Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice

QT interval parameters, anti-Ro antibody status, and disease activity in systemic lupus erythematosus

BACKGROUND

The QT interval a marker of ventricular depolarization and repolarization is reported to be prolonged in some proportion of patients with systemic lupus erythematosus (SLE). We studied electrocardiographic (ECG) abnormalities, in particular QT interval and its relationship with anti-Ro antibodies, disease activity, and serum interleukin 1β (IL-1β), interleukin 6 (IL-6) in SLE.

METHODS

A 12-lead resting ECG was performed on 140 adult SLE patients fulflling SLICC/ACR classification criteria. All patients received hydroxychloroquine and prednisolone. Corrected QT (QTc) °440 milliseconds (ms) was defined as prolonged QTc. QT dispersion (QTd) °60 ms was defined as increased QTd.

RESULTS

Eighty-four patients had some form of ECG abnormality. Prolongation of QTc and QTd was present in 24 (17.1%) and 50 (35.7%) respectively. Anti-Ro/SSA antibodies were present in 63 (45%). Prolongation of QTc in anti-Ro positive versus anti-Ro negative was 17.5% and 17% respectively, p=0.98. Prolongation of QTd in anti-Ro-positive versus anti-Ro-negative was 32% and 39% respectively, p=0.37. Prolonged QTc was observed in 15% patients with SLEDAI ˛4 compared to 17.5% patients with SLEDAI °5, p=0.78. The median serum concentrations of IL-1β and IL-6 were similar in the groups with and without prolonged QTc, with and without prolonged QTd. On binary logistic regression analyses neither clinical nor laboratory factors were predictors of prolonged QTc. However, having valvular regurgitation and hypercholesterolemia was associated with significantly reduced odds of having prolonged QTd, adjusted OR 0.33 (CI 0.14-0.83), p=0.018 and 0.19 (CI 0.05-0.80), p=0.023 respectively. Those with high LDL cholesterol and hypertriglyceridemia had a significantly higher odds of having a normal QTd with adjusted OR of 4.34 (1.31-14.46) p=0.017and 5.59 (1.62-19.38) p=0.007respectively.

CONCLUSION

Though 17% and 35% SLE patients have QTc and QTd prolongation, association with anti-Ro antibodies or disease activity was absent. A large proportion has other asymptomatic ECG abnormalities that may reflect subclinical cardiac involvement.

Exercise-induced electrocardiographic changes after treadmill exercise testing in healthy children: A comprehensive study

Background:

Aims and Objectives:

Materials and Methods:

Results:

Conclusion:

Assessment of Structure, Function, and Rhythm of the Heart with Echocardiography and Electrocardiography in Adolescent Swimmers

The aim of this study was to evaluate the cardiac parameters by using electrocardiography and echocardiography in adolescent swimmers. Twenty-two adolescent swimmers and 22 gender- and age-matched sedentary controls admitted to our center between November 2018 and May 2019 were included in this study. In addition to demographical characteristics, participants were assessed via a 12-lead electrocardiography and two-dimensional echocardiography for cardiac function. On the echocardiography, end-systolic and end-diastolic interventricular septum, end-systolic and end-diastolic left ventricular posterior wall thicknesses, left atrial width, Tricuspid E, left ventricular mass and left ventricular mass index were higher in the swimmers when compared to the sedentary controls (P < 0.05). On the electrocardiography, Tp-e duration which reflects ventricular transmural repolarization, and Tp-e/QT and Tp-e/corrected QT ratios were higher in the swimmers than the sedentary controls (P < 0.05). In conclusion, swimming exercise in children leads to concentric thickening of left ventricle and induces an increase in Tp-e duration, and Tp-e/QT and Tp-e/corrected QT ratios, which are the novel markers for risk of ventricular arrhythmias.

Effects of Antipsychotics on Arrhythmogenic Parameters in Schizophrenia Patients: Beyond Corrected QT Interval

PURPOSE

Antipsychotic drugs have been implicated as risk factors for QT prolongation, which is a predictor of sudden cardiac death. However, the QT interval is considered an imperfect marker for proarrhythmic risk. Recently, improved methods, namely, QT dispersion (QTD), QTD ratio (QTDR), T wave peak-to-end interval (Tp-e), Tp-e/QT ratio and Tp-e/QTc ratio, have been regarded as proarrhythmic risk markers. We attempted to reevaluate the risk of sudden cardiac death due to antipsychotics use by measuring these improved evaluation methods.

PATIENTS AND METHODS

We retrospectively evaluated QTc, QTD, QTDR, Tp-e, Tp-e/QT ratio and Tp-e/QTc ratio from the medical records of 410 patients with schizophrenia diagnosed by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision, or 5th Edition. Information on drugs administered was obtained from medical records. We investigated the correlation between each index on ECG and medication, such as antipsychotics, prescribed to participants with linear regression analysis. We also compared each index between 235 healthy controls and 235 patients matched for age and sex.

RESULTS

Positive correlations between QTc and levomepromazine and brexpiprazole were identified. Levomepromazine and lithium were positively correlated with QTD. Levomepromazine, quetiapine, asenapine, clozapine and carbamazepine were positively correlated with QTDR. Levomepromazine, olanzapine, brexpiprazole and lithium were positively correlated with Tp-e. Olanzapine, brexpiprazole and lithium were positively correlated with the Tp-e/QT ratio. Olanzapine, brexpiprazole and lithium were positively correlated with Tp-e/QTc ratio. Significant differences in all indexes were noted between the patients and healthy controls.

CONCLUSION

According to our results, the prediction of the risk of sudden cardiac death by each index was inconsistent. We should evaluate the predictive factor of ventricular arrhythmia according to various electrocardiogram indexes because QTc alone could not identify the risk of sudden cardiac death.

Evaluation of inflammatory and cardiac-electrophysiological markers in patients undergoing peritoneal dialysis

Background: The Tp-e/QT (peak to end of T-wave duration/QT interval) ratio is a promising marker of myocardial repolarization and ventricular arrhythmogenesis. Its elevation is associated with sudden cardiac death in different clinical conditions. This study was designed to assess the possible association between increased Tp-e/QT ratio and clinical factors in peritoneal dialysis patients. Materials & methods: We devised a prospective cross-sectional study, which included 107 patients who were divided into groups according to their Tp-e/QT ratio. The association of an increased Tp-e/QT ratio with related factors was analyzed with multivariate logistic regression. Results: Thirty-one patients, who had an elevated Tp-e/QT ratio, showed higher values of IL-6, left ventricular end-systolic diameter, Tp-e, percentage of diabetes mellitus, coronary artery calcification, and left ventricular ejection fraction. Multivariate analysis revealed that IL-6 was an independent risk factor for a higher Tp-e/QT ratio after adjustments. Conclusion: Our study revealed that a high serum IL-6 level in peritoneal dialysis patients increased the risk of a higher Tp-e/QT ratio, which indicated a potentially hazardous interplay between inflammation and arrhythmogenesis.

Importance of electrocardiographic markers in predicting cardiac events in children

ECG is a common diagnostic tool in medical practice. Sudden cardiac death (SCD) is a rare but devastating event. The most common cause of SCD in the young is a primary arrhythmic event, which is often produced by malignant ventricular arrhythmia. Several electrocardiographic markers for ventricular repolarization and depolarization have been proposed to predict this arrhythmic risk and SCD in children. Although many of these parameters can easily be used in clinical practice, some of them need specific techniques for interpretation. In this review, we summarized the current knowledge regarding the clinical importance and the ability of these ECG parameters to predict adverse cardiac events in the pediatric population.

Influence of disease severity and cardiac autonomic tone on ventricular repolarization and dispersion in electrocardiographic assessment of patients with systemic lupus erythematosus

Background

There are no data on the influence of disease severity and cardiac autonomic tone on ventricular repolarization and dispersion in 24-hour Holter monitoring in systemic lupus erythematosus (SLE).

