Usefulness of N-terminal pro-B-type natriuretic Peptide increase as a marker for cardiac arrhythmia in patients with syncope

Abstract

B-type natriuretic peptides (BNPs) have been investigated as biomarkers for risk stratification of patients with syncope. Their concentration can be influenced by age and co-morbidities. In the present study, we compared the change in N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels within 6 hours in patients with vasovagal and arrhythmic syncope to determine whether this change can predict arrhythmic syncope. Using a case-control design, 33 patients were enrolled. Of the 33 patients, 18 with arrhythmic syncope, as they underwent controlled ventricular tachycardia or ventricular fibrillation (VF) during device safety testing of an implantable cardioverter defibrillator implantation or battery replacement, were compared with 15 patients, who during a tilt-table test were diagnosed with vasovagal syncope (VS). For each patient, a blood sample for NT-proBNP evaluation was collected at baseline and 6 hours after the episode of ventricular tachycardia, VF, or VS. We calculated the percentage of increase in the 6-hour NT-proBNP concentration between the 2 groups using nonparametric techniques. We also calculated the area under a receiver operating characteristic curve with the 95% confidence intervals. The 6-hour change in the NT-proBNP concentrations between patients who had had an episode of ventricular tachycardia or VF and patients with VS was significantly different, with a median increase of 32% in the ventricular tachycardia or VF group versus 5% in the VS group (p <0.01). The area under a receiver operating characteristic curve to predict arrhythmic syncope was 0.8 (95% confidence interval 0.65 to 0.95). In conclusion, the results of the present study suggest that a 6-hour NT-proBNP increase might be able to predict arrhythmic syncope. Future work is needed to confirm these findings in undifferentiated emergency department patients who present with syncope.