Left Ventricular Mechanical Dyssynchrony Impairs Exercise Capacity in Patients With Coronary Artery Disease With Preserved Left Ventricular Systolic Function and a QRS Duration ≤120ms

Abstract

Left ventricular (LV) mechanical dyssynchrony can lead to impairment of LV function and is associated with adverse clinical outcomes in coronary artery disease (CAD) patients. The impact of LV dyssynchrony on exercise capacity (EC) in patients with CAD was investigated. An echocardiographic examination with tissue Doppler imaging and exercise treadmill testing in 151 CAD patients with normal LV ejection fraction was performed. LV intra- and inter-ventricular dyssynchrony were defined by the standard deviation of time interval between LV 6 basal segments (Ts-SD), and the time interval from the right ventricular (RV) free wall to LV lateral wall (Ts-RV) respectively, and EC was measured as metabolic equivalents (METs) on the treadmill. Patients with impaired EC (defined by a METs ≤ 8, which is the mean MET of the study population) were older (71 ± 7 vs. 62 ± 2 years, P<0.01), however, there were no differences in gender and clinical status such as prevalence of prior myocardial infarction (MI), regional wall motion abnormality (RWMA), and coronary revascularization between patients with (n=90) or without (n=61) impaired EC. Univariate analysis showed that age, body mass index, LV systolic and diastolic volume, mitral inflow A velocity, and Ts-SD were all significantly associated with METs (all P<0.05). However, multivariate regression analysis revealed that old age (odd ratio [OR]: 1.136, 95% confidence interval [CI]: 1.080-1.196, P<0.001), and Ts-SD (OR: 1.026, 95%CI: 1.003-1.049, P=0.027) only were independent predictors for impaired EC. In patients with CAD, LV systolic dyssynchrony predicts impaired EC independently of history of previous MI or RWMA.