Methods

Consecutive 92 SLE and 51 healthy subjects were studied. The standard 12-lead electrocardiography (ECG), Holter monitoring with heart rate turbulence (HRT) and QT, Tp-e and Tp-e/QT ratio assessment (including corrected values) were performed. Subjects with conditions causing repolarization abnormalities or insufficient number of beats suitable for QT evaluation were excluded (17 SLE and 8 controls).

Results

Finally, 75 SLE and 43 sex- and age-matched controls were included to the study. In SLE patients, the median disease severity score (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR-DI)) was 3.0. The mean values of QTc, cTp-e and cTp-e/QTc were significantly higher in SLE patients than in controls. QTc ≥ 460 ms was observed in 18.7% of patients using standard ECG and in 58.7% using Holter monitoring. With Holter monitoring, patients with SLICC/ACR-DI >3.0 presented longer QTc than those with SLICC/ACR-DI ≤3.0 (418±15 vs. 409 ± 16, p = 0.04), while cTp-e and cTp-e/QTc values were similar. Patients with abnormal HRT presented longer cTp-e and higher cTp-e/QTc than those with normal HRT (92 ± 52 vs. 71 ± 16 ms, p = 0.04; 0.244 ± 0.126 vs. 0.187 ± 0.035, p = 0.03), while QTc values were similar. No differences in QT and Tp-e parameters were observed according to disease duration.

Conclusion

In SLE patients, Holter monitoring revealed QTc prolongation more frequently than standard ECG. Longer QTc values were observed in patients with more advanced disease, while increased cTp-e and cTp-e/QTc were related to cardiac autonomic dysfunction expressed by abnormal HRT.

Wet Cupping Therapy Improves the Parameters of Ventricular Repolarization

BACKGROUND

Cupping therapy (CT) is an ancient medical treatment since antiquity and is used for the treatment of such various disease states as contagious diseases, chronic or acute inflammatory disease, and autoimmune disorders. Ventricular repolarization is represented by QT and corrected-QT (QTc) intervals from surface electrocardiography.

OBJECTIVES

As novel repolarization parameters, Tpeak-toTend (Tp-Te) interval, and Tp-Te/QT and Tp-Te/QTc ratios are suggested to correlate better with ventricular arrhythmia risk in various clinical conditions than sole QT and QTc intervals. In this study, we aimed to determine whether these parameters changed significantly after CT in healthy individuals.

METHODS

One hundred and twenty participants (57 women and 63 men; mean age: 49.0 ± 13.0 years) participated in this study. ECGs strips were recorded 1 hour before and 1 hour after CT from each participant, and relevant ECG parameters were compared.

RESULTS

Tp-Te interval [69.51 ± 11.54 msec vs 63.15 ± 10.89 msec, p = 0.001], Tp-Te/QT ratio [0.191 ± 0.030 vs 0.174 ± 0.031, p = 0.002] and Tp-Te/QTc ratio [0.175 ± 0.030 vs 0.159 ± 0.026, p = 0.001] were found to be significantly decreased 1 hour after the procedure compared with the pre-procedure values. However, no statistically significant change was observed in mean heart rate, QT and QTc intervals, QT/QRS and cQT/QRS, and frontal QRS/T angle after the procedure compared with the same parameters before the procedure (p > 0.05).

CONCLUSIONS

In accordance with the results of our study, it is plausible to conclude that CT may exert cardioprotective effect. However, larger scale prospective studies are needed to support our findings.

Investigation of the effect of epicardial adipose tissue thickness on cardiac conduction system in children with type 1 diabetes mellitus

Objectives Investigation of the association between epicardial adipose tissue thickness (EATT) and P-wave dispersion (Pd), QT dispersion (QTd), corrected QT dispersion (QTcd) and Tp-e interval in children with Type 1 Diabetes Mellitus (T1DM) was aimed. Methods Forty-one children with T1DM and 41 age- and gender-matched healthy children were included in the study. Demographical characteristics of all cases were examined. In echocardiography; in addition to conventional echocardiographic measurements, end-systolic EATT was measured from right ventricular free wall. In electrocardiogram; Pd, QTd, QTcd and Tp-e interval durations, as well as Tp-e/QT and Tp-e/QTc ratios were calculated. Correlation values between EATT and electrocardiographic parameters were also noted. Results Mean age of the patient group was determined to be 12.43 ± 3.04 years and that of the control group was determined to be 12.08 ± 2.56 years. There was no significant difference between the groups in regard to age, gender, body weight, height and body mass index. In the patient group; EATT, Pd, QTd, QTcd and Tp-e interval were determined to be significantly higher compared to the control group. In the patient group, no significant correlation was determined between EATT and Pd, QTd, QTcd and Tp-e. However, when both patient and control groups were evaluated together, a statistically significant positive correlation was determined between EATT and Pd, QTd, QTcd and Tp-e. Conclusions In children with T1DM, an increase in epicardial adipose tissue thickness and in risk of cardiac arrhythmias has been demonstrated. To reveal the possible unfavorable effects of EATT on cardiac conduction system in T1DM patients needs further studies.

Evaluation of Electrocardiographic Ventricular Depolarization and Repolarization Variables in Type 1 Diabetes Mellitus

Background

The risk of cardiovascular events and sudden death increases with type 1 diabetes mellitus (T1DM).

Objective

To evaluate electrocardiographic markers of arrhythmias in T1DM patients.

Methods

Electrocardiographic parameters reflecting ventricular depolarization and repolarization, namely, QT, QTc, QTd, QTdc, Tp-e, JT, and JTc intervals and Tp-e/QT and Tp-e/QTc ratios, of 46 patients diagnosed with T1DM were retrospectively analyzed and compared with 46 healthy age-, sex-, and body mass-matched controls. Correlations between T1DM duration, hemoglobin A1c (HbA1c), and ventricular repolarization variables were analyzed. P values lower than 0.05 were considered statistically significant.

Results

Diabetes duration was 16.6 ± 7.1 years, and HbA1c was 10.81% ± 3.27% in the T1DM group. In comparison with the control group, heart rate, QTc, QTd, QTdc, Tp-e and JTc intervals, Tp-e/QT ratio (p < 0.001), and Tp-e/QTc ratio (p = 0.007) were significantly higher in T1DM patients. T1DM duration and HbA1c levels were significantly correlated with QTc, QTd, QTdc, Tp-e, and JTc intervals and Tp-e/QT and Tp-e/QTc ratios.

Conclusions

In T1DM patients, potential electrocardiographic repolarization predictors were significantly increased in correlation with disease duration and HbA1c levels. These findings may contribute to the understanding of sudden cardiac death in patients with T1DM.

Risk stratification in hypertrophic cardiomyopathy

Sudden cardiac death (SCD) is the most devastating complication of hypertrophic cardiomyopathy (HCM). The greatest challenge in the management of HCM is identifying those at increased risk, since an implantable cardioverter-defibrillator (ICD) is a potentially life-saving therapy. We sought to summarize the available data on SCD in HCM and provide a clinical perspective on the current differing and somewhat conflicting data on risk stratification, with balanced guidance regarding rational clinical decision-making. Additionally, we sought to determine the status of the current implementation of guidelines compiled by HCM experts worldwide. The HCM Risk-SCD model helps improve the risk stratification of HCM patients for primary prevention of SCD by calculating an individual risk estimate that contributes to the clinical decision-making process. Improved risk stratification is important for decision-making before ICD implantation for the primary prevention of SCD.

Increased QT Interval Dispersion is Associated with Coronary Artery Involvement in Children with Kawasaki Disease

Objectives

Coronary artery (CA) involvement is the most well known complication of Kawasaki disease (KD). Previous studies have suggested that QT dispersion has a predictive value in diagnosing cardiac ischemia, ventricular arrhythmia, and sudden cardiac death. However, limited data exits regarding the application of QT dispersion in KD. Therefore, we sought to determine whether there is a relationship between QT dispersion and CA involvement in patients with KD.

