AMA Publishing Group: Cardiac Biomarkers Topic Collection

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

Beatty AL, Ku IA, Christenson RH, et al. — Mon, 13 May 2013 00:00:00 GMT

Importance

Levels of high-sensitivity cardiac troponin T (hs-cTnT) predict secondary cardiovascular events in patients with stable coronary heart disease.

Objectives

To determine the association of hs-cTnT levels with structural and functional measures of heart disease and the extent to which these measures explain the relationship between hs-cTnT and secondary events.

Design

We measured serum concentrations of hs-cTnT and performed exercise treadmill testing with stress echocardiography in a prospective cohort study of outpatients with coronary heart disease who were enrolled from September 11, 2000, through December 20, 2002, and followed up for a median of 8.2 years.

Setting

Twelve outpatient clinics in the San Francisco Bay Area.

Participants

Nine hundred eighty-four patients with stable coronary heart disease.

Main Outcomes and Measures

Cardiovascular events (myocardial infarction, heart failure, or cardiovascular death), determined by review of medical records and death certificates.

Results

Of 984 participants, 794 (80.7%) had detectable hs-cTnT 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 portion of the prohormone of brain-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% CI, 1.14-1.65]; P = .001).

Conclusions and Relevance

In 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.

Routine Noninvasive Testing and Highly Sensitive Troponin Immunoassays

Lippi G, Cervellin G. — Mon, 13 May 2013 00:00:00 GMT

In a recent article published in this journal, Prasad et al reviewed the current practice of routine noninvasive testing in patients with chest pain admitted to the emergency department (ED). Although stress testing is currently recommended in those patients with nondiagnostic results of serial electrocardiograms and biomarkers, the definition of “negative cardiac biomarker findings” may be an important drawback in this approach. At the time when the American College of Cardiology/American Heart Association guidelines were released (ie, 2007), the designation of “nondiagnostic biomarker” was based on the so-called contemporary-sensitive troponin immunoassays, which generate measurable values in approximately 35% of a healthy population, at best. The recent development and gradual commercialization of the novel highly sensitive immunoassays represent a major breakthrough in the management of chest pain in the ED, considering that a large number of these patients have comorbidities that contribute to increase troponin concentration because of an increased turnover of myocardiocytes (eg, nonischemic heart injury) or impaired protein catabolism (eg, kidney disease). With this development, measurable troponin values can now be obtained in up to 96% of cases of a presumably healthy population, and thereby in virtually all subjects admitted to the ED.

Routine Noninvasive Testing and Highly Sensitive Troponin Immunoassays—Reply

Prasad V, Cheung M, Cifu A. — Mon, 13 May 2013 00:00:00 GMT

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