Relation of High-sensitivity Cardiac Troponin I Elevation With Exercise to Major Adverse Cardiovascular Events in Patients With Coronary Artery Disease

Abstract

High sensitive cardiac troponin I (hs-cTnI) increases with inducible myocardial ischemia in patients with coronary artery disease (CAD). We aimed to assess if the change in hs-cTnI levels with exercise stress testing is associated with major adverse cardiac events (MACE). A cohort of 365 (age 62 ± 9 years, 77% men) patients with stable CAD underwent 99mTc sestamibi myocardial perfusion imaging with treadmill testing. Plasma hs-cTnI level was measured at rest and at 45 min after stress. Multivariable Fine & Gray's subdistribution hazards models were used to determine the association between the change in hs-cTnI and MACE, a composite end point of cardiovascular death, myocardial infarction, and unstable angina requiring revascularization. During a median follow-up of 3 years, 39 (11%) patients experienced MACE. After adjustment, for each two-fold increment in hs-cTnI with stress, there was a 2.2 (95% confidence interval 1.3-3.6)-fold increase in the hazard for MACE. Presence of both a high resting hs-cTnI level (>median) and ≥ 20% stress-induced hs-cTnI elevation was associated with the highest incidence of MACE (subdistribution hazards models 4.6, 95% confidence interval 1.6 to 13.0) compared with low levels of both. Risk discrimination statistics significantly improved after addition of resting and change in hs-cTnI levels to a model including traditional risk factors and inducible ischemia (0.67 to 0.71). Conversely, adding inducible ischemia by SPECT did not significantly improve the C-statistic from a model including traditional risk factors, baseline and change in hs-cTnI (0.70 to 0.71). In stable CAD patients, higher resting levels and elevation of hs-cTnI with exercise are predictors of adverse cardiovascular outcomes beyond traditional cardiovascular risk factors and presence of inducible ischemia.