Stress-Delta B-Type Natriuretic Peptide Does Not Exclude ACS in the ED

Background: There are many detectable changes in circulating biomarkers in the setting of myocardial ischemia. We hypothesize that there are associated changes in circulating B-type natriuretic peptide (BNP) level after stress-induced myocardial ischemia, which can be used for emergency department (ED) acute coronary syndrome (ACS) risk stratification. Methods: In a prospective study, we enrolled 340 patients over the age of 30 receiving an exercise echocardiography stress test in an ED observational unit for suspected ACS. We collected blood samples at baseline and at 2 and 4 h post-stress test, measuring the relative and absolute changes (stress-delta) in plasma BNP concentrations. In addition, patients were contacted at 90 days and at 1 year posttest for a follow-up. We calculated the diagnostic test characteristics of stress-delta BNP for a composite outcome of ischemic imaging on stress echocardiogram, nonelective percutaneous coronary intervention, coronary artery bypass graft surgery, subsequent acute myocardial infarction, or cardiac death at 1 year via a logistic regression. We analyzed the 2-h BNP concentrations using an ANOVA model to adjust for the baseline BNP level. Results: Baseline and 2-h post-stress BNP were both higher in the positive outcome group, but the stress-delta BNP was not. Stress-delta BNP had a sensitivity and specificity, respectively, of 53% and 76% at 2 h and 67% and 68% at 4 h. It was noted that patients with the composite outcome had a higher baseline BNP level. Conclusions: BNP stress-deltas are poor diagnostic means for ACS risk stratification, but resting BNP remains a promising prognostic tool for ED patients with suspected ACS

Predictors of Stress-Delta High-Sensitivity Troponin T in Emergency Department Patients Undergoing Stress Testing

Background and objective: Elevations in high-sensitivity troponin T (hs-TnT) are frequently observed following extreme physical exercise. In light of this, we sought to determine whether specific clinical characteristics are associated with this phenomenon in patients undergoing cardiac exercise tolerance testing (ETT). Methods: We conducted a retrospective analysis of a prospectively collected biospecimen repository of 257 patients undergoing a stress echocardiogram for possible acute coronary syndrome (ACS). Ischemic electrocardiogram (ECG) changes during ETT and the presence or absence of ischemia on imaging were determined by a board-licensed cardiologist. N-terminal pro-brain natriuretic peptide (NT-proBNP) and hs-TnT assays were obtained immediately before and two hours following ETT. We developed linear regression models including several clinical characteristics to predict two-hour stress-delta hs-TnT. Variable selection was performed using the least absolute shrinkage and selection operator (LASSO). Results: The mean age of the patients was 52 years [standard deviation (SD): 11.4]; 125 (48.6%) of them were men, and 88 (34.2%) were African-American. Twenty-two patients (8.6%) had ischemia evident on echocardiography, and 31 (12.1%) had ischemic ECG changes during exercise. The mean baseline hs-TnT was 5.6 ng/L (SD: 6.4) and the mean two-hour hs-TnT was 7.1 ng/L (SD: 10.2). Age and ischemic ECG changes were associated with two-hour stress-delta hs-TnT values. Conclusions: Based on our findings, ischemic changes in stress ECG and age were associated with an increase in hs-TnT levels following exercise during a stress echo