ABSTRACT

The atrioventricular (AV) interval during AV sequential pacing influences left ventricular (LV) systolic performance by modulating preload. However, the value of AV optimization in patients with severe congestive heart failure (CHF) has been questioned because the high LV filling pressure may minimize the preload contribution of atrial systole. The majority of the acute and long-term benefit from cardiac resynchronization therapy (CRT) is independent of the programmed AV interval.1 The influence of the AV delay appears to be less important than the proper choice of LV pacing site.2

Nevertheless, programming of the left-sided AV delay is important in CRT patients. Appropriate AV interval timing can maximize the benefit of CRT, and if programmed poorly, it has the potential to curtail the beneficial effects. Optimization will not convert a non-responder to a responder, but may convert an underresponder to improved status.