Nutzen kardialer Biomarker in der Notaufnahme für die Diagnosestellung und Prognoseabschätzung bei Patienten mit Synkope

Introduction/Background: Commonly cardiac enzymes are measured at the emergency department. In this study we examined the prognostic and diagnostic values of the cardiac enzymes cardiac troponin T high-sensitive and NT-proBNP. Study design, methods: Prospective, single-center study of patients presenting with syncope or near syncope to a German Emergency department from 17 July to 31 October 2011. The primary endpoint is defined as the identification of cardiac syncope by increased levels of cardiac troponins T high-sensitive (cTnT hs) and NT-proBNP, secondary endpoints are any adverse events during a 30-days follow-up period. Predefined adverse events were cardiac events such as myocardial infarction, cardiopulmonary resuscitation, dysrhythmias, acute heart failure or other events like severe infections, pulmonary embolism, electrolyte imbalance or unexplained death. At the emergency department from every patient vital signs laboratory analysis, including cTnT hs- and NT-proBNP-levels and ECG were obtained. Results: 241 patients were enrolled (median age: 72 years; male: 57%, 26% >80 years). Cardiac syncope was present in 25%, 109 patients (45%) had cTnT hs levels above the 99% confidence interval (Cut-off point), NT-proBNP was increased above 125 pg/mL in 164 patients (68%) and above 300 pg/mL in 126 patients (52%). In patients with serious adverse event Charlson Comorbidity Index was higher (Median 3) than in patients without any event (Median 1). During a 30-days follow-up period serious adverse events occurred in 87 patients (36%). The diagnostic accuracy for cTnT hs levels to determine the diagnosis of cardiac syncope was quantified by the AUC (0.736, CI: 0661-0.812; p<0.001) and for NT-proBNP an AUC with 0,790, CI: 0,725-0,855 was obtained. And the analysis for the predictive value during a 30-days follow-up period resulted in a comparable AUC (0,759, CI: 0.693-0.826; p<0.001 for cTnT hs and 0.767, CI: 0.706-0,829 for NT-proBNP). Most frequently cardiac endpoint were dysrhythmias (12%). With 5% severe infection/sepsis was the most common non cardiac endpoint. 5 patients died during a follow-up period of 30 days. Patients with cardiac syncope displayed a high risk for adverse outcome: after 30 days only 12% of the patients stayed event-free. Cardiac syncope itself constitutes an independent risk factor for adverse events. Conclusion: The rate of serious adverse outcomes during short-term follow-up in the present cohort is high (36%). Patients with syncope presenting to the ED display a high proportion of life-threatening conditions. cTnT hs levels are above the Cut-off point in a high proportion of patients (45%) and NT-proBNP-levels above 300 pg/mL in 52% of the patients. While increased cTnT and NT-proBNP levels are not associated with the finding of a cardiac cause of syncope, increased levels of cardiac enzymes may indicate an increased risk of adverse events during follow-up especially in patients with non-cardiac cause of syncope.