Ahmed Karim Talib

Enhanced transmural dispersion of repolarization in patients with J wave syndromes.

J Wave Syndromes. Introduction: Recently, great attention has been paid to the risk stratification of asymptomatic patients with an electrocardiographic early repolarization (ER) pattern. We investigated several repolarization parameters including the Tpeak‐Tend interval and Tpeak‐Tend/QT ratio in healthy individuals and patients with J wave syndrome who were aborted from sudden cardiac death.

Repolarization characteristics in early repolarization and brugada syndromes: insight into an overlapping mechanism of lethal arrhythmias.

We reported impaired QT‐rate dependence in early repolarization syndrome (ERS); however, contemporary data have shown peak incidence of sudden cardiac death (SCD) in ERS and Brugada syndrome (BrS) at mid‐night and early morning. Taken together, we analyzed the nocturnal QT‐rate dependence in both syndromes.

Non-Reentrant Fascicular Tachycardia: Clinical and Electrophysiological Characteristics of a Distinct Type of Idiopathic Ventricular Tachycardia.

Background—The most common form of idiopathic Purkinje-related ventricular tachycardia (VT) is the reentrant type. We describe the clinical and electrophysiological characteristics of focal non-reentrant fascicular tachycardia. Methods and Results—Among 530 idiopathic VT patients who were referred for ablation, we identified 15 (2.8%) with non-reentrant fascicular tachycardia (11 men, 45±21 years). Sinus rhythm ECG showed normal conduction intervals with a His–ventricular interval of 41±4 ms. All patients had monomorphic VT (cycle length: 337±88 ms) with a relatively narrow QRS (123±12 ms), and they did not respond to verapamil during the initial presentation. VT exhibited right bundle-branch block/superior axis configuration in 11 patients (73%) and inferior axis in 3 (20%). In 1 patient (7%), VT exhibited left bundle-branch block/superior axis configuration. During ablation, spontaneous VT occurred in 3 patients (20%) and nonentraintable VT or identical premature ventricular complex was induced in 9 (60%). A high-frequency presystolic Purkinje potential was recorded during VT/premature ventricular complex, preceding the QRS by 25±16 ms. VT recurrence was observed in 4 patients (27%), and among them, 3 underwent pacemap-guided ablation during the first session. A second ablation with activation mapping guidance eliminated the VT during the 88±8-month follow-up. Conclusions—Among idiopathic VT cases referred for ablation, 2.8% were focal non-reentrant fascicular tachycardia, which had distinct clinical characteristics and usually originated from the left posterior fascicle, and less commonly from the left anterior fascicle and right ventricular Purkinje network. Catheter ablation is effective, whereas pacemap-guided approach is less efficacious.

Impaired Ventricular Repolarization Dynamics in Patients with Early Repolarization Syndrome

Almost all current investigations on early repolarization syndrome (ERS) have focused on the J‐wave characteristics and ST‐segment configuration; however, few have reported on ventricular repolarization indexes in ERS.

Late gadolinium enhancement of cardiac magnetic resonance imaging indicates abnormalities of time-domain T-wave alternans in hypertrophic cardiomyopathy with ventricular tachycardia

BACKGROUND The presence of myocardial scar detected by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging has been described as a good independent predictor of mortality in patients with hypertrophic cardiomyopathy (HCM). Time-domain T-wave alternans (TWA) is also a potential predictor of cardiac mortality in patients with left ventricular dysfunction. OBJECTIVE The purpose of this study was to elucidate the relationship between LGE distribution and TWA in patients with HCM. METHODS CMR and TWA analyses using Holter monitoring were performed in 42 patients with HCM. The average transmural extent of LGE was scored as 1-4 in each segment, and the sum of the LGE scores (total LGE score) was calculated for each patient. The correlation between the maximal time-domain TWA voltage and LGE findings was analyzed, and the differences in time-domain TWA voltage, total LGE score, and cardiac function assessed by CMR imaging in the presence or absence of ventricular tachycardia (VT) were also compared. RESULTS The total LGE score was significantly and positively correlated with the maximal time-domain TWA voltage (r = 0.59; P < .001). Furthermore, the total LGE score and maximal time-domain TWA voltage were significantly greater in patients who had episodes of VT (n = 21) than in those without VT (23 ± 7 vs. 10 ± 8; P < .001 and 87 ± 26 μV vs. 62 ± 12 μV; P < .001, respectively). However, the left ventricular ejection fraction did not statistically differ between patients with VT and those without VT (56% ± 14% vs. 61% ± 7%; P = .102). CONCLUSION The magnitude of the localized LGE was significantly correlated with abnormalities in ventricular repolarization as assessed by TWA and QT dispersion.

Three cases of corticosteroid therapy triggering ventricular fibrillation in J-wave syndromes

We describe three cases of J-wave syndrome in which ventricular fibrillation (VF) was probably induced by corticosteroid therapy. The patients involved were being treated with prednisolone for concomitant bronchial asthma. One of the three patients had only one episode of VF during her long follow-up period (14 years). Two patients had hypokalemia during their VF episodes. Corticosteroids have been shown to induce various types of arrhythmia and to modify cardiac potassium channels. We discuss the possible association between corticosteroid therapy and VF in J-wave syndrome based on the cases we have encountered.

Late Gadolinium Enhancement on Cardiac MRI Correlates with QT Dynamicity Represented by QT/RR Relationship in Patients with Ventricular Arrhythmias

The distribution of late gadolinium enhancement (LGE) on the cardiac MRI (CMR) indicates myocardial fibrosis and provides information of possible reentry substrates. QT dynamicity reflecting repolarization abnormalities has gained attention as a potential prognostic predictive factor.

The relationship between repolarization parameters and serum electrolyte levels in patients with J wave syndromes

BACKGROUND Intravenous administration of magnesium (Mg(2+)) is effective for polymorphic ventricular tachycardia via homogenization of transmural ventricular repolarization. Mg(2+) likely plays some role in the heterogeneity of repolarization in J wave syndromes. OBJECTIVE To investigate the relationship between the repolarization parameters and serum Mg(2+), potassium (K(+)), and calcium (Ca(2+)) levels in J wave syndromes. METHODS Thirteen J-wave syndrome patients (Brugada and early repolarization [ER] syndromes), with documented episodes of ventricular fibrillation (VF), and 13 ER pattern (ERP) or Brugada type ECG patients were enrolled (25 males, mean age 48 ± 15 years). The 12-lead ECG-derived parameters including the QT, QT dispersion (QTd), Tpeak-Tend (Tp-e) interval, Tp-e dispersion (Tp-ed), Tp-e/QT ratio, and activation recovery interval (ARI) dispersion were calculated; the correlations between these parameters and electrolytes including Mg(2+), K(+), and Ca(2+) were analyzed. RESULTS Although there was no association between serum K(+) or Ca(2+) and QTd, there was a strong negative correlation between serum Mg(2+) and QTd in J wave syndrome patients with a history of VF (r = -0.715, p = 0.006). Also, there was a tendency for a negative correlation between Mg(2+) and Tp-ed or ARI dispersion in J wave syndrome patients with a history of VF (r = -0.513, p = 0.072 and r = -0.53, p = 0.063, respectively). On the other hand, in 13 patients with a Brugada type ECG or ERP, no correlation was observed between serum Mg(2+) and the QTd, Tp-ed or ARI dispersion. CONCLUSION Serum Mg(2+) may play an important role in the cardiac repolarization process in J wave syndromes.