Methods

We performed a cross-sectional study of all consecutive patients with KD who were followed-up at the Pediatric Rheumatology Department (Pediatrics Center of Excellence affiliated to Tehran University of Medical Sciences, Tehran, Iran) from September 2013 to November 2015. Patients who met the criteria for KD, based on the American Heart Association guideline, were enrolled in the study. We collected data regarding patients' demographics, clinical manifestations, laboratory, and echocardiographic findings.

Results

A total of 70 KD patients were identified, including 43 males (61.4%) and 27 females (38.6%). The median age of patients was 21.0 (11.0-48.0) months. We found statistically significant differences between age, gender, and platelet count among patients with and without CA involvement (p < 0.050). Median corrected QT dispersion in patients with CA involvement calculated from 12 leads in the acute phase was significantly higher compared to the non-CA involvement group (108.0 (89.5-138.5) ms vs. 63.0 (54.0-74.5) ms, respectively (p < 0.001)).

Conclusions

Prolonged QT dispersion (corrected or non-corrected) during the acute and convalescence phases in patients with KD is associated with coronary involvement.

Differential Diagnostic Models Between Vasovagal Syncope and Psychogenic Pseudosyncope in Children

Objective: We aimed to establish useful models for the clinical differential diagnosis between vasovagal syncope (VVS) and psychogenic pseudosyncope (PPS). Methods: This bicentric study included 176 patients (150 VVS and 26 PPS cases) for model development. Based on the results of univariate and multivariate analyses, a logistic regression model and a scoring model were established and their abilities to differentiate VVS from PPS were tested. Another 78 patients (53 VVS and 25 PPS) were used for external validation. Results: In the logistic regression model, the outcome indicated that the QT-dispersion (QTd) (P < 0.001), syncope duration (P < 0.001), and upright posture (P < 0.001) acted as independent factors for the differentiation of VVS from PPS, which generated an area under the curve (AUC) of 0.892. A cutoff value of 0.234 yielded a sensitivity and specificity of 89.3 and 80.8%, respectively, for the differentiation between VVS and PPS in the logistic regression model. In the scoring model which consists of three variables, a cutoff score of three points yielded a sensitivity and specificity of 91.3 and 76.9%, respectively, with an AUC of 0.909. The external validation test indicated that the negative and positive predictive values of the scoring model were 78.8 and 91.7%, respectively, and the accuracy was 80.8%. Conclusion: The scoring model consisting of three variables is an easy-to-perform, inexpensive, and non-invasive measure for initial differential diagnosis between VVS and PPS.

Effect of habitual cigarette smoking on the index of cardiac electrophysiological balance in apparently healthy individuals

BACKGROUND AND AIM

Chronic cigarette smoking has been suggested to portend risk for cardiac arrhythmia generation. Index of cardiac electrophysiological balance (iCEB) is a relatively new ECG parameter indicating balance between ventricular depolarization and repolarization, thereby providing more insight concerning ventricular arrhythmogenesis (VA) than other classical ECG parameters such as QT and corrected QT (QTc) intervals. The present study aimed to assess the status of iCEB in healthy habitual smokers.

METHODS

This retrospective study included a total of 80 apparently healthy subjects (45% female, mean age 39.4 ± 8.1 years) with smoking habit and 82 healthy non-smoking subjects (40% female, mean age 37.0 ± 8.6 years) were included between January-September 2019. Demographic, clinical and ECG characteristics were obtained from medical records. iCEB and corrected iCEB values were calculated by dividing respective QT and QTc intervals by QRS duration.

RESULTS

Mean PR, QRS and QT intervals were similar between the groups, whereas mean heart rate and QTc interval were greater in the smoker group compared with the non-smokers [(82.0 ± 8.9 bpm vs 77.8 ± 12.4 bpm, respectively, p = 0.016) and (427.05 ± 22.6 msec vs 399.9 ± 12.8 msec, respectively, p < 0.001)]. Subject with smoking habit had greater iCEBc than the controls (5.10 ± 0.49 vs 4.68 ± 0.39, respectively, p < 0.001). However, there was no significant difference in regard of iCEB between the groups (4.37 ± 0.46 vs 4.32 ± 0.42, respectively, p = 0.456).

CONCLUSION

iCEBc increases significantly in healthy smokers compared with non-smokers. This may suggest an increased predisposition to Torsades de Pointes-mediated VA in healthy smokers, or in chronic smokers with inherent QT-prolonging genetic variations or those on QT-prolonging drug therapy.

An Open Invitation to Join the International Brugada Electrocardiographic Indices Registry

Background: The Brugada Electrocardiographic Indices Registry is a comprehensive data registry composed of patients with Brugada patterns on the electrocardiogram (ECG). The aim is to test the hypotheses that (i) ECG indices combining both depolarization and repolarization abnormalities can better predict spontaneous ventricular arrhythmias than existing ECG markers in Brugada syndrome and (ii) that serial ECG measurements will provide additional information for risk stratification, especially in asymptomatic patients.

Methods: Patients with both Brugada pattern ECGs and Brugada syndrome are eligible for inclusion in this registry. Baseline characteristics and ECG variables reflecting depolarization and repolarization will be determined. The primary outcome is spontaneous ventricular tachycardia/ventricular fibrillation or sudden cardiac death. Secondary outcomes are inducible ventricular tachycardia/ventricular fibrillation and syncope.

Results: As of November 15, 2019, 39 investigators from 32 cities in 18 countries had joined this registry. As of December 15, 2019, 1383 cases had been enrolled.

Conclusions: The Brugada Electrocardiographic Indices Registry will evaluate the disease life course, risk factors, and prognosis in a large series of Brugada patients. It will therefore provide insights for improving risk stratification.

Different habitus but similar electrocardiogram: Cardiac repolarization parameters in children - Comparison of elite athletes to obese children

Introduction:

The standard 12-lead electrocardiogram (ECG) remains a widely used tool in the basic cardiac evaluation of children and adolescents. With the emergence of inherited arrhythmia syndromes, the period of cardiac repolarization has been the focus of attention. So far, data on cardiac repolarization and its normal variants in healthy children are scarce. This may cause uncertainties in the differentiation between pathologies and normal variants. As abnormal autonomic regulation seems to be a major influencing factor on cardiac repolarization, this study aimed to evaluate the parameters of cardiac repolarization of children in extremely good physical shape to obese children to improve knowledge about cardiac repolarization in these subgroups of pediatric patients that are vastly affected by the alterations of autonomic regulation.

Methods:

A total of 426 pediatric volunteers (84 lean, healthy controls; 130 obese healthy pediatric volunteers; and 212 elite athletes) were enrolled in the study, and the parameters of cardiac repolarization were determined in 12-lead ECG.

Results:

Most importantly, there were no pathological findings, neither in the healthy controls nor in the obese or athletes. Athletes showed overall shorter corrected QT intervals than children from the other groups. This is also true if a correction of the QT interval is performed using the Hodges formula to avoid bias due to a tendency to lower heart rates in athletes. Athletes showed the shortest Tpeak-to-end ratios between the groups. The comparison of athletes from primarily strength and power sports versus those from endurance sports showed endurance-trained athletes to have significantly longer QT intervals.

Conclusions:

This study suggests that neither obesity nor extensive sports seems to result in pathological cardiac repolarization parameters in healthy children. Therefore, pathology has to be assumed if abnormal repolarization parameters are seen and might not be simply attributed to the child's habitus or an excellent level of fitness.

Changes in left ventricular repolarization after short-term testosterone replacement therapy in hypogonadal males

BACKGROUND AND AIM

Evidences suggest that androgen deficiency is associated with sudden cardiac death (SCD). Our purpose was to analyse some electrocardiographic (ECG) markers of repolarization phase in hypogonadal patients either at baseline or after testosterone replacement therapy (TRT).

PATIENTS AND METHODS

Baseline and after 6 months of testosterone replacement therapy, 14 hypogonadal patients and 10 age-matched controls underwent a short-term ECG recordings at rest and immediately after a maximal exercise test. The following ECG parameters have been collected: QTe (the interval between the q wave the end of T wave), QTp (the interval between the q wave and the peak of T wave), and Te (the interval between the peak and the end of T wave).

