Four months of sustained endurance training in a canine model increased susceptibility to elicited ventricular fibrillation compared to sedentary controls (60% vs 30%) and induced electrophysiological remodeling.
Does chronic endurance training induce electrophysiological remodeling and increase arrhythmia susceptibility in a canine model?
In a canine model, chronic endurance training induces structural and electrophysiological remodeling, including prolonged repolarization and increased HCN4 expression, which enhances susceptibility to ventricular arrhythmias.
Tasa de eventos absoluta: 60% vs 30%
valor p: p=<0.05
The health benefits of regular physical exercise are well known. Even so, there is increasing evidence that the exercise regimes of elite athletes can evoke cardiac arrhythmias including ventricular fibrillation and even sudden cardiac death (SCD). The mechanism of exercise-induced arrhythmia and SCD is poorly understood. Here, we show that chronic training in a canine model (12 sedentary and 12 trained dogs) that mimics the regime of elite athletes induces electrophysiological remodeling (measured by ECG, patch-clamp, and immunocytochemical techniques) resulting in increases of both the trigger and the substrate for ventricular arrhythmias. Thus, 4 months sustained training lengthened ventricular repolarization (QTc: 237.1±3.4 ms vs. 213.6±2.8 ms, n=12; APD90: 472.8±29.6 ms vs. 370.1±32.7 ms, n=29 vs. 25), decreased transient outward potassium current (6.4±0.5 pA/pF vs. 8.8±0.9 pA/pF at 50 mV, n=54 vs. 42), and increased the short-term variability of repolarization (29.5±3.8 ms vs. 17.5±4.0 ms, n=27 vs. 18). Left ventricular fibrosis and HCN4 protein expression were also enhanced. These changes were associated with enhanced ectopic activity (number of escape beats from 0/hr to 29.7±20.3/hr) in vivo and arrhythmia susceptibility (elicited ventricular fibrillation: 3 of 10 sedentary dogs vs. 6 of 10 trained dogs). Our findings provide in vivo, cellular electrophysiological and molecular biological evidence for the enhanced susceptibility to ventricular arrhythmia in an experimental large animal model of endurance training.
Polyák et al. (Thu,) conducted a other in Arrhythmia susceptibility (n=24). Sustained endurance training vs. Sedentary control was evaluated on Elicited ventricular fibrillation (p=<0.05). Four months of sustained endurance training in a canine model increased susceptibility to elicited ventricular fibrillation compared to sedentary controls (60% vs 30%) and induced electrophysiological remodeling.