QT interval: how to measure it and what is "normal"

A smartphone application for semi-automated QT interval analysis based on a snapshot of an electrocardiogram trace displayed on a patient monitor

We developed a smartphone application (SMART-QT application) that can semi-automatically measure QT and QTc intervals based on a snapshot of the electrocardiogram (ECG) trace and the heart rate displayed on a patient monitor. In this study, we aimed to validate the SMART-QT application. In this prospective single-center method comparison study, we measured QT and QTc intervals with the SMART-QT application (QTAPP and QTcAPP; test method) and simultaneously manually measured QT and QTc intervals from a 12-lead ECG (QTREF and QTcREF; reference method) in 57 adult volunteers and patients who had sinus rhythm and no acute or chronic cardiac comorbidities. To investigate the agreement between QTAPP and QTREF and between QTcAPP and QTcREF, we performed Bland-Altman analyses and calculated the mean of the differences, the standard deviation, and the 95%-limits of agreement (95%-LOA). We defined clinically acceptable agreement as maximum mean of the differences ± standard deviation of 20 ± 20 ms. The mean of the differences between QTAPP and QTREF was 14 ± 20 ms (95%-LOA -26 to 54 ms). The mean of the differences between QTcAPP and QTcREF was 13 ± 15 ms (95%-LOA -16 to 42 ms). The agreement between QTAPP and QTREF and between QTcAPP and QTcREF was clinically acceptable in adult volunteers and patients without cardiac comorbidities.

Prevalence and prognostic relevance of electrocardiographic abnormalities among patients with ANCA-associated vasculitis

OBJECTIVES

Current guidelines provide limited evidence for cardiovascular screening in ANCA-associated vasculitis (AAV). This study aimed to investigate the prevalence of ECG abnormalities and associations between no, minor or major ECG abnormalities with cardiovascular mortality in AAV patients compared with matched controls.

METHODS

Using a risk-set matched cohort design, patients diagnosed with granulomatosis with polyangiitis or microscopic polyangiitis with digital ECGs were identified from Danish registers from 2000 to 2021. Patients were matched 1:3 to controls without AAV on age, sex and year of ECG measurement. Associated hazards of cardiovascular mortality according to ECG abnormalities were assessed in Cox regression models adjusted for age, sex and comorbidities, with subsequent computation of 5-year risk of cardiovascular mortality standardized to the age- and sex-distribution of the sample.

RESULTS

A total of 1431 AAV patients were included (median age: 69 years, 52.3% male). Median follow-up was 4.8 years. AAV was associated with a higher prevalence of left ventricular hypertrophy (17.5% vs 12.5%), ST-T deviations (10.1% vs 7.1%), atrial fibrillation (9.6% vs 7.5%) and QTc prolongation (5.9% vs 3.6%). Only AAV patients with major ECG abnormalities demonstrated a significantly elevated risk of cardiovascular mortality [HR 1.99 (1.49-2.65)] compared with controls. This corresponded to a 5-year risk of cardiovascular mortality of 19.14% (16-22%) vs 9.41% (8-11%).

CONCLUSION

Patients with AAV demonstrated a higher prevalence of major ECG abnormalities than controls. Notably, major ECG abnormalities were associated with a significantly increased risk of cardiovascular mortality. These results advocate for the inclusion of ECG assessment into routine clinical care for AAV patients.

The Association Between Antidepressant Treatment and Heart Rate Deceleration Capacity in Patients With Mood disorders-A Potential New Predictor of Sudden Cardiac Death

Purpose

Patients with mood disorders treated with antidepressants are at high risk of sudden cardiac death, and QT interval prolongation has been as an indicator of sudden cardiac death, however there is no clarity. Recently, a decreased heart rate deceleration capacity (DC) has been regarded as an accurate predictor of cardiac mortality. We attempted to reevaluate the risk of sudden cardiac death associated with antidepressant use assessed via DC.

Patients and Methods

We investigated the correlation of the DC of 107 patients with major depressive disorder (MDD) and bipolar disorder (BD), diagnosed by the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, with prescribed doses of antidepressants or other psychotropic drugs via linear regression analysis. We then compared the DC of 68 age- and sex-matched healthy controls with that of 68 MDD patients.

Results

DC was negatively correlated with both tricyclic antidepressant (TCAs) (PRC = -3.62, 95% CI= -5.69--1,55, p<0.001) and non-tricyclic antidepressant (non-TCAs) use (PRC = -0.69, 95% CI= -1.34--0.042, p<0.05) in a dose-dependent manner. Additionally, we found that MDD patients taking antidepressants had significantly lower DC compared to healthy controls (5.32 vs 7.60ms, p<0.001).

Conclusion

The use of TCAs would influence the decline in DC, and even the use of non-TCAs may influence the decline in DC when multiple medications are used. Evaluating DC may improve the predictive accuracy of sudden cardiac death in patients with mood disorders taking antidepressants.

Electrocardiographic Early Changes After Abdominoplasty

INTRODUCTION

Abdominoplasty aims to reduce the abdominal excess tissue and tighten the abdominal wall. The tightening of the abdominal wall has structural and habitual consequences on the body, which might have an early effect on electrocardiography (ECG) of the patients through volumetric and pressure changes in thoracic and abdominal cavities. ECG serves as a diagnostic tool for assessing cardiac electrical conductions in routine clinical practice. In this study, we aimed to examine whether abdominoplasty has any discernible effect on early ECG results, with the goal of assessing potential cardiological benefits for the patients undergoing this procedure by comparing pre- and early postoperative ECGs.

METHOD

Study population included 49 patients who had abdominoplasty. ECG records before the procedure and 12-24 h after the surgery were analyzed retrospectively. Patients had no known cardiac diseases and did not have any diagnosed arrhythmia.

RESULTS

The mean age of the study population was 37.1 ± 8.5. The mean body mass index of the study population was 26.4. The mean weight of total removed abdominal skin tissue was 1057 grams. There were significant changes in ECG of the patients postoperatively. Heart rate was increased, and significant change was found in QRS axis (p < 0.001) and T wave axis (p < 0.001). Atrial conduction parameters such as PR duration (p  < 0.001), Pmax duration (p  =  0.001) and P-wave dispersion (p = 0.003) were significantly changed postoperatively. Ventricular conduction parameters such as QRS duration (p = 0.029), QT interval (p   < 0.001), QTc (p  < 0.001), TPe duration (p < 0.001), TPe / QT (p < 0.001) and TPe / QTc (p < 0.001) ratios were found significantly changed.

CONCLUSION

Abdominoplasty changes the intra-abdominal pressure in the first 24 h after the surgery, which may impact cardiac conduction. The understanding and recognition of possible early ECG changes is crucial during postoperative follow-up of the patients who undergo abdominoplasty surgery.

LEVEL OF EVIDENCE I

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The association between insulin resistance and QT interval: A systematic review and Meta-Analysis

BACKGROUND

Insulin resistance (IR) is a major health concern associated with various diseases, and prolonged QT interval can potentially lead to life-threatening arrhythmias and death. There are conflicting views on the relationship between IR and QT interval. This meta-analysis aims to comprehensively investigate the association between IR and QT interval.

METHODS

An extensive search in databases PubMed, Scopus, Cochrane Library, Embase, and Web of Science up to October 2024 was conducted. Cohort studies which reported means and standard deviations for the QTc interval across the case and control groups with and without insulin resistance based on HOMA-IR were eligible for inclusion. Research with partial or inaccessible primary data, those involving participants with pre-existing cardiac conditions, and those with ambiguous results were excluded. The evaluation of study quality utilized the Newcastle-Ottawa Scale. A random-effects model was applied for the meta-analysis, and Egger's test was used to assess publication bias. GRADEproGDT was used to evaluate the certainty of the evidence.

RESULTS

Five studies, encompassing 603 participants, met the inclusion criteria. A significant positive association was observed between IR and QT interval (Weighted Mean Difference [WMD] = 12.38, 95% Confidence Interval [CI]: 5.51, 19.25). All included studies demonstrated high methodological quality. Assessment for publication bias revealed no significant findings (p-value for Egger's test = 0.39). The quality of evidence for the main outcome was moderate. Subgroup analyses revealed a significant link between IR and QT interval in studies from Turkey and India, with samples over fifty, and involving adults.

CONCLUSIONS

This meta-analysis highlights that IR is linked to an elevated risk of QT prolongation. Early identification of IR is crucial to mitigate the risk of QT prolongation and subsequent arrhythmias, thus emphasizing the importance of early intervention to prevent adverse cardiac outcomes and sudden cardiac death. Caution is needed when interpreting our results due to study heterogeneity, certainty of evidence, and sensitivity analysis findings. More rigorous research on this subject is required.

Comparison of clinicodemographic characteristics in patients with selective serotonin reuptake inhibitors poisoning: A cross-sectional study

Background

Our objective of this study was to evaluate patients of Selective Serotonin Reuptake Inhibitors (SSRIs) overdose and compare the toxicological effects of citalopram overdose with other SSRIs in adult poisoning cases.

