High-Sensitivity Cardiac Troponin T Levels and Secondary Events in Outpatients With Coronary Heart Disease From the Heart and Soul Study

Study Questions:

Are high-sensitivity cardiac troponin T (hs-cTnT) levels associated with structural and functional measures of heart disease and increased risk for secondary events?

Methods:

Subjects enrolled in the Heart and Soul Study, a prospective cohort study of outpatients with coronary heart disease, who were enrolled from September 11, 2000, through December 20, 2002, and were followed for a median of 8.2 years, were included in this analysis. Patients were eligible if they had at least one of the following: history of myocardial infarction, angiographic evidence of at least 50% stenosis in at least one coronary vessel, evidence of exercise-induced ischemia by treadmill electrocardiography or stress nuclear perfusion imaging, or a history of coronary revascularization. Patients were excluded if they were unable to walk one block, had an acute coronary syndrome within the previous 6 months, or were likely to move out of the area within 3 years. Serum concentrations of hs-cTnT were measured among participants who also performed exercise treadmill testing with stress echocardiography. The primary outcome was cardiovascular events (myocardial infarction, heart failure, or cardiovascular death), determined by review of medical records and death certificates.

Results:

A total of 984 participants with stable coronary heart disease from 12 outpatient clinics in San Francisco, CA, were included. Of these participants, 794 (80.7%) had detectable hs-cTnT. With the standard TnT assay, only 58 participants (5.9% of the entire cohort) had detectable troponin levels. At baseline, higher hs-cTnT levels were associated with greater inducible ischemia and worse left ventricular ejection fraction, left atrial function, diastolic function, left ventricular mass, and treadmill exercise capacity. During follow-up, 317 participants (32.2%) experienced a cardiovascular event. After adjustment for clinical risk factors, baseline cardiac structure and function, and other biomarkers (N-terminal pro–B-type natriuretic peptide and C-reactive protein levels), each doubling in hs-cTnT level remained associated with a 37% higher rate of cardiovascular events (hazard ratio, 1.37; 95% confidence interval, 1.14-1.65; p = 0.001).

Conclusions:

The investigators concluded that among outpatients with stable coronary heart disease, higher hs-cTnT levels were associated with multiple abnormalities of cardiac structure and function, but remained independently predictive of secondary events. These findings suggest that hs-cTnT levels may detect an element of risk that is not captured by existing measures of cardiac disease severity.

Perspective:

These data suggest that hs-cTnT may add clinical information for patients with stable CAD who may be at higher risk for cardiac events. Further research is warranted to understand if gaps in secondary prevention exist, which if modified among these patients, would reduce future events.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Acute Heart Failure, Heart Failure and Cardiac Biomarkers

Keywords: Myocardial Infarction, Death Certificates, Troponin T, Coronary Disease, Risk Factors, Medical Records, Atrial Function, Left, C-Reactive Protein, Biological Markers, Outpatients, San Francisco, Heart Failure, Natriuretic Peptide, Brain, Exercise Test


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