Further information: Regulation of Cardiac Contraction and Relaxation (see p1189) from Cardiovascular Medicine, 3rd Edn*

From 1996 to 2000, 8290 patients were enrolled in a clinical trial titled, “Prevention of Events with Angiotensin Converting Enzyme Inhibition (PEACE),” [1] to evaluate the use of ACE inhibitors in patients with stable coronary artery disease (CAD). Recently, the PEACE investigators used a subset of those patients to determine whether or not the risk of future cardiovascular events could be detected in patients who had stable coronary artery disease (CAD), but not heart failure or left ventricular systolic dysfunction, when a recently developed and highly sensitive assay was used to measure cardiac troponin T [2]. The highly sensitive assay can measure troponin levels that are lower than a factor of 10 than those measured with conventional assays. From the original group of patients, this study used stored plasma samples from 3679 patients for whom baseline troponin T measurements were available, and results were analyzed relative to the occurrence of cardiovascular events during a median follow-up period of 5.2 years. Results showed that in 3593 (97.7%) patients with stable CAD, the concentrations of troponin T when measured with the highly sensitive assay were at or above the limit of detection (0.001 µg/l), and equal to or greater than the 99th percentile for apparently healthy patients (0.0133 µg/l) in 407 patients (11.1%).

In the compilation of data after adjustments were made for other prognostic risk factors, a strong increase was shown in the incidence of cardiovascular death (adjusted hazard ratio [AHR] per unit increase in the natural logarithm of the troponin T level, 2.09; 95% confidence interval [CI], 1.60–2.74; P<0.001) and of heart failure (AHR, 2.20; 95% CI, 1.66–2.90; P<0.001) in this group. However, in regard to myocardial infarction (MI), there were 233 fatal or nonfatal acute MIs with a weak but significant increase in the cumulative incidence of MIs with increasing troponin T levels, but after adjustment, the association was no longer considered significant (HR, 1.16; 95% CI, 0.97–1.40; P=0.11). Also shown was a weak association between risk of MI and increasing quartiles of troponin T, but after adjustment, the association was not significant. Authors concluded that in patients with stable CAD whose troponin T levels were well below the detection limit of previous assays, but with increased troponin T values compared to normal controls, there was a strong association with the incidence of cardiovascular death and heart failure, but troponin T levels were not independently associated with incidence of MI.

Readers may also wish to read summaries posted in October on the this website of articles published in the August 27, 2009 issue of The New England Journal of Medicine regarding the use of sensitive troponin assays for the detection of acute MI [3,4,5,6].

[1] The PEACE Trial Investigators. Angiotensin-converting-enzyme inhibition in stable coronary artery disease. N Engl J Med 2009;351:2058-68

[2] Omland T, de Lemos JA, Sabatine MS, et al. A sensitive cardiac troponin T assay in stable coronary artery disease (PEACE trial investigators) N Engl J Med 2009;361:2538-47

[3] New generation sensitive troponin assays. http://cardiovascular-medicine.com/?p=189 (Accessed 3.2.10)

[4] Schouten O, Boersma E, Hoeks SE, et al. Fluvastatin and perioperative events in patients undergoing vascular surgery. N Engl J Med 2009;361:980-9

[5] Keller T, Zeller T, Peetz D, et al. Sensitive troponin I assay in early diagnosis of acute myocardial infarction. N Engl J Med 2009;361:868-77

[6] Morrow D. Clinical application of sensitive troponin assays. N Engl J Med 2009;361:913-15

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