Patients with micro or other myocardial infarctions have equal long-term survival

To investigate differences in prognosis after myocardial infarction (MI) in patients classified according to the old and new definitions of MI. Patients not fulfilling the old definitions were classified as having a micro MI.

Data on 1216 consecutive patients with a diagnosis of first MI (38.3% women) and who were discharged from or died in one hospital in the 5-year period from 2001 were included in the study. Surviving patients were followed for a mean of 8.2 years. Risk factors and death after MI were analysed according to MI classification.

Of the patients, 20.1% were classified as having a micro MI. During follow-up, 47.2% of all the patients died. Patients with micro MI were older and fewer were current smokers than patients with other MI. In multivariate Cox regression analysis for the total risk of mortality, age, diabetes mellitus, a positive smoking history, history of stroke and living alone were significantly related to long-term prognosis, and there was no difference in long-term survival between the two types of MI (p 0.50).

After adjustment for confounders, patients with micro MI had no significant difference in long-term survival compared with those with other MI.