High sensitivity cardiac troponin testing.

Bösner and colleagues have presented evidence for a simple rule for ruling out coronary artery disease in the primary care setting. It is noteworthy that no laboratory measurements have been included in their model, with reference to their introductory statement that “ ... electrocardiography and cardiac troponin test are of limited value in primary care... ” This point deserves some discussion as the utility of cardiac troponin testing appears to be expanding in step with increasing assay sensitivity. With high-sensitivity assays clinically available — an example being the high sensitivity cardiac troponin T (TnT hs) assay now in use in Europe and available in Canada later this year, the ability to use this test in the primary setting for ruling out individuals at risk is an intriguing possibility. This is supported by recent studies in stable highrisk populations where the majority of individuals had measurable TnT hs concentrations, thus perhaps permitting interpreting TnT hs concentrations in the nonacute setting. More work is needed in this regard to establish cutoffs using the high-sensitivity assays in the primary care setting, but the ability to measure cardiac troponin in the stable setting is a provocative new route for possible risk stratification. Furthermore, even if these high sensitivity assays add prognostic information, an important question will remain whether inclusion of this marker to the existing five determinants will further improve an already impressive area under the curve of 0.90.