Haemodynamic evaluation of alternative left ventricular endocardial pacing sites in clinical non-responders to cardiac resynchronisation therapy

INTRODUCTION: Non response to cardiac resynchronisation therapy (CRT) may be related to the position of the coronary sinus lead. METHODS: We studied the acute haemodynamic response (AHR) from alternative left ventricular (LV) endocardial pacing sites in clinical non-responders to CRT. AHR and the interval from QRS onset to LV sensing (Q-LV interval) from four different endocardial pacing sites were evaluated in 24 clinical non-responders. A rise in LVdP/dtmax ≥ 15 % from baseline was considered a positive AHR. We also compared the AHR from endocardial with the corresponding epicardial lead position. RESULTS: The implanted system showed an AHR ≥ 15 % in 5 patients. In 9 of the 19 remaining patients, AHR could be elevated to ≥ 15 % by endocardial LV pacing. The optimal endocardial pacing site was posterolateral. There was no significant difference in AHR between the epicardial and the corresponding endocardial position. The longest Q-LV interval corresponded with the best AHR in 12 out of the 14 patients with a positive AHR, with an average Q-LV/QRS width ratio of 90 %. CONCLUSIONS: Acute haemodynamic testing may indicate an alternative endocardial pacing site with a positive AHR in clinical non-responders. The Q-LV interval is a strongly correlated with the optimal endocardial pacing site. Endocardial pacing opposite epicardial sites does not result in a better AHR.