Characteristics and Outcomes of Type 2 Myocardial Infarction

IMPORTANCE: In contrast to type 1 myocardial infarction (T1MI) caused by atherothrombosis, characteristics and outcomes of type 2 myocardial infarction (T2MI) caused by supply-demand mismatch are incompletely understood.

OBJECTIVE: To explore the characteristics and outcomes of patients with T2MI compared with those with T1MI.

DESIGN, SETTING, AND PARTICIPANTS: In a prospective, international, multicenter cohort study including 12 emergency departments (EDs) in 5 European countries, unselected patients presenting with acute chest discomfort were enrolled from April 2006 to April 2018. Follow-up was done by telephone or in written form 3, 12, and 24 months after hospital discharge. Data were analyzed from April 2006 to April 2020.

INTERVENTIONS: The final diagnoses of T2MI and T1MI were centrally adjudicated according to the Fourth Universal Definition of Myocardial Infarction by 2 independent cardiologists, including the pathophysiological trigger of T2MI.

MAIN OUTCOMES AND MEASURES: Patient characteristics and outcomes, including 2-year all-cause and cardiovascular mortality and future T2MI and T1MI events.

RESULTS: Of 6253 included patients, 2078 (33.2%) were women, and the median (IQR) age was 61 (48-74) years. Among 6253 patients with acute chest discomfort, the final adjudicated diagnosis was T2MI in 251 patients (4.0%), with tachyarrhythmia and hypertension responsible for two-thirds of cases, and T1MI in 1027 patients (16.4%). All-cause and cardiovascular mortality were comparable at 2 years (T2MI: adjusted hazard ratio, 1.0; 95% CI, 0.7-1.5; T1MI: adjusted hazard ratio, 0.7; 95% CI, 0.4-1.1). Patients with tachyarrhythmia or hypertension as their underlying trigger of T2MI had a lower mortality compared with patients with hypotension, hypoxemia, or anemia. Future T2MI was more likely among patients with index T2MI compared with patients with index T1MI (hazard ratio, 3.2; 95% CI, 1.4-7.5). Similarly, future T1MI was more likely to occur among patients with index T1MI (hazard ratio, 3.0; 95% CI, 1.2-7.4).

CONCLUSIONS AND RELEVANCE: Among patients with T2MI, tachyarrhythmia and hypertension were responsible for more than two-thirds of T2MI cases. While T2MI and T1MI had comparable all-cause and cardiovascular mortality at 2 years, patients with tachyarrhythmia or hypertension as their underlying trigger of T2MI had a lower mortality compared with patients with hypotension, hypoxemia, or anemia. Future T2MI occurred 3-fold more frequently among patients with T2MI vs T1MI as the index event. Improved understanding of the specifics of patients with T2MI should help improve management strategies.