Evidence Mounts for Myocardial Injury After Noncardiac Surgery

Patrice Wendling

December 11, 2017

BASEL, SWITZERLAND — A new study of more than 2000 patients provides further evidence that myocardial injury is a common and problematic complication after noncardiac surgery[1].

Based on an absolute rise of high-sensitivity cardiac troponin T (hs-cTnT) of >14 ng/L from presurgery to postsurgery levels, perioperative myocardial injury (PMI) occurred in one out of seven surgeries (16%) in the prospective BASEL-PMI study.

Despite being at increased CV risk, 82% of patients did not show any ischemic symptoms and only 6% had chest pain. Overall, only 29% of patients fulfilled any of the additional criteria required for spontaneous acute MI such as loss of viable myocardium on imaging or ECG findings suggestive of myocardial ischemia.

Even with screening, however, prognosis was poor. The adjusted risk of death with PMI was almost threefold higher at 30 days (hazard ratio [HR] 2.7, 95% CI 1.5–4.8) and nearly twofold higher at 1 year (HR 1.6, 95% CI 1.2–2.2).

"So what we have is a complication that is usually quite silent but is still a quite problematic and dangerous complication that happens often after noncardiac surgery," lead author Dr Christian Puelacher (University Hospital of Basel, Switzerland) said in an interview.

The study, published online December 4, 2017 in Circulation, extends the findings of the recently reported VISION trial, in which the incidence of PMI was comparable at 17.9% and overall 30-day mortality was 1.2%.

"This study showed that people who are at increased risk of heart damage can suffer heart damage during major operations and need to be managed even more carefully with respect to their heart—I'm thinking about avoiding prolonged periods of low blood pressure, avoiding hypovolemia. I view it as an alert to us caring for older patients and patients at risk for heart problems during major operations," past American Heart Association president Dr Timothy Gardner (Christiana Care Center for Heart & Vascular Health, Newark, DE) told theheart.org | Medscape Cardiology.

He continued, "But I think from a practical perspective, it doesn't change the way we evaluate patients at risk before surgery. I think if we're concerned about high-risk patients it might be worth doing," but "I don't think it makes sense to screen routinely. In fact, in this study, only 16% of patients were positive."

While the evidence for PMI is mounting, Puelacher agreed it's not yet time for universal screening.

"As with any screening, the trick is to find the population in which it works. The VISION data and our data are not as readily comparable as we wish because we don't know how many patients in VISION had a delta of 14," he said.

VISION used multiple hs-cTnT thresholds, did not report 1-year mortality, and enrolled 21,050 patients at least 45 years of age irrespective of preexisting atherosclerotic disease.

In contrast, the 2018 consecutive patients in BASEL-PMI were at least 65 years or at least 45 years with preexisting coronary artery disease (CAD), peripheral arterial disease, or stroke.

"If we find the correct population group, a group at high risk, then screening should be something to consider," Puelacher added.

Senior author and long-time proponent of hs-cTnT, Dr Christian Mueller (University Hospital of Basel), said in an email, "The current evidence may justify different conclusions on which patients undergoing noncardiac operations should receive hs-cTnT screening. Likely Dr Puelacher's is the more precise one.

"On the other hand, the criteria to receive screening in our study are such that not all physicians (and patients) would consider these patients 'high-risk patients' (eg, all patients above the age of 65 years [until 85 years])."

Routine screening for PMI was implemented in 2014 at the University Hospital of Basel as part of the standard of care for high-risk patients undergoing inpatient noncardiac (visceral, orthopedic, trauma, vascular, urologic, spinal, and thoracic) surgery. Plasma hs-cTnT concentrations were measured within 30 days prior to surgery and the first 2 days after surgery or later if clinically indicated. PMI was centrally adjudicated by two independent experts.

Patients with PMI had more CV comorbidities at baseline and a higher rate of nonelective surgery than those without.

Patients with PMI had six times the 30-day mortality of those without PMI (9.8% vs 1.6%), with the excess mortality persisting up to 1 year (22.5% vs 9.3%; both P<0.001).

Of special note, 30-day and 1-year mortality was comparable in PMI patients not fulfilling any additional criteria required for spontaneous AMI vs those fulfilling at least one additional criteria (10.4% vs 8.7%, P=0.684; and 22.1% vs 29.1%, P=0.47).

In most cases, cardiomyocyte injury was likely caused by supply-demand mismatch due to hypotension, anemia, and tachycardia, Puelacher said.

Although the use of hs-cTnT testing was approved in the US in 2017, he's aware of only three hospitals that do routine troponin testing in noncardiac surgery patients—two in Switzerland and one in Brazil.

"We have a very close cooperation with anesthesiology and also with the surgical department, and that's a prerequisite for actually doing this; maybe we need to look outside of our own realm to actually find this cooperation," he added.

For those wanting to screen, the researchers caution that preoperative troponin measurements are needed to reliably distinguish PMI from chronic hs-cTnT elevations. In BASEL-PMI, 51% of patients already had preoperative hs-cTnT levels at or above 14 ng/L, while 13.8% patients in VISION had their peak value before surgery.

Finally, coronary angiography was recommended by the cardiology consultant in only 10% of PMI patients, highlighting the need for "improved, more focused cardiac management, because some of these patients are in fact having evidence of heart damage," Gardner said.

The study was funded by the University of Basel, University Hospital of Basel, Swiss Heart Foundation, Abbott, AstraZeneca, the PhD Educational Platform for Health Sciences, the Forschungsfond Kantonsspital Aarau, and the Cardiovascular Research Foundation Basel. Puelacher reports grants from PhD Educational Platform for Health Sciences and the University Hospital of Basel. Mueller reports grants from the Swiss Heart Foundation and grants and nonfinancial support from several diagnostic companies during conduct of the study; as well as grants, personal fees, and nonfinancial support from several diagnostic companies outside the submitted work. Disclosures for the coauthors are listed in the paper. Gardner reports serving as an editor for Circulation.

Follow Patrice Wendling on Twitter: @pwendl. For more from theheart.org | Medscape Cardiology, follow us on Twitter and Facebook.

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