Methods

This cross-sectional study focused on acute, known-type SSRI ingestions. Demographic and toxicological data were collected on the patients. The outcomes analyzed were length of hospital stay, coma, seizures, electrocardiographic abnormalities, abnormal heart examination, and the presence of serotonin syndrome.

Results

There were a total of 199 cases, with 165 (82.9%) being women. The majority of cases (n = 76, 38.2%) were attributed to citalopram, followed by sertraline (n = 67, 33.7%), fluoxetine (n = 33, 16.6%), fluvoxamine (n = 10, 5%), escitalopram (n = 6, 3%), paroxetine (n = 1, 0.5%), and mixed (n = 6, 3%). The most common symptoms were nausea and vomiting (n = 96, 48.2%). Most patients (58.3%) were conscious, with only 7 patients (3.5%) experiencing seizures. Among those with seizures, six patients had taken citalopram, with 50% of them ingesting 400 mg of citalopram. Tachycardia was observed in 62 (31.2%) patients, while no QT interval prolongation, PR interval changes, or arrhythmias were reported. Serotonin toxicity was noted in only 6 patients (3%), with 4 of them being poisoned with citalopram. The incidence of seizures with citalopram was significantly higher than with other SSRIs (odds ratio (OR) = 10.457; 1.6-2.88, P = 0.008), while nausea and vomiting were significantly more common in poisoning cases involving other SSRIs (OR = 0.51; 0.2-0.9, P = 0.02). There were no reported deaths.

Conclusion

Ingesting SSRIs results in minimal toxicity. However, seizures are more likely to occur with citalopram compared to other SSRIs.

An Evaluation of Whether Routine QTc Interval Screening Is Necessary Prior to Starting ADHD Medications: Experience from a Large Retrospective Study

BACKGROUND/OBJECTIVES

Routine screening electrocardiograms (ECGs) prior to starting medications for attention-deficit/hyperactivity disorder (ADHD) remain controversial. This real-world study assessed corrected QT (QTc) interval data from pediatric patients who had a baseline ECG performed prior to initiating treatment with ADHD medications and ≥6 months of clinical follow-up.

METHODS

A retrospective chart review of children aged 2-18 years diagnosed with ADHD with/without autism spectrum disorder (ASD) at child neurology clinics in Jordan (June 2019 and June 2021) was performed, and children were prescribed with ADHD medications to manage symptoms. Patients had ≥6 months of follow-up and no known cardiac disease/family history. A baseline ECG and regular clinical exams were performed for each child.

RESULTS

Of 458 patients with baseline ECGs, 362 met the study inclusion criteria. Overall, 286 (79.0%) patients were diagnosed with ASD/comorbid ADHD and 76 (21.0%) with ADHD alone; 61 (16.9%) were prescribed atomoxetine, 38 (10.5%) methylphenidate, 134 (37.0%) risperidone, and 129 (35.6%) aripiprazole. The patients' mean ± SD age was 6.4 ± 3.5 years, and most were male (n = 268, 74.0%). The mean baseline QTc interval was 400 ± 22 ms (median, 400 ms); one patient had a QTc interval >460 ms and was excluded from initiating treatment with any ADHD medications. During the ≥6-month follow-up, none of the patients had any signs or symptoms of adverse cardiac effects.

CONCLUSIONS

Routine screening ECGs prior to treatment with ADHD medications may not be necessary in healthy children with no family history of cardiac disease. However, further studies are needed to evaluate the long-term effects of ADHD medications in low-risk pediatric patients.

Sex-Specific Changes in Cardiac Function and Electrophysiology During Progression of Adenine-Induced Chronic Kidney Disease in Mice

Chronic kidney disease (CKD) and cardiovascular disease (CVD) often co-exist, with notable sex-dependent differences in manifestation and progression despite both sexes sharing similar risk factors. Identifying sex-specific diagnostic markers in CKD-induced CVD could elucidate why the development and progression of these diseases differ by sex. Adult, C57BL/6J male and female mice were fed a high-adenine diet for 12 weeks to induce CKD, while control mice were given a normal diet. Adenine-treated males showed more severe CKD than females. Cardiac physiology was evaluated using electrocardiogram (ECG) and echocardiogram markers. Only adenine-treated male mice showed markers of left ventricular (LV) hypertrophy. Adenine males showed markers of LV systolic and diastolic dysfunction throughout regimen duration, worsening as the disease progressed. Adenine males had prolonged QTc interval compared to adenine females and control males. We identified a new ECG marker, Speak-J duration, which increased with disease progression and appeared earlier in adenine-treated males than in females. We identified sex-dependent differences in cardiac structure, function, and electrophysiology in a CKD-induced CVD mouse model, with adenine-treated males displaying markers of LV hypertrophy, dysfunction, and electrophysiological changes. This study demonstrates the feasibility of using this model to investigate sex-dependent cardiac differences resulting from CKD.

QTc Interval: A frequently unrecognized electrocardiographic interval

The QT interval, an electrocardiographic temporal representation of the ventricular depolarization and repolarization, is an integral parameter that must be carefully evaluated to gather critical information regarding electrical instability that may cause malignant ventricular dysrhythmias or sudden cardiac death. The QT interval is affected by several inheritable and acquired factors, such as genetic mutations, electrolyte disturbances, and medication interactions. We strongly believe that prompt and accurate recognition of any QT interval abnormalities is critical in many clinical settings. This concise review article highlights the importance of accurate measurement of the QT interval, enhances understanding of the most prevalent factors yielding abnormalities within the QT interval and the prognostic value of the QT interval, as well as provides several key practical reminders for healthcare professionals to strengthen our clinical practice.

Intraoperative QTc interval interpretation: Effects of anaesthesia, ECG, correction formulae, sex, and current limits: A Prospective Observational Study

BACKGROUND

Severe QT interval prolongation requires monitoring QTc intervals during anaesthesia with recommended therapeutic interventions at a threshold of 500 ms. The need for 12-lead ECG and lack of standardisation limit such monitoring. We determined whether automated continuous intraoperative QTc monitoring with 5-lead ECG measures QTc intervals comparable to 12-lead ECG and whether the interpretation of QTc intervals depends on the correction formulae and the patient's sex. We compared intraoperative QTc times to QTc times from resting ECGs of a population from the same region, to substantiate the hypothesis that patients under general anaesthesia may need specific treatment thresholds.

METHODS

In this prospective observational study, intraoperative QT/QTc intervals were automatically recorded using 12 and 5-lead ECG in 100 patients (44% males). QTc values were analysed for sex and formula-specific aspects after correction for heart rate according to Bazett, Fridericia, Hodges, Framingham, Charbit and QTcRAS, and compared to a regional community-based cohort. The level of significance was set to α = 0.05.

RESULTS

QT interval duration was not significantly different between 12-lead and 5-lead ECG (difference - 0.09 ms ± 8.5 ms, p = 0.793). The QTc interval duration significantly differed between the correction formulae (p < 0.001) and between sexes (p < 0.001). Mean intraoperative QTc duration was higher than in resting ECGs from a large community-based population with the same regional background (438 vs. 417 ms). The incidence of prolonged values >500 ms significantly depended on the correction formula (p < 0.001) and was up to tenfold higher in women versus men.

CONCLUSION

Intraoperative QTc interval measurement using a 5-lead ECG is valid. Correction formulae and gender influence the intraoperative QTc interval duration and the incidence of pathologically prolonged values according to current limits. The consideration and definition of sex-specific normal limits for QTc times under general anaesthesia, therefore, warrant further investigation.

Diagnostic cost-effectiveness of a two-stage cardiovascular evaluation program in young-adolescent athletes. Role of echocardiography

BACKGROUND

Sports medical examinations are a tool to detect potentially life-threatening situations during physical activity, but their usefulness and protocols in young athletes remain controversial. The aim was to describe the diagnostic performance of a 2-step ECG and echocardiogram screening model in a large sample of healthy young-adolescent athletes (aged 11-16 years), evaluating its cost-effectiveness for cardiovascular disease (CVD) detection.

METHODS

Cross-sectional study of 2617 individuals (81 % male, mean age 15 years), over 20 federated sports (La Rioja-Spain). A cardiological examination included family and personal history, physical examination, ECG, and transthoracic echocardiogram. The previous ECG, conducted at 11-13 years old, was reviewed in 1589 individuals (60 %). ECGs were interpreted according to 2017 international criteria. The prevalence of structural cardiac disease (CD) was investigated, and the diagnostic performance of both tests and the cost of screening was evaluated.

RESULTS

CVD was diagnosed in 63 athletes (2.4 %) and 16 (0.6 %) with pathology related to sudden cardiac death (SCD). In 3 cases (0.11 %), cessation of sporting activity was indicated, and in 2 cases (0.07 %) treatment for congenital CD was indicated. ECG alterations were infrequent (2.5 %). Eighty percent of the structural CD diagnosed by echocardiogram had a normal ECG. The cost per CVD detected was €3,080, and for CVD associated with SCD, it was €12,323.

