcF values were recorded with levomethadone (delta −32 ms vs. rac-methadone) in the bipolar patients, as well as the schizophrenia patients in remission (delta −45.19 ms vs. rac-methadone). Our patients were safely stabilized. Levomethadone, compared to the racemate, contributes to reducing the illicit use, especially of opioids and cannabinoids at significantly lower doses with cardiovascular safety, which, in bipolar patients, is clinically significant.

Monitoring prolongation of QT interval in patients with multidrug-resistant tuberculosis and non-tuberculous mycobacterium using mobile health device AliveCor

Multidrug resistant tuberculosis and non-tuberculous mycobacterium infections present challenges due to complex treatment regimens. Extended treatment regimes expose patients to higher risks of toxic side-effects. A high drug toxicity profile necessitates closer monitoring. One of the more challenging issues is QTc prolongation with non-injectable regimens. This study investigates the portable AliveCor device to record and measure the QTc on a 6-lead ECG. An automated QTc readout from 12-Lead ECG for each patient (n = 13) and mean QTc value calculated from each patients' respective AliveCor tracing were compared. The general trend suggests AliveCor underestimates QTc - 92% cases calculated the AliveCor QTc as lower than their corresponding 12-Lead QTc readout. The use of AliveCor could potentially be translated into current clinical practice with caution of percentage variation either side. This could facilitate the use of AliveCor as a promising and convenient screening tool before further evaluation by a 12-Lead ECG is required.

Association of abnormal electrocardiograph metrics with prolonged recovery time in incident hemodialysis patients

BACKGROUND

Patients receiving intermittent hemodialysis have variable times of recovery to feeling better after dialysis. QT prolongation, a precursor to clinical and subclinical cardiovascular events, may contribute to delayed recovery time. We hypothesized that abnormal electrocardiographic parameters indicating perturbations in ventricular action are associated with longer recovery times thus impacting a patient-centered quality of life.

METHODS

Among 242 incident in-center hemodialysis participants from the Predictors of Arrhythmic and Cardiovascular Risk in End Stage Renal Disease (PACE) study, corrected QT interval (QTc), QRST angle and heart rate variance were measured on non-dialysis days using a standard 5-min electrocardiograph recording. Left ventricular hypertrophy (LVH) was defined using the Cornell voltage product. Recovery time was ascertained during a phone interview with a standardized validated questionnaire. Associations between QTc, QRST angle, heart rate variance, and LVH and natural log-transformed recovery time were examined using linear regression adjusted for participant characteristics and electrolytes.

RESULTS

Mean age was 55 (standard deviation 13) years, 55% were male, 72% were African American. Longer QTc interval was associated with increased recovery time (per 10 ms increase in QTc, recovery time increased by 6.2%; 95% confidence interval: 0.0-10.5). QRST angle, heart rate, heart rate variability and LVH were not significantly associated with recovery time.

CONCLUSION

Longer QTc intervals are associated with longer recovery time independent of serum electrolytes. This supports a relationship between a patient's underlying arrhythmic status and time to recovery after hemodialysis. Future studies will determine if maneuvers to reduce QTc improves recovery time and quality of life of patients on hemodialysis.

A genetic-based population PK/PD modeling of methadone in Chinese opiate dependence patients

PURPOSE

The full potential of methadone maintenance treatment (MMT) is often limited by the large inter-individual variability in both pharmacokinetics (PK) and pharmacodynamics (PD), and by the risk of torsade de pointes, a severe adverse effect caused by QTc prolongation. The current study aims to quantitate the contribution of genetic polymorphisms and other variables in PK/PD variability, and their contribution to the QTc interval prolongation in Chinese MMT patients.

METHODS

Population PK models were developed to fit (R)- and (S)-methadone PK data. Hierarchical models were tested to characterize the PK profile, the concentration-QTc relationship, and concentration-urinalysis illicit drug testing relationship, with demographics and genetic variants being included as covariates. Simulation based on the developed PK/PD models was performed to assess the effect of methadone dose and genetic variants on QTc interval prolongation.

RESULTS

The PK data were best-fit by a one-compartment, first-order absorption model. Clearance of (R)- and (S)-methadone was both affected by the weighted activity score derived from genetic variants. A linear model was used to describe both the methadone concentration-urinalysis illicit drug testing relationship and the methadone concentration-QTc relationship. Concentration of (R)- and (S)-methadone exhibits a comparable effect on QTc prolongation. Simulation showed that the percentage of QTc higher than 450 ms was almost doubled in the lowest clearance group as compared the highest when methadone dose was greater than 120 mg.

CONCLUSIONS

The large variability in PK/PD profiles can be partially explained by the genetic variants in an extent different from other population, which confirmed the necessity to conduct such a study in the specific Chinese patients.

