Heart rhythm : the official journal of the Heart Rhythm Society
-
Comparative Study
Long-term follow-up of patients with cardiac sarcoidosis and implantable cardioverter-defibrillators.
Ventricular tachyarrhythmias are an important cause of morbidity and mortality in cardiac sarcoidosis. To date, the prevalence and incidence of ventricular tachycardia/ventricular fibrillation (VT/VF) in this population remain unknown. ⋯ Ventricular tachyarrhythmias requiring ICD therapy were common in patients with cardiac sarcoidosis, with an estimated incidence rate of 15% per year. Longer follow-up, left ventricular systolic dysfunction, and complete heart block were associated with VT/VF. Patients with primary prevention ICDs had high rates of appropriate ICD therapy but not as high as did secondary prevention patients. In the absence of reliable risk stratification techniques, consideration should be given to prophylactic ICD implantation in patients with cardiac sarcoidosis.
-
Multicenter Study Comparative Study
Should all individuals with a nondiagnostic Brugada-electrocardiogram undergo sodium-channel blocker test?
The diagnostic Brugada-electrocardiogram (Br-ECG) is characterized by "coved-type" ST-segment elevation (type 1) in V(1) to V(2)/V(3). The sodium-channel blocker test is clinically used to unmask diagnostic Br-ECG in patients with nondiagnostic "saddle-back" Br-ECG (type 2 and type 3). ⋯ In asymptomatic individuals with a nondiagnostic Br-ECG, the incidence of events is low regardless of the sodium-channel blocker test result while in symptomatic patients a positive sodium-channel blocker test result is associated with an adverse arrhythmic outcome and may contribute to risk stratification.
-
Action potential duration is widely used as a measure of refractory period in ischemia. Although the end of repolarization closely corresponds to the end of refractoriness in the well-perfused, well-oxygenated myocardium, it is no longer true for the ischemic myocardium, in which the recovery of excitability lags behind full repolarization. ⋯ The findings showed that although postrepolarization refractoriness is profoundly proarrhythmic during ischemia, it may protect the heart from reentrant arrhythmias in the absence of depolarization of the resting membrane. An increase in postrepolarization refractoriness induced by sodium-channel-blocking drugs may exert an antifibrillatory action.
-
Comparative Study
Value of right ventricular mapping in patients with postinfarction ventricular tachycardia.
Postinfarction ventricular tachycardia (VT) typically involves the left ventricular endocardium. Right ventricular involvement in the arrhythmogenic substrate of postinfarction VT is considered unusual. ⋯ Right ventricular mapping and ablation may be necessary in order to eliminate all inducible VTs in patients with postinfarction VT. More than half the patients with septal myocardial infarction have right ventricular septal areas that are critical for postinfarction VT and that cannot be eliminated by left ventricular ablation alone.
-
Cardiac sodium channel β-subunit mutations have been associated with several inherited cardiac arrhythmia syndromes. ⋯ Our results suggest that R214Q variation in SCN1Bb is a functional polymorphism that may serve as a modifier of the substrate responsible for BrS or SIDS phenotypes via a combined loss of function of sodium channel current and gain of function of transient outward potassium current.