Aims: Optimal left ventricular (LV) lead position improves the response to cardiac resynchronization therapy (CRT). However, in some patients it is not possible to position the LV lead at an optimal pacing site. The aim of this study was to determine whether optimization of the pacing settings atrioventricular delay (AVD) and interventricular delay (VVD) can compensate for a non-optimal LV pacing site.
Methods and results: In 16 patients with heart failure [New York Heart Association class III (13) or IV (3), median QRS duration of 172 ms and median LV ejection fraction of 20%] the acute haemodynamic effect of biventricular pacing was assessed at > or =2 pacing sites by the increase in maximum rate of LV pressure rise (%dP/dt(max)). At each site the AVD and VVD were optimized. Biventricular pacing with nominal settings at a non-optimal LV pacing site improved dP/dt(max) by 12.8% (-0.5 to 23.2%). This could be further improved by 6.5 percentage points (1.2-13.9) by optimization of pacing settings (P = 0.001) and by 9.9 percentage points (3.7-13.3, P = 0.004) by optimization of pacing site. Optimization of the LV pacing site and pacing settings together improved %dP/dt(max) by 16.2 per cent points (10.0-21.8, P < 0.001).
Conclusion: Optimization of the AVD and VVD can partly compensate for a non-optimal LV pacing site. However, a combination of an optimal LV pacing site and optimized pacing settings gives the best acute haemodynamic response.