Sandy M. Green

Prospective, Comprehensive Assessment of Cardiac Troponin T Testing After Coronary Artery Bypass Graft Surgery

Background— The significance and clinical role of cardiac troponin testing after coronary artery bypass grafting remain unclear. Methods and Results— Cardiac troponin T (cTnT) was measured during the first 24 hours after coronary artery bypass graft surgery in 847 consecutive patients. Only 17 patients (2.0%) had new Q waves or left bundle-branch block after surgery; however, cTnT elevation was observed in nearly all subjects, with a median cTnT concentration of 1.08 ng/mL overall. Direct predictors of postoperative cTnT values included preoperative myocardial infarction (P<0.001), preoperative intraaortic balloon pump (P<0.001), intraoperative/postoperative intraaortic balloon pump (P<0.001), number of distal anastomoses (P=0.005), bypass time (P<0.001), and number of intraoperative defibrillations (P=0.009), whereas glomerular filtration rate (P<0.001), off-pump coronary artery bypass grafting (P=0.003), and use of warm cardioplegia (P=0.02) were inversely associated with cTnT values. A linear association was seen between cTnT levels and length of stay and ventilator hours, and in an analysis adjusted for the Society for Thoracic Surgery Risk Model, cTnT remained independently prognostic for death (odds ratio, 3.20; P=0.003), death or heart failure (odds ratio, 2.04; P=0.008), death or need for vasopressors (odds ratio, 2.70; P<0.001), and the composite of all 3 (odds ratio, 2.57; P<0.001). In contrast to consensus-endorsed cTnT cut points for postoperative evaluation, a cTnT <1.60 ng/mL had a negative predictive value of 93% to 99% for excluding various post–coronary artery bypass graft surgery complications. Conclusions— cTnT concentrations after coronary artery bypass graft surgery are nearly universally elevated, are determined by numerous factors, and are independently prognostic for impending postoperative complications when used at appropriate cut points.

Clinical Uncertainty, Diagnostic Accuracy, and Outcomes in Emergency Department Patients Presenting With Dyspnea

BACKGROUND Dyspnea is a common complaint in the emergency department (ED) and may be a diagnostic challenge. We hypothesized that diagnostic uncertainty in this setting is associated with adverse outcomes, and amino-terminal pro-B-type natriuretic peptide (NT-proBNP) testing would improve diagnostic accuracy and reduce diagnostic uncertainty. METHODS A total of 592 dyspneic patients were evaluated from the ProBNP Investigation of Dyspnea in the Emergency Department (PRIDE) study. Managing physicians were asked to provide estimates from 0% to 100%of the likelihood of acutely destabilized heart failure (ADHF). A certainty estimate of either 20% or lower or 80% or higher was classified as clinical certainty, while estimates between 21% and 79% were defined as clinical uncertainty. Associations between clinical uncertainty,hospital length of stay, morbidity, and mortality were examined. The diagnostic value of clinical judgment vs NT-proBNP measurement was compared across categories of clinical certainty. RESULTS Clinical uncertainty was present in 185 patients (31%), 103 (56%) of whom had ADHF. Patients judged with clinical uncertainty had longer hospital length of stay and increased morbidity and mortality,especially those with ADHF. Receiver operating characteristic analysis of clinical judgment yielded an area under the curve (AUC) of 0.88 in the clinical certainty group and 0.76 in the uncertainty group (P<.001); NT-proBNP testing alone in these same groups had AUCs of 0.96 and 0.91, respectively. The combination of clinical judgment with NT-proBNP testing yielded improvements in AUC. CONCLUSIONS Among dyspneic patients in the ED, clinical uncertainty is associated with increased morbidity and mortality, especially in those with ADHF.The addition of NT-proBNP testing to clinical judgment may reduce diagnostic uncertainty in this setting.

