Electrical Remodeling and Atrial Dilation During Atrial Tachycardia are Influenced by Ventricular Rate Role of Developing Tachycardiomyopathy

Background Atrial fibrillation (AF) and chronic heart failure (CHF) are two clinical entities that often coincide. Our aim was to establish the influence of a concomitant high ventricular rate and the consequent development of CHF on electrical remodeling and dilation during atrial tachycardia. Methods and Results A total of 14 goats was studied. Five goats were subjected to 3:1 atrioventricular (AV) pacing (A-paced group, atrial rate 240 bpm, ventricular rate 80 bpm). Nine goats were subjected to rapid 1:1 AV pacing (AV-paced group, atrial and ventricular rate 240 bpm). During 4 weeks, right atrial (RA) and left ventricular (LV) diameters were measured during sinus rhythm. Atrial effective refractory periods (AERP) and inducibility of AF were assessed at three basic cycle lengths (BCL). After 4 weeks of rapid AV pacing RA and LV diameters had increased to 151 % and 113 % of baseline, while after rapid atrial pacing alone these parameters were unchanged. Right AERP (157±10 ms vs. 144±16 ms, at baseline at a BCL of 400 ms in the A-paced and AV-paced group, respectively) initially decreased in both groups, reaching minimum value