Frequency and Prognosis of Alternative Definitions of Occlusion Myocardial Infarction Across the Whole Spectrum of Acute Coronary Syndromes.

BACKGROUND: Occlusion myocardial infarction (OMI) refers to a myocardial infarction caused by a persistent or transient, complete or near-complete coronary artery occlusion. Multiple definitions have been proposed, yet their frequency and comparative prognostic relevance remain unclear.

OBJECTIVES: This study sought to evaluate the frequency and prognosis of previously proposed OMI definitions across the whole spectrum of acute coronary syndromes (ACS) from the MATRIX trial.

METHODS: Five alternative OMI definitions were assessed: 1) culprit artery (CA) TIMI flow grade 0; 2) CA-TIMI flow grade 0-1; 3) CA-TIMI flow grade 0-2; 4) CA-TIMI flow grade 0-2 or TIMI flow grade 3 with cardiac troponin >30× upper reference limit; and 5) CA-TIMI flow grade 0-2 or CA-TIMI flow grade 3 with cardiac troponin >100× upper reference limit. The endpoint of interest was 1-year all-cause mortality.

RESULTS: Among 6,558 patients with ACS, OMI frequency ranged from 37.8% for definition 1 to 76.1% for definition 4. OMI was independently associated with higher 1-year mortality according to definitions 1-4 (adjusted HR: 2.08 [95% CI: 1.56-2.78], 1.97[1.47-2.63], 1.70 [1.25-2.32], 1.47 [1.01-2.12], respectively) but not according to definition 5 (adjusted HR: 1.26 [0.90-1.75]). OMI definitions exclusively based on impaired CA flow (ie, definitions 1-3) improved discrimination, reclassification, and model fit when added to the conventional STE/NSTE-ACS classification. One-year mortality did not differ among patients with NSTE-ACS with OMI definition 1 or 2 compared with ST-segment elevation MI (STEMI) patients.

CONCLUSIONS: OMI defined by impaired CA flow confers prognostic implications beyond the presence or absence of ST-segment elevation in a broad ACS population and identifies patients without ST-segment elevation with 1-year mortality similar to that of STEMI.