RESULTS

At baseline, in the hypogonadal patients, corrected QTe and QTp values were longer at rest than in the controls at rest (p < 0.05), whereas, during the recovery phase, only the QTp remained significantly longer (p < 0.05). After TRT, hypogonadal patients showed an improvement only in Te (p < 0.05). Conversely, any difference between hypogonadal patients and control subjects was found with respect to the markers of temporal dispersion of repolarization phases, except for a worse QTp → Te coherence (p = 0.001) obtained during the recovery phase.

CONCLUSIONS

In conclusion, at rest, hypogonadal patients suffer from a stable increase in the myocardial repolarization phase without an increase in its temporal dispersion and, hence, the SCD risk seems to be low.

A systematic review of cardiovascular responses associated with ambient black carbon and fine particulate matter

BACKGROUND

Exposure to fine particulate matter (PM_2.5), an ambient air pollutant with mass-based standards promulgated under the Clean Air Act, and black carbon (BC), a common component of PM_2.5, are both associated with cardiovascular health effects.

OBJECTIVES

To elucidate whether BC is associated with distinct, or stronger, cardiovascular responses compared to PM_2.5, we conducted a systematic review. We evaluated the associations of short- and long-term BC, or the related component elemental carbon (EC), with cardiovascular endpoints including heart rate variability, heart rhythm, blood pressure and vascular function, ST segment depression, repolarization abnormalities, atherosclerosis and heart function, in the context of what is already known about PM_2.5.

DATA SOURCES

We conducted a stepwise systematic literature search of the PubMed, Web of Science and TOXLINE databases and applied Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines for reporting our results.

STUDY ELIGIBILITY CRITERIA

Studies reporting effect estimates for the association of quantitative measurements of ambient BC (or EC) and PM_2.5, with relevant cardiovascular endpoints (i.e. meeting inclusion criteria) were included in the review. Included studies were evaluated for risk of bias in study design and results.

STUDY APPRAISAL AND SYNTHESIS METHODS

Risk of bias evaluations assessed aspects of internal validity of study findings based on study design, conduct, and reporting to identify potential issues related to confounding or other biases. Study results are presented to facilitate comparison of the consistency of associations with PM_2.5 and BC within and across studies.

RESULTS

Our results demonstrate similar associations for BC (or EC) and PM_2.5 with the cardiovascular endpoints examined. Across studies, associations for BC and PM_2.5 varied in their magnitude and precision, and confidence intervals were generally overlapping within studies. Where differences in the magnitude of the association between BC or EC and PM_2.5 within a study could be discerned, no consistent pattern across the studies examined was apparent.

LIMITATIONS

We were unable to assess the independence of the effect of BC, relative the effect of PM_2.5, on the cardiovascular system, nor was information available to understand the impact of differential exposure misclassification.

CONCLUSIONS

Overall, the evidence indicates that both BC (or EC) and PM_2.5 are associated with cardiovascular effects but the available evidence is not sufficient to distinguish the effect of BC (or EC) from that of PM_2.5 mass.

A Comparison of the Effect of Sevoflurane and Propofol on Ventricular Repolarisation after Preoperative Cefuroxime Infusion

The aim of this study is to investigate the changes in QT, QTc, and Tp-e intervals and Tp-e/QT ratio on surface electrocardiogram (ECG) signals during anaesthesia induction using propofol or sevoflurane after preoperative cefuroxime infusion. Some 120 cases of gynaecological patients are randomly divided into propofol (P) and sevoflurane (S) groups (n=60). After cefuroxime (1.5 g) was infused in the two groups of patients, propofol target controlled infusion (TCI) was conducted in the P group for 5 min to realise a plasma concentration of 4 μg/ml while patients in the S group inhaled anaesthesia by infusing 1.3 MAC sevoflurane for 6 min. The 12-lead ECGs were separately collected before infusing cefuroxime (T₁), after infusing cefuroxime (T₂), and after infusing propofol or sevoflurane (T₃) to measure QT and Tp-e intervals, calculate QTc and Tp-e/QT, and record MAP and HR. Finally, we demonstrated that QT, QTc, and Tp-e intervals and Tp-e/QT ratio had no change (P > 0.05) after cefuroxime infusion in the two groups of patients compared with that before infusing antibiotics. Moreover, after conducting preoperative cefuroxime infusion, using propofol and sevoflurane had no influence on Tp-e interval, but sevoflurane can significantly prolong QT and QTc intervals (P < 0.05).

Association between ventricular repolarization variables and cardiac diastolic function: A cross-sectional study of a healthy Chinese population

BACKGROUND

Diastolic electromechanical couple, a well-described phenomenon in symptomatic heart failure, has not been well studied in healthy people. We hypothesized that ventricular repolarization variables, such as the QT interval, Tpeak-to-Tend (Tpe) interval and Tpe/QT ratio, are associated with cardiac diastolic function in the healthy Chinese population.

AIM

To assess the relationship between ventricular repolarization variables and cardiac diastolic function in apparently healthy Chinese individuals.

METHODS

This was a community-based cross-sectional study conducted in Shenyang, China. A total of 414 healthy subjects aged 35-91 years were enrolled. All subjects underwent standard 12-lead electrocardiography (ECG) and comprehensive echocardiography. ECG enabled the measurement of QT and Tpe intervals and Tpe/QT ratio. echocardiographic parameters, such as the ratio of mitral early diastolic inflow velocity (E) and late diastolic inflow velocity (A), E-wave deceleration time, left atrial volume (LAV) and LAV index, were measured to assess diastolic function. E/A < 0.75 was considered to indicate reduced diastolic function. ECG and echocardiography results were analyzed separately and in a blinded fashion. Correlation and regression analyses were applied to determine associations.

RESULTS

Ventricular repolarization variables, such as the QTc interval (393.59 ± 26.74 vs 403.86 ± 33.56; P < 0.001), Tpe interval (72.68 ± 12.41 vs 77.26 ± 17.86; P < 0.01), Tpe_c interval (76.36 ± 13.53 vs 83.32 ± 21.25; P < 0.001) and Tpe/QT ratio (0.19 ± 0.03 vs 0.20 ± 0.04; P < 0.01), were significantly different between the normal diastolic function group and the reduced diastolic function group. Significant associations were found between repolarization variables and diastolic function. After adjusting for all other possible confounders, the QTc and Tpe_c intervals were significantly associated with the E/A ratio (P = 0.008; P = 0.010). In men, the QTc interval was associated with abnormal diastolic function, and compared to the third QTc tertile, in the second QTc tertile, the odds ratio was 0.257 (95%CI: 0.102–0.649; P = 0.004).

CONCLUSION

Repolarization variables are associated with cardiac diastolic function even in healthy people. Moderate levels of the QTc interval exert a protective effect on diastolic dysfunction in men.

Electrocardiographic conduction and repolarization markers associated with sudden cardiac death: moving along the electrocardiography waveform

The QT interval along with its heart rate corrected form (QTc) are well-established ECG markers that have been found to be associated with malignant ventricular arrhythmogenesis. However, extensive preclinical and clinical investigations over the years have allowed for novel clinical ECG markers to be generated as predictors of arrhythmogenesis and sudden cardiac death. Repolarization markers include the older QTc, QT dispersion and newer Tpeak - Tend intervals, (Tpeak - Tend) / QT ratios, T-wave alternans (TWA), microvolt TWA and T-wave area dispersion. Meanwhile, conduction markers dissecting the QRS complex, such as QRS dispersion (QRSD) and fragmented QRS, were also found to correlate conduction velocity and unidirectional block with re-entrant substrates in various cardiac conditions. Both repolarization and conduction parameters can be combined into the excitation wavelength (λ). A surrogate marker for λ is the index of Cardiac Electrophysiological Balance (iCEB: QT / QRSd). Other markers based on conduction-repolarization are [QRSD x (Tpeak-Tend) / QRSd] and [QRSD x (Tpeak-Tend) / (QRSd x QT)]. Advancement in technology permitted sophisticated electrophysiological analyses such as principal component analysis and periodic repolarization dynamics to further improve risk stratification. This was closely followed by other novel indices including ventricular ectopic QRS interval, the f99 index and EntropyXQT, which integrates mathematical and physical calculations for determining the risk markers. Though proven to be effective in limited patient cohorts, more clinical studies across different cardiac pathologies are required to confirm their validity. As such, this review seeks to encapsulate the development of old and new ECG markers along with their associated utility and shortcomings in clinical practice.

