Assessment of Echocardiography
According to the recommendations from the American Society of Echocardiography, we measured the LV end-diastolic volume (LVEDV), LVESV, and LVEF using the biplane Simpson’s method. Mitral regurgitation (MR) was categorized into five grades, as follows: none = grade 0; trace = grade 1; mild = grade 2; moderate = grade 3; and severe = grade 4. Two-dimensional echocardiography at rest was performed at baseline and 6 months follow-up to assess the LVEF and LVESV. Responders to CRT were defined as patients displaying a 15% reduction in the LVESV at least 6 months after the CRT implantation.