CONCLUSIONS

Our study shows the diagnostic cost-effectiveness of a two-step cardiac screening protocol, including ECG, and highlights the role of echocardiography in young adolescent athletes, which could be implemented at a low and reasonable cost.

QTc Interval Prolongation as an Adverse Event of Azole Antifungal Drugs: Case Report and Literature Review

QTc prolongation and torsade de pointes (TdP) are significant adverse events linked to azole antifungals. Reports on QTc interval prolongation caused by these agents are limited. In this study, we report a case of a 77-year-old male with cardiovascular disease who experienced QTc prolongation and subsequent TdP while being treated with fluconazole for Candida albicans-induced knee arthritis. Additionally, a literature review was conducted on cases where QTc prolongation and TdP were triggered as adverse events of azole antifungal drugs. The case study detailed the patient's experience, whereas the literature review analyzed cases from May 1997 to February 2023, focusing on patient demographics, underlying diseases, antifungal regimens, concurrent medications, QTc changes, and outcomes. The review identified 16 cases, mainly in younger individuals (median age of 29) and women (75%). Fluconazole (63%) and voriconazole (37%) were the most common agents. Concurrent medications were present in 75% of cases, and TdP occurred in 81%. Management typically involved discontinuing or switching antifungals and correcting electrolytes, with all patients surviving. Risk assessment and concurrent medication review are essential before starting azole therapy. High-risk patients require careful electrocardiogram monitoring to prevent arrhythmias. Remote monitoring may enhance safety for patients with implanted devices. Further studies are needed to understand risk factors and management strategies.

Exploring the multiple effects of nifedipine and captopril administration in spontaneously hypertensive rats through pharmacokinetic-pharmacodynamic analyses

This study assessed the pharmacokinetics (PKs) and pharmacodynamics (PDs) of two antihypertensive drugs, nifedipine and captopril, by exploring their main (blood pressure [BP]) and secondary effects (heart rate [HR] and QT interval [QT]) in spontaneously hypertensive rats. This study aimed to assess the relationship between PKs and PDs. Using these PD parameters, BP, HR, and QT during coadministration were estimated. The coadministration of nifedipine and captopril resulted in an increase in nifedipine's total body clearance (CLtot) and a reduction in its mean residence time (MRT) with an increase in the terminal elimination half-life (t1/2) and volume of distribution at steady state (Vdss) of captopril. However, no significant PK interactions were observed. During monotherapy, BP reduced rapidly following nifedipine infusion. Subsequently, despite the increase in nifedipine plasma concentration, BP recovered, likely because of homeostasis. Similar results were observed with coadministration. Subsequently, BP demonstrated a sustained reduction that was greater than or equal to the additive effect estimated from each PK. Captopril exhibited a minimal effect on HR, except for a transient increase observed immediately after starting infusion, consistent with observations during coadministration. Subsequently, the HR reduction was nearly equal to that calculated from the nifedipine PK. QT prolongation was more rapid with captopril than with nifedipine. Although QT prolongation during the initial 60 min of coadministration was approximately the sum of both effects, the recovery period to baseline QT was faster than that in the simulation.

From genes to clinical management: A comprehensive review of long QT syndrome pathogenesis and treatment

Background

Long QT syndrome (LQTS) is a rare cardiac disorder characterized by prolonged ventricular repolarization and increased risk of ventricular arrhythmias. This review summarizes current knowledge of LQTS pathogenesis and treatment strategies.

Objectives

The purpose of this study was to provide an in-depth understanding of LQTS genetic and molecular mechanisms, discuss clinical presentation and diagnosis, evaluate treatment options, and highlight future research directions.

Methods

A systematic search of PubMed, Embase, and Cochrane Library databases was conducted to identify relevant studies published up to April 2024.

Results

LQTS involves mutations in ion channel-related genes encoding cardiac ion channels, regulatory proteins, and other associated factors, leading to altered cellular electrophysiology. Acquired causes can also contribute. Diagnosis relies on clinical history, electrocardiographic findings, and genetic testing. Treatment strategies include lifestyle modifications, β-blockers, potassium channel openers, device therapy, and surgical interventions.

Conclusion

Advances in understanding LQTS have improved diagnosis and personalized treatment approaches. Challenges remain in risk stratification and management of certain patient subgroups. Future research should focus on developing novel pharmacological agents, refining device technologies, and conducting large-scale clinical trials. Increased awareness and education are crucial for early detection and appropriate management of LQTS.

Postextrasystolic repolarization changes of ventricular premature beats correlate with structural heart disease and suggest prognostic implications

Ventricular premature beats (VPBs) can potentially lead to life-threatening arrhythmias, especially in patients with structural heart disease (SHD). However, identifying dangerous VPBs has always been a topic and challenge in clinical research. This study aimed to evaluate the relationship of postextrasystolic repolarization changes of VPBs with SHD and its possible additional prognostic value. 125 cases of frequent VPBs with SHD and 156 cases without SHD were included. VPBs were stratified selected from 24 h Holter recording according to the scale of heart rate. Average QTDV (difference value of QT interval between the first beat follow VPB with beats preceding VPB) and max QTDV were significantly longer in SHD group than that in the non-SHD group. For identifying patients with SHD, the best cutoff value were 19 ms for average QTDV (AUC = 0.931) and 29 ms for max QTDV (AUC = 0.910) respectively. For Tu morphology analysis, PT2 (postextrasystolic T wave amplitude change ≥2 mV), reversed T wave, and Pu (postextrasystolic u wave) change were all highly specific, but low sensitive as identification of SHD. Compared with average QTDV < 19 ms patients, average QTDV ≥ 19 ms patients had significantly larger left heart size and wores left cardiac function. The presence of non-persistent ventricular tachycardia runs was higher in average QTDV ≥ 19 ms group and positive Pu change group than that in control groups. The findings indicated that postextrasystolic repolarization changes of VPBs correlated with SHD and suggested potential value in prognosis asssessment.

A mild phenotype associated with KCNQ1 p.V205M mediated long QT syndrome in First Nations children of Northern British Columbia: effect of additional variants and considerations for management

Introduction

Congenital Long QT Syndrome (LQTS) is common in a First Nations community in Northern British Columbia due to the founder variant KCNQ1 p.V205M. Although well characterized molecularly and clinically in adults, no data have been previously reported on the pediatric population. The phenotype in adults has been shown to be modified by a splice site variant in KCNQ1 (p.L353L). The CPT1A p.P479L metabolic variant, also common in Northern Indigenous populations, is associated with hypoglycemia and infant death. Since hypoglycemia can affect the corrected QT interval (QTc) and may confer risk for seizures (also associated with LQTS), we sought to determine the effect of all three variants on the LQTS phenotype in children within our First Nations cohort.

Methods

As part of a larger study assessing those with LQTS and their relatives in a Northern BC First Nation, we assessed those entering the study from birth to age 18 years. We compared the corrected peak QTc and potential cardiac events (syncope/seizures) of 186 children from birth to 18 years, with and without the KCNQ1 (p.V205M and p.L353L) and CPT1A variants, alone and in combination. Linear and logistic regression and student t-tests were applied as appropriate.

Results

Only the KCNQ1 p.V205M variant conferred a significant increase in peak QTc 23.8 ms (p < 0.001) above baseline, with females increased by 30.1 ms (p < 0.001) and males by 18.9 ms (p < 0.01). There was no evidence of interaction effects with the other two variants studied. Although the p.V205M variant was not significantly associated with syncope/seizures, the odds of having a seizure/syncope were significantly increased for those homozygous for CPT1A p.P479L compared to homozygous wild type (Odds Ratio [OR]3.0 [95% confidence interval (CI) 1.2-7.7]; p = 0.019).

Conclusion

While the KCNQ1 p.V205M variant prolongs the peak QTc, especially in females, the CPT1A p.P479L variant is more strongly associated with loss of consciousness events. These findings suggest that effect of the KCNQ1 p.V205M variant is mild in this cohort, which may have implications for standard management. Our findings also suggest the CPT1A p.P479L variant is a risk factor for seizures and possibly syncope, which may mimic a long QT phenotype.

Dental pulp stem cells ameliorate D-galactose-induced cardiac ageing in rats

BACKGROUND

Ageing is a key risk factor for cardiovascular disease and is linked to several alterations in cardiac structure and function, including left ventricular hypertrophy and increased cardiomyocyte volume, as well as a decline in the number of cardiomyocytes and ventricular dysfunction, emphasizing the pathological impacts of cardiomyocyte ageing. Dental pulp stem cells (DPSCs) are promising as a cellular therapeutic source due to their minimally invasive surgical approach and remarkable proliferative ability.

AIM

This study is the first to investigate the outcomes of the systemic transplantation of DPSCs in a D-galactose (D-gal)-induced rat model of cardiac ageing. Methods. Thirty 9-week-old Sprague-Dawley male rats were randomly assigned into three groups: control, ageing (D-gal), and transplanted groups (D-gal + DPSCs). D-gal (300 mg/kg/day) was administered intraperitoneally daily for 8 weeks. The rats in the transplantation group were intravenously injected with DPSCs at a dose of 1 × 106 once every 2 weeks.

