Study examines definition of clinically important myocardial injury after cardiac surgery
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The minimum high-sensitivity cardiac troponin I tied to 30-day death after cardiac surgery was found to be significantly greater than what is currently recommended to diagnose periprocedural myocardial injury, researchers reported.
According to data published in The New England Journal of Medicine, the minimum high-sensitivity cardiac troponin I level associated with 30-day mortality risk after CABG and aortic valve replacement or repair observed by researchers was approximately 218 times greater than the upper reference limit.
The Fourth Universal Definition of MI states that, in patients who have normal cardiac troponin at baseline, levels more than 10 times the upper reference limit in the first 48 hours after CABG with evidence of new myocardial ischemia should be the threshold for the diagnosis of periprocedural MI, whereas the Academic Research Consortium-2 consensus document endorsed a threshold of 35 times the upper reference limit with new ischemia or 70 times the upper reference limit without ischemia, according to the study background.
The VISION study
“Many hospitals now use high-sensitivity cardiac troponin assays; however, limited data are available to define a prognostically important degree of myocardial injury after cardiac surgery on the basis of those assays,” Philip J. Devereaux, MD, PhD, Salim Yusuf Chair in cardiology, director of the division of cardiology and scientific leader of the anesthesiology, perioperative medicine and surgical research group at the Population Health Research Institute at McMaster University in Hamilton, Ontario, and colleagues wrote. “We found that the lowest threshold values of high-sensitivity cardiac troponin I associated with increased rates of death from any cause and major vascular complications at 30 days after surgery were markedly higher than the threshold values recommended in consensus statements for the detection of perioperative myocardial infarction and clinically important perioperative myocardial injury.”
To evaluate the relationship between peak troponin and 30-day mortality, Devereaux and colleagues conducted the prospective VISION Cardiac Surgery study, which included 13,862 adult patients who underwent CABG or surgical AVR (mean age, 63 years; 71% men; 70% white; 29% with prior MI). Postprocedural cardiac troponin I measurements were obtained at 3 to 12 hours and on days 1, 2 and 3 after surgery. Researchers used an upper reference limit of 26 ng/L.
Researchers also adjusted results for EuroSCORE II.
Median preoperative troponin I value was 9 ng/L at baseline and approximately 2.1% of the cohort died within 30 days after surgery.
Peak troponin and 30-day mortality
Within the first day following cardiac surgery, researchers observed peak troponin of more than 260 ng/L in 97.5% of the cohort (> 10 times the upper reference limit), peak troponin of at least 910 ng/L in 89.4% ( 35 times the upper reference limit) and peak troponin of 1,820 ng/L in 74.7% ( 70 times the upper reference limit).
The troponin I threshold measured within the first day after CABG or AVR associated with an adjusted HR of more than 1 for 30-day mortality was 5,670 ng/L, a level 218 times the upper reference limit (95% CI, 1,045-8,260), according to the study.
For those who underwent other cardiac surgery aside from CABG or AVR, the troponin I threshold for an aHR of more than 1 was 12,981 ng/L, a level 499 times the upper reference limit (95% CI, 2,673-16,591), according to the study.
“Our analysis differs from the recommendations in consensus statements in that we did not take into account new evidence of ischemia (such as electrocardiographic, angiographic or imaging data),” the researchers wrote. “Thus, our thresholds do not allow for direct comparison with the consensus definitions of periprocedural myocardial infarction.”
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