Evaluation of index of cardiac-electrophysiological balance before and after hemodialysis in patients with end-stage renal disease

BACKGROUND

Ventricular arrhythmias and sudden cardiac deaths are the most common cause of mortality in patients with end-stage renal disease (ESRD). Index of cardiac-electrophysiological balance (iCEB) (QT/QRS) may predict malignant ventricular arrhythmias. In this study, we investigated whether iCEB value is increased in ESRD patients and whether it changes before and after hemodialysis.

METHODS

The study included 52 ESRD patients and 53 control subjects matched for age and comorbidities. Biochemical, electrocardiographic and echocardiographic values of all participants were recorded. QRS, QT, Tp-e were measured manually. QTC was calculated using Bazett's formula. Then, Tp-e/QT, Tp-e/QTc, QT/QRS, and QTc/QRS ratios were calculated. The changes in ECG parameters of the ESRD patients before and after HD were compared using paired t-test.

RESULTS

Mean age and male sex ratio was comparable in both groups (p = 0.448 and p = 0.777, respectively). Comorbidity incidences, and biochemical parameters except eGFR (p < 0.001), albumin (p < 0.001), HDL cholesterol (p = 0.03) and platelet counts (p < 0.001) were comparable in both groups. Compared to the control group, QT, QTc, Tp-e, Tp-e/QT, Tp-e/QTc, QT/QRS, and QTc/QRS ratios were higher in the ESRD group (p < 0.05 for each). While QT and QTc intervals did not change after HD in ESRD patients, Tp-e, Tp-e/QT, Tp-e/QTc, QT/QRS, and QTc/QRS parameters increased significantly.

CONCLUSION

In addition to ventricular repolarization dispersion indices in ESRD patients, iCEB elevation and increasing values after HD session indicate the increased risk of TdP-mediated ventricular arrhythmia after HD. Larger studies are needed to confirm our results.

The Effect of Lower and Higher Calorie Meal on the Parameters of Ventricular Repolarization in Healthy Subjects

BACKGROUND:

Cardiovascular modulation following meal consumption has been known. Little and conflicting data is present regarding electrocardiographic QT and QTc intervals after a meal, and status of ventricular repolarization following meal is not known comprehensively.

AIM:

To inquire the electrocardiographic status of ventricular repolarisation thoroughly after lower and higher calorie meal consumption in a comparative manner.

METHODS:

A group of 61 healthy individuals were studied before and after lunch. They were divided into two groups according to the calorie consumed (higher calorie and lower calorie; median 1580 and 900 kcals, respectively). Calorie consumed was estimated using dietary guidelines. Data was collected from 12-lead ECG both in a fasted state and 2nd postprandial hour for each participant. Parameters of ventricular repolarization, namely, JTp, Tp-e, QT, QTc intervals and their ratios, as well as RR intervals, were compared between fasted and postprandial states for every participant.

RESULTS:

Tp-e and QTc intervals, and Tp-e/QTc ratio do not significantly change after both higher- and lower-calorie meals. JTp and QT intervals significantly shorten in both groups, regardless of the calorie consumed. While JTp shows a positive correlation with RR interval both before and after a meal in lower calorie intake group, no correlation was found with RR interval after a meal in higher calorie group. Logistic regression analysis revealed that higher calorie intake during a meal is a predictor for greater shortening in JTp and QT, compared to lower calorie meal.

CONCLUSION:

Our study may guide future studies on ventricular repolarisation, particularly those conducted on various disease conditions or drug effect of cardiac electrophysiology.

Investigation of the Proarrhythmic Effects of Antidepressants according to QT Interval, QT Dispersion and T Wave Peak-to-End Interval in the Clinical Setting

OBJECTIVE

Some antidepressants have been implicated as risk factors for QT prolongation, which is a predictor of sudden cardiac death. However, the QT interval is considered an imperfect biomarker for proarrhythmic risk. Therefore, we reevaluated the risk of sudden cardiac death due to antidepressants using improved.

METHODS

, namely, QT dispersion (QTD), T wave peak-to-end interval (Tp-e), and Tp-e/QT ratio.

METHODS

We compared the effects of antidepressants on QTc (QT/RR1/3), QTD, Tp-e, and Tp-e/QT ratio in 378 patients with mood disorder. We also compared each index between 165 healthy controls and 215 randomly selected age-matched patients.

RESULTS

Age (p<0.01), sex (p<0.05), tricyclic antidepressant (TCA) use (p<0.05), and clomipramine (p<0.01) and mianserin (p<0.05) use in particular, significantly associated with a prolonged QTc. We also found that age (p<0.01), TCA use (p<0.05), and clomipramine (p<0.01) and mianserin (p<0.05) use in particular, significantly prolonged QTD. However, there was no correlation between each variable and Tp-e or Tp-e/QT ratio. Significant differences in QTc and QTD were found between the patients and healthy controls.

CONCLUSION

From our results, prediction of risk of sudden cardiac death by QTD, Tp-e, or Tp-e/QT ratio was inconsistent. Increased QTD may be more suitable for predicting sudden cardiac death due to antidepressants.

Evaluation of electrocardiographic ventricular repolarization parameters in extreme obesity

BACKGROUND AND OBJECTIVES

The risk of sudden death and cardiac arrhythmia increases in morbidly obese patients. We aimed to evaluate the marker of arrhythmias such as Tp-e/QT, Tp-e/QTc, Tp-e/JT and Tp-e/JTc ratios in extreme obesity.

METHODS

The study included 41 extremely obese patients and 41 control subjects. QTmax, QTmin, QRS, JT and Tp-e intervals were measured od 12‑lead electrocardiographies. In addition, Tp-e/QT, Tp-e/QTc, Tp-e/JT and Tp-e/JTc rates and QTc, cQTd and JTc intervals were calculated.

RESULTS

Tp-e interval (79.2 ± 9.7 ms (milisecond) vs. 68.6 ± 8.1, p < 0.001), QTc interval (395.9 ± 18.8 vs. 377.9 ± 19.3 ms, p < 0.001), JTc interval (317.1 ± 27.0 vs. 297.4 ± 23.2 ms, p = 0.001), Tp-e/QT ratio (0.22 ± 0.03vs. 0.19 ± 0.02, p < 0.001), Tp-e/QTc ratio (0.20 ± 0.26vs. 0.18 ± 0.02, p = 0.001), Tp-e/JT ratio (0.29 ± 0.04 vs. 0.25 ± 0.03, p < 0.001), TPe/JTc ratio (0.25 ± 0.04 vs. 0.23 ± 0.03, p = 0.018), QTd (32.8 ± 10 vs.15 ± 6.4 ms, p < 0.001) and cQTd (70.0 ± 30.1 vs. 31.3 ± 22.4 ms, p < 0.001) were significantly higher in obese patients.

CONCLUSION

Compared to healthy subjects potential ECG repolarization predictors were significantly increased in extremely obese patients.

