Effect of atenolol on myocardial infarct expansion in a nonreperfused rat model

Acute myocardial infarct expansion is associated with a poor prognosis. This study was performed to assess potential beneficial effects of beta-blockers on inhibiting expansion. A pilot study showed that atenolol (10 mg/kg) achieved sustained beta-blockade in rats. In the main study, following left coronary ligation, 36 rats received atenolol and 18 rats received placebo daily for 7 days. Infarct size was similar in treated and control rats (25 +/- 13% versus 28 +/- 11%). Expansion grades and a quantitative index of expansion were similar for both groups. Infarct size and expansion index were significantly related, but linear regression lines were similar for treated and control rats. We conclude that atenolol has no significant effect on infarct expansion in this nonreperfused rat model.