Cardiac resynchronization therapy beyond nominal settings: who needs individual programming of the atrioventricular and interventricular delay?

AIMS: This study aimed to determine the additional acute haemodynamic effect of atrioventricular (AV) and interventricular (VV) delay optimization compared with current nominal cardiac resynchronization therapy (CRT) device settings, and to explore whether clinical characteristics correlate to the effect of optimization.

METHODS AND RESULTS: Fifty CRT patients were prospectively enrolled. The optimal AV and VV delays were guided by relative improvement in maximum rate of left ventricular (LV) pressure rise (%dP/dt(max)). A significant improvement in %dP/dt(max) was obtained by optimization in 23-33% (sensed AV delay), 32-57% (paced AV delay), and 45% of patients (VV delay). Adjustment of the device nominal VV delay from 0 to 40 ms LV pre-activation would diminish the proportion of patients with additional effect of individual optimization from 45 to 15%. Heart failure aetiology [ischaemic 2 ± 2 vs. non-ischaemic 1 ± 1 percentage points (PP) %dP/dt(max), P= 0.013], gender (men 2 ± 2 vs. women 1 ± 1 PP %dP/dt(max), P= 0.012) and intrinsic PR interval (R= 0.49, P= 0.002) correlated to the degree of effect of AV delay optimization. Women yielded more effect of VV delay optimization (4 ± 3 vs. 2 ± 1 PP %dP/dt(max), P= 0.026).

CONCLUSION: Compared with the best of the currently available device nominal AV and VV delays, 23-45% of CRT patients can yield additional acute haemodynamic effect by individual optimization of the delays. A new nominal VV delay of 40 ms LV pre-activation is recommended. Male gender, ischaemic aetiology, and longer PR interval are associated with a larger effect of individual optimization.