Infarct site-related mortality in patients with recurrent myocardial infarction. SPRINT Study Group

The purpose of this study was to determine the effect of acute and old myocardial infarction (MI) sites on early (15 days) mortality in patients with a second MI.

Data are derived from the SPRINT 2 study population that included 1,161 consecutive patients with acute MI, aged 50 to 79 years, recruited from 14 coronary care units in Israel between November 1985 and July 1986. Two hundred twenty-six of these patients (19.5%) had a previous MI prior to the index acute MI. Sixty-two patients were excluded from the analysis either because the MI site was not of anterior or inferior location, or because of incomplete data. In the 164 (73%) remaining patients, acute and old MI locations were determined to be either anterior or inferior and were accordingly divided into 4 groups: acute anterior-old anterior (Group 1-23 patients); acute anterior-old inferior (Group 2-86 patients); acute inferior-old anterior (Group 3-34 patients); acute inferior-old inferior (Group 4-21 patients).

Significant differences in clinical parameters among the four groups included a higher proportion of Q-wave MI (p = 0.04), severe congestive heart failure during admission (p = 0.04), and markedly elevated serum lactate dehydrogenase levels (p = 0.05) in Group 3. High-degree atrioventricular block (p = 0.001) and cardiogenic shock (p = 0.05) also developed more often in this group during hospitalization. Twenty-three patients (14%) died within 15 days. Death rates in the acute anterior (Group 1 plus Group 2) and the acute inferior (Group 3 plus Group 4) groups were 11% versus 20%, respectively (NS). However, death rate variability across the four groups was statistically significant (p = 0.018), with the highest mortality observed in Group 3 (old anterior-acute inferior MI-29%). Multivariate analysis identified acute inferior MI following old anterior MI as a strong independent predictor of early death (relative odds vis-à-vis other combinations 5.0, 95% confidence interval 1.5 to 16.6).

This study identifies a subgroup of patients with acute inferior MI at high risk for early mortality. It is possible that such patients would benefit from early reperfusion therapy.