The effects of cardiac resynchronization therapy on left ventricular and mitral valve geometry and secondary mitral regurgitation in patients with left bundle branch block

Abstract

Background Secondary mitral regurgitation (MR) is common in patients with left bundle branch block (LBBB) undergoing cardiac resynchronization therapy (CRT). We aimed to define CRT effects on left ventricular (LV) and mitral valve (MV) geometry, and their correlation with MR severity. Methods Forty‐one patients with LBBB and ≥mild secondary MR underwent CRT between 2009 and 2012, and had baseline and follow‐up echocardiograms available. Repeated measure and linear regression analyses were performed to assess for changes in MV and LV geometry and MR severity, and associations with follow‐up MR grade. Results The mean age and baseline QRS duration were 65.5 ± 14.9 years and 160 ± 24 ms. At a mean follow‐up of 2.6 ± 1.8 years, there was an increase in LV ejection fraction and reductions in LV end‐systolic volume index, MR grade, and end‐systolic interpapillary muscle distance (P < .05 for all). Linear correlations were observed between follow‐up MR grade and baseline MV tenting height (r = .44), left atrial volume index (r = .41), LV end‐systolic volume index (r = .4), MV tenting area (r = .38), LV ejection fraction (r = −.34), and end‐systolic interpapillary muscle distance (r = .34) (P < .05 for all). Multiple regression analysis revealed associations between follow‐up MR grade and baseline MV tenting height (β/mm = 0.42, P = .006) and left atrial volume index (β/mL/m2 = 0.4, P = .008), independent of QRS duration (β/ms=−0.07; P = 0.6) and nonischemic cardiomyopathy (β = −0.34, P = .02). Conclusions Cardiac resynchronization therapy in patients with LBBB and secondary MR results in LV and MV geometric reverse remodeling and decreases MR severity. Extent of baseline MV tethering is independently associated with persistent MR at follow‐up.

Paroxysmal Severe Mitral Regurgitation

“…Given the contribution of electromechanical disturbance, CRT may be the more logical first approach in patients with this mechanism of MR, particularly given its success in the treatment of 2 o MR from LV dyssynchrony in patients with advanced systolic HF. 14 Patients with type 2 underwent surgical MV replacement and had no recurrence of HF, though the efficacy of MV repair (surgical or percutaneous) for type 2 is unknown. Patients with type 3 were treated with medical therapy consisting of high-dose calcium channel blockers and had no recurrence of HF.…”

Mitral Regurgitation in Patients Undergoing Noncardiac Surgery

“…Cardiac resynchronization therapy may improve functional MR in patients with conduction delays by shortening the QRS interval and facilitating a more efficient LV contraction. 28 Hypertrophic cardiomyopathy is also associated with MR; the most classic example is the patient with asymmetric basal septal hypertrophy and hypertrophic obstructive cardiomyopathy (HOCM). In this disease, the narrowed left ventricular outflow tract (LVOT) forces ejected blood to accelerate as it leaves the heart.…”