Troponin release following exercise test in patients with stable angina pectoris - risk factors and prognostic significance

Abstract

Background: Increase of troponin (cTn) is a marker of myocardial injury caused by different mechanisms. Exercise testing (ExT) is a useful clinical tool in predicting the risk of myocardial ischemia, especially in patients with multivessel coronary artery disease (CAD), who are more often endangered by medical complications. The test is however limited by its low sensitivity and specificity.
Aim: To evaluate the reasons for troponin I (cTnI) release after ExT, and to determine its clinical and prognostic implications in patients with stable CAD, referred for elective coronary angiography (ANG).
Methods: 118 patients without signs of systolic heart failure, referred for planned coronary ANG were included in the analysis. After baseline measurements of NT-proBNP, hsCRP, cTnI, CK-MB levels, maximal ExT was performed, followed by the consecutive measurements of cTnI and CK-MB 12 and 24 hours after examination. All patients underwent coronary ANG and ECHO within 7 days of taking blood samples. All patients were followed up on average for 35.5 months.
Results: The cTnI elevation ≥ 0.14 ng/mL (≥ 99th percentile value of the reference group) after 24 hours of the ExT was observed in 11 (9%) patients. Predictors of cTnI release in patients after ExT were as follows: ejection fraction ≤ 50%, lack or insufficient physical activity, max systolic blood pressure > 160 mm Hg at peak of ExT (OR 6.6, 95% CI 1.2-35.4, p = 0.027; OR 5.5, 95% CI 1.1-28.8, p = 0.04; OR 6.3, 95% CI 1.3-31.6, p = 0.025, respectively). Increase of cTnI after ExT did not correlate with multivessel CAD nor with future adverse clinical events.
Conclusions: The cTnI release post ExT is more frequently observed in patients with stable CAD with ejection fraction ≤ 50%, low physical activity, and max systolic blood pressure > 160 mm Hg at peak ExT. Post ExT cTnI increase in patients with stable CAD did not correlate with the number of atherosclerotic coronary vessels, and had no prognostic implications. Increase of cTnI after ExT did not have any predictive value in respect to acute coronary syndrome and/or death during long-term follow up.