Accumulating evidence shows myocardial injuries are common after noncardiac surgery and prognostically important even with clinically silent troponin elevations.
To improve recognition and understanding, the American Heart Association (AHA) issued its first scientific statement reviewing the diagnostic criteria for myocardial injury after noncardiac surgery (MINS) and offering current best practices for surveillance, prevention, and management of this relatively new diagnosis, first introduced in 2014.
"That's only 7, 8 years ago and there was a lot of skepticism because the most important thing is that we are dealing with asymptomatic patients and if you have a troponin elevation, or any kind of lab elevation, most clinicians would say, 'why should you care, the patient doesn't have any symptoms'," Kurt Ruetzler, MD, PhD, chair of the writing group, told theheart.org | Medscape Cardiology.
"But over the last few years we were providing a lot of evidence that, unfortunately, a troponin elevation, no matter if the patient is symptomatic or not, is important in terms of mortality for these patients. So now is the time for this [statement] because we have enough evidence to summarize this and make everyone aware," said Ruetzler, an anesthesiologist at the Cleveland Clinic.
The new statement was published online October 4 in Circulation.
Research suggests about 20% of noncardiac surgeries are complicated by MINS and about 90% of patients have no identifiable symptoms.
Diagnostic criteria include at least one elevated postoperative troponin T level above the 99th percentile upper reference limit (URL) for the assay judged to be due to an ischemic mechanism (i.e., supply–demand mismatch or atherothrombosis), with or without ischemic symptoms or electrocardiographic abnormalities. When using fourth-generation and high-sensitivity troponin T (hs-TnT) assays, available "prognostically important" thresholds should be considered instead of the 99th percentile URL, the writing group notes.
Although the troponin elevations must occur in the first 30 days after surgery, data from the VISION trial show that 94.1% of MINS diagnoses occurred by the second day after surgery.
The diagnosis of MINS is more likely to occur in people with pre-existing cardiovascular risk factors, including older age (especially 75 years and older), male sex, diabetes, hypertension, heart failure, obstructive sleep apnea, and anemia.
Studies also show that people undergoing emergency surgery have a two- to threefold higher adjusted odds of MINS, and that the risks for MINS are higher with several types of surgery, including vascular procedures (especially open aortic or infrainguinal surgery) and general abdominal surgery, the writing group notes
Importantly, evidence from prospective and retrospective analyses clearly indicate that troponin T elevations after noncardiac surgery are independently associated with short-and long-term mortality, Ruetzler said. In VISION, for example, the 30-day mortality rate was 3% with peak postsurgery hs-TnT levels of at least 20 ng/L to less than 65 ng/L and ballooned to 29.6% for patients with levels above 1000 ng/L.
"There are three important things," he said, "MINS is common, silent, and deadly."
Who to Screen
The writing group recommends troponin measurements before and in the first 48 to 72 hours after noncardiac surgery for patients at high clinical risk, such as adults 65 years and older or adults 45 years and older with established coronary or peripheral atherosclerotic cardiovascular disease.
If a postoperative troponin level is elevated but a recent previous measurement isn't available, a second test should be performed to determine whether a rising or falling pattern, indicative of acute myocardial injury, is present, they note.
"With this statement, we are providing the scientific background but the problem, of course, is there are a lot of resources needed to actually implement it and financial things to consider," observed Ruetzler. "But we strongly believe it needs to be done."
Although some guidelines recommend systematic screening with perioperative cardiac troponin T for patients at risk for postoperative complications, there has been resistance to the broad application of this strategy because of the lack of guidance regarding which patients to screen, which criteria to use for the diagnosis of perioperative myocardial injury, and how to manage these patients, observes clinical cardiologist Danielle Menosi Gualandro, MD, PhD, University Hospital Basel at the University of Basel, Switzerland.
"This statement is a major step in the field of myocardial injury and hopefully the first step to promote the broad use of troponin screening in people at risk of cardiovascular complications," she says in a related commentary published on the AHA Professional Heart Daily website. "Increased screening can help to improve patient care and reduce cardiac complications and mortality of patients undergoing noncardiac surgery."
Although there's no consensus about the diagnostic thresholds for several cardiac troponin I assays, Gualandro notes that her team recently reported that MINS and acute perioperative myocardial injury diagnosed with hs-troponin I are independent predictors of mortality and major cardiovascular events at 30 days and 1 year.
Postop Management of MINS
The writing group notes a lack of prospective data regarding management of patients diagnosed with MINS, but the consensus is that treatment should be tailored to the etiology. When there is doubt about the mechanism, additional cardiovascular testing may be warranted.
The document provides a lot of retrospective evidence that intraoperative and postoperative blood pressure is very important in terms of avoidance of MINS, Ruetzler said, but the overall optimal treatment options are unclear.
The strongest evidence available thus far on postoperative anticoagulation in MINS comes from the placebo-controlled MANAGE trial, in which daily dabigatran (Pradaxa, Boehringer Ingelheim) showed a 28% reduction in the risk for major vascular events over 16 months without increasing major bleeding.
"So-called secondary prophylaxis is extremely important for these patients, so it makes sense to borrow the evidence from patients with a myocardial infarction in the nonsurgical setting," Ruetzler said. "And there's a lot of evidence for aspirin but also for statins, smoking cessation, lifestyle changes, and weight loss, so I think all of this should be done in these patients."
Future trials will provide new insights into MINS, including the GUARDIAN trial, which is testing whether tight perioperative blood pressure management reduces serious perfusion-related complications after major noncardiac surgery and the recently completed but not yet reported POISE-3 trial, he said. The latter examined the effects of tranexamic acid versus placebo and managing hypotension versus standard of care on a composite cardiovascular endpoint at 1 year in patients at risk for a perioperative cardiovascular event undergoing noncardiac surgery.
Ruetzler reports no relevant financial relationships. Coauthor disclosures are listed in the paper.
Circulation. Published online October 4, 2021. Full text
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