Kowal RC et al. (2004) Biventricular pacing reduces the induction of monomorphic ventricular tachycardia: a potential mechanism for arrhythmia suppression. Heart Rhythm 3: 295–300

There is evidence that biventricular (BV) pacing reduces the frequency of ventricular arrhythmias, although the underlying mechanism has not been established. Kowal et al. have investigated this in the first prospective, randomized study in this setting.

Eighteen patients were subjected to programmed electrical stimulation (PES) for syncope, primary prevention, sustained ventricular tachycardia or wide complex tachycardia. Pacing was performed using either right-ventricular (RV)-PES or BV-PES. Each patient subsequently underwent pacing by the alternative method. In each case, the effective refractory periods were measured at the RV apex and the RV outflow tract. The local left-ventricular (LV) S1–S2 coupling intervals were also monitored.

There was no significant difference between the RV effective refractory periods during RV-PES and BV-PES. Local LV S1–S2 coupling intervals were significantly longer, however, during BV-PES than during RV-PES. Although the overall frequency of induced ventricular arrhythmias was similar using the two pacing methods, ventricular tachycardia was significantly less frequent in BV-PES than in RV-BES (one patient vs six patients, risk reduction 83%, P = 0.01).

Kowal et al. conclude that these findings may help to account for the decreased frequency of ventricular arrhythmias seen in chronic BV-PES treatment.