Signs of myocardial injury after surgery often missed

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A new diagnosis of Myocardial Injury after Noncardiac Surgery (MINS), defined as myocardial injury caused by ischemia that may or may not lead to necrosis, is common and may lead to considerable mortality, according to a study published in the March issue of Anesthesiology.

“Emerging evidence suggests that many patients sustain myocardial injury in the perioperative period which will not satisfy the diagnostic criteria for myocardial infarction,” wrote the members of the Vascular events In noncardiac Surgery patients cOhort evaluatioN (VISION) writing group.

The VISION study is an ongoing international, prospective cohort study of 15,065 patients 45 years of age and older who underwent inpatient noncardiac surgery. All patients had a troponin T test during the first three days after surgery. Patients with a troponin T level of 0.04 ng/ml or higher underwent assessment for ischemia as indicated by symptoms and electrocardiography.

The authors sought to assess the diagnostic criteria, characteristics, predictors and 30-day outcomes of myocardial injury after noncardiac surgery.

Elevated troponin after noncardiac surgery was an independent predictor of 30-day mortality regardless of the presence of ischemia. As a result, the authors included a peak troponin T level of 0.03 ng/ml or higher as a diagnostic criterion for MINS. MINS independently predicted 30-day mortality (adjusted hazard ratio, 3.87) and had the highest population-attributable risk (34 percent) of all perioperative complications.

There were 1,200 patients who experienced MINS (8 percent), and it would not have been defined as MI in nearly 60 percent of those cases. Of these MINS patients, only 15.8 percent had an ischemic symptom.

“Therefore, 84.2 percent of MINS probably would have gone undetected without systematic troponin monitoring after surgery,” the authors wrote.

They also argued that MINS is common and about 10 percent of patients with MINS will die within 30 days. “Failure to monitor troponin measurements after noncardiac surgery will result in missing more than 80 percent of MINS events.”