Heart rhythm : the official journal of the Heart Rhythm Society
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Heart rate variability (HRV), calculated in the frequency or time domain, decreases in congestive heart failure (CHF). In HRV power spectral analysis, the low-frequency (LF) component diminishes in patients with CHF and the decrease is related to an increased risk of sudden death. ⋯ The spectral variables (LF power and the LF/HF ratio) and direct variables measuring sympathetic nerve activity (iSGNA) correlate at baseline but not during CHF. At baseline, the vagal activity (iVNA) is associated with an increase in HFnu and a decrease in LFnu. These data indicate that the reduction in LF power and LF/HF ratio observed in heart failure dogs are likely to reflect a diminished sinus node responsiveness to autonomic modulation or an abnormal baroreflex function rather than an increased sympathetic activity.
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Premature ventricular contractions (PVCs) do not occur frequently but can induce ventricular fibrillation (VF) in patients with Brugada syndrome. The effect of SCN5A mutation on the onset of ventricular arrhythmias is unknown. ⋯ Patients without SCN5A mutation often had PVCs of LBBB, inferior-axis morphology, suggesting a right ventricular outflow tract origin. Patients with SCN5A mutations had PVCs that originated from both the right and left ventricles.
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Patients carrying loss-of-function SCN5A mutations linked to Brugada syndrome (BrS) or progressive cardiac conduction disease (PCCD) are at risk of sudden cardiac death at a young age. The penetrance and expressivity of the disease are highly variable, and new tools for risk stratification are needed. ⋯ In loss-of-function SCN5A channelopathies, patients carrying T and M(inactive) mutations develop a more severe phenotype than those with M(active) mutations. This is associated with more severe conduction disorders. This is the first time that genetic data are proposed for risk stratification in BrS.
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Randomized Controlled Trial
Systematic electrocardioversion for atrial fibrillation and role of antiarrhythmic drugs: a substudy of the SAFE-T trial.
Energy levels for electrocardioversion in atrial fibrillation (AF) have been empiric, and the influence of antiarrhythmic therapy compared with placebo is largely unknown. ⋯ Amiodarone and sotalol facilitated successful electrocardioversion, which could be achieved in a stepwise fashion. Upon achievement of successful electrocardioversion, amiodarone is superior to placebo, and sotalol has a lesser effect. Antiarrhythmic drugs had no effect on the total number of energy step use in patients who had successful electrocardioversion. Calcium channel blockers had no influence on the success rate in achieving sinus rhythm. Successful electrocardioversion was associated with lower BMI and AF history < or =1 year. Lower energy use was associated with biphasic shocks, lower BMI, and AF duration < or =1 year.
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Multicenter Study
Role of radiofrequency catheter ablation of ventricular tachycardia in cardiac sarcoidosis: report from a multicenter registry.
Management of ventricular tachycardia (VT) is challenging in patients with cardiac sarcoidosis. ⋯ Catheter ablation of VT in patients with cardiac sarcoidosis refractory to medical therapy is effective in eliminating VT or markedly reducing the VT burden. The disease process in cardiac sarcoidosis often involves a specific area in the basal right ventricle predisposing to peritricuspid reentry.