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Published on: June 28, 2019
Perioperative infarction during coronary bypass surgery: an attempt to refine the diagnostic criteria using data from
Lars Niclauss1, Liam-Kani Roulet2, Piergiorgio Tozzi1
1Cardiovascular Surgery, University Hospital of Lausanne, Lausanne, Switzerland.
Insights
Defining myocardial infarction after coronary artery bypass graft surgery is challenging. Elevated cardiac enzymes alone lack specificity, necessitating higher thresholds for accurate diagnosis and improved patient outcomes.
Area of Science:
- Cardiology
- Cardiac Surgery
- Biomarkers
Background:
- The definition of myocardial infarction (MI) following coronary artery bypass graft (CABG) surgery is debated due to multifactorial causes of postoperative cardiac enzyme elevation.
- Accurate diagnosis of perioperative MI is crucial for patient management and outcome assessment.
Purpose of the Study:
- To identify risk factors associated with perioperative MI after CABG.
- To determine appropriate cardiac enzyme activity thresholds for diagnosing MI in the perioperative setting.
- To evaluate the diagnostic value and specificity of cardiac biomarkers for perioperative MI.
Main Methods:
- A retrospective case-control study was conducted.
- Patients experiencing perioperative MI (defined by enzyme release, ECG, and echocardiography) were compared to those without ischemia.
- Risk factors and cardiac enzyme thresholds were analyzed.
Main Results:
- The incidence of CABG-associated MI was estimated at 2.8%.
- Identified risk factors included family history of cardiovascular disease, tobacco abuse, recent MI, and triple-vessel disease.
- Patients with MI exhibited higher mortality, prolonged intubation, and extended intensive care stays.
- Conventional MI thresholds (10x URL) for troponin I and hs-cTnT were exceeded in a high percentage of patients without ischemia (88.4% and 96%, respectively).
Conclusions:
- Conventional cardiac enzyme thresholds have low specificity for diagnosing perioperative MI.
- Elevated enzyme activity alone has limited diagnostic value for perioperative MI, which is linked to increased mortality.
- A higher threshold for high-sensitivity troponin T (hs-cTnT) (e.g., >45x URL) may improve specificity for detecting graft failure.
Objective:
The definition of coronary artery bypass graft (CABG)-associated myocardial infarction (MI) is controversial because the postoperative increases in cardiac enzyme activities are multifactorial in origin.
Methods:
We performed a retrospective case-control study of patients who experienced perioperative MI (cardiac enzyme release, electrocardiographic changes, dysfunction on echocardiography) and those without ischemia to identify risk factors and enzyme activity thresholds.
Results:
The estimated incidence of CABG-associated MI was 2.8%. The risk factors were a family history of cardiovascular disease (odds ratio (OR) 2.8), tobacco abuse (OR 3.8), recent MI (OR 3.6), and triple-vessel disease (OR 2.8). The MI group showed higher mortality (OR 2.3), prolonged intubation (OR 3.1), and a prolonged stay in intensive care (OR 4.3). The type 5 MI threshold (10 times the upper limit of the reference range (URL)) was exceeded in 88.4% (troponin I) and 96% (high-sensitivity troponin T; hs-cTnT) of patients without ischemia.
Conclusions:
The frequent exceeding of conventional MI-indicating thresholds in patients without ischemia indicates their low specificity. An enzyme activity increase alone is of limited diagnostic value for perioperative MI, which is associated with greater mortality. Finally, the use of a higher threshold for hs-cTnT (>45 × URL) may increase its specificity for graft failure.
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