Correlation between Mitral Regurgitation and Myocardial Mechanical Dyssynchrony and QRS Duration in Patients with Cardiomyopathy

Several competing geometric and hemodynamic factors are suggested as contributing mechanisms for functional mitral regurgitation (MR) in heart failure patients. We aimed to study the relationships between the severity of MR and the QRS duration and dyssynchrony markers in patients with ischemic or dilated cardiomyopathy. We prospectively evaluated 251 heart failure patients with indications for echocardiographic evaluation of possible cardiac resynchronization therapy. All the patients were subjected to transthoracic echocardiography and tissue Doppler imaging to evaluate the left ventricular (LV) synchronicity. The patients were divided into two groups according to the severity of MR: ≤ mild MR and ≥ moderate MR. The effects of different dyssynchrony indices were adjusted for global and regional left ventricular remodeling parameters. From the 251 patients (74.5% male, mean age = 53.38 ± 16.68 years), 130 had ≤ mild MR and 121 had ≥ moderate MR. There were no differences between the groups regarding the mean age, frequency of sex, and etiology of cardiomyopathy. The LV systolic and diastolic dimensions were greater in the patients with ≥ moderate MR (all p values < 0.001). Among the different echocardiographic factors, the QRS duration (150.75 ± 34.66 vs. 126.77 ± 29.044 ms; p value = 0.050) and interventricular mechanical delay (41.60 ± 29.50 vs. 35.00 ms ± 22.01; p value = 0.045) were significantly longer in the patients with ≤ mild MR in the univariate analysis. After adjusting the effect of these parameters on the severity of MR for the regional and global LV remodeling parameters, no significant impact of the QRS duration and dyssynchrony indices was observed. Our results showed that the degree of functional MR was not associated with the QRS duration and inter- and intraventricular dyssynchrony in our patients with cardiomyopathy. No association was found between the severity of MR and the ischemic or dilated etiology for cardiomyopathy.