Midregional pro-adrenomedullin and copeptin: exercise kinetics and association with the cardiopulmonary exercise response in comparison to B-type natriuretic peptide.

PURPOSE: Midregional pro-adrenomedullin (MR-proADM) and C-terminal pro-vasopressin (copeptin) are novel biomarkers providing prognostic information in various settings. We aimed to (1) assess the kinetics of MR-proADM and copeptin during cardiopulmonary exercise testing (CPET); (2) assess the relationship of MR-proADM and copeptin measured at rest with peak oxygen consumption (peak VO2) and other key CPET parameters; (3) compare this relationship to that of B-type natriuretic peptide (BNP). METHODS: In 162 patients undergoing symptom-limited CPET for evaluation of exercise intolerance, MR-proADM, copeptin, and BNP were measured at rest and peak exercise. RESULTS: There was a significant rise in copeptin and BNP (p < 0.001) but not in MR-proADM (p = 0.60) from rest to peak exercise. MR-proADM (r = -0.57; p < 0.001) and BNP (r = -0.49; p < 0.001) but not copeptin were significantly and inversely related to peak VO2. MR-proADM was inversely correlated to the percentage of predicted heart rate achieved and peak oxygen pulse and directly related to the peak ventilation/carbon dioxide production relationship, the physiological dead space-to-tidal volume ratio, and the alveolo-arterial oxygen gradient (p ≤ 0.01 for all), and these associations were at least as strong as for BNP. In contrast, copeptin was not significantly related to any of these parameters (p > 0.05 for all). CONCLUSION: In contrast to BNP and copeptin, MR-proADM is not immediately affected by a maximal exercise test. MR-proADM but not copeptin is at least as good an indicator of low peak VO2 and CPET parameters reflecting an impaired cardiac output reserve, ventilatory efficiency and diffusion capacity as BNP, and thereby a global cardiopulmonary stress marker.

How safe is the outpatient management of patients with acute chest pain and mildly increased cardiac troponin concentrations?

BACKGROUND: The appropriate management of patients discharged from the emergency department (ED) with increased high-sensitivity cardiac troponin T (hs-cTnT) but normal or borderline-high conventional cardiac troponin concentrations is unknown. METHODS: We investigated 643 consecutive ED patients with acute chest pain who had been discharged for outpatient management after acute myocardial infarction (AMI) had been ruled out by serial measurements of conventional cardiac troponin. hs-cTnT was measured blindly, and we calculated the rates of all-cause mortality (primary endpoint) and subsequent AMI (secondary endpoint) at 30, 90, and 360 days. RESULTS: hs-cTnT concentrations were increased (>14 ng/L) in 114 patients (18%) but <30 ng/L in 95% of these patients. Of those 114 patients, 96 (84%) had an adjudicated noncoronary cause of chest pain. Thirty-day mortality (95% CI) was 0.9% (0.1%-6.1%), 90-day mortality was 2.7% (0.9%-8.1%), and 360-day mortality was 5.2% (2.2%-11.9%) in patients with increased hs-cTnT; respective rates (95% CI) of AMI were 0.0%, 1.9% (0.5%-7.2%), and 7.6% (3.7%-15.3%). Increased hs-cTnT was associated with increased mortality and AMI at 90 days (P = 0.006 and P = 0.081, respectively) and 360 days (P = 0.001 for both). CONCLUSIONS: hs-cTnT is a strong prognosticator of intermediate and long-term mortality and AMI in low-risk patients discharged from the ED after AMI has been ruled out. The relatively low rate of 30-day events may suggest that patients without acute coronary syndrome and small increases in cardiac troponin are in need of further investigations and treatments, but not necessarily immediate hospitalization.