Perioperative myocardial injury (PMI) after coronary artery bypass grafting (CABG) and other cardiac surgeries reflected by high perioperative high-sensitivity cardiac troponin T (hs-cTnT) is associated with high 30-day mortality, a new study shows.
The same was true for 5-year mortality, except for isolated surgical aortic valve replacement (AVR), according to the study.
These results were reported by Leo Pölzl, MD, of Medical University of Innsbruck, Austria, and colleagues in a manuscript published Monday online and, in the Sept. 26 issue of the Journal of the American College of Cardiology.
Highly sensitive assays for cardiac troponin I and T are valuable tools to detect PMI. There is clear evidence that the release of troponin I after cardiac surgery correlates with 30-day mortality. However, the association for PMI reflected by other troponin isoforms (such as hs-cTnT) after cardiac surgery with 30-day mortality and long-term survival has yet to be established.
This retrospective study was conducted on patients who underwent cardiac surgery between May 2010 and December 2020 at the Medical University of Innsbruck. Levels of hs-cTnT were measured both pre-surgery and post-surgery, up to 72 hours after the procedure. The study population was categorized into three groups: (A) isolated CABG; (B) isolated surgical AVR; and (C) other cardiac surgical procedures.
The primary outcome was 30-day all-cause mortality, while the secondary outcome was death within 5 years after cardiac surgery. The relationship between postoperative hs-cTnT release and both 30-day mortality and 5-year mortality was analyzed, and adjusted with EuroSCORE II, utilizing a Cox proportional hazards model.
Based on the defined inclusion and exclusion criteria, a total of 8,292 patients were included in the study. Isolated CABG was performed in 2,676 patients (32.3%), isolated SAVR in 1,159 patients (14%), and other cardiac surgery in 4,457 patients (53.8%). The median age of the study cohort was 68.0 years. Within this cohort, 31% were female, 24% had a history of myocardial infarction, and 14% had a prior PCI.
Death within 30 days occurred in 2.5% of the patients. The prognostic hs-cTnT concentrations used to determine the thresholds for myocardial injury were 2,385 ng/L for isolated CABG (i.e., 170 times the upper reference limit [URL] of normal in a seemingly healthy population), 568 ng/L for SAVR (i.e., 41 times URL), and 1,873 ng/L for other cardiac procedures (i.e., 134 times URL).
These postoperative hs-cTnT cutoffs to identify survival-relevant PMI are higher than those currently recommended in existing definitions. Having hs-cTnT levels above these cutoffs resulted in a hazard ratio for 30-day mortality for CABG of 12.56 (95% confidence interval [CI]: 6.81-23.16; P < 0.001), for AVR of 4.44 (95% CI: 1.61-12.25; P = 0.004), and for other cardiac surgery of 3.97 (95% CI: 1.61-12.25; P < 0.001).
The predictive value of postoperative hs-cTnT declined markedly in all patients over time, resulting in an area under the curve of 0.586 for 5-year mortality. However, the 5-year mortality was increased in patients above the calculated thresholds undergoing CABG and other cardiac surgery procedures but not in AVR patients.
In an accompanying editorial, Philip James Devereaux, MD, PhD, of Population Health Research Institute and McMaster University in Hamilton, Ontario, and colleagues emphasized the importance of establishing a sensible diagnostic criterion for perioperative myocardial injury/infarction (PMII) after cardiac surgery, particularly cardiac surgery other than CABG. This is crucial because the current definition for PMII by the Fourth Universal Definition of Myocardial Infarction and the Academic Research Consortium-2 (ARC-2) consensus documents does not provide diagnostic criteria for PMII after non-CABG cardiac surgeries.
The editorialists compared the results of this study with their own recently published similar study, the VISION Cardiac Surgery (Vascular Events in Surgery patIents cOhort evaluatioN-Cardiac), and highlighted the differences in the findings between these two studies.
The commenters also emphasized the significance of hs-cTnT’s predictive value for 30-day mortality after cardiac surgery. “In addition, researchers, research funders, and regulators need to require and fund high-quality research to establish diagnostic criteria informed by prognostic relevance.” Devereaux and colleagues wrote.
Pölzl L, Engler C, Sterzinger P, et al. Association of High-Sensitivity Cardiac Troponin T With 30-Day and 5-Year Mortality After Cardiac Surgery. J Am Coll Cardiol. 2023;82:1301–1312.
Devereaux PJ, Whitlock R, Lamy A. Perioperative Myocardial Injury/Infarction After Cardiac Surgery: The Diagnostic Criteria Need to Change. J Am Coll Cardiol. 2023;82:1313–1315.
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