Higher Dispersion Measures of Conduction and Repolarization in Type 1 Compared to Non-type 1 Brugada Syndrome Patients: An Electrocardiographic Study From a Single Center

Background: Brugada syndrome (BrS) is a cardiac ion channelopathy that predisposes affected individuals to sudden cardiac death (SCD). Type 1 BrS is thought to take a more malignant clinical course than non-type 1 BrS. We hypothesized that the degrees of abnormal repolarization and conduction are greater in type 1 subjects and these differences can be detected by electrocardiography (ECG). Methods: Electrocardiographic data from spontaneous type 1 and non-type 1 BrS patients were analyzed. ECG parameters were measured from leads V1 to V3. Values were expressed as median [lower quartile-upper quartile] and compared using Kruskal-Wallis ANOVA. Results: Compared to non-type 1 BrS patients (n = 29), patients with spontaneous type 1 patterns (n = 22) showed similar (P > 0.05) heart rate (73 [64-77] vs. 68 [62-80] bpm), QRS duration (136 [124-161] vs. 127 [117-144] ms), uncorrected QT (418 [393-443] vs. 402 [386-424] ms) and corrected QT intervals (457 [414-474] vs. 430 [417-457] ms), JTpeak intervals (174 [144-183] vs. 174 [150-188] ms), Tpeak- Tend intervals (101 [93-120] vs. 99 [90-105] ms), Tpeak- Tend/QT ratios (0.25 [0.23-0.27] vs. 0.24 [0.22-0.27]), Tpeak- Tend/QRS (0.77 [0.62-0.87] vs. 0.77 [0.69-0.86]), Tpeak- Tend/(QRS × QT) (0.00074 [0.00034-0.00096] vs. 0.00073 [0.00048-0.00012] ms-1), index of Cardiac Electrophysiological Balance (iCEB, QT/QRS, marker of wavelength: 3.14 [2.56-3.35] vs. 3.21 [2.85-3.46]) and corrected iCEB (QTc/QRS: 3.25 [2.91-3.73] vs. 3.49 [2.99-3.78]). Higher QRS dispersion was seen in type 1 subjects (QRSd: 34 [24-66] vs. 24 [12-34] ms) but QT dispersion (QTd: 48 [39-71] vs. 43 [22-94] ms), QTc dispersion (QTcd: 52 [41-79] vs. 46 [23-104] ms), JTpeak dispersion (44 [23-62] vs. 45 [30-62] ms), Tpeak- Tend dispersion (28 [15-34] vs. 29 [22-53] ms) or Tpeak- Tend/QT dispersion (0.06 [0.03-0.08] vs. 0.08 [0.04-0.12]) did not differ between the two groups. Type 1 subjects showed higher (QRSd × Tpeak- Tend)/QRS (25 [19-44] vs. 19 [9-30] ms) but similar iCEB dispersion (0.83 [0.49-1.14] vs. 0.61 [0.34-0.92]) and iCEBc dispersion (0.93 [0.51-1.15] vs. 0.65 [0.39-0.96]). Conclusion: Higher levels of dispersion in conduction and repolarization are found in type 1 than non-type 1 BrS patients, potentially explaining the higher incidence of ventricular arrhythmias in the former group.

The effect of revascularization of a chronic total coronary occlusion on electrocardiographic variables. A sub-study of the EXPLORE trial

INTRODUCTION

Chronic total coronary occlusions (CTOs) have been associated with a higher prevalence of ventricular arrhythmias compared to patients without a CTO. We evaluated the effect of CTO revascularization on electrocardiographic (ECG) variables.

METHODS

We studied a selection of ST-elevation myocardial infarction patients with a concomitant CTO enrolled in the EXPLORE trial. ECG variables and cardiac function were analysed at baseline and at 4 months follow-up.

RESULTS

Patients were randomized to percutaneous coronary intervention (PCI) of their CTO (n = 77) or to no-CTO PCI (n = 81). At follow-up, median QT dispersion was significantly lower in the CTO PCI group compared to the no-CTO PCI group (46 ms [33-58] vs. 54 ms [37-68], P = 0.043). No independent association was observed between ECG variables and cardiac function.

CONCLUSION

Revascularization of a CTO after STEMI significantly shortened QT dispersion at 4 months follow-up. These findings support the hypothesis that CTO revascularization reduces the pro-arrhythmic substrate in CTO patients.

Traditional and novel electrocardiographic conduction and repolarization markers of sudden cardiac death

Sudden cardiac death, frequently due to ventricular arrhythmias, is a significant problem globally. Most affected individuals do not arrive at hospital in time for medical treatment. Therefore, there is an urgent need to identify the most-at-risk patients for insertion of prophylactic implantable cardioverter defibrillators. Clinical risk markers derived from electrocardiography are important for this purpose. They can be based on repolarization, including corrected QT (QTc) interval, QT dispersion (QTD), interval from the peak to the end of the T-wave (Tpeak - Tend), (Tpeak - Tend)/QT, T-wave alternans (TWA), and microvolt TWA. Abnormal repolarization properties can increase the risk of triggered activity and re-entrant arrhythmias. Other risk markers are based solely on conduction, such as QRS duration (QRSd), which is a surrogate marker of conduction velocity (CV) and QRS dispersion (QRSD) reflecting CV dispersion. Conduction abnormalities in the form of reduced CV, unidirectional block, together with a functional or a structural obstacle, are conditions required for circus-type or spiral wave re-entry. Conduction and repolarization can be represented by a single parameter, excitation wavelength (λ = CV × effective refractory period). λ is an important determinant of arrhythmogenesis in different settings. Novel conduction-repolarization markers incorporating λ include Lu et al.' index of cardiac electrophysiological balance (iCEB: QT/QRSd), [QRSD× (Tpeak - Tend)/QRSd] and [QRSD × (Tpeak - Tend)/(QRSd × QT)] recently proposed by Tse and Yan. The aim of this review is to provide up to date information on traditional and novel markers and discuss their utility and downfalls for risk stratification.

Index of cardiac electrophysiological balance and transmural dispersion of the repolarization index relationships with pericardial fat volume and coronary calcification

AIM

To assess the possible relationship between coronary atherosclerosis markers, pericardial fat volume (PFV) and coronary artery calcification, with ECG markers of index of the cardiac electrophysiological balance (iCEB) and transmural dispersion of the repolarization in patients with suspected coronary artery disease.

METHODOLOGY

One hundred patients who underwent 64-slice multidetector computed tomography angiography were found to be eligible and were enrolled in the study.

RESULTS

Patients with high iCEB levels tended to have a higher PFV values compared with patients with low iCEB levels (median [interquartile range]) (152 [29-206] vs 96 [14-177]; p = 0.03). No significant differences in coronary artery calcification values were observed between iCEB and transmural dispersion of the repolarization groups.

CONCLUSION

A higher PFV value was observed in patients with high iCEB. Larger prospective studies are required to confirm the results.

Evaluation of Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio in patients with mitral valve stenosis before and after balloon valvuloplasty

Objective:

Sympathetic activity increases in patients with mitral stenosis (MS). The association between prolonged Tpeak-Tend (Tp-e) interval and increased sympathetic activity has been demonstrated. This study aimed to evaluate Tp-e interval, Tp-e/QT ratio, and Tp-e/corrected QT interval (QTc) ratio in patients with MS before and after balloon valvuloplasty.

Methods:

Thirty patients with severe MS and 30 sex-, body mass index-, and and age-matched healthy control subjects were enrolled. The severity of MS was defined following clinical, transthoracic, and transesophageal echocardiographic examinations. All patients underwent successful mitral balloon valvuloplasty. Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios were measured using 12-lead electrocardiogram. First, the abovementioned parameters were compared between patients with MS and healthy control subjects. Second, these parameters were compared before and after balloon valvuloplasty in patients with MS.

Results:

The mean Tp-e interval was significantly prolonged in patients with MS compared with healthy control subjects (85.02±9.12 ms vs. 75.38±6.04 ms; p<0.001). In addition, Tp-e/QT ratio and Tp-e/QTc ratio were significantly higher in patients with MS than in healthy control subjects (0.217±0.025 vs. 0.196±0.02 and 0.203±0.02 vs. 0.184±0.019; p<0.001).The mean valve area significantly increased after balloon valvuloplasty compared with that before balloon valvuloplasty (1.83±0.32 cm² vs. 1.18±0.15 cm²; p<0.001). Compared with those before balloon valvuloplasty, Tp-e interval (85.02±9.12 ms vs. 78.06±9.2 ms; p<0.001), Tp-e/QT ratio (0.217±0.02 vs. 0.201±0.02; p<0.001), and Tp-e/QTc ratio (0.203±0.02 vs. 0.184±0.02; p<0.001) decreased after balloon valvuloplasty.

