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Perioperative myocardial injury as a complication of non-cardiac surgery is associated with higher odds of mortality down the line -- even when caught early, according to the experience of a Swiss hospital.

Myocardial injury, defined by an uptick in high-sensitivity cardiac troponin T (hs-cTnT) plasma concentration, occurred within 7 days after , Christian Mueller, MD, of Switzerland's University Hospital Basel, and colleagues reported in a study published online in Circulation.

Surgical patients with myocardial injury had almost triple the risk of 30-day mortality as those without (9.8% versus 1.6%, HR 2.7, 95% CI 1.5-4.8). Their disadvantage in survival persisted to the end of the first year (22.5% versus 9.3%, HR 1.6, 95% CI 1.2-2.2).

"Perioperative myocardial injury is a common complication following non-cardiac surgery and despite early detection during routine clinical screening, is associated with substantial short- and long-term mortality," Mueller's group concluded.

More than 1 in 10 cases of myocardial injury were due to severe sepsis or uncontrolled infection, the authors found. They had performed a prospective screening of all of those getting non-cardiac surgery at their institution in 2014-2015 with a post-operative stay of at least 24 hours (n=2,018).

Unlike spontaneous MI, perioperative myocardial injury is not usually tied to any symptoms. Indeed, in Mueller's study, only 6% of patients with postoperative myocardial injury reported chest pain; overall, 18% experienced some sort of ischemic symptom.

Whether these patients fit another criterion for having spontaneous acute MI did not have an impact on their mortality risk in the short term (10.4% no versus 8.7% yes, P=0.684) or long term (22.1% versus 29.1%, P=0.47). Those possible criteria included having ischemic symptoms, new ST-segment T-wave changes or new left bundle branch block, development of pathological Q waves on EKG, imaging evidence of new loss of viable myocardium or new regional wall motion abnormality, or identification of an intracoronary thrombus.

Patients included in Mueller's study were considered to be at high cardiovascular risk, being age 65 or older or having pre-existing atherosclerosis. Median age was 74 years, and 42% were women.

Hs-cTnT was measured up to 30 days before surgery and again on postoperative days 1 and 2 (and afterward if injury was suspected). Perioperative myocardial injury was defined as an hs-cTnT increase of 14 ng/L or greater within 7 days of surgery (symptoms and EKG changes were not required for the diagnosis).

Among the limitations of the study was the lack of a universally-accepted definition of perioperative myocardial injury, which impacts the generalizability of the data.

"The high incidence of perioperative myocardial injury and the high mortality rate observed in this study suggests that the specific selection criteria used to identify high-risk patients deserve to be replicated in future studies," the investigators maintained. "Ideally, these should include a randomized controlled trial testing the effect of active surveillance combined with an active response protocol on clinical and economic outcomes."

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