RESULTS

The transplanted cells migrated to the heart, differentiated into cardiomyocytes, improved cardiac function, upregulated Sirt1 expression, exerted antioxidative effects, modulated connexin-43 expression, attenuated cardiac histopathological alterations, and had anti-senescent and anti-apoptotic effects.

CONCLUSION

Our results reveal the beneficial effects of DPSC transplantation in a cardiac ageing rat model, suggesting their potential as a viable cell therapy for ageing hearts.

The Relationship between Frontal QRS-T Angle and Vitamin D Deficiency

Background and Objectives: A deficiency in serum 25-hydroxyvitamin D levels is associated with a number of cardiovascular situations, such as high blood pressure, heart failure, atherosclerotic heart disease, and peripheral artery disease. The frontal QRS-T angle has recently been proposed as a marker of ventricular repolarization. A wider frontal QRS-T angle has been positively correlated with adverse cardiac events. The objective of our study was to examine the association between serum 25-hydroxyvitamin D level and the frontal QRS-T angle. Materials and Methods: A total of 173 consecutive patients aged 18-60 years undergoing routine cardiology check-up evaluation, and not receiving concurrent vitamin D treatment were included in the study. Patients were classified in three groups, depending on their vitamin D levels, and categorized as follows: Group 1-deficient (<20 ng/mL), Group 2-insufficient (20-29 ng/mL), or Group 3-optimal (≥30 ng/mL). The frontal QRS-T angle was determined using the automated reports generated by the electrocardiography machine. Results: The average age of participants was 45.8 (±12.2) years, and 55.5% of participants were female (p < 0.001). Individuals with low vitamin D concentrations exhibited a wider frontal QRS-T angle. It was determined that vitamin D level is an independent predictive factor for the frontal QRS-T angle. Conclusions: As the levels of 25-hydroxyvitamin D decrease, repolarization time assessed by frontal QRS-T angle is widened. Our findings indicate that lower concentrations of vitamin D may increase the susceptibility to ventricular arrhythmia.

QTNet: Predicting Drug-Induced QT Prolongation With Artificial Intelligence-Enabled Electrocardiograms

BACKGROUND

Prediction of drug-induced long QT syndrome (diLQTS) is of critical importance given its association with torsades de pointes. There is no reliable method for the outpatient prediction of diLQTS.

OBJECTIVES

This study sought to evaluate the use of a convolutional neural network (CNN) applied to electrocardiograms (ECGs) to predict diLQTS in an outpatient population.

METHODS

We identified all adult outpatients newly prescribed a QT-prolonging medication between January 1, 2003, and March 31, 2022, who had a 12-lead sinus ECG in the preceding 6 months. Using risk factor data and the ECG signal as inputs, the CNN QTNet was implemented in TensorFlow to predict diLQTS.

RESULTS

Models were evaluated in a held-out test dataset of 44,386 patients (57% female) with a median age of 62 years. Compared with 3 other models relying on risk factors or ECG signal or baseline QTc alone, QTNet achieved the best (P < 0.001) performance with a mean area under the curve of 0.802 (95% CI: 0.786-0.818). In a survival analysis, QTNet also had the highest inverse probability of censorship-weighted area under the receiver-operating characteristic curve at day 2 (0.875; 95% CI: 0.848-0.904) and up to 6 months. In a subgroup analysis, QTNet performed best among males and patients ≤50 years or with baseline QTc <450 ms. In an external validation cohort of solely suburban outpatient practices, QTNet similarly maintained the highest predictive performance.

CONCLUSIONS

An ECG-based CNN can accurately predict diLQTS in the outpatient setting while maintaining its predictive performance over time. In the outpatient setting, our model could identify higher-risk individuals who would benefit from closer monitoring.

Use of different anticholinergic scales and their correlation with anticholinergic symptom burden in a cohort of people living with HIV

OBJECTIVES

How to detect the clinical impact of anticholinergic (AC) burden in people with HIV (PWH) remains poorly investigated. We cross-sectionally described the prevalence and type of AC signs/symptoms and the screening accuracy of three AC scales in detecting their presence in a modern cohort of PWH.

METHODS

We calculated AC Burden Scale (ABS), AC Risk Score (ARS) and AC Drug Score (ADS) in 721 adult PWH and recorded the presence of AC signs/symptoms over the previous 3 months. High AC risk was defined by ABS score ≥2, and ARS or ADS score ≥3. Comparisons among the scale were based on Cohen's inter-rater agreement, and their screening accuracy was assessed by receiver operating characteristics (ROC) curves and performance measures.

RESULTS

We enrolled 721 PWH, of whom 72.0% of participants were male; the median age was 53 years, and 164 participants (22.7%) were on at least one AC drug. Among these, 28.6% experienced at least one AC sign/symptom. Agreement in AC risk classification was substantial only between ARS and ADS (k = 0.6). Lower and higher risk of AC signs/symptoms was associated with dual regimens [adjusted OR (aOR) = 0.12 versus three-drug regimens, P = 0.002] and increasing number of AC drugs (aOR = 12.91, P < 0.001). Depression and COPD were also associated with higher risk of AC signs/symptoms in analysis unadjusted for number of AC drugs. ABS and ADS showed the best area under the ROC curve (AUROC) of 0.85 (0.78-0.92) and 0.84 (0.75-0.92; P < 0.001 for both). However, at the cut-off used for the general population, the sensitivity of all three scales was very low (34.0%, 46.8% and 46.8%).

CONCLUSIONS

Up to one-fourth of participants in our cohort were exposed to at least one AC drug, and among them AC signs/symptoms affected more than one-fourth. Both polypharmacy (as number of antiretrovirals and of co-medications with AC properties) and to a lesser extent specific comorbidities shaped the risk of developing AC signs/symptoms. Sensitive screenings for AC risk in PWH should prefer ABS or ADS based on lower cut-offs than those suggested for the general population.

High-dose benzodiazepine use and QTc interval prolongation, a latent class analysis study

Benzodiazepine (BDZ) addiction is a widespread and multifaceted phenomenon. For many patients, especially females, the concomitant use of other drugs also increases their risk of QTc prolongation, possibly leading to complications such as seizures and even sudden death. However, the relationship between BDZ use and QTc prolongation is currently unclear. The present study aims to examine patterns of polysubstance use among a sample of Italian adults with BDZ dependence in relation with their QTc prolongation risk. We used Latent Class Analysis (LCA) on data collected from 251 inpatients of the Addiction Medicine Unit in Verona to group patients into three classes according to their substance use and their QTc prolongation risk. Results showed no significant relationship between QTc prolongation and BDZ use in any of the classes considered. We conclude that BDZs, even if used long-term and at high dosages, can be considered safe in terms of cardiovascular complications for patients.

QT interval and short-term outcome in acute heart failure

OBJECTIVE

To investigate the association of corrected QT (QTc) interval duration and short-term outcomes in patients with acute heart failure (AHF).

METHODS

We analyzed AHF patients enrolled in 11 Spanish emergency departments (ED) for whom an ECG with QTc measurement was available. Patients with pace-maker rhythm were excluded. Primary outcome was 30-day all-cause mortality and secondary outcomes were need of hospitalization, in-hospital mortality and prolonged hospitalization (> 7 days). Association between QTc and outcomes was explored by restricted cubic spline (RCS) curves. Results were expressed as odds ratios (OR) and 95%CI adjusted by patients baseline and decompensation characteristics, using a QTc = 450 ms as reference.

RESULTS

Of 1800 patients meeting entry criteria (median age 84 years (IQR = 77-89), 56% female), their median QTc was 453 ms (IQR = 422-483). The 30-day mortality was 9.7%, while need of hospitalization, in-hospital mortality and prolonged hospitalization were 77.8%, 9.0% and 50.0%, respectively. RCS curves found longer QTc was associated with 30-day mortality if > 561 ms, OR = 1.86 (1.00-3.45), and increased up to OR = 10.5 (2.25-49.1), for QTc = 674 ms. A similar pattern was observed for in-hospital mortality; OR = 2.64 (1.04-6.69), for QTc = 588 ms, and increasing up to OR = 8.02 (1.30-49.3), for QTc = 674 ms. Conversely, the need of hospitalization had a U-shaped relationship: being increased in patients with shorter QTc [OR = 1.45 (1.00-2.09) for QTc = 381 ms, OR = 5.88 (1.25-27.6) for the shortest QTc of 200 ms], and also increasing for prolonged QTc [OR = 1.06 (1.00-1.13), for QTc = 459 ms, and reaching OR = 2.15 (1.00-4.62) for QTc = 588 ms]. QTc was not associated with prolonged hospitalization.

CONCLUSION

In ED AHF patients, initial QTc provides independent short-term prognostic information, with increasing QTc associated with increasing mortality, while both, shortened and prolonged QTc are associated with need of hospitalization.

