The prognostic value of high-sensitivity cardiac troponin T (hs-cTnT) in patients with stable coronary artery disease (CAD) is based on a single measurement although plasma fluctuations of the biomarker are not well defined. We assessed hs-cTnT variability over a year and hypothesized that hs-cTnT detections and its fluctuations may vary according to patients' specific CAD history. We prospectively studied 100 stable subjects (aged 64 ± 8 y, 83% men) belonging to 4 groups (N=25/group) according to their history of: 1) recurrent (≥3) acute coronary events; 2) an isolated myocardial infarction ≥7 years previously; 3) longstanding (≥7 years) always stable CAD; 4) no angiographically documented CAD (age-matched controls). We obtained 15 hs-cTnT samples per subject covering 21 time-points: 3 times during one day; 5 consecutive days; 4 consecutive weeks; 4 consecutive months; and every 3 months (x 4). The assay detection limit is 3 ng/L and the necrosis threshold value is 14 ng/L. Reference change values (RCV) were used to assess the variability in each group, during a week (RCVw) and months (RCVm). Table shows number of subjects in each group with detectable hs-cTnT in ≥1 sample, in all 15 samples, with ≥1 sample value ≥14 ng/L, the range and the RCV of detectable hs-cTnT. Hs-cTnT was detected in 71% of CAD subjects including 16% above the necrosis threshold value, and was independently associated with recurrent events group (p=0.0016) and hypertension (p=0.027). There was marked variability in detectable hs-cTnT within groups. In these stable CAD patients the detection of hs-cTnT but not its fluctuations was related to the clinical history. Study is needed to understand the marked hs-cTnT fluctuations, even over the necrosis threshold, and their prognostic implications.

BACKGROUND:C-reactive protein (CRP) is proposed as a screening test for predicting risk and guiding preventive approaches in coronary artery disease (CAD). However, the stability of repeated CRP measurements over time in subjects with and without CAD is not well defined. We sought to determine the stability of serial CRP measurements in stable subjects with distinct CAD manifestations and a group without CAD while carefully controlling for known confounders.METHODS:We prospectively studied 4 groups of 25 stable subjects each 1) a history of recurrent acute coronary events; 2) a single myocardial infarction ≥7 years ago; 3) longstanding CAD (≥7 years) that had never been unstable; 4) no CAD. Fifteen measurements of CRP were obtained to cover 21 time-points: 3 times during one day; 5 consecutive days; 4 consecutive weeks; 4 consecutive months; and every 3 months over the year. CRP risk threshold was set at 2.0 mg/L. We estimated variance across time-points using standard descriptive statistics and Bayesian hierarchical models.RESULTS:Median CRP values of the 4 groups and their pattern of variability did not differ substantially so all subjects were analyzed together. The median individual standard deviation (SD) CRP values within-day, within-week, between-weeks and between-months were 0.07, 0.19, 0.36 and 0.63 mg/L, respectively. Forty-six percent of subjects changed CRP risk category at least once and 21% had ≥4 weekly and monthly CRP values in both low and high-risk categories.CONCLUSIONS:Considering its large intra-individual variability, it may be problematic to rely on CRP values for CAD risk prediction and therapeutic decision-making in individual subjects.