[Mechano-electric feedback and ventricular arrhythmias in heart failure. The possible role of permanent cardiac stimulation in preventing ventricular tachycardia].

Left ventricular dysfunction has been identified as the strongest independent predictor of sudden death in patients with ventricular tachyarrhythmias. It has been suggested that some of these arrhythmias might be due to myocardial stretch which may alter cellular electrophysiological properties. In heart failure (HF) the abnormal mechanics of contraction may directly initiate an arrhythmia by mechano-electric feedback (MEF), defined as changes in mechanical state that precede and alter transmembrane potential. So far, the significance of MEF and its role in clinical arrhythmogenesis have received minimal attention. We report data of 3 patients, aged from 60 to 64 years (mean age 62 +/- 2), affected by HF from 28.3 +/- 3.5 months and ventricular arrhythmias recorded by Holter: premature contractions, couplets, nonsustained ventricular tachycardia (VT). Sinus rhythm was present in 2 patients, atrial fibrillation in the last one. Many VT episodes started after an abrupt spontaneous increase in ventricular cycle length or following an ectopic beat. A permanent VVI pacemaker (MEDTRONIC Legend) was implanted in each patient and programmed at different rate from 50 to 80 b/min. During the upper rates, 70 and 80 b/min, VT episodes decreased from 292 +/- 181 to 161 +/- 95 and 97 +/- 63 (p < 0.05), respectively. In fact, the permanent pacemaker could prevent the lengthening of ventricular cycle and the myocardial fibers stretch due to the increase in ventricular volume. In conclusion, in patients with HF and ventricular arrhythmias a pacemaker may be useful in preventing VT episodes and, probably, sudden death.