Conclusion:

We revealed that Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio increased in patients with severe MS. Furthermore, balloon valvuloplasty had a favorable effect on parameters associated with myocardial repolarization.

Effect of sodium-glucose co-transporter-2 inhibitors on impaired ventricular repolarization in people with Type 2 diabetes

AIMS

To test the hypothesis that treatment with a sodium-glucose co-transporter-2 inhibitor would reverse ventricular repolarization heterogeneity, a predictor of cardiovascular mortality, in people with Type 2 diabetes.

METHODS

We retrospectively analysed changes in indices of ventricular repolarization before and after treatment with a sodium-glucose co-transporter-2 inhibitor in 46 people with Type 2 diabetes.

RESULTS

Sodium-glucose co-transporter-2 inhibitor treatment reduced HbA_1c concentration [62±13 mmol/mol (7.7±1.2%) vs 59±16 mmol/mol (7.5±1.4%)], body weight (77.8±13.9 vs 74.7±12.5 kg) and systolic blood pressure (133±18 vs 126±12 mmHg) in the study participants. Heart rate and QTc interval were not changed by sodium-glucose co-transporter-2 inhibitor treatment, but QTc dispersion was significantly reduced (median, 48.8 vs 44.2 ms). Sodium-glucose co-transporter-2 inhibitor treatment reversed QTc dispersion more in participants who had larger QTc dispersion before the treatment. Changes in systolic blood pressure (Spearman's ρ= 0.319; P=0.031), but not in HbA_1c concentration, were correlated with changes in QTc dispersion after sodium-glucose co-transporter-2 inhibitor treatment.

CONCLUSIONS

The findings suggest that sodium-glucose co-transporter-2 inhibitor treatment reverses ventricular repolarization heterogeneity in people with Type 2 diabetes, independently of its effect on glycaemic control. The favourable effect on ventricular repolarization heterogeneity could be the mechanism by which empaglifozin reduced cardiovascular events in a recent study.

Low Iron Stores in Otherwise Healthy Children Affect Electrocardiographic Markers of Important Cardiac Events

Both an excess of iron and iron deficiency (ID) may lead to significant cardiac problems. Parameters that represent ventricular repolarization heterogeneity, like QT dispersion (QTd), corrected QT dispersion (QTcd), the interval between the peak and the end of the T wave (Tp-e), and Tp-e dispersion, have not been evaluated in otherwise healthy children with low iron levels before. Here we assessed the effects of low iron storage on P wave dispersion (PWd), QTd, Tp-e intervals, and Tp-e dispersion in otherwise healthy children. We prospectively reviewed 283 patients who were referred to pediatric cardiology department for cardiac evaluation due to murmurs and who were found to have no structural heart disease. The patients were divided into three groups according to their ferritin levels: Group 1: ferritin <15 ng/mL (n = 58); Group 2: ferritin 15-25 ng/mL (n = 80); Group 3: ferritin >25 ng/mL (n = 145). P wave duration (PW), QT and Tp-e intervals, and PW, QT, corrected QT (QTc), and Tp-e dispersions were significantly higher in patients whose ferritin level was <15 ng/mL. A negative correlation was found between ferritin level and QT and QTc intervals, and QT, QTc, and Tp-e dispersions. Our results showed that a low serum ferritin level is associated with changes in some ECG parameters such as prolonged PWd, Tp-e interval, QT, QTc, and Tp-e dispersions in otherwise healthy children, and studies of other populations indicated that these parameters may predict arrhythmias in selected patients. These patients may be considered at some risk of developing arrhythmias. Therefore, careful evaluation of these ECG parameters is necessary in otherwise healthy children with low iron stores.

Subclinical ventricular repolarization abnormality in uncontrolled compared with controlled treated hypertension

Background

Antihypertensive medications have variable effects on the duration of the QT interval. This study aims to demonstrate the subclinical ventricular conduction defect in treating hypertensive patients taking in consideration the status of the blood pressure control with the antihypertensive agents.

Methods

This cross-section study was performed at the Departments of Physiology and Pharmacology, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq. A total number of 97 hypertensive patients (30 males and 67 females) were eligible to enroll in the study. The patients were grouped into controlled hypertension (Group I) and uncontrolled hypertension (Group II). Each participant is subjected to the electrocardiograph (ECG) investigation. A QT nomogram plot used to identify the patients who are vulnerable or at risk of developing cardiac arrhythmias.

Results

There were no significant differences in the values of the electrocardiogram determinants between Group I and Group II. Abnormal prolonged QTcB interval observed in 18 out of 80 (22.5%) patients of Group II compared with 4 out of 17. The JT index value of ≥112 was observed in 20 out of 80 (25%) patients of Group II compared with 6 out of 17 (35.3%) patients of Group I. A significant correlation between the QTcB duration with JT index observed in both Groups I and II.

Conclusion

Patients with hypertension have variability in ventricular repolarization (QTcB and JT) irrespective of their blood pressure control putting them at higher risk of cardiac arrhythmias.

Age- and sex-based reference ranges for non-invasive ventricular repolarisation parameters

BACKGROUND

Some electrocardiographic parameters are able to assess indirectly ventricular repolarisation homogeneity. It is consequently essential to discriminate between normal and abnormal values in clinical decision-making. Considering there is still not a consensus about normal cut-off values, the aim of this study was to document reference intervals in all age groups of a healthy population, providing for age- and sex-percentile tables, which can be used easily and quickly in clinical practice.

METHODS

We evaluated repolarisation markers in 606 sex-matched participants aged 1 day-94 years. Each subject underwent a 12-lead electrocardiogram at rest, and the following parameters were measured: QT, corrected QT, QTpeak, Tpeak-Tend, Tpeak-Tend dispersion, Tpeak-Tend/QT and QTpeak/QT ratio.

RESULTS

A relationship was demonstrated between age and QTpeak, Tpeak-Tend, QT and QTc. In children, QTpeak, Tpeak-Tend and QT intervals increased linearly with age. In adolescents, all the three parameters remained stable. In adults, QTpeak and QT showed a further significant increase. On the contrary, Tpeak-Tend interval was longer in adults aged between 20 and 64 years than in participants aged 65 years or over, but the difference was not statistically significant. Male vs female participants showed longer Tpeak-Tend intervals; this sex difference was not statistically significant at birth and during childhood, whereas it was in adolescents and in adults.

CONCLUSIONS

Repolarisation parameters showed age- and sex-based variations, which are important to know to differentiate normal from pathological values.

QRS duration and dispersion for predicting ventricular arrhythmias in early stage of acute myocardial infraction

OBJECTIVE

To determine the relationship between QRS duration and dispersion and the occurrence of ventricular arrhythmias in early stages of acute myocardial infarction (AMI).

DESIGN

A retrospective, longitudinal descriptive study was carried out.

SETTING

Hospital General Universitario "Camilo Cienfuegos", Sancti Spíritus, Cuba. Secondary health care.

PATIENTS OR PARTICIPANTS

A total of 209 patients diagnosed with ST-segment elevation AMI from January 2012 to June 2014.

MAIN VARIABLES OF INTEREST

The duration and dispersion of the QT interval, corrected QT interval, and QRS complex were measured in the first electrocardiogram performed at the hospital. The presence of ventricular tachycardia/fibrillation was assessed during follow-up (length of hospital stay).

RESULTS

Arrhythmias were found in 46 patients (22%); in 25 of them (15.9%), arrhythmias originated in ventricles, and were more common in those subjects with extensive anterior wall AMI, which was responsible for 81.8% of the ventricular fibrillations and more than half (57.1%) of the ventricular tachycardias. The widest QRS complexes (77.3±13.3 vs. 71.5±6.4ms; P=.029) and their greatest dispersion (24.1±16.2 vs. 16.5±4.8ms; P=.019) were found on those leads that explore the regions affected by ischemia. The highest values of all measurements were found in extensive anterior wall AMI, with significant differences: QRS 92.3±18.8ms, QRS dispersion 37.9±23.9ms, corrected QT 518.5±72.2ms, and corrected QT interval dispersion 94.9±26.8ms. Patients with higher QRS dispersion values were more likely to have ventricular arrhythmias, with cutoff points at 23.5ms and 24.5ms for tachycardia and ventricular fibrillation, respectively.

