Subsequent myocardial infarction, non-ST elevation myocardial infarction

**Definition:** Extension or recurrent myocardial infarction. For morbidity coding, this category should be assigned for infarction of any myocardial site, occurring within 4 weeks (28 days) from onset of a previous infarction. This most commonly results from severe obstruction, but not total occlusion, of the culprit coronary artery.