Does left ventricular dyssynchrony immediately after acute myocardial infarction result in left ventricular dilatation?

BACKGROUND: Reverse remodeling of the left ventricle (LV) is one of the advantageous mechanisms of cardiac resynchronization therapy (CRT). Substantial LV dyssynchrony seems mandatory for echocardiographic response to CRT. Conversely, LV dyssynchrony early after acute myocardial infarction may result in LV dilatation during follow-up.

OBJECTIVE: The purpose of this study was to evaluate the relation between LV dyssynchrony early after acute myocardial infarction and the occurrence of long-term LV dilatation.

METHODS: A total of 124 consecutive patients presenting with acute myocardial infarction who underwent primary percutaneous coronary intervention were included. Within 48 hours of intervention, two-dimensional echocardiography was performed to assess LV volumes, LV ejection fraction (LVEF), and wall motion score index (WMSI). LV dyssynchrony was quantified using color-coded tissue Doppler imaging (TDI). At 6-month follow-up, LV volumes and LVEF were reassessed.

RESULTS: Patients with substantial LV dyssynchrony (> or =65 ms) at baseline (18%) had comparable baseline characteristics to patients without substantial LV dyssynchrony (82%), except for a higher prevalence of multivessel coronary artery disease (P = .019), higher WMSI (P = .042), and higher peak levels of creatine phosphokinase (P = .021). During 6 months of follow-up, 91% of the patients with substantial LV dyssynchrony at baseline developed LV remodeling, compared with 2% in the patients without substantial LV dyssynchrony. LV dyssynchrony at baseline was strongly related to the extent of long-term LV dilatation at 6 months of follow-up.

CONCLUSION: Most patients with substantial LV dyssynchrony immediately after acute myocardial infarction develop LV dilatation during 6 months of follow-up.