QT Prolongation in Critically Ill Patients With SARS-CoV-2 Infection

BACKGROUND

Several reports linked the use of repurposed drugs such as hydroxychloroquine (HCQ), azithromycin, lopinavir/ritonavir, and favipiravir with QT interval prolongation in patients with SARS-CoV2 infection. Little is known about the risk factors for QT interval prolongation in this population. We sought to describe the prevalence and identify the main risk factors associated with clinically significant corrected QT (QTc) prolongation in this population.

METHODS

We conducted a retrospective analysis of critically ill patients who were admitted to our intensive care unit (ICU), had at least one electrocardiogram performed during their ICU stay, and tested positive for SARs-CoV-2. Clinically significant QTc interval prolongation was defined as QTc >500 milliseconds (ms).

RESULTS

Out of the 111 critically ill patients with SARS-CoV-2 infection, QTc was significantly prolonged in 47 cases (42.3%). Patients with a clinically significant QTc prolongation had significantly higher proportions of history of cardiac diseases/surgery (22 [46.8%] vs. 10 [15.6%], P < .001), hypokalemia (10 [21.3] vs. 5 [7.8%], P = .04), and male gender (95% vs. 82.8%, P = .036) than patients with QTc ≤500 ms, respectively. A total of 46 patients (41.4%) received HCQ, 28 (25.2%) received lopinavir/ritonavir, and 5 (4.5%) received azithromycin. Multivariate logistic regression analysis showed that a history of cardiac disease was the only independent factor associated with clinically significant QTc prolongation (P = .004 for the likelihood-ratio test).

CONCLUSION

The prevalence of clinically significant QTc prolongation in critically ill patients with SARS-CoV-2 infection was high and independent of drugs used. Larger prospective observational studies are warranted to elucidate independent risk factors associated with clinically significant QTc prolongation in this study population.

Comparison of the effect of citalopram, bupropion, sertraline, and tricyclic antidepressants on QTc: A cross-sectional study

BACKGROUND

Some data suggests that citalopram has more risk of corrected QT interval (QTc) prolongation than other selective serotonin reuptake inhibitors. Consequently the U.S. Food and Drug Administration distributed a safety warning limiting the maximum dose for citalopram. There is also a suggestion that bupropion may decrease QTc in patients on drugs that increase QTc. The goals of this cross-sectional study were to examine (1) effects on QTc of citalopram compared to sertraline, bupropion, and tricyclic antidepressants; (2) dose dependent effects of citalopram; and (3) effects of bupropion on citalopram-mediated changes in QTc.

METHODS

Records of subjects who received an EKG while taking one of the specified antidepressants were reviewed to collect demographic information, antidepressant history, and information about other confounders. Linear regression was used to examine the relationship between QTc and antidepressants.

RESULTS

487 subjects provided 798 EKG records. The sample was 95% male with an average age of 61 years. No differences were found in QTc between citalopram and other antidepressants. No dose relationship was detected between citalopram and QTc. Bupropion did not affect the relationship between citalopram and QTc (coefficient = -3.4; 95%CI = -14.2, 7.5; p = 0.54).

LIMITATIONS

Observational study designs are prone to biases from retrospective data collection. Some data subsets had small numbers of subjects.

CONCLUSIONS

No effect of citalopram on QTc was found at therapeutic doses. Neither was there evidence of a "QTc-sparing" effect of bupropion. The risk of adverse cardiovascular effects from citalopram at doses of 60 mg per day or less appears minimal.

Case Report: High doses of Zolpidem and QT interval lengthening: Is there a relationship? A case series

Zolpidem is indicated in cases of severe insomnia in adults and, as for BDZs, its assumption should be limited to short periods under close medical supervision. Since several drugs cause corrected QT interval (QTc) elongation, the authors investigated whether high daily doses of Zolpidem could cause QTc elongation. The study was conducted in the Addiction Medicine Unit of the G.B. Rossi University Hospital in Verona. The data were collected from hospitalizations carried out between January 2015 and February 2020 and refer to a total of 74 patients, 38 males and 36 females, who were treated for detoxification from high doses of Zolpidem with the "Verona Detox Approach With Flumazenil." One patient out of 74 had QTc elongation (479 ms). The patient was male and took a daily dose of 50 mg of Zolpidem; he did not take concomitant therapies that could cause QTc lengthening. He had no electrolyte alterations, no contemporary or previous intake of barbiturates, heroin, cocaine, THC, alcohol, NMDA or nicotine which could cause an elongation of the QTc interval. The present study highlights the low risk of QTc elongation due to high dosages of Zolpidem; however, if, on one hand, we can affirm that Zolpidem is a safe drug, on the other, the widespread use of high dosages of this drug for prolonged periods of time is problematic and worrying.

