Abnormal elevation of myocardial necrosis biomarkers after coronary artery bypass grafting without established myocardial infarction assessed by cardiac magnetic resonance

European Association of Cardio-Thoracic Surgery (EACTS) expert consensus statement on perioperative myocardial infarction after cardiac surgery

Cardiac surgery may lead to myocardial damage and release of cardiac biomarkers through various mechanisms such as cardiac manipulation, systemic inflammation, myocardial hypoxia, cardioplegic arrest and ischaemia caused by coronary or graft occlusion. Defining perioperative myocardial infarction (PMI) after cardiac surgery presents challenges, and the association between the current PMI definitions and postoperative outcomes remains uncertain. To address these challenges, the European Association of Cardio-Thoracic Surgery (EACTS) facilitated collaboration among a multidisciplinary group to evaluate the existing evidence on the mechanisms, diagnosis and prognostic implications of PMI after cardiac surgery. The review found that the postoperative troponin value thresholds associated with an increased risk of mortality are markedly higher than those proposed by all the current definitions of PMI. Additionally, it was found that large postoperative increases in cardiac biomarkers are prognostically relevant even in absence of additional supportive signs of ischaemia. A new algorithm for PMI detection after cardiac surgery was also proposed, and a consensus was reached within the group that establishing a prognostically relevant definition of PMI is critically needed in the cardiovascular field and that PMI should be included in the primary composite outcome of coronary intervention trials.

High-Sensitivity Cardiac Troponin I and T Kinetics Differ following Coronary Bypass Surgery: A Systematic Review and Meta-Analysis

Background

Cardiac troponin I and T are both used for diagnosing myocardial infarction (MI) after coronary artery bypass grafting (CABG), also known as type 5 MI (MI-5). Different MI-5 definitions have been formulated, using multiples of the 99th percentile upper reference limit (10×, 35×, or 70× URL), with or without supporting evidence. These definitions are arbitrarily chosen based on conventional assays and do not differentiate between troponin I and T. We therefore investigated the kinetics of high-sensitivity cardiac troponin I (hs-cTnI) and T (hs-cTnT) following CABG.

Methods

A systematic search was applied to MEDLINE and EMBASE databases including the search terms “coronary artery bypass grafting” AND “high-sensitivity cardiac troponin.” Studies reporting hs-cTnI or hs-cTnT on at least 2 different time points were included. Troponin concentrations were extracted and normalized to the assay-specific URL.

Results

For hs-cTnI and hs-cTnT, 17 (n = 1661 patients) and 15 studies (n = 2646 patients) were included, respectively. Preoperative hs-cTnI was 6.1× URL (95% confidence intervals: 4.9–7.2) and hs-cTnT 1.2× URL (0.9–1.4). Mean peak was reached 6–8 h postoperatively (126× URL, 99–153 and 45× URL, 29–61, respectively). Subanalysis of hs-cTnI illustrated assay-specific peak heights and kinetics, while subanalysis of surgical strategies revealed 3-fold higher hs-cTnI than hs-cTnT for on-pump CABG and 5-fold for off-pump CABG.

Conclusion

Postoperative hs-cTnI and hs-cTnT following CABG surpass most current diagnostic cutoff values. hs-cTnI was almost 3-fold higher than hs-cTnT, and appeared to be highly dependent on the assay used and surgical strategy. There is a need for assay-specific hs-cTnI and hs-cTnT cutoff values for accurate, timely identification of MI-5.

Meta-Analysis Evaluating High-Sensitivity Cardiac Troponin T Kinetics after Coronary Artery Bypass Grafting in Relation to the Current Definitions of Myocardial Infarction

Various definitions of myocardial infarction type 5 after coronary artery bypass grafting (CABG) have been proposed (myocardial infarction [MI-5], also known as peri-procedural MI), using different biomarkers and different and arbitrary cut-off values. This meta-analysis aims to determine the expected release of high-sensitivity cardiac troponin T (hs-cTnT) after CABG in general and after uncomplicated surgery and off-pump CABG in particular. A systematic search was applied to 3 databases. Studies on CABG as a single intervention and reporting on postoperative hs-cTnT concentrations on at least 2 different time points were included. All data on hs-cTnT concentrations were extracted, and mean concentrations at various points in time were stratified. Eventually, 15 studies were included, encompassing 2,646 patients. Preoperative hs-cTnT was 17 ng/L (95% confidence interval [CI] 13 to 20 ng/L). Hs-cTnT peaked at 6 to 8 hours postoperatively (628 ng/L, 95% CI 400 to 856 ng/L; 45x upper reference limit [URL]) and was still increased after 48 hours. In addition, peak hs-cTnT concentration was 614 ng/L (95% CI 282 to 947 ng/L) in patients with a definite uncomplicated postoperative course (i.e., without MI). For patients after off-pump CABG compared to on-pump CABG, the mean peak hs-cTnT concentration was 186 ng/L (95% CI 172 to 200 ng/L, 13 × URL) versus 629 ng/L (95% CI 529 to 726 ng/L, 45 × URL), respectively. In conclusion, postoperative hs-cTnT concentrations surpass most of the currently defined cut-off values for MI-5, even in perceived uncomplicated surgery, suggesting thorough reassessment. Hs-cTnT release differences following on-pump CABG versus off-pump CABG were observed, implying the need for different cut-off values for different surgical strategies.

Long-term prognostic value of late gadolinium enhancement and periprocedural myocardial infarction after uncomplicated revascularization: MASS-V follow-up

AIMS

Cardiac biomarkers elevation is common after revascularization, even in absence of periprocedural myocardial infarction (PMI) detection by imaging methods. Thus, late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) may be useful on PMI diagnosis and prognosis. We sought to evaluate long-term prognostic value of PMI and new LGE after revascularization.

METHODS AND RESULTS

Two hundred and two patients with multivessel coronary disease and preserved ventricular function who underwent elective revascularization were included, of whom 136 (67.3%) underwent coronary artery bypass grafting and 66 (32.7%) percutaneous coronary intervention. The median follow-up was 5 years (4.8-5.8 years). Cardiac biomarkers measurement and LGE-CMR were performed before and after procedures. The Society for Cardiovascular Angiography and Interventions definition was used to assess PMI. Primary endpoint was composed of death, infarction, additional revascularization, or cardiac hospitalization. Primary endpoint was observed in 29 (14.3%) patients, of whom 13 (14.9%) had PMI and 16 (13.9%) did not (P = 0.93). Thirty-six (17.8%) patients had new LGE. Twenty (12.0%) events occurred in patients without new LGE and 9 (25.2%) in patients with it (P = 0.045). LGE was also associated to increased mortality, with 4 (2.4%) and 4 (11.1%) deaths in subjects without and with it (P = 0.02). LGE was the only independent predictor of primary endpoint and mortality (P = 0.03 and P = 0.02). Median LGE mass was estimated at 4.6 g. Patients with new LGE had a greater biomarkers release (median troponin: 8.9 ng/mL vs. 1.8 ng/mL and median creatine kinase-MB: 38.0 ng/mL vs. 12.3 ng/mL; P < 0.001 in both comparisons).

CONCLUSIONS

New LGE was shown to be better prognostic predictor than biomarker-only PMI definition after uncomplicated revascularization. Furthermore, new LGE was the only independent predictor of cardiovascular events and mortality.

CLINICAL TRIAL REGISTRATION

http://www.controlled-trials.com/ISRCTN09454308.