12 Comparison of slow vs. rapid ajmaline infusion protocol for the diagnosis of brugada syndrome (BrS): ten year experience of the Northern Ireland inherited cardiac conditions service (NI ICC)

IntroductionBrS is diagnosed in patients with ST-segment elevation with type 1 morphology ≥ 2mm in one or more leads among the right precordial leads V1 and/or V2 positioned in the second, third or fourth intercostal space. This may be spontaneous or after provocation challenge with intravenous administration of a sodium channel blocker (i.e. ajmaline, flecainide, procainamide or pilsicainide). The specific protocol for ajmaline provocation challenge for diagnosis of BrS has been debated between ICC services worldwide. Concerns regarding safety and false positive rates are perceived to be associated with a more rapid infusion protocol. This retrospective observational cohort study describes the safety and positivity rates for patients undergoing ajmaline provocation challenge by both protocols over ten years.MethodsData on consecutive adults undergoing ajmaline challenge test from Mach 2011 to March 2021 were retrospectively collected. Patient demographics, indication for testing, genetic information, adverse events and positivity rates were compared by test protocol used. Slow protocol was defined as total dose of 1mg/kg ajmaline capped at 100mg, given at rate of 10mg/min. Rapid protocol was defined as 1mg/kg ajmaline capped at 100mg given in 10 divided doses over 5 minutes.ResultsA total of 414 ajmaline challenges were included (251 (61%) slow vs. 163 (39%) rapid protocol) [Mean age 41 ± 16yrs; 50% male]. Indications for conducting the test were a) family history of BrS 182 (44%), b) family history of SADS/SUD 138 (33%), c) OOHCA 26 (6%), d) abnormal ECG 47 (11%) and e) syncope 21 (5%). There was no difference in positivity rate between the two protocols (slow (23%) vs. rapid protocol (17%), p=0.13) [table 1]. Comparison of patients by provocation result regardless of the protocol used showed a predominance of (males, 51% in both groups, p=0.96) and (similar mean age of patients, p=0.91). Positive patients were more likely to have (a family history of BrS, p=0.006) or (an SCN5A genetic variant, p