Value of right ventricular-left ventricular interlead electrical delay to predict reverse remodelling in cardiac resynchronization therapy: the INTER-V pilot study

Aims: Few studies have systematically evaluated the value of intra-procedural parameters in predicting response to cardiac resynchronization therapy (CRT). We investigated whether intracardiac (electrogram) measurements of electrical delays between the positioned right ventricular (RV) and left ventricular (LV) leads at implantation could predict the mid-term CRT response. Methods and results: Fifty-two patients underwent CRT implantation according to standard techniques and clinical indications. The RV-LV interlead electrical delay measured during spontaneous rhythm and the difference between the pacing-induced (Deltap) RV-LV interlead electrical delays measured during RV and LV pacing were defined intraoperatively using the electrical depolarizations registered at the ventricular leads on the device programmer. At 6 months, a reduction of LV end-systolic volume > or = 15% was used to define CRT responders. Responders (62%), when compared with non-responders, showed a higher proportion of ischaemic aetiology (P = 0.007) and a lower value of DeltapRV-LV interlead electrical delay (22.1 +/- 18.4 vs. 46.3 +/- 15.0 ms, P = 0.0001). At multivariate analysis, the DeltapRV-LV interlead electrical delay was the only independent predictor of response to CRT (P = 0.001). For such a parameter, the receiving operating characteristic curve analysis identified a cut-off value of 42 ms corresponding with the highest accuracy: sensitivity 90.6%; specificity 70%; positive and negative predictive value 83% and 82%, respectively. Conversely, no difference was ascertained between responders and non-responders when RV-LV interlead electrical delay was measured during spontaneous rhythm (76.1 +/- 28.5 vs. 89.6 +/- 21.2, P = 0.078).