Background: A new classification of type 1 and 2 myocardial infarction (MI) derived from the fourth universal definition of MI (UDMI) has been recently proposed, based on pathophysiology of coronary artery disease (CAD). We assessed the impact of this new MI categorization on epidemiology and outcomes, considering type 1 MI (T1MI) and type 2 MI (T2MI), with and without CAD.
Methods: Retrospective study including all consecutive patients hospitalized for an acute MI in a multicenter database (RICO). MI was defined according to current UDMI. Rates and outcomes of T1MI and T2MI were addressed according to the new classification.
Results: Among the 4,573 patients included in our study, 3,710 patients (81.1%) were initially diagnosed with T1M1 and 863 (18.9%) with T2MI. After reclassification, 96 T2MI patients were moved into the T1MI category. Out of the remaining 767 patients with T2MI, 567 underwent coronary angiography, and were adjudicated as type 2A MI (68.6%) with obstructive CAD, and type 2B MI (31.4%) without obstructive CAD. When compared with T1MI and T2BMI, T2AMI patients had worse in-hospital outcomes, including severe heart failure (P < .001), atrial fibrillation or flutter (P < .001) and severe bleeding (P < .001). Kaplan-Meier 1-year survival curves showed higher all-cause and CV causes mortality in T2AMI patients compared to T1MI and T2BMI (P < .001). In multivariate Cox regression analysis, type of MI was independent predictor of death.
Conclusion: Our large observational multicenter study shows major disparities in mortality according to type of MI and support the relevance of the new MI classification to improve risk classification, taking into account CAD in T2MI. Our findings may help identifying specific phenotypes and considering personalized diagnostic and management strategies.
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