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Circulation. 2020 Jan 6. doi: 10.1161/CIRCULATIONAHA.119.043100. [Epub ahead of print]

Incidence, Trends and Outcomes of Type 2 Myocardial Infarction in a Community Cohort.

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1
Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN.

Abstract

Background: Type 2 myocardial infarction (T2MI) occurs due to an acute imbalance in myocardial oxygen supply and demand in the absence of athero-thrombosis. Despite being frequently encountered in clinical practice, the population-based incidence and trends remain unknown and the long-term outcomes incompletely characterized. Methods: We prospectively recruited residents of Olmsted County, Minnesota who experienced an event associated with a cardiac troponin T (cTnT) >99th percentile of a normal reference population (≥0.01 ng/mL) between 1/1/2003 and 12/31/2012. Events were retrospectively classified into type 1 MI (T1MI, atherothombotic event), T2MI or myocardial injury (troponin rise not meeting criteria for MI) using the universal definition. Outcomes were long term all-cause and cardiovascular mortality and recurrent MI. T2MI was further subclassified by inciting event for supply/demand mismatch. Results: A total of 5460 patients had at least one cTnT ≥0.01 ng/mL, of whom 1365 were classified as index T1MI (age 68.5±14.8 years, 63% male) and 1054 T2MI (age 73.7±15.8 years, 46% male). The annual incidence of T1MI decreased markedly from 202 to 84 per 100,000 persons between 2003 and 2012 (p<0.001), while the incidence of T2MI declined from 130 to 78 per 100,000 persons (p=0.02). Compared to T1MI, patients with T2MI had higher long-term all-cause mortality after adjustment for age and sex, driven by early and non-cardiovascular death. Rates of cardiovascular death were similar after either type of MI (HR 0.8, 95% CI 0.7-1.0, p=0.11). Sub-classification of T2MI by etiology demonstrated a more favorable prognosis when the principal provoking mechanism was arrhythmia, compared with post-operative status, hypotension, anemia and hypoxia. After index T2MI, the most common MI during follow-up was a recurrent T2MI while the occurrence of a new T1MI was relatively rare (estimated rates 9.7% and 1.7% at 5 years). Conclusions: There has been an evolution in type of MI occurring in the community over a decade, with the incidence of T2MI now being similar to T1MI. Mortality after T2MI is higher and driven by early and non-cardiovascular death. The provoking mechanism of supply/demand mismatch affects long-term survival. These findings underscore the healthcare burden of T2MI and provide benchmarks for clinical trial design.

KEYWORDS:

type 1 MI; type 1 myocardial infarction; type 2 MI; type 2 myocardial infarction

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