As right ventricular lead is positioned endocardialy and left ventricular lead epicardialy, we hypothesized that baseline epi-endo gradient could predict CRT response.

We studied 46 patients referred for CRT. Transthoracic echocardiography (TTE) was performed for all patients before and one year after implantation. Offline analysis with speckle tracking imaging (STI) analysis of LV endocardial and epicardial wall was performed. Specifically, epi-endo gradient delay (GD) and gradient contraction (GC) measurements were performed on the septal and lateral LV wall before and one year after implantation. CRT response was defined as a reduction>15% of LV end systolic volume one year after CRT.

Mean age was 62±11 year-old and mean EF was 26±7%. Twenty-two patients were classified as responders. Baseline characteristics of patients with or without CRT response were similar, except for QRS duration. Before implantation, septal (10±31ms vs. 20±133ms, p=0.67) and lateral GD (1±25ms vs. 4±26ms, p=0.76) were low and similar in both groups. However lateral GC was higher in CRT responders (–4.05±2.29% vs. –2.38±2.82%, p=0.009). After multivariate analysis, lateral GC was the best predictor of CRT response (p=0.013). One year after implantation, septal GD and GC were comparable in CRT responders or not. However lateral GC significantly decreased in CRT responders (–4.05±2.29% at baseline vs. –1.86±2.2%, p<0.01) whereas no changes were observed for non-responders. Finally lateral GD was significantly increased at one year in CRT non responders 4±26ms at baseline vs. 18±43ms, p<0.01). Conclusion: At baseline no significant LV epicardial-endocardial delay gradient was observed in patients with CRT response or not. However lateral epi-endo gradient contraction is highly independently associated with CRT response. Finally this gradient was homo-genezing one year after CRT for responders.