Background: Each year, millions of patients worldwide have a perioperative myocardial infarction (MI) after noncardiac surgery.
Objective: To examine the characteristics and short-term outcome of perioperative MI.
Design: Cohort study. (ClinicalTrials.gov registration number: NCT00182039)
Setting: 190 centers in 23 countries.
Patients: 8351 patients included in the POISE (PeriOperative ISchemic Evaluation) trial.
Measurements: Four cardiac biomarker or enzyme assays were measured within 3 days of surgery. The definition of perioperative MI included either autopsy findings of acute MI or an elevated level of a cardiac biomarker or enzyme and at least 1 of the following defining features: ischemic symptoms, development of pathologic Q waves, ischemic changes on electrocardiography, coronary artery intervention, or cardiac imaging evidence of MI.
Results: Within 30 days of random assignment, 415 patients (5.0%) had a perioperative MI. Most MIs (74.1%) occurred within 48 hours of surgery; 65.3% of patients did not experience ischemic symptoms. The 30-day mortality rate was 11.6% (48 of 415 patients) among patients who had a perioperative MI and 2.2% (178 of 7936 patients) among those who did not (P < 0.001). Among patients with a perioperative MI, mortality rates were elevated and similar between those with (9.7%; adjusted odds ratio, 4.76 [95% CI, 2.68 to 8.43]) and without (12.5%; adjusted odds ratio, 4.00 [CI, 2.65 to 6.06]) ischemic symptoms.
Limitation: Cardiac markers were measured only until day 3 after surgery, and additional asymptomatic MIs may have been missed.
Conclusion: Most patients with a perioperative MI will not experience ischemic symptoms. Data suggest that routine monitoring of troponin levels in at-risk patients is needed after surgery to detect most MIs, which have an equally poor prognosis regardless of whether they are symptomatic or asymptomatic.
Primary Funding Source: Canadian Institutes of Health Research.