Familial atrioventricular nodal re-entrant tachycardia: A case seriers and a systematic review.

Multiple reports of familial clustering suggest that genetic factors may contribute in the pathogenesis of atrioventricular nodal re-entrant tachycardia (AVNRT). We report three cases of AVNRT in a father and his two sons along with a review of literature of other similar cases. Electrophysiological studies induced typical AVNRT, which was successfully eliminated by radiofrequency ablation in all of them. Of the 22 reported cases, 96% had typical (slow-fast) variant of AVNRT. The predominant pattern of inheritance appears to be autosomal dominant, though other patterns may exist. Further research is needed to understand the genetic influence of AVNRT and its pathophysiology.

The Utility of Exercise Testing in Risk Stratification of Asymptomatic Patients With Type 1 Brugada Pattern.

INTRODUCTION: Risk stratification of asymptomatic patients with a Brugada type 1 ECG pattern remains an unresolved clinical conundrum. In contrast to provocative pharmacological testing in Brugada syndrome, there is limited data on the role of exercise stress testing as a risk stratification modality. The objective of this study was to evaluate the utility of exercise testing in asymptomatic patients with type 1 Brugada pattern to prognosticate major arrhythmic events (MAE) during follow-up. METHODS AND RESULTS: Treadmill exercise testing was conducted for 75 asymptomatic patients with type 1 Brugada pattern and for 88 healthy control subjects. The clinical end point of MAE was defined as the occurrence of sudden cardiac death (SCD) or resuscitated ventricular fibrillation (VF). During a follow-up of 77.9 ± 28.9 months, eight MAE occurred (five VF and three SCD). Multivariate Cox regression analysis showed that the following were independent predictors of MAE in asymptomatic patients with a type 1 Brugada pattern: increase in S wave upslope duration ratio >30% at peak exercise (HR 1.35, 95% CI 1.08-10.97, P = 0.023), augmentation of J point elevation in lead aVR >2 mm in late recovery (HR 1.88, 95% 1.21-15.67, P = 0.011), and delayed HR recovery (HR 1.14, 95% CI 1.06-18.22, P = 0.042). A high-risk cohort was identified by the final step-wise regression model with good accuracy (specificity = 98.4%, sensitivity = 62.5%) and discriminative power (AUC = 0.93, 95% CI 0.89-0.96, P = 0.002). Kaplan-Meier analysis revealed increasing MAE in subjects with one, two, or three predictors, respectively (log rank P < 0.001). CONCLUSIONS: Exercise testing in asymptomatic patients with type 1 Brugada pattern aids in identification of high-risk patients and provides a unique window of opportunity for early intervention.

Supra-Hisian Conduction Block as an Unusual Presenting Feature of Takotsubo Cardiomyopathy.

BACKGROUND: Atrioventricular (AV) block is rare in Takotsubo cardiomyopathy (TC). CASE REPORT: A 66-year-old female presented with fatigue. Her electrocardiogram revealed 3:2 Mobitz Type II AV block, confirmed to be supra-Hisian by electrophysiological study. Echocardiogram and left ventricular angiogram showed moderate left ventricular dysfunction and apical ballooning, whereas coronary angiogram revealed mildly ectatic coronaries. At 2 weeks AV block persisted, needing permanent pacemaker implantation. At 1-month follow-up, she had normal ventricular function and no AV block. CONCLUSION: Delayed recovery of AV conduction is possible in TC, thus implying to wait for a longer period before implanting a pacemaker.