A-016 Prevalence of macrotroponin-T in an Asian population: Preliminary findings

Introduction: Macrotroponin is a possible confounder in the assessment of patients with acute coronary syndrome (ACS) and can lead to unnecessary investigations and patient anxiety. Several studies have investigated the impact of macrotroponin I and estimated the prevalence to be between <5% to 9.9% in healthy patients, increasing to up to 27.9% in patients with cardiomyopathy. However, few studies have assessed the prevalence of macrotroponin T. Our institution utilizes the Roche high sensitivity cardiac troponin T (hs-cTnT) assay (Cobas e801), and we explored the prevalence of macrotroponin T in our population. Methods: In this preliminary study, we analysed plasma samples from 100 subjects with hs-cTnT values between 50 to 100 ng/L on the Roche Cobas platform. Aliquots of the samples were treated according to our Polyethylene glycol (PEG) protocol (100uL of sample and 100uL of 25% PEG6000, mixed thoroughly, and centrifuged at 18626 RCF for 2 minutes before testing the supernatant). Macrotroponin T was considered to be present if the recovery was < 40% post-PEG treatment, and absent if recovery was > 60% post-PEG. Cases with recovery of < 40% were subsequently treated with an antibody binding agent (Scantibodies) to corroborate the presence of macrotroponin T. Results: Post-PEG results ranged from 27 to 117 ng/L. Out of 100 subjects, only 1 sample had a recovery < 40% (31.3%), with 96 samples having recoveries of > 60%. Of note, the baseline value of this sample with possible macrotroponin was 86.4 ng/L, with a post-PEG concentration of 27.0 ng/L. The sample was then treated with Scantibodies. The troponin T concentration post-scantibodies treatment was 54.5ng/L (recovery of 63.1%), indicating the absence of macrotroponin T. Furthermore, based on the European Society of Cardiology 0/2-hour rule-out protocols for ACS, the baseline value would have been a clear indication for ruling-in ACS, whereas the post-PEG result would have resulted in the patient being kept for observation and serial troponin testing performed. Conclusions: Although there are concerns that macrotroponin represents a possible confounder, it is still uncommon occurring in <1% of cases in our preliminary study. Discrepant results may be obtained with different methods for the detection of macrotroponin may yield different results. Further studies with a larger population should be undertaken to confirm these preliminary findings.