Relation between high-sensitivity troponin i serum levels and myocardial ischemia in patients with suspected chronic coronary syndrome: the RESET-MI study

Abstract

Abstract Background Previous studies showed that exercise may increase cardiac troponin serum levels; however, whether exercise-induced myocardial ischemia influences the exercise-induced increase of troponin levels remains debatable. Methods We prospectively enrolled consecutive patients undergoing an elective stress myocardial perfusion scintigraphy (MPS) because of a clinical suspicion of obstructive coronary artery disease (CAD). Patients were divided into 3 groups according to the evidence and degree of stress-induced myocardial ischemia at MPS: 1) Group 1, no ischemia (≤4% of myocardium); 2) Group 2, mild ischemia (5-10%); 3) Group 3, moderate-to-severe myocardial ischemia (≥10%). High-sensitivity cardiac troponin I (cTnI) was measured immediately before (T0) and 1 hour (T1) and 4 hours (T2) after the stress test. A successive evaluation of patients was performed at 24 months. Results One-hundred consecutive patients (64 males; age 65.5±9.5 years) were enrolled in the study. An exercise stress test and a dipyridamole stress test were performed in 81 and 19 patients, respectively. Serum hs-cTnI concentrations significantly increased after stress test, compared to baseline, in the whole population, from (median, interquartile range) 3.9 (2.5-6.1) ng/L at T0, to 4.2 (2.8-7.3) ng/L at T1 (p<0.001) and 6.7 (3.8-14.1) ng/L at T2 (p<0.001 vs. both T0 and T1). The increase in hs-cTnI did not significantly differ between the 3 groups (p=0.35; Figure). The increase was significant after both exercise (+54.5%) and dipyridamole (+18.2%), although the increase was greater after exercise (p=0.002). Heart rate achieved during the test was the strongest determinant of cTnI increase after the stress test (p < 0.001). Conclusions In patients with suspected CAD, stress MPS induces an increase of cTnI that is independent of the induction and severity of myocardial ischemia and is mainly related to myocardial work, as indicated by heart rate achieved during the stress test.Figure