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

Abstract

Previous studies showed that exercise may increase cardiac troponin serum levels; whether the occurrence of myocardial ischemia influences the changes of exercise-induced troponin raise, however, remains debatable. We prospectively enrolled consecutive patients undergoing for the first time an elective stress myocardial perfusion scintigraphy (MPS) because of clinical suspicion of obstructive coronary artery disease (CAD). Patients were divided into 3 groups based on the evidence and degree of stress-induced myocardial ischemia at MPS: 1) group 1, no myocardial ischemia (≤4 %); 2) group 2, mild myocardial 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 h (T₂) after the stress test. One hundred-seven patients (71 males; age 65.6 ± 9.4 years) were enrolled in the study. Serum hs-cTnI concentrations (logarithmic values) significantly increased after MPS, compared to baseline, in the whole population, from 1.47±1.26 ng/L at T₀, to 1.68±1.12 ng/L at T₁ (p<0.001) and 2.15±1.02 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 = 0.44). The heart rate achieved during the test was the strongest determinant of cTnI increase (p < 0.001) after the stress test. In patients with suspected CAD, stress MPS induces an increase of cTnI that is independent of the induction and extension/severity of myocardial ischemia and is mainly related to myocardial work, as indicated by the heart rate achieved during the test.