Congenital Long QT Syndrome: A Review of Genetic and Pathophysiologic Etiologies, Phenotypic Subtypes, and Clinical Management

Congenital Long QT Syndrome (CLQTS) is the most common inherited arrhythmia. The QT interval, which marks the duration of ventricular depolarization and repolarization in the myocardium, can be prolonged due to mutations in genes coding for the ion channel proteins that govern the cardiac action potential. The lengthening of the QT interval can lead to a wide range of clinical symptoms, including seizures, torsades de pointes, and fatal arrhythmias. There is a growing body of evidence that has revealed the genetic mutations responsible for the pathophysiology of CLQTS, and this has led to hypotheses regarding unique triggers and clinical features associated with specific gene mutations. Epidemiologic evidence has revealed a 1-year mortality rate of approximately 20% in untreated CLQTS patients, and a <1% of 1-year mortality rate in treated patients, underscoring the importance of timely diagnosis and effective clinical management. There are many phenotypic syndromes that constitute CLQTS, including but not limited to, Jervell and Lange-Nielsen syndrome, Romano and Ward syndrome, Andersen-Tawil syndrome, and Timothy syndrome. In this review, we aim to (1) summarize the genetic, epidemiologic, and pathophysiological basis of CLQTS and (2) outline the unique features of the phenotypic subtypes and their clinical management.

Electrocardiographic findings in pediatric versus young-adolescent athletes: A comparative analysis using general international criteria

BACKGROUND

The inclusion of electrocardiogram (ECG) in medical examinations for sports practice serves as a valuable tool for identifying potential life-threatening conditions during physical exercise. However, its applicability in young individuals remains a subject of controversy, primarily due to relatively high rates of false positives and the associated costs of further investigations. Furthermore, the validation of International Criteria for athletes below 12 years of age in optimizing pre-participation screening for young athletes is yet to be established. In light of these considerations, this study aims to describe the prevalence of ECG findings in a sample of children and young-adolescent athletes aged 11-16 years, employing refined Seattle interpretation criteria. Additionally, we seek to compare these findings based on age group and sex.

METHODS

This was a retrospective and observational study of 3747 athletes 11-16 year-olds. Evaluation included interviewer-administered questionnaires for relevant history, physical examination and resting 12 - lead ECG for each participant. The primary outcome measure was abnormal ECG findings according to the International Recommendations for Electrocardiographic Interpretation in Athletes.

RESULTS

Among the evaluated population of pediatric and young adolescent athletes (77.5% boys; >99% Caucasian), the vast majority exhibited normal electrocardiogram (ECG) results, with adaptive findings related to sports participation being more frequent among young adolescents and males. The presence of significant ECG abnormalities in young-adolescent athletes was uncommon (2.05%; 1.92% children and 2.32% young-adolescent) and required additional examinations. 0.27% of the total population were diagnosed with a previously unknown cardiac pathology only through the ECG.

CONCLUSIONS

This study provides valuable insights into the prevalence of normal, borderline, and abnormal electrocardiogram (ECG) findings in a large population of pediatric and young-adolescent athletes. These findings serve as guidance in detecting potentially serious cardiac alterations within this specific group, considering variations based on age and sex. The study confirms that ECG screening is a useful tool for identifying cardiac abnormalities in pediatric and young-adolescent athletes, even though the prevalence of significant findings in this population is relatively low. Furthermore, our findings support the utilization of the refined Seattle criteria as a sensitive and specific technique for screening pediatric and young-adolescent athletes, further enhancing the accuracy of ECG-based evaluations.

Association of electrocardiographic and echocardiographic variables with neurological outcomes after ischemic Stroke

Background

Cardiac dysfunction is often seen following neurological injury. Data regarding cardiac involvement after ischemic stroke is sparse. We investigated the association of electrocardiographic (ECG) and echocardiographic variables with neurological outcomes after an acute ischemic stroke.

Methods

We retrospectively collected baseline characteristics, stroke location, National Institute of Health Stroke Scale (NIHSS) at the time of admission, acute reperfusion treatment, ECG parameters, and echocardiographic data on 174 patients admitted with acute ischemic stroke. Outcomes of the stroke were based on cerebral performance category (CPC) with a CPC score of 1-2 indicating a good outcome and a CPC score of 3-5 indicating a poor outcome.

Results

Older age (75.31 ± 11.89 vs. 65.16 ± 15.87, p < 0.001, OR = 1.04, 95 % CI 1.01-1.07), higher heart rate (80.63 ± 18.69 vs. 74.45 ± 17.17 bpm, p = 0.024, OR = 1.02, 95 % CI 1.00-1.05) longer QTc interval (461.69 ± 39.94 vs. 450.75 ± 35.24, p = 0.024, OR = 1.01, 95 % CI 0.99-1.02), NIHSS score (60.9 % vs. 17.8 %, p < 0.001, OR = 14.90, 95 % CI 3.83-69.5), and thrombolysis (15 % vs. 5 %, p = 0.049, OR = 0.55, 95 % CI 0.10-2.55) were associated with poor neurological outcomes. However, when adjusted for age and NIHSS, heart rate and QTc were no longer statistically significant. None of the other ECG and echocardiographic variables were associated neurological outcomes.

Conclusions

Elevated heart rate and longer QTc intervals may potentially predict poor neurological outcomes. Further studies are needed for validation and possible integration of these variables in outcome predicting models.

Possible Delay in Symptomatology of a Methadone Overdose in a Patient Ingesting an Energy Drink and Dextroamphetamine/Amphetamine

Introduction: Methadone is a mu-opioid agonist with a delayed time to peak concentration that requires an extended period of monitoring following an overdose. Available data suggests that the combination of psychostimulants with methadone may augment antinociception and tolerance to opioids. Case Report: A 26-year-old male (83.9 kg) presented to the ED approximately 1 hour after unintentionally ingesting 200-250 mg of liquid methadone and an energy drink, along with 20 mg of dextroamphetamine/amphetamine prior to the event. Vital signs were: blood pressure (BP), 143/91 mmHg; heart rate (HR), 74; respirations (RR), 16; oxygen saturation 95% on room air. His urine drug screen was positive for amphetamines and methadone. Patient was monitored for 4 hours with no change in status and was discharged home. Approximately 26 hours later patient was found cyanotic and apneic. Patient was given 2 mg of naloxone and awoke with normal mental status. On presentation the patient's vital signs were: BP, 114/70 mmHg; HR, 114; RR 16; oxygen saturation 94% on 3 liters nasal cannula. During his ED stay, he required 2 doses of naloxone secondary to oxygen desaturation and was admitted to the hospital. His repeat urine drug screen was positive for amphetamines and methadone. The patient was discharged the following day. Discussion: This case illustrates an unintentional methadone overdose combined with the intentional ingestion of an energy drink and dextroamphetamine/amphetamine that possibly masked the toxicity for over 24 hrs. Monitoring parameters for methadone overdoses may need re-evaluation in the setting of the co-ingestion of a stimulant.

Atrial fibrillation and QT corrected. What is the best formula to use?

BACKGROUND

QT interval varies with the heart rate (HR), so a correction in QT calculation is needed (QTc). Atrial fibrillation (AF) is associated with elevated HR and beat-to-beat variation.

AIM

To find best correlation between QTc in atrial fibrillation (AF) versus restored sinus rhytm (SR) after electrical cardioversion (ECV) (primary end point) and to determine which correction formula and method are the best to determine QTc in AF (secondary end point).

METHODS

During a 3-month period, we considered patients who underwent 12-lead ECG recording and received an AF diagnosis with indication for ECV. Exclusion criteria were as follows: QRS duration >120 ms, therapy with QT-prolonging drugs, a rate control strategy and a nonelectrical cardioversion. The QT interval was corrected using Bazzett's, Framingham, Fridericia and Hodges formulas during the last ECG during AF and the first one immediately after ECV. QTc mean was calculated as mQTc (average of 10 QTc calculated beat per beat) and as QTcM (QTc calculated from the average of 10 raw QT and RR for each beat).

RESULTS

Fifty consecutive patients were enrolled in the study. Bazett's formula showed a significant change in mean QTc value between the two rhythms (421.5 ± 33.9 vs. 446.1 ± 31.9; p < 0.001 for mQTc and 420.9 ± 34.1 vs. 441.8 ± 30.9; p = 0.003 for QTcM). On the contrary, in patients with SR, QTc assessed by the Framingham, Fridericia, and Hodges formulas was similar to that in AF. Furthermore, good correlations between mQTc and QTcM are present for each formula, even in AF or SR.

CONCLUSIONS

During AF, Bazzett's formula, seems to be the most imprecise in QTc estimation.

Cardio-Oncology for the Primary Care Provider

Cardiovascular disease is a major cause of mortality among oncologic patients. As cancer therapies continue to evolve and advance, cancer survival rates have been increasing and so has the burden of cardiovascular disease within this population. For this reason, cardio-oncology plays an important role in promoting multidisciplinary care with the primary care provider, oncology, and cardiology. In this review, we discuss the roles of different providers, strategies to monitor patients receiving cardiotoxic therapies, and summarize cancer therapy class-specific toxicities. Continued collaboration among providers and ongoing research related to cardiotoxic cancer therapies will enable patients to receive maximal, evidence-based, comprehensive care.

