Brain natriuretic peptide and high-sensitivity Troponin at 3 hours post emergency department attendance with unexplained syncope predict 90 day outcome

To investigate if Brain Natriuretic Peptide (BNP) and highsensitivity troponin I predict significant arrhythmia, symptomatic significant arrhythmia and 90-day death and/or Major Adverse Cardiac Event in Emergency Department (ED) unexplained syncope patients investigated with a 14-day ambulatory electrocardiogram (ECG) recorder. Single-centre, prospective, cohort study. Patients 16 years or over presenting within 6 hours of an episode of unexplained syncope were fitted with an ambulatory ECG recorder (Zio® XT monitor) and had high-sensitivity troponin I and BNP measured on ED admission and 3 hours later. Between 17/11/2015 and 13/06/2017, 86 patients were recruited. 24 had significant arrhythmia, 9 symptomatic significant arrhythmia and 26 patients had death and/or Major adverse cardiac events by 90 days. BNP at admission, three hours and change in BNP and high-sensitivity troponin I at three hours were associated with significant arrhythmia and serious outcome. BNP>20pg/mL and/or high-sensitivity troponin I above the 99% sex specific centile (M>34ng/L, F>16ng/L) at 3 hours had a sensitivity of 100% (21/21; 95% CI 81%-100%) and specificity of 43% (16/37; 28%-60%) for significant arrhythmia and a sensitivity of 100% (22/22; 95% CI 82%- 100%) and specificity of 44% (16/36; 28%-62%) for serious outcome both at 90 days. The combination of BNP and high-sensitivity troponin I at 3 hours shows promise as a potential predictive marker for serious arrhythmia and serious outcome at 90 days and deserves further exploration as a rule out test to enable safe discharge of patients from the ED who are at low risk of having cardiac syncope and subsequent adverse events.