Comparative effects of carvedilol and metoprolol in preventing from left ventricular remodeling after acute myocardial infarction in rats

OBJECTIVE: To compare the effects of carvedilol and metoprolol in preventing from left ventricular remodeling (LVRM) after acute myocardial infarction (AMI) in rats. METHODS: Twenty-four hours after ligating left coronary artery, 105 surviving female SD rats were randomly assigned to AMI control, carvedilol 1 mg/(kg.d) and metoprolol 2 mg/(kg.d) groups. Sham-operated rats (n = 16) were selected randomly as non-infarction control. After four weeks of drugs therapy, hemodynamic studies and pathologic analysis were performed. Exclusive of MI size 55%, complete experimental variables were obtained in 46 rats, which were comprised of AMI (n = 11), carvedilol (n = 12), metoprolol (n = 11), and Sham-operated (n = 12) groups. RESULTS: Compared with sham-operated group, left ventricular (LV) end diastolic pressure (LVEDP), volume (LVV) and weight (LVW), were all significantly increased (P < 0.05-0.001), while maximal rate of rise and fall (+/- dp/dt) of LV pressure as well as their corrected values (+/- dp/dt/LVSP) were all significantly decreased (P < 0.01-0.001) in AMI group. In comparison with AMI group, the LVEDP and LVV were all significantly decreased (all P < 0.001), while +/- dp/dt and +/- dp/dt/LVSP were significantly increased (P < 0.05-0.001) in both carvedilol and metoprolol group, with LVW and RVW only decreased in carvedilol group (P < 0.05-0.01). CONCLUSIONS: 1. Carvedilol can effectively attenuate LVRM, and improve hemodynamics and LV function after AMI in rats, 2. Metoprolol has equivalent beneficial effects as carvedilol on hemodynamics, LV dilatation and function, but not LV hypertrophy.