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 Effects of Moxifloxacin and Gemifloxacin on the ECG Morphology in Healthy Volunteers: A Phase 1 Randomized Clinical Trial

Moxifloxacin and gemifloxacin are the two newer broad-spectrum 8-methoxy-quinolone derivatives that are used to treat various bacterial infections in cardiac patients. In this research study, we assessed the impact of moxifloxacin and gemifloxacin on the QT intervals of electrocardiograms in normal adult doses and draw a comparison, in a controlled environment, on healthy volunteers. Additionally, the effect of both test drugs on the QRS complex was checked. Sixty healthy volunteers were randomly assigned to two groups via R-software, and each respectively received moxifloxacin and gemifloxacin for five days. The research ethics committee approved the research, and it was registered for clinical trial under NCT04692623. The participants' electrocardiograms were obtained before the start of the dose (baseline) and on the fifth day. Significant prolongation of QT interval was noted in moxifloxacin (p < 0.0001) as compared to gemifloxacin treated groups. There were no cases of QTc prolongation over the usual limits (450-470 ms) in the gemifloxacin-treated group, however, QTc prolongations at the rate of 30 and 60 ms from the baseline were noted, interpreted as per the EMEA guidelines. These findings indicate that moxifloxacin caused significant (p < 0.0001) QT interval prolongation (QTIP) as compared to gemifloxacin. In contrast to the previously reported literature, the prominent effect of moxifloxacin on the widening of the QRS-complex was noted with no such effect on QRS-widening in the gemifloxacin-treated group. It is concluded that both drugs have the potential for considerable QT interval prolongation (QTIP) effects, which is one of the risk factors for developing torsade de pointes (TdPs) in cardiac patients. Thus, clinicians should exercise caution when prescribing moxifloxacin and gemifloxacin to cardiac patients and should consider alternate treatment options.

Effect of antipsychotic use by patients with schizophrenia on deceleration capacity and its relation to the corrected QT interval

OBJECTIVE

Schizophrenia patients treated with antipsychotics are at higher risk of sudden cardiac death. Decreased deceleration capacity (DC) of the heart rate is an accurate predictor of cardiac mortality. We evaluated the risk of sudden cardiac death due to antipsychotic use by assessing DC and examining the association between DC and the corrected QT interval (QTc) in schizophrenia patients.

METHODS

We measured the DC and QTc of 138 schizophrenia patients. We then compared the DC of 86 age- and sex-matched healthy controls with that of 86 schizophrenia patients. We investigated the correlation of DC of approximately 138 schizophrenia patients with prescribed doses of antipsychotics using linear regression analysis. We compared the DC of schizophrenia patients with and without prolonged QT intervals.

RESULTS

We found DC significantly differed between schizophrenia patients on antipsychotic medication and healthy controls. Additionally, DC was negatively correlated with antipsychotic use, especially chlorpromazine, zotepine, olanzapine and clozapine, in a dose-dependent manner. There was no significant association between DC and the QTc.

CONCLUSION

Assessing DC could facilitate monitoring and identification of increased risk of cardiac mortality in patients with schizophrenia that take antipsychotics. Assessing both DC and the QTc may enhance the accuracy of predicting sudden cardiac death.

Electrocardiographic changes after breast reduction surgery

Macromastia is associated with symptoms related to postural changes and decreased mobility. Breast reduction surgery (BRS) is the treatment of choice for these patients. Anatomical and structural changes in body posture and habitus might cause changes in electrocardiography (ECG). In this study, we aimed to evaluate the outcome of BRS on ECG changes of the patients after surgery. Study population included 33 female patients who had undergone BRS. ECG records of every patient before procedure and 6 months after procedure were analyzed retrospectively. Patients were naïve of known cardiac diseases and the patients did not have any known arrhythmia. The mean age of the study population was 40.8 ± 9.6. Total removed breast tissue from both sides was 1493 (1052-2138) mL, as 800 (513-1093) mL removed from right side and 740 (519-1050) mL removed from left side. There were significant changes in ECG of the patients in post-operative period. Atrial conduction parameters such as, PR duration (p<.001), Pmax duration (p<.001) and P wave dispersion (p<.001) were significantly decreased post-operatively. Additionally, ventricular conduction parameters such as, TPe duration (p<.001), TPe/QT (p=.013) and TPe/QTc (p=.005) ratios were found significantly decreased in ECGs of the patients. BRS as a treatment for macromastia does not only improve posture and mobility of the patients and also have positive impact on cardiac conductions. In patients those had BRS, atrial and ventricular conductions detected by ECG recordings were improved after surgery.

Development of an AI-Driven QT Correction Algorithm for Patients in Atrial Fibrillation

BACKGROUND

Prolongation of the QTc interval is associated with the risk of torsades de pointes. Determination of the QTc interval is therefore of critical importance. There is no reliable method for measuring or correcting the QT interval in atrial fibrillation (AF).

OBJECTIVES

The authors sought to evaluate the use of a convolutional neural network (CNN) applied to AF electrocardiograms (ECGs) for accurately estimating the QTc interval and ruling out prolongation of the QTc interval.

METHODS

The authors identified patients with a 12-lead ECG in AF within 10 days of a sinus ECG, with similar (±10 ms) QRS durations, between October 23, 2001, and November 5, 2021. A multilayered deep CNN was implemented in TensorFlow 2.5 (Google) to predict the MUSE (GE Healthcare) software-generated sinus QTc value from an AF ECG waveform, demographic characteristics, and software-generated features.

RESULTS

The study identified 6,432 patients (44% female) with an average age of 71 years. The CNN predicted sinus QTc values with a mean absolute error of 22.2 ms and root mean squared error of 30.6 ms, similar to the intrinsic variability of the sinus QTc interval. Approximately 84% and 97% of the model's predictions were contained within 1 SD (±30.6 ms) and 2 SD (±61.2 ms) from the sinus QTc interval. The model outperformed the AFQTc method, exhibiting narrower error ranges (mean absolute error comparison P < 0.0001). The model performed best for ruling out QTc prolongation (negative predictive value 0.82 male, 0.92 female; specificity 0.92 male, 0.97 female).

CONCLUSIONS

A CNN model applied to AF ECGs accurately predicted the sinus QTc interval, outperforming current alternatives and exhibiting a high negative predictive value.

Prolongation of the heart rate-corrected QT interval is associated with cardiovascular diseases: Systematic review and meta-analysis

BACKGROUND

Conflicting findings have described the association between prolonged heart rate-corrected QT interval (QTc) and cardiovascular disease.

AIMS

To identify articles investigating the association between QTc and cardiovascular disease morbidity and mortality, and to summarize the available evidence for the general and type 2 diabetes populations.

METHODS

A systematic search was performed in PubMed and Embase in May 2022 to identify studies that investigated the association between QTc prolongation and cardiovascular disease in both the general and type 2 diabetes populations. Screening, full-text assessment, data extraction and risk of bias assessment were performed independently by two reviewers. Effect estimates were pooled across studies using random-effect models.

RESULTS

Of the 59 studies included, 36 qualified for meta-analysis. Meta-analysis of the general population studies showed a significant association for: overall cardiovascular disease (fatal and non-fatal) (hazard ratio [HR] 1.68, 95% confidence interval [CI] 1.33-2.12; I²=69%); coronary heart disease (fatal and non-fatal) in women (HR 1.27, 95% CI 1.08-1.50; I²=38%; coronary heart disease (fatal and non-fatal) in men (HR 2.07, 95% CI 1.26-3.39; I²=78%); stroke (HR 1.59, 95% CI 1.29-1.96; I²=45%); sudden cardiac death (HR 1.60, 95% CI 1.14-2.25; I²=68%); and atrial fibrillation (HR 1.55, 95% CI 1.31-1.83; I²=0.0%). No significant association was found for cardiovascular disease in the type 2 diabetes population.

CONCLUSION

QTc prolongation was associated with risk of cardiovascular disease in the general population, but not in the type 2 diabetes population.

Exercise-related hypoglycaemia induces QTc-interval prolongation in individuals with type 1 diabetes

AIMS

To investigate changes in cardiac repolarisation during exercise-related hypoglycaemia compared to hypoglycaemia induced at rest in people with type 1 diabetes.

MATERIAL AND METHODS

In a randomised crossover study, 15 men with type 1 diabetes underwent two separate hyperinsulinaemic euglycaemic-hypoglycaemic clamp experiments during Holter-ECG monitoring. One experiment included a bout of moderate-intensity cycling exercise (60 min) along with declining plasma glucose (PG; Clamp-exercise). In the other experiment, hypoglycaemia was induced with the participants at rest (Clamp-rest). We studied QTc interval, T-peak to T-end (Tpe) interval and hormonal responses during three steady-state phases: (i) baseline (PG 4.0-8.0 mmol/L); (ii) hypoglycaemic phase (PG <3.0 mmol/L); and (iii) recovery phase (PG 4.0-8.0 mmol/L).

