WASHINGTON – A rise in the blood level of troponin T immediately after patients underwent noncardiac surgery identified a high risk group with a 30-day mortality rate nearly fivefold higher than that of patients who did not have a postoperative troponin T spike, according to a prospective study of more than 21,000 patients.
For 93% of the patients who have these perioperative spikes in troponin T, a marker of myocardial ischemia, the increased level was the only indicator of a heart problem, P.J. Devereaux, MD, said at the annual meeting of the American College of Cardiology. The painkillers that patients receive following surgery generally mask the chest discomfort they might otherwise feel from their heart damage, he explained. The clinical condition is called myocardial injury after noncardiac surgery.
“We’re seeing more older patients with a high burden of vascular disease undergoing surgery, and surgery is a very significant stress, so a large proportion of these patients will have [myocardial injury after noncardiac surgery] and that affects 30-day survival,” said Dr. Devereaux, professor and director of cardiology at McMaster University in Hamilton, Ont.
Based on the new findings, he recommended performing a baseline assessment of troponin T levels in patients scheduled for noncardiac surgery if they are at least 65 years of age, or if they are age 45-64 years with known vascular disease, followed by repeat testing 1 and 2 days after surgery to check whether a spike in the measure had occurred. The high sensitivity troponin T (hsTnT) test he used in the study is relatively costly (and received Food and Drug Administration approval for U.S. marketing in January 2017), but Dr. Devereaux believed that, used in this way, the cost for testing would be reasonable, given its powerful ability to identify high-risk patients and relative to the cost of other screening tools routinely used in U.S. medical practice.
“It looks very cost-effective,” he said in a video interview.
If the baseline and two follow-up measures of hsTnT showed a postoperative level of at least 20 ng/L that rose above the baseline level by at least 5 ng/L, or if the postoperative level was at least 65 ng/L, Dr. Devereaux recommended starting daily treatment with aspirin and a statin to try to contain any perioperative myocardial damage the patient may have, and follow with comprehensive assessment of the patient by a cardiologist or other internal medicine physician.
“Given the risks associated with a rise in hsTnT in this study, Dr. Devereaux’s recommendations are very reasonable until we collect more data on this,” said Frank W. Sellke, MD, professor of surgery and chief of cardiothoracic surgery at Brown Medical School and the Lifespan Hospitals in Providence, R.I. “What was surprising was how few patients had symptoms” of myocardial ischemia. “You can’t do hsTnT measurements on every patient who goes in for a hernia operation; it’s not practical. But his findings are fairly compelling, and hopefully the cost of this testing will come down,” Dr. Sellke said in an interview.
In the multicenter study of 21,842 patients, 24% had a postoperative hsTnT level of 20 ng/L or greater, including 5% with a level of 65 ng/L or greater. The 30-day mortality rate was 3% among those with a perioperative level of 20-64 ng/L, 9% among patients with perioperative hsTnT levels of 65-999 ng/L, and 30% among the 54 patients (0.2% of the study group) with perioperative levels that reached 1,000 ng/L or greater. Dr. Devereaux reported.
This iteration of the Vascular Events In Noncardiac Surgery Patients Cohort Evaluation Study (VISION) enrolled patients who were at least 45 years of age and underwent noncardiac surgery at 23 centers in 13 countries, including the United States and Canada. All patients underwent hsTnT testing 6-12 hours after surgery and 1, 2, and 3 days after surgery, but only 40% also had a baseline measurement before their surgery began. Full 30-day follow-up occurred for 21,050. The patients’ average age was 63 years. The most common surgery was “low-risk,” in 35%, followed by “major” general surgery in 20%, and “major” orthopedic surgery in 16%. At 30 days, 266 patients (1.2%) had died.
Dr. Athena Poppas
These findings “help define a cutoff for hsTnT that will be clinically useful to change practice,” said Athena Poppas, MD, a cardiologist and director of the Cardiovascular Institute at Rhode Island Hospital in Providence. Dr. Poppas was a designated discussant for Dr. Devereaux’s report at the meeting.
In January 2017, the Canadian Cardiovascular Society issued guidelines for perioperative cardiac risk assessment and management for patients undergoing noncardiac surgery (Can J Cardiol. 2017 Jan;33[1]:17-32). Dr. Devereaux was a member of the writing panel for these guidelines. This is what the guidelines said about using troponin T measurements:
“We recommend obtaining daily troponin measurements for 48-72 hours after noncardiac surgery in patients with a baseline risk greater than 5% for cardiovascular death or nonfatal myocardial infarction at 30 days after surgery (i.e., patients with an elevated NT-proBNP/BNP measurement before surgery or, if there is no NT-proBNP/BNP measurement before surgery, in those who have an RCRI [revised cardiac risk index] score of 1 or greater, age 45-64 years with significant cardiovascular disease, or age 65 years or older).”
The VISION study is sponsored by Roche Diagnostics, which markets the high sensitivity troponin T assay used in the study. Dr. Devereaux has received research funding from Roche Diagnostics and from Abbott Diagnostics and Boehringer Ingelheim. Dr. Sellke and Dr. Poppas had no relevant disclosures.
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