Dispersion of ventricular repolarization: Temporal and spatial

The Role of Ranolazine in the Treatment of Ventricular Tachycardia and Atrial Fibrillation: A Narrative Review of the Clinical Evidence

Cardiac arrhythmias are among the leading causes of morbidity and mortality worldwide. While antiarrhythmic drugs traditionally represent the first-line management strategy, their use is often limited by profound proarrhythmic effects. Several studies, including randomized control trials (RCTs), have demonstrated the antiarrhythmic efficacy of ranolazine, which is registered as an antianginal agent, while also establishing its safety profile. This review compiles clinical evidence investigating the antiarrhythmic properties of ranolazine, focusing primarily on ventricular tachycardia (VT) and atrial fibrillation (AF), as they are common rhythm abnormalities with serious complications. Data from RCTs indicate that ranolazine reduces VT incidence, although this effect is not universal. Therefore, we attempt to better describe the patient population that gains the most benefit from ranolazine due to VT suppression. Additionally, ranolazine is known to enhance the conversion rate of AF to sinus rhythm when combined with other antiarrhythmic drugs such as amiodarone, highlighting its synergistic effect in the atrium without provoking ventricular dysrhythmias. Despite the heterogeneity in the currently available data, ranolazine appears to be an effective and safe option for the management of various arrhythmias.

Effect of long-term use of antipsychotics on the ventricular repolarization index

BACKGROUND

The risk of arrhythmia is usually assessed by the length of the corrected QT interval (QTc) when patients use antipsychotics. Prolonged QTc intervals are thought to increase the probability of malignant ventricular arrhythmias, and if we focus only on the QTc interval, we may be influenced by a single factor and make decisions that are not conducive to effective treatment. The index of cardiac electrophysiological balance (iCEB) is considered more valuable than the QTc for predicting drug-induced arrhythmias. It has been used in clinical practice, but no studies have observed changes in this index after the use of antipsychotics.

OBJECTIVE

To investigate the changes in ventricular repolarization indices and the occurrence of arrhythmias in patients who have been using antipsychotic drugs for a long time, to compare the changes in iCEBc and QTc and to predict abnormal iCEBc values.

METHODS

Patients with schizophrenia who had been hospitalized for more than 4 years and who were receiving atypical antipsychotics underwent a 12-lead synchronized electrocardiogram (ECG) every 2-4 weeks. The baseline data were measured at admission, defined as the baseline (time0), and the most obvious abnormal changes in ventricular depolarization and repolarization measured every 12 months were one-year follow-up (time1), two-year follow-up (time2), three-year follow-up (time3), and four-year follow-up (time4). Repeated measures analysis of variance was used for comparisons. The types and doses of drugs taken at 5 time points were recorded and converted into chlorpromazine equivalents for comparison. The incidence of arrhythmia during the observation cycle was recorded.

RESULTS

The patients had been treated with antipsychotic medication for 4 years, and the duration of the QRS wave was longer in males than in females. TpTe, TpTe/QRS, TpTe/QT, TpTe/QTc, iCEB, and iCEBc increased significantly with hospital stay, while TpTe, TpTe/QRS, TpTe/QT, and TpTe/QTc exhibited more obvious changes in these indicators in female patients (P < 0.01). The changes in iCEB and iCEBc were more significant in males (P < 0.01). The incidences of arrhythmia (arrhythmic events included premature ventricular beats and premature atrial beats) within 5 time points were 2.5%, 6.25%, 6.25%, 6.25% and 5%, respectively. More than 90% of patients treated with antipsychotics did not have any arrhythmias. No TdP syncope or other cardiovascular symptoms were found in any of the patients.

CONCLUSION

After long-term use of antipsychotics, the ventricular repolarization index gradually increased with time. The new ventricular repolarization indices iCEB and iCEBc were more sensitive than the QTc at predicting arrhythmia. According to the abnormal QTc values in men and women, we predict that the abnormal value of the iCEBc in males is 4.528 and that in females is 5.315.

Evaluation of cardiac electrophysiological features in patients with premature adrenarche

OBJECTIVES

This study aimed to analyze the cardiac effects of hyperandrogenism in premature adrenarche (PA) and evaluate the risk of arrhythmia development.

METHODS

Fifty patients with PA and 50 healthy children from a pediatric endocrinology outpatient clinic were included in the study. The patients underwent echocardiography and electrocardiographic evaluations. Conventional echocardiography, tissue Doppler echocardiography, repolarization time, and repolarization dispersion time were evaluated.

RESULTS

The median age in the PA and control groups was 7.91 years (5.83-9.25), 8.08 years (5.75-9.33), respectively. Thirty percent of patients in the PA group were male. While mitral early diastolic velocity deceleration time (DT), isovolumetric relaxation time (IRT), and E/e' ratio were significantly higher in the PA group than in the control group, mitral lateral annulus tissue Doppler early diastolic velocity was significantly lower (p=0.0001, 0.0001, 0.003, 0.0001). While P wave dispersion (PWD), Tpe, and QT-dispersion (QT-d) values were significantly higher in the PA group than in the control group, the P minimum value was significantly lower in the PA group (p=0.0001, 0.02, 0.004, and 0.0001, respectively).

CONCLUSIONS

Early subclinical diastolic dysfunction was observed in the PA group. There was an increased risk of atrial arrhythmia with PWD and an increased risk of ventricular arrhythmia with increased Tpe and QT-d. There was a correlation between testosterone levels and diastolic function parameters. The increased risk of atrial arrhythmia is closely related to diastolic function.