RESULTS

Both QTc interval and Tpe interval increased significantly from baseline during the hypoglycaemic phase but with no significant difference between test days. These changes were accompanied by an increase in plasma adrenaline and a decrease in plasma potassium on both days. During the recovery phase, ΔQTc interval was longer during Clamp-rest compared to Clamp-exercise, whereas ΔTpe interval remained similar on the two test days.

CONCLUSIONS

We found that both exercise-related hypoglycaemia and hypoglycaemia induced at rest can cause QTc-interval prolongation and Tpe-interval prolongation in people with type 1 diabetes. Thus, both scenarios may increase susceptibility to ventricular arrhythmias.

A case report of sudden cardiac arrest and torsade de pointes induced by the second-generation tyrosine kinase inhibitor dasatinib combined with fluconazole

A-41-year-old man diagnosed with acute myeloid leukemia (AML) survived dasatinib + fluconazole drug-induced long QT syndrome, sudden cardiac arrest, and torsade de pointes. Drug features and interaction jointly contributed to the whole process. Therefore, appropriate attention to drug interaction and close ECG monitoring are highly recommended for hospitalized patients, especially for those undergoing multi-drug regimens.

Triple Combination with Direct Acting Antivirals in the Treatment of Hepatitis C Does not Prolong the QT Interval

AIMS

Antiviral drugs are considered as potentially cardiotoxic, due to prolongation of QT interval which may affect incidence of severe ventricular arrhythmias. The main aim of this retrospective study was to assess the influence of treatment by three antiviral drugs on QT interval and to find patients who are at an increased risk of developing malignant ventricular arrhythmias.

METHODS

The study included 23 patients (14 men, 9 women) who were treated with a combination of interferon alpha, ribavirin, and an NS3/4A protease inhibitor. The parameters from the 12 leads electrocardiograms were evaluated before treatment, and then 3 ± 1 and 6 ± 1 months after treatment.

RESULTS

Heart rate (HR) 69 ± 12 / min and corrected QT interval (QTc) 412 ± 35 ms were obtained before the treatment and there was not observed a significant prolongation of intervals after 3 months (HR 72 ± 11 / min, QTc 412 ± 33 ms) and after 6 months (HR 64 ± 12 / min, QTc 405 ± 28 ms) respectively. In total QTc interval was prolonged from the baseline in 53% and in 43% of the patients 3 months respectively 6 months after treatment. A QTc prolongation over of 450 ms and new treatment-related repolarization change was noted in 1 (4%) patient.

CONCLUSION

The study demonstrates that a combination therapy of 3 antiviral drugs does not significantly prolong the QTc interval and does not cause severe pathological changes on the ECG. Patients undergoing this treatment are not at risk of developing heart disease as an undesirable side effect.

Higher prevalence of QTc interval prolongation among virologically suppressed older people with HIV

OBJECTIVE

To assess the prevalence, and factors associated with QTc interval prolongation, among 383 virologically suppressed people with HIV (PWH), without evidence of cardiovascular disease and active opportunistic infections in Thailand.

DESIGN

Cross-sectional study.

METHODS

Resting 12-lead digital ECGs were performed in 2019. QT interval corrected for heart rate (QTc) >450 ms in males and >460 ms in females was defined as QTc interval prolongation. We used multivariable logistic regression to investigate factors associated with QTc interval prolongation.

RESULTS

Mean (standard deviation) age was 56 (5.5) years and 42% were female. The median current CD4+ was 619 (interquartile range [IQR] 487, 769) cells/mm 3 . The median duration of antiretroviral therapy (ART) was 11.9 (IQR 7.1-16.1) years. Commonly used ART were rilpivirine (37.9%), efavirenz (20.1%), atazanavir/ritonavir (15.7%), lopinavir/ritonavir (12.3%) and dolutegravir (5%). The prevalence of QTc interval prolongation was 22.7%. In multivariable analysis, older age (odds ratio [OR] 1.07, 95% confidence interval [CI] 1.02-1.12, P  = 0.005), female sex (OR 1.69, 95% CI 1.01-2.82, P  = 0.046) and increasing BMI (OR 1.08, 95% CI 1.01-1.15, P  = 0.03) were associated with QTc interval prolongation. With every 1-year increase in age, the odds of QTc interval prolongation increased by 7%.

CONCLUSIONS

In this well-suppressed aging Asian HIV cohort, the prevalence of QTc interval prolongation was relatively high, and associated with increasing age, female sex, and higher BMI. For PLWH with these characteristics, QTc interval should be monitored before and after initiating any medications known to prolong QTc intervals, to prevent fatal cardiac arrhythmias.

Prolonged QT Interval in Cirrhosis: Twisting Time?

Approximately 30% to 70% of patients with cirrhosis have QT interval prolongation. In patients without cirrhosis, QT prolongation is associated with an increased risk of ventricular arrhythmias, such as torsade de pointes (TdP). In cirrhotic patients, there is likely a significant association between the corrected QT (QTc) interval and the severity of liver disease, and possibly with increased mortality. We present a stepwise overview of the pathophysiology and management of acquired long QT syndrome in cirrhosis. The QT interval is mainly determined by ventricular repolarization. To compare the QT interval in time it should be corrected for heart rate (QTc), preferably by the Fridericia method. A QTc interval >450 ms in males and >470 ms in females is considered prolonged. The pathophysiological mechanism remains incompletely understood, but may include metabolic, autonomic or hormonal imbalances, cirrhotic heart failure and/or genetic predisposition. Additional external risk factors for QTc prolongation include medication (IKr blockade and altered cytochrome P450 activity), bradycardia, electrolyte abnormalities, underlying cardiomyopathy and acute illness. In patients with cirrhosis, multiple hits and cardiac-hepatic interactions are often required to sufficiently erode the repolarization reserve before long QT syndrome and TdP can occur. While some risk factors are unavoidable, overall risk can be mitigated by electrocardiogram monitoring and avoiding drug interactions and electrolyte and acidbase disturbances. In cirrhotic patients with prolonged QTc interval, a joint effort by cardiologists and hepatologists may be useful and significantly improve the clinical course and outcome.

To Modify or Not to Modify: Allele‐Specific Effects of 3'UTR‐ KCNQ1 Single Nucleotide Polymorphisms on Clinical Phenotype in a Long QT 1 Founder Population Segregating a Dominant‐Negative Mutation

Background

There are conflicting reports with regard to the allele‐specific gene suppression effects of single nucleotide polymorphisms (SNPs) in the 3'untranslated region (3'UTR) of the KCNQ1 gene in long QT syndrome type 1 (LQT1) populations. Here we assess the allele‐specific effects of 3 previously published 3'UTR‐ KCNQ1 's SNPs in a LQT1 founder population segregating a dominant‐negative mutation.

Methods and Results

Bidirectional sequencing of the KCNQ1 ' s 3'UTR was performed in the p.Y111C founder population (n=232, 147 genotype positive), with a minor allele frequency of 0.1 for SNP1 (rs2519184) and 0.6 for linked SNP2 (rs8234) and SNP3 (rs107980). Allelic phase was assessed in trios aided by haplotype data, revealing a high prevalence of derived SNP2/3 in cis with p.Y111C (89%). Allele‐specific association analyses, corrected using a relatedness matrix, were performed between 3'UTR‐ KCNQ1 SNP genotypes and clinical phenotypes. SNP1 in trans was associated with a significantly higher proportion of symptomatic phenotype compared with no derived SNP1 allele in trans (58% versus 32%, corrected P =0.027). SNP2/3 in cis was associated with a significantly lower proportion of symptomatic phenotype compared with no derived SNP2/3 allele in cis (32% versus 69%, corrected P =0.010).

Conclusions

Allele‐specific modifying effects on symptomatic phenotype of 3'UTR‐ KCNQ1 SNPs rs2519184, rs8234, and rs107980 were seen in a LQT1 founder population segregating a dominant‐negative mutation. The high prevalence of suppressive 3'UTR‐ KCNQ1 SNPs segregating with the founder mutation could contribute to the previously documented low incidence of cardiac events in heterozygous carriers of the p.Y111C KCNQ1 mutation.

