Objective: Mitral regurgitation (MR) increases mortality in dilated cardiomyopathy (DCM). We investigated the prevalence of functional MR in non-ischemic DCM patients with narrow QRS intervals and its association with papillary muscle dyssynchrony.
Methods: Ninety-three patients were enrolled consecutively in this cross-sectional study. Patients were evaluated for the presence of intraventricular (DYS Sep-Lat Sys) and papillary muscle (DYS Inter PAP Sys) systolic dyssynchrony using tissue Doppler echocardiographic imaging (TDI). Two-dimensional and Doppler echocardiography were used for quantification of MR. Statistical analyses were performed using unpaired t test, Mann-Whitney U test, correlation and logistic regression analyses.
Results: Thirty-seven patients (39%) had significant DYS Sep-Lat Sys and 25 patients (26%) had DYS Inter PAP Sys. Patients with DYS Inter PAP Sys had lower basal septum systolic (p=0.007) and late diastolic velocities (p=0.049), greater MR volume (p=0.01), effective regurgitant orifice (ERO) (p=0.01), and E/A ratios (p=0.03) than the patients without DYS Inter PAP Sys. Fifty-five patients with narrow QRS intervals were also evaluated for DYS Inter PAP Sys. Patients with DYS Inter PAP Sys and narrow QRS had lower basal septum TDI peak systolic velocities (p=0.038), higher MR volume (p=0.03) and ERO (p=0.03). Logistic regression analysis revealed that NYHA Class III-IV (OR=6.4, 95% CI: 1.1-37.1, p=0.038) and DYS Inter PAP Sys (OR=9.5, 95% CI: 1.17-75.78, p=0.034) were the independent predictors of functional MR >20 ml.
Conclusion: Papillary muscle systolic dyssynchrony is common and correlated with functional MR in non-ischemic DCM patients with sinus rhythm and narrow QRS. Papillary muscle systolic dyssynchrony may help predict patients who will benefit from cardiac resynchronization therapy.