Experimental: CRT implantation guided by XSpline

The sample size estimation was based on two recent studies including CRT patients with similar clinical and demographic characteristics as in this study: the SMART-MSP and the SMART CRT. The SMART-MSP is a prospective, observational study that enrolled 584 CRT recipients at 52 US sites. In a typical modern CRT population, 75% of patients had a reduction of the end-systolic volume ≥ 15% at 6-month follow-up. The SMART-CRT study enrolled 699 CRT patients randomized to a treatment arm and a control group. At 6-months follow-up, a reduction of LVESV ≥15% was achieved for 67.7% of the patients in the control group and for 74.8% of those in the treatment arm. Therefore, it is assumed that in a modern CRT population at least 70% of the patients will have a reduction of the LVESV ≥15% of the baseline value at 6-months after CRT implantation. To demonstrate that this proportion of patients can be equally achieved with the approach tested in this study at least 150 patients need to be included.