Importance of Formula-Specific Centile Thresholds for Evaluation of Heart Rate-Corrected QT Prolongation in Williams Syndrome

Patients with Williams syndrome (WS) have a 25- to 100-fold higher risk of sudden death and prolonged heart rate-corrected QT (QTc). A recent study using the Fridericia formula for QT correction suggested that prolongation is principally an issue of heart rate. We used multiple published heart rate correction formulas to reevaluate the prevalence of QTc prolongation in our original dataset from our 2010 study at the Children's Hospital of Philadelphia. The ninety-eighth centile for QTc and corrected JT Interval (JTc) of the control population for each formula were used to set the threshold for prolongation. Prevalence comparison was done with Fisher's exact test. Predictors of longer QTc/JTc were assessed using linear regression models adjusting for age, gender, and heart rate. Adjusted odds of QTc/JTc prolongation were evaluated with conditional logistic regression models matched based on age and heart rate. There were 482 electrocardiograms from 188 patients with WS and 1,522 from normal controls. Patients with WS were younger, with higher heart rates and shorter RR and QRS intervals. WS was associated with longer QTc/JTc compared with controls. There were higher odds of prolonged QTc/JTc in patients with WS than controls using both Bazett and Fridericia formulas. In conclusion, this study confirms the higher prevalence of QTc prolongation in WS compared with controls and highlights the importance of setting appropriate formula-specific upper thresholds for QTc prolongation for accurate diagnosis.

Moderately Prolonged QTc in Computer-Assessed ECG, Random Variation or Significant Risk Factor? A Literature Review

Most ECGs in European hospitals are recorded with equipment giving computer measured intervals and interpretation of the recording. In addition to measurements of interval and QRS axis, this interpretation frequently provides the Bazett’s-corrected QTc time. The introduction of computer-corrected QTc revealed QTc prolongation to be a frequent condition among medical patients. Nevertheless, the finding is frequently overlooked by the treating physician. The authors combine experience from a local hospital with a review of the current literature in this field in order to elucidate the importance of this risk factor both as congenital long QT syndrome and as acquired QT prolongation.

The Relationship between Body Composition and ECG Ventricular Activity in Young Adults

This study aimed to determine the correlation between body composition (measured as weight, body mass index, and body fat percentage (BFP)) and electrocardiographic ventricular parameters (the QT and TQ intervals and the ratios between the electrical diastole and electrical systole (TQ/QT) and between the cardiac cycle and electrical diastole (RR/TQ), both for uncorrected and corrected intervals) in a sample of 50 healthy subjects (age interval 19-23 years, mean age 21.27 ± 1.41 years, 33 women and 17 men). Subjects' measurements were performed with a bioimpedancemetry body composition analyzer and a portable ECG monitor with six leads. Starting from the correlations obtained between the investigated continuous variables, we performed a standard linear regression analysis between the body composition parameters and the ECG ones. Our results revealed that some of our regression models are statistically significant (p < 0.001). Thus, a specific part of the variability of the dependent variables (ECG ventricular activity parameters for corrected QT intervals) is explained by the independent variable BFP. Therefore, body composition influences ventricular electrical activity in young adults, which implies a differentiated interpretation of the electrocardiogram in these situations.

Cardiac safety analysis of anti-HER2-targeted therapy in early breast cancer

To evaluate the cardiac safety of anti-HER2-targeted therapy for early breast cancer; to investigate whether trastuzumab combined with pertuzumab increases cardiac toxicity compared with trastuzumab; to evaluate the predictive value of high-sensitivity Troponin (hs-TnI) and QTc for the cardiotoxicity associated with anti-HER2 targeted therapy in early breast cancer. A total of 420 patients with early-stage HER2-positive breast cancer who received trastuzumab or trastuzumab combined with pertuzumab for more than half a year in Tianjin Medical University Cancer Hospital from January 2018 to February 2021 were included. Left ventricle ejection fraction (LVEF), hs-TnI values, and QTc were measured at baseline and 3, 6, 9, 12 months. Cardiotoxicity was defined as a decrease in LVEF of at least 10 percentage points from baseline on follow-up echocardiography. Cardiotoxicity developed in 67 of the 420 patients (15.9%) and all patients had LVEF above 50% before and after treatment. The incidence of cardiotoxicity in trastuzumab and trastuzumab combined with pertuzumab was 14.3% and 17.9%, respectively (P > 0.05). Logistic regression analysis showed that age, coronary heart disease, left chest wall radiotherapy, and anthracyclines sequential therapy were independent risk factors for cardiotoxicity (P < 0.05). The value of hs-TnI and QTc at the end of treatment (12th month) were selected for ROC curve prediction analysis and the area under the ROC curve was 0.724 and 0.713, respectively, which was significantly different from the area of 0.5 (P < 0.05). The decrease of LVEF in the study was mostly asymptomatic, from the heart safety point of view, the anti-HER2 targeted therapy for early breast cancer was well tolerated. Trastuzumab combined with pertuzumab did not significantly increase cardiotoxicity. However, subgroup analysis suggests that in the presence of coronary artery disease (CAD) and sequential treatment with anthracene, trastuzumab and pertuzumab may increase the cardiac burden compared with trastuzumab. Hs-TnI and QTc may be useful in monitoring and predicting cardiotoxicity associated with anti-HER2 targeted therapy for early breast cancer.

Sex-Specific Associations of Anxiety With Left Ventricular Hypertrophy and Transmural Dispersion of Repolarization in Hypertensive Patients

Background

The previous studies have shown that individuals with hypertension and anxiety have a higher mean left ventricular mass index (LVMI) and QTc dispersion. We explored the associations between anxiety and left ventricular hypertrophy (LVH) and between anxiety and transmural dispersion of repolarization (TDR) (as detected by T peak-T end interval/QT interval, Tp–Te/QT ratio) in patients with hypertension.

Methods

A total of 353 patients with uncomplicated hypertension from the Shaanxi Provincial People’s Hospital were enrolled between 2017 and 2021. Anxiety was defined as a Hamilton Anxiety Scale (HAM-A) score ≥ 14. Logistic regression models were used to estimate the association between HAM-A and LVH. The association between HAM-A score and Tp–Te/QT was estimated using linear regression.

Results

Participants were divided into two groups based on the presence of anxiety. LVMI was significantly higher in patients with hypertension and anxiety than in those with hypertension without anxiety (no anxiety: 84.36 ± 23.82, anxiety: 105.75 ± 25.45 g/m², p < 0.001). HAM-A score was positively correlated with LVMI (r = 0.578, p < 0.001) and with Tp–Te/QT (r = 0.252, p < 0.001). Logistic regression models showed that patients with hypertension and anxiety were at higher risk of LVH than were patients with hypertension without anxiety (adjusted OR, 2.44, 95% CI, 1.35–4.43, p = 0.003). The linear regression analysis showed that the HAM-A score was associated with Tp–Te/QT ratio (adjusted β, 0.001, 95% CI, 0.001–0.002, p = 0.013). There was an interaction between sex and anxiety for LVH risk (p for interaction = 0.035) and for increased Tp–Te/QT (p for interaction = 0.014). After stratification by sex, anxiety was associated with increased risk for LVH in men with hypertension (adjusted OR, 5.56, 95% CI, 2.07–14.98, p = 0.001), but not in women (adjusted: OR, 1.44, 95% CI, 0.64–3.26, p = 0.377) with hypertension. The HAM-A score was also positively associated with Tp–Te/QT ratio in male (adjusted β, 0.002, 95% CI, 0.001–0.003, p < 0.001), but not in women (adjusted β, 0.001, 95% CI, –0.0002–0.002, p = 0.165).

Conclusion

Our results indicated that anxiety was associated with LVH and with increased TDR in men with hypertension, but not in women with hypertension.

Prolongation of QTc interval due to increased parity and great grand multiparity

Women are more prone to cardiac arrhythmias. Increased exposure to sex hormones may alter the ventricular repolarisation of the heart as the parity number increases. In this study, we aim to investigate the effect of parity number to electrocardiographic parameters. A total of 205 adult women were included for the study. Nulliparous (NP), primiparous (PP), multiparous (MP), grand multiparous (GMP) and great grand multiparous (GGMP) women constituted the study population. Increased parity has positive correlation with QTc interval (p=.000, r = 0.303). GGMP has significantly higher QTc compared to NP, PP, MP and GMP (p=.001, p=.000, p=.004 and p=.007, respectively). GGMP and parity have explanatory power on QTc (p=.019 and p=.020, respectively). Parity and GGMP affect cardiac repolarisation and prolong the QTc interval most probably due to repeated exposure to sex hormones. This study showed that GGMP and parity are independent risk factors for QTc interval prolongation.Impact StatementWhat is already known on this subject? Increased exposure to sex hormones may alter the ventricular repolarisation of the heart as the parity number increases. Previous studies showed that increased parity (up to 7) deteriorates ventricular diastolic functions, prolongs QTc interval and these conditions cause cardiovascular diseases.What do the results of this study add? In this study, we added great grand multiparity (10 or more parity) (GGMP) group that have never been studied before. We found that GGMP has much more impact on QTc prolongation than fewer parity groups and this result shows us that GGMP deteriorates ventricular functions more.What are the implications of these findings for clinical practice and/or further research? These results show us that women should be discouraged from having more delivery. Also, women with a pregnancy history of five and more (grand multiparity) should be evaluated with an electrocardiography and a cardiology consultation should be performed before re-conception. In the future, larger prospective studies are needed on this subject. In addition, other electrocardiographic parameters (QRS-T angle and Tpe/QTc in electrocardiography, etc.) that related with diastolic functions should be evaluated for comparison of GGMP and non-GGMP populations in future studies.