Gender differences in postinfarction left ventricular remodeling

Objective: Previous studies suggest that gender affects the adaptive respon ses of the heart to some forms of cardiac overload. It is unknown whether g ender influences left ventricular (LV) remodeling after myocardial infarcti on (MI). Methods: We performed transthoracic echocardiographic-Doppler exam inations in age-matched male (n = 17) and female (n = 16) rats before, and 1 and 6 weeks after transmural Mr or sham surgery. Results: Following large MI (male = 45 +/- 1% LV circumference vs. female = 48 +/- 4%, p = NS), bot h male and female rats developed progressive LV dilatation. Infarctions cau sed a similar degree of global and regional LV systolic dysfunction in male s and females. Male rats had significant increases in the thickness of the noninfarcted posterior wall by 6 weeks after MI. However, posterior wall th ickness did not change in the infarcted female rats. Average myocyte diamet er in the noninfarcted region of the heart was also greater in male than fe male MI rats. The combination of increased cavity size with little change i n wall thickness resulted in a greater decline in relative wall thickness i n the female rats compared to the mates. Male rats with Mi showed progressi vely restricted LV diastolic filling as assessed by transmitral Doppler rec ordings. Female rats had less of an increase in the ratio of early to late transmitral velocities and less of an increase in the E wave deceleration r ate after MI. Conclusions: Female rats showed a different pattern of LV rem odeling than males with less of an increase in thickness of the noninfarcte d portions of the left ventricle than males, but comparable LV cavity enlar gement and systolic dysfunction. Despite similar infarct size, females deve loped less pronounced abnormalities of LV diastolic filling. We hypothesize that the gender-related differences in postinfarction LV remodeling may co ntribute to the different LV filling patterns, and might ultimately relate to differences in clinical outcome.