Soluble ST2 Plasma Concentrations Predict 1-Year Mortality in Acutely Dyspneic Emergency Department Patients With Pulmonary Disease

We evaluated the association between ST2 concentrations and mortality at 1 year in 231 acutely dyspneic patients with pulmonary diseases seen in the emergency department. Blood concentrations of ST2 were ascertained; using 1-year survival as the reference standard, receiver operating characteristic curves with resultant area under the curve (AUC) were measured. Cox proportional hazards models identified independent predictors of 1-year death. Hazard curves compared rates of death as a function of ST2 concentration. Concentrations of ST2 were significantly higher in patients with pulmonary diseases compared with 153 subjects without cardiopulmonary disease (0.23 vs 0.11 ng/mL; P = .01). Among patients with pulmonary diseases, concentrations of ST2 were higher among decedents compared with survivors (1.14 ng/mL vs 0.19 ng/mL; P < .001). ST2 had an AUC of 0.72 as a predictor of death (P < .0001). An ST2 of 0.20 ng/mL had a hazard ratio for death of 6.1 (95% confidence interval, 1.8-21.0; P = .004). Compared with patients with lower ST2 concentrations, mortality rates for patients with an enrollment ST2 of 0.20 ng/mL or more diverged early and rose progressively in 1 year (P < .001). ST2 concentrations are frequently elevated in acute pulmonary diseases and are markedly prognostic for death by 1 year.

Elevation of Myeloperoxidase in Conjunction With Cardiac-Specific Markers After Marathon Running

Cardiac-related death has been reported following strenuous exercise, and biochemical markers predicting adverse outcomes would be useful. Despite the fact the myeloperoxidase (MPO) release may precede myocardial injury and identify at-risk patients earlier than traditional markers, information on the effects of marathon running on MPO levels is lacking. We measured MPO in conjunction with the creatine kinase MB fraction (CK-MB), myoglobin, troponin T (TnT), and N-terminal B-type natriuretic peptide (NT-proBNP) in 24 athletes before and after a marathon race. Of the 24 athletes, 22 (92%) had an increased MPO level, and the mean MPO level increased from 281.44 pmol/L to 785.21 pmol/L (P < .0001). Results for 14 (58%) of the athletes reached or exceeded the manufacturers recommended clinical threshold. The increases in CK-MB, myoglobin, TnT, and NT-proBNP also reached statistical significance. Although the elevation in MPO most likely represents a systemic inflammatory response, the concurrent elevations in TnT and NT-proBNP suggest that myocardial injury cannot be excluded.

The impact of amino-terminal pro-brain natriuretic peptide testing on hospital length of stay and morbidity in patients with acute decompensated heart failure

CONTEXT In clinical trials, N-terminal pro-brain natriuretic peptide (NT-proBNP) testing has been shown to be valuable for diagnosis and triage of patients with acute decompensated heart failure. It is not yet clear what benefits might be expected from the initiation of NT-proBNP testing in an everyday clinical setting. OBJECTIVE To determine the effects of NT-proBNP testing on hospital length of stay as well as on 60-day morbidity and mortality in patients with acute decompensated heart failure before and after the test was implemented in the clinical laboratory. DESIGN We measured hospital length of stay and 60-day morbidity and mortality rates among patients with acute decompensated heart failure admitted before and after initiation of NT-proBNP testing in our hospital. Differences in demographics between preimplementation and postimplementation groups were compared with the chi2 test for categorical variables and the Wilcoxon rank sum test for continuous variables. Comparison between the hospital length of stay for each group was evaluated using the Mann-Whitney U test. Differences in rates of rehospitalization or death at 60 days following presentation were assessed using chi2 cross-tabulation. RESULTS Patients in the postimplementation group had similar clinical features as those in the preimplementation group. The hospital length of stay for patients in the postimplementation study group decreased both with respect to mean (1.86-day reduction) and median (1.3-day reduction) hospital stay (both, P = .03). Additionally, significantly lower rates of death (6.6% absolute risk reduction, P = .01), rehospitalization (12.1% absolute risk reduction, P = .005), and the composite of the 2 rates (18.7% absolute risk reduction, P = .008) were found following initiation of NT-proBNP testing. CONCLUSIONS Implementation of NT-proBNP testing may result in significant reductions in hospital length of stay as well as improvements in rates of morbidity and mortality in patients with acute decompensated heart failure.

Natriuretic peptide testing for heart failure therapy guidance in the inpatient and outpatient setting.

Acutely destabilized heart failure is one of the most common diagnoses in the modern health care system. It has high hospital readmission rates and significant short-, medium-, and long-term mortality, likely due to misdiagnosis or failure to assess adequate treatment before discharge. Cardiac biomarkers such as B-type natriuretic peptide and its amino terminal cleavage equivalent N-terminal fragment have rapidly become one of the key tools in the diagnosis and guidance of heart failure therapy. In this article, we shall review the data on the current use of the natriuretic peptides for the diagnosis, prognosis, and management of heart failure in both the outpatient and inpatient settings.