Should we use the rate-adaptive AV delay in cardiac resynchronization therapy-pacing?

Recommendations for programming the rate-adaptive AV delay in CRT.

In cases of continual biventricular pacing, the optimal AV delay in CRT (AVD(opt)) is the net effect of the pacemaker-related interatrial conduction time (IACT), duration of the left-atrial electromechanical action (LA-EAC(long)), and the duration of the left-ventricular latency period (S(V)-EAC(short)). It can be calculated by AVD(opt) = IACT+LA-EAC(long)-S(V)-EAC(short). We measured these three components in 20 CRT-ICD patients during rest and submaximal ergo metric exercise (71 +/- 9 W) resulting in a 22.5 +/- 9.6 bpm rate increase. IACT and S(V)-EAC(short) did not reveal significant differences. LA-EAC(long), however, varied significantly by -10.7 +/- 16.1 ms (P = 0.008) during exercise. In contrast to AVD(optVDD), there was a significant difference in AVD(optDDD) of -8.8 +/- 14.5 ms (P = 0.014) between the resting and submaximal exercise conditions. In DDD pacing, AVD(opt) was shortened by 2.6 ms/10 bpm.

In consideration of the findings of the studies performed to date, the rate-adaptive AV delay should be deactivated.