Estimation of cardiac QTc intervals in people prescribed antipsychotics: a comparison of correction factors

BACKGROUND

A prolonged electrocardiogram (ECG) QT interval is associated with cardiac events and increased mortality. Antipsychotics can prolong the QT interval. The QT interval requires correction (QTc) for heart rate using a formula or QT-nomogram. The QT and QTc can be calculated automatically by the ECG machine or manually; however, machine-measured QT(c) intervals may be inaccurate.

OBJECTIVE

We aimed to investigate the mean QTc and proportion of prolonged QTc intervals in people taking antipsychotic medicines.

METHODS

We conducted an observational retrospective chart review and data analysis of all consecutive patients taking antipsychotics, with an ECG record, admitted to the psychiatric unit of a large tertiary hospital in Brisbane, Australia, between 1 January 2017 and 30 January 2019. We investigated the mean QTc of people taking antipsychotics to determine differences using (a) machine versus manual QT interval measurement and (b) QTc correction formulae (Bazett, Fridericia, Framingham, Hodges and Rautaharju) and the QT-nomogram. We also determined the number of people with a prolonged QTc using different methods and compared rates of prolonged QTc with antipsychotic monotherapy and polypharmacy.

RESULTS

Of 920 included people, the mean (±SD) machine-measured, Bazett-corrected QT interval (recorded from the ECG) was 435 ms (±27), significantly longer (p < 0.001) than the mean manually measured corrected QT intervals with Fridericia 394 ms (±24), Framingham 395 ms (±22), Hodges 398 ms (±22) and Rautaharju 400 ms (±24) formulae. There were significantly more people with a prolonged QTc using machine-measured QT and the Bazett formula (12.0%, 110/920) when compared with manually measured QT and the Fridericia formula (2.2%, 20/920) or QT-nomogram (0.7%, 6/920). Rates of QTc prolongation did not differ between people taking antipsychotic polypharmacy compared with monotherapy.

CONCLUSION

Machine-measured QTc using the Bazett formula overestimates the QTc interval length and number of people with a prolonged QTc, compared with other formulae and the QT-nomogram. We recommend manually measuring the QT and correcting with the Fridericia formula or QT-nomogram prior to modifying antipsychotic therapies.

A new predictor for indicating clinical severity and prognosis in COVID-19 patients: Frontal QRS-T angle

Objective

COVID-19; It spread rapidly around the world and led to a global pandemic. Indicators of poor prognosis are important in the treatment and follow-up of COVID-19 patients and have always been a matter of interest to researchers. The aim of this study was to investigate the relationship between frontal QRS-T angle values and clinical severity and prognosis in COVID-19 patients.

Methods

This prospective case-control study was conducted with 130 COVID-19 patients whose diagnosis was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and 100 healthy controls. The CURB-65 score was used as the clinical severity score.

Results

A total of 130 patients and 100 healthy controls were included in the study. When the patient and control groups were compared a significant difference was found between QT (378.07 ± 33.75 vs. 368.63 ± 19.65, p < 0.001), QTc (410.79 ± 28.19 vs. 403.68 ± 11.70, p < 0.001), QRS time (95.04 ± 21.67 vs. 91.42 ± 11.08, p < 0.001) and frontal QRS-T angle (36.57 ± 22.86 vs. 22.72 ± 14.08, p < 0.001). According to clinical severity scoring, QT (370.27 ± 25.20 vs. 387.75 ± 40.19, p = 0.003), QTc (402.18 ± 19.92 vs. 421.48 ± 33.08, p < 0.001), frontal QRS-T angle (32.25 ± 18.79 vs. 41.94 ± 26.27), p = 0.0.16) parameters were found to be significantly different. Age (odds ratio [OR], 1.201; 95% confidence interval [CI], 1.111–1.298; p < 0.001) and frontal QRS-T angle ([OR], 1.045; 95% [CI], 1.015–1.075; p = 0.003) values were found to be an independent predictor for the severity of the disease. Frontal QRS-T angle ([OR], 1.101; 95% [CI], 1.030–1.176; p = 0.004), and CRP ([OR], 1.029; 95% [CI], 1.007–1.051; p = 0.01) parameters were found to be independent predictors for the mortality of the disease. As a mortality indicator; for the frontal QRS-T angle of ≥44.5°, specificity and sensitivity were 93.8% and 84.2%, respectively.

Conclusion

Frontal QRS-T angle can be used as a reproducible, convenient, inexpensive, new and powerful predictor in determining the clinical severity and prognosis of COVID-19 patients.