CONCLUSIONS

Increased QRS duration and dispersion implied a greater likelihood of ventricular arrhythmias in early stages of AMI than increased duration and dispersion of the corrected QT interval.

Long-Term Antiarrhythmic Effects of Thrombolytic Therapy in Pulmonary Embolism

BACKGROUND

The role of thrombolytic therapy in acute pulmonary embolism patients is still controversial considering the occurrence of arrhythmias. Short-term effects of thrombolytics are well-known whereas long-term effects on cardiac electrophysiology have not been reported before. The objective of our study was to assess the arrhythmic differences in pulmonary embolism patients who received thrombolytics followed by anticoagulation or anticoagulation alone.

METHODS

Sixty patients who received thrombolytic therapy followed by anticoagulation (group 1) and 60 patients who received anticoagulation alone (group 2) were included in this retrospective, single-centre observational study. Twenty-four-hour ambulatory electrocardiography was performed 31 ± 9 months after pulmonary embolism hospitalisation in order to compare arrhythmias originating from both ventricles and atria.

RESULTS

The age and gender distribution of the patients were statistically similar. Ventricular arrhythmias were found to be the same between t-PA and non t-PA groups. All types of atrial arrhythmias were found to be increased in non t-PA group even though left and right atrial volume indexes were statistically identical between the two groups.

CONCLUSION

In long-term pulmonary embolism, follow-up thrombolytic therapy was demonstrated to have atrial antiarrhythmic effects.

Proposed pathophysiologic framework to explain some excess cardiovascular death associated with ambient air particle pollution: Insights for public health translation

The paper proposes a pathophysiologic framework to explain the well-established epidemiological association between exposure to ambient air particle pollution and premature cardiovascular mortality, and offers insights into public health solutions that extend beyond regulatory environmental protections to actions that can be taken by individuals, public health officials, healthcare professionals, city and regional planners, local and state governmental officials and all those who possess the capacity to improve cardiovascular health within the population. The foundation of the framework rests on the contribution of traditional cardiovascular risk factors acting alone and in concert with long-term exposures to air pollutants to create a conditional susceptibility for clinical vascular events, such as myocardial ischemia and infarction; stroke and lethal ventricular arrhythmias. The conceptual framework focuses on the fact that short-term exposures to ambient air particulate matter (PM) are associated with vascular thrombosis (acute coronary syndrome, stroke, deep venous thrombosis, and pulmonary embolism) and electrical dysfunction (ventricular arrhythmia); and that individuals having prevalent heart disease are at greatest risk. Moreover, exposure is concomitant with changes in autonomic nervous system balance, systemic inflammation, and prothrombotic/anti-thrombotic and profibrinolytic-antifibrinolytic balance. Thus, a comprehensive solution to the problem of premature mortality triggered by air pollutant exposure will require compliance with regulations to control ambient air particle pollution levels, minimize exposures to air pollutants, as well as a concerted effort to decrease the number of people at-risk for serious clinical cardiovascular events triggered by air pollutant exposure by improving the overall state of cardiovascular health in the population. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.

Transgenic rabbit models to investigate the cardiac ion channel disease long QT syndrome

Long QT syndrome (LQTS) is a rare inherited channelopathy caused mainly by different mutations in genes encoding for cardiac K(+) or Na(+) channels, but can also be caused by commonly used ion-channel-blocking and QT-prolonging drugs, thus affecting a much larger population. To develop novel diagnostic and therapeutic strategies to improve the clinical management of these patients, a thorough understanding of the pathophysiological mechanisms of arrhythmogenesis and potential pharmacological targets is needed. Drug-induced and genetic animal models of various species have been generated and have been instrumental for identifying pro-arrhythmic triggers and important characteristics of the arrhythmogenic substrate in LQTS. However, due to species differences in features of cardiac electrical function, these different models do not entirely recapitulate all aspects of the human disease. In this review, we summarize advantages and shortcomings of different drug-induced and genetically mediated LQTS animal models - focusing on mouse and rabbit models since these represent the most commonly used small animal models for LQTS that can be subjected to genetic manipulation. In particular, we highlight the different aspects of arrhythmogenic mechanisms, pro-arrhythmic triggering factors, anti-arrhythmic agents, and electro-mechanical dysfunction investigated in transgenic LQTS rabbit models and their translational application for the clinical management of LQTS patients in detail. Transgenic LQTS rabbits have been instrumental to increase our understanding of the role of spatial and temporal dispersion of repolarization to provide an arrhythmogenic substrate, genotype-differences in the mechanisms for early afterdepolarization formation and arrhythmia maintenance, mechanisms of hormonal modification of arrhythmogenesis and regional heterogeneities in electro-mechanical dysfunction in LQTS.

Novel indexes of arrhythmogenesis in preeclampsia: QT dispersion, Tp-e interval, and Tp-e/QT ratio

OBJECTIVE

There is increasing evidence that preeclampsia (PE) may also be a risk factor for future cardiovascular diseases (CVDs), including arrhythmia. In this study we aimed to evaluate the association between PE and ventricular repolarization using novel electrocardiogram markers: QT interval duration, Tp-e interval, and Tp-e/QT ratio.

MATERIALS AND METHODS

In this controlled cross-sectional study sixty-four pregnant women with PE (31 with mild and 33 with severe disease) and 32 healthy women with uncomplicated pregnancies in the third trimester were compared by measuring QT parameters, Tp-e interval, and Tp-e/QT ratio.

RESULTS

Tp-e interval and Tp-e/QT ratio values were significantly higher in both the mild and severe PE groups compared to the healthy pregnant group.

CONCLUSION

Prevention of CVD requires that patients be aware of their risk factors, be educated about their risk, and perhaps most importantly perceive them to be at risk. In this study, we documented that PE has a significant effect on ventricular repolarization. This alteration could, in part, explain the increased cardiovascular risk in women with a history of PE. This important association can be used to screen women for increased risk in order to better target counseling regarding lifestyle modifications and to follow up and manage women with a history of hypertensive disease of pregnancy more closely.

Electro-mechanical dysfunction in long QT syndrome: Role for arrhythmogenic risk prediction and modulation by sex and sex hormones

Long QT syndrome (LQTS) is a congenital arrhythmogenic channelopathy characterized by impaired cardiac repolarization. Increasing evidence supports the notion that LQTS is not purely an "electrical" disease but rather an "electro-mechanical" disease with regionally heterogeneously impaired electrical and mechanical cardiac function. In the first part, this article reviews current knowledge on electro-mechanical (dys)function in LQTS, clinical consequences of the observed electro-mechanical dysfunction, and potential underlying mechanisms. Since several novel imaging techniques - Strain Echocardiography (SE) and Magnetic Resonance Tissue Phase Mapping (TPM) - are applied in clinical and experimental settings to assess the (regional) mechanical function, advantages of these non-invasive techniques and their feasibility in the clinical routine are particularly highlighted. The second part provides novel insights into sex differences and sex hormone effects on electro-mechanical cardiac function in a transgenic LQT2 rabbit model. Here we demonstrate that female LQT2 rabbits exhibit a prolonged time to diastolic peak - as marker for contraction duration and early relaxation - compared to males. Chronic estradiol-treatment enhances these differences in time to diastolic peak even more and additionally increases the risk for ventricular arrhythmia. Importantly, time to diastolic peak is particularly prolonged in rabbits exhibiting ventricular arrhythmia - regardless of hormone treatment - contrasting with a lack of differences in QT duration between symptomatic and asymptomatic LQT2 rabbits. This indicates the potential added value of the assessment of mechanical dysfunction in future risk stratification of LQTS patients.