MI monitoring of noncardiac surgery patients vital
MedWire News: Researchers analyzing follow-up data from the POISE trial have found that patients must be carefully monitored in the 48 hours following noncardiac surgery, as this is when they are most at risk for perioperative myocardial infarction (MI).
A team of scientists led by PJ Devereaux (McMaster University, Canada) conducted a cohort study of 8351 participants in the POISE (PeriOperative Ischemic Evaluation) trial.
They evaluated MIs within 30 days after randomization, where MI was defined as elevated cardiac biomarker or enzyme levels and one or more of the following: ischemic symptoms; pathologic Q waves; ischemic changes detected with ECG; coronary artery intervention; evidence of MI on cardiac imaging; and autopsy findings.
A total of 415 patients (5.0%) had perioperative MI within 30 days of random assignment. Devereaux et al report that of these, most symptomatic (64.6%) and asymptomatic (79.3%) MIs, and elevated levels of isolated cardiac biomarkers/enzymes (61.8%) occurred within 48 hours of surgery.
There was a statistically significant higher 30-day mortality rate among patients who had a perioperative MI than those who did not (11.6% vs 2.2%, p<0.001). Multivariate analysis revealed that perioperative MI was independently associated with death at 30 days, with an almost five times higher risk for 30-day mortality among those with ischemic symptoms, and a four times higher risk among those without (adjusted odds ratio [OR]=4.76 and OR=4.00, respectively).
Further analysis showed that aspirin and statins were associated with a reduced risk for 30-day mortality amongst those who suffered MI, with aspirin reducing the rate by half and statins by three-quarters.
Reporting their findings in the Annals of Internal Medicine, the authors point out that a major limitation of their study was that cardiac markers were only measured until day 3 after surgery which, they say, means that additional asymptomatic MIs may have been missed.
Devereaux et al propose that clinicians must rapidly diagnose, monitor, and implement treatments for perioperative MI, including perioperative troponin monitoring to avoid missing prognostically important MIs. Their study found that the highest-quartile elevation of an isolated cardiac biomarker or enzyme level was an independent predictor of 30-day mortality, which they believe suggests that the current definition of perioperative MI should be modified.
"Randomized, controlled trials to establish effective treatments for perioperative MI are urgently needed," they conclude.
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By Piriya Mahendra