High-Sensitivity Cardiac Troponin I and CAD Among Asymptomatic Older Adults
What are the correlates of high-sensitivity cardiac troponin I (hs-cTnI) and its incremental prognostic utility for incident coronary heart disease (CHD) among older asymptomatic patients?
The investigators performed a cohort study among 1,135 asymptomatic control participants in the ADVANCE (Atherosclerotic Disease, VAscular FunctioN and GenetiC Epidemiology) study at Kaiser Permanente Northern California and Stanford University, with follow-up through December 31, 2014. Hs-cTnI was measured in stored baseline (2002–2004) serum samples. To ascertain independent correlates of hs-cTnI, the authors used multivariable linear regression with log-transformed hs-cTnI as the dependent variable and all study covariates as independent variables simultaneously entered in the same model.
After a median follow-up of 11.3 years, 164 CHD events were documented. The most significant correlates of hs-cTnI were black race, body mass index, hypertension, low-density lipoprotein cholesterol, and estimated glomerular filtration rate (eGFR) (R2 = 0.16) After adjustment for race/ethnicity, education level, diabetes status, Adult Treatment Panel (ATP)-III Framingham risk score (FRS), C-reactive protein (CRP), and eGFR, each one-standard deviation increment of log-transformed hs-cTnI was associated with 1.11 (95% confidence interval [CI], 1.01-1.23; p = 0.04) increased hazard of CHD. The c-statistic increased to 0.70 from 0.68 (p = 0.16) and the category-based net reclassification index was 18% (95% CI, 8%-30%) after adding hs-cTnI to the model containing the ATP-III FRS.
The authors concluded that hs-cTnI conveys incremental prognostic information for incident CHD among asymptomatic older adults.
This study reports that circulating levels of cTnI can be detected using a high-sensitivity assay in free-living populations without prior clinical cardiovascular disease. Furthermore, this population-based cohort study demonstrates an independent association between circulating ambulatory levels of hs-cTnI and subsequent nonfatal or fatal CHD among asymptomatic patients. More specifically, subjects above the 75th percentile were at about 2.5-fold increased risk, irrespective of traditional risk factors, CRP, and renal function. This represents a shift in paradigm from using troponin as a diagnostic tool in the acute coronary syndrome setting to using it for risk stratification in primary prevention. Further research is needed to establish optimal cut-off thresholds for risk stratification, along with whether modification of hs-cTnI levels with treatment adjustment impacts clinical outcomes.
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