ACC/AHA/ESC/WHF Universal Definition of Myocardial Infarction Classification System and the Risk of Cardiovascular Death: Observations From the TRITON-TIMI 38 Trial
What is the prognostic implication of the subtypes of myocardial infarction (MI), as defined by the universal definition of MI?
The authors retrospectively evaluated the association between new or recurrent MI by subtype according to the American College of Cardiology/American Heart Association/European Society of Cardiology/World Heart Federation (ACC/AHA/ESC/WHF) Task Force for the Redefinition of MI Classification System, and the risk of cardiac death among 13,608 patients with acute coronary syndrome who were enrolled in the TRITON-TIMI 38 trial. The adjusted risk of cardiac death was evaluated by landmark analysis, starting at the time of the MI through 180 days after the event.
The risk of cardiac death at 6 months was higher in patients who had an MI compared with patients without an MI (6.5% vs. 1.3%; p < 0.001). This higher risk was present across all subtypes of MI including Type 4a (peri-percutaneous coronary intervention [PCI], 3.2%; p < 0.001) and Type 4b (stent thrombosis, 15.4%; p < 0.001). After adjusting for important clinical covariates, the occurrence of any MI was associated with a fivefold higher risk of death at 6 months (95% confidence interval [CI], 3.8-7.1) with increased risk across subtypes. The hazard of death was increased four times after Type 1 MI (spontaneous) (adjusted hazard ratio [HR], 4.1; 95% CI, 2.7-6.3; p < 0.001), threefold after Type 2 (demand related) (HR, 2.8; 95% CI, 0.9-8.8; p = 0.085), doubled in those with a Type 4a MI (peri-PCI) (HR, 2.4; 95% CI, 1.6-3.7; p < 0.001), and more than 10-fold (HR, 10.5; 95% CI, 1.18-93.6; p = 0.035) in those experiencing Type 5 MI (coronary artery bypass grafting related).
The authors concluded that all types of MI are associated with a significantly increased risk of cardiovascular death on follow-up.
The change in the definition of MI to include the use of sensitive biomarkers had raised concerns about the clinical relevance of small elevation in biomarkers. This study demonstrates a clear adverse impact of all subtypes of MI on mortality, and supports the use of the universal definition for clinical as well as research purposes.
Keywords: Myocardial Infarction, Acute Coronary Syndrome, Follow-Up Studies, Platelet Aggregation Inhibitors, Thiophenes, Piperazines, Risk Factors, Angioplasty, Balloon, Coronary, Stents, Percutaneous Coronary Intervention, Prognosis, Biomarkers, Thrombosis, Cardiovascular Diseases, Confidence Intervals, Coronary Artery Bypass, United States
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