Modeling ventricular repolarization gradients in normal cases using the equivalent dipole layer

Background Electrical activity underlying the T-wave is less well understood than the QRS-complex. This study investigated the relationship between normal T-wave morphology and the underlying ventricular repolarization gradients using the equivalent dipole layer (EDL). Methods Body-surface-potential-maps (BSPM, 67‑leads) were obtained in nine normal cases. Subject specific MRI-based anatomical heart/torso-models with electrode positions were created. The boundary element method was used to account for the volume conductor effects. To simulate the measured T-waves, the EDL was used to apply different ventricular repolarization gradients: a) transmural, b) interventricular c) apico-basal and d) all three gradients (a-c) combined. The combined gradient (d) was optimized using an inverse procedure (Levenberg-Marquardt). Correspondence between simulated and measured T-waves was assessed using correlation coefficient (CC) and relative difference (RD). Results Realistic T-waves were simulated if repolarization times of: (a) the epicardium were smaller than the endocardium; (b) the left ventricle were smaller than the right ventricle and (c) the apex increased towards the base. The apico-basal gradient resulted in the highest correspondence between measured and simulated T-waves (CC = 0.84(0.81-0.91);RD = 0.68(0.60-0.71)) compared to a transmural gradient (CC = 0.77(0.71-0.80);RD = 1.46(0.82-1.75)) and an interventricular gradient (CC = 0.71(0.67-0.80);RD = 0.85(0.75-0.87)). All three gradients combined further improved the correspondence between measured and simulated T-waves (CC = 0.83(0.82-0.89);RD = 0.60(0.51-0.63)), especially after optimization (CC = 0.96(0.94-0.98);RD = 0.27(0.22-0.34)). Conclusion The application of all repolarization gradients combined resulted in the largest agreement between simulated and measured T-waves, followed by the apico-basal repolarization gradient. With these findings, we will optimize our EDL-based inverse procedure to assess repolarization abnormalities.

Evaluation of Tp-e interval and Tp-e/QTc ratio in patients with inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD), a multisystemic inflammatory disorder, has been associated with increased risk of cardiovascular problems, including complications such as conduction defects and arrhythmias. Therefore, the early assessment of the risk factors predisposing to ventricular arrhythmias is crucial, since it can improve clinical outcomes. The objective of the present study is to evaluate ventricular repolarization by using Tp‑e interval and Tp-e/QTc ratio as candidate markers of ventricular arrhythmias in patients with IBD.

METHODS

The presented study was designed as a single-center prospective cohort study. The study population consisted of 175 patients with IBD and 175 healthy volunteers. The Tp‑e interval, corrected QT (QTc), and Tp-e/QTc ratio were measured from the 12-lead electrocardiogram. These parameters were compared between groups.

RESULTS

The groups were similar in terms of electrocardiographic findings such as heart rate, QRS interval, and QTc interval. However, Tp‑e interval (87.0 ms, interquartile range, IQR 81.0-105.0 ms vs. 84.0 ms, IQR 74.0-92.0 ms; p < 0.001) and Tp-e/QTc ratio (0.21 ± 0.04 vs. 0.19 ± 0.05; p < 0.001) were significantly increased in IBD patient group compared to control group. Notably, a positive correlation was demonstrated between Tp‑e interval, Tp-e/QTc ratio and disease duration (Spearman's Rho = 0.36, p < 0.001 for Tp‑e; Spearman's Rho = 0.28, p < 0.001 for Tp-e/QTc).

CONCLUSION

This study demonstrated that IBD patients are at increased risk of disrupted ventricular repolarization (increased Tpe, Tpe/QTc ratio). In addition, a positive correlation was demonstrated between Tp‑e interval, Tp-e/QTc ratio, and disease duration. Therefore, IBD patients, especially those with long-standing diseases, should be more closely screened for ventricular arrhythmias.

Initial and terminal T wave angle as hyperkalemia indicator in chronic kidney disease

BACKGROUND

Hyperkalemia is one prevalent complication in chronic kidney disease and is considered fatal since it potentially causes malignant arrhythmias and mortality. It is associated with electrocardiography (ECG) changes, such as peaked T wave in all ECG leads. However, the universal definition of the peaked T wave is still unclear, with low sensitivity and specificity.

AIM

: This study aims to determine the predictive value of initial and terminal T wave angle in detecting hyperkalemia among CKD patients.

METHODS

: A cross-sectional study was conducted at Dr. Soetomo General Hospital, including all adult hospitalized CKD patients. A caliper was used to measure T wave morphology. The initial deflection angle (Tia) and terminal deflection angle (Tta) were calculated from an arctan of T peak amplitude and the respective initial or terminal length. The receiver operating characteristics (ROC) curve was analyzed to determine the area under the curve (AUC) and optimal cut-off.

RESULTS

: A total of 220 CKD patients were enrolled in this study, with 98 patients with hyperkalemia (potassium >5.0). The majority of the patients were male, with a mean age of 51.12±12.58 years. Ti-Tp duration, Tp-Tt duration, Tia, Tta, and Tp amplitude were significantly higher in the hyperkalemia group (all p<0.05). A Spearman correlation analysis demonstrated a significant positive correlation of Tia (r=0.346 and p<0.001) and Tta (r=0.445 and p<0.001) with potassium levels in the participants. The optimal cut-off angle for Tta was 66.20^o (sensitivity=67.3% and specificity=73.8%) and Tia was 61.07^o (sensitivity=66.3% and specificity=69.7%).

CONCLUSION

: The terminal T wave angle outperformed the initial angle in predicting hyperkalemia in CKD patients.