Optimisation of atrioventricular delay during exercise improves cardiac output in patients stabilised with cardiac resynchronisation therapy

Background Atrioventricular (AV) delay in cardiac resynchronisation therapy (CRT) recipients are typically optimised at rest. However, there are limited data on the impact of exercise-induced changes in heart rate on the optimal AV delay and left ventricular function. Methods and results The authors serially programmed AV delays in 41 CRT patients with intrinsic sinus rhythm at rest and during two stages of supine bicycle exercise with heart rates at 20 bpm (stage I) and 40 bpm (stage II) above baseline. The optimal AV delay during exercise was determined by the iterative method to maximise cardiac output using Doppler echocardiography. Results were compared to physiological change in PR intervals in 56 normal controls during treadmill exercise. The optimal AV delay was progressively shortened (p 2 =0.639, p 2 =0.646, p Conclusions Haemodynamically optimal AV delay shortened progressively with increasing heart rate during exercise, which suggests the need for programming of rate-adaptive AV delay in CRT recipients.