Heart rhythm : the official journal of the Heart Rhythm Society
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Atrial fibrosis plays a role in the development of a vulnerable substrate for atrial fibrillation (AF). Transforming growth factor (TGF)-β(1) is related to the degree of atrial fibrosis and the recurrence of AF after surgical maze procedures. Whether TGF-β(1) is associated with the outcome after catheter ablation for AF remains unclear. ⋯ TGF-β(1) level is an independent predictor of AF recurrence in patients with nonparoxysmal AF and might be useful for identifying those patients likely to have better outcomes after catheter ablation.
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Patients with chronic right ventricular pacing (RVP) upgraded to cardiac resynchronization therapy (CRT) have been excluded from the majority of clinical trials of CRT. Little is known about the predictors of response in this population. We hypothesized that reversal of RVP-induced electrical dyssynchrony (indexed by QRS duration) by CRT would predict a favorable response. ⋯ Reversal of electrical dyssynchrony predicts response to CRT in chronically RV-paced patients upgraded to CRT. Traditional factors associated with a favorable response to CRT in de novo implants (female gender, nonischemic cardiomyopathy, and wider baseline QRS duration) are not significantly associated with response in upgraded patients. Duration of RVP before CRT upgrade is not an important determinant of response.
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Coronary artery disease carries dual risk for atrial tachyarrhythmias and sudden cardiac death. ⋯ Combined administration of low doses of ranolazine and dronedarone exerts a potent antiarrhythmic action on ischemia-induced vulnerability to AF and ventricular tachyarrhythmias due to direct effects on myocardial electrical properties.
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Comparative Study
Autonomic nerve activity and the short-term variability of the Tpeak-Tend interval in dogs with pacing-induced heart failure.
In congestive heart failure (CHF), autonomic nervous system (ANS) activity is known to modulate arrhythmic risk through its effects on myocardial repolarization. An increased interval between the peak and the end of the T wave (T(peak)-T(end)) has been reported to increase the incidence of sudden cardiac death. However, the ANS influence on the T(peak)-T(end) interval remains unclear. ⋯ In a canine model of pacing-induced CHF, iSGNA correlates positively while iVNA correlates negatively with T(peak)-T(end)STV(T). These findings suggest that SGNA increases while VNA decreases the dispersion of ventricular repolarization in ambulatory dogs with CHF.
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Mortality is increased among implantable cardioverter-defibrillator (ICD) recipients who receive shocks; however, whether shocks cause this increase or are simply a marker of risk is unknown. Antiarrhythmic medications, catheter ablation, and enhanced ICD programming all may reduce ICD shocks, but whether shock reduction decreases mortality is unknown. ⋯ There is no compelling evidence that existing interventions that reduce ICD shocks significantly improve survival.