Exercise and Diastolic Function after Myocardial Infarction

PURPOSE: The purpose of this study was to determine the effects of exercise training on LV geometry and LV diastolic function in a rat model of MI. METHODS: One month after MI induced by ligation of the left anterior descending artery (N = 45) or sham operation (N = 26), rats were randomized to either a sedentary or exercise group. Exercise consisted of treadmill running at 24 m.min-1, 1 h.d-1, 5 d.wk-1, for 3 wk. Passive LV pressure volume relationships were established with an isolated, red-cell-perfused Langendorff preparation. Infarct size was determined histologically and categorized as small (<30% of LV) or large (> or =30% of LV). RESULTS: LV end-diastolic pressure-volume relationships were shifted rightward with increasing infarct size (P < 0.05). Exercise training further shifted the LV end-diastolic pressure-volume relationships rightward in sham, small MI and large MI (P < 0.05). Peak LV developed pressure was comparable in sedentary and exercised-trained hearts in sham, small MI, and large MI. LV diameter and septal wall thickness were greatest in large MI (P < 0.05). Exercise-trained hearts showed a tendency for a greater LV diameter and septal wall thickness in sham, small MI, and large MI. Scar thinning was most notable in large MI (P < 0.05). CONCLUSION: Moderate-intensity treadmill running induces myocardial remodeling and a rightward shift in the LV end-diastolic pressure-volume relationship after MI, an adaptation similar to what is observed with exercise training in sham hearts without MI.