Abstract 13476: Usefulness of Dual Induction Tests for Coronary Artery Spasm and Lethal Ventricular Arrhythmias in Patients Surviving Out-of-Hospital Cardiac Arrest

Abstract

Background: It remains to be established how to treat patients with out-of-hospital cardiac arrest (OHCA) without significant organic heart disease, especially regarding the use of implantable cardioverter-defibrillator (ICD). Among the possible causes of OHCA, coronary artery spasm (CAS) and lethal ventricular arrhythmias (VAs) are important causes of the disorder. Methods and Results: In 47 consecutive OHCA survivors without organic heart disease who had fully recovered (M/F 44/3, 43±13 yrs.), we performed dual induction tests for CAS and VAs. We first performed acetylcholine provocation test with subsequent calcium channel blocker-based antianginal medications and then performed ventricular fibrillation (VF) induction test with programmed stimulation at an interval of 1~2 weeks. ICD was implanted in all patients. According to the results of the dual induction tests, we divided them into 4 groups; CAS-alone (n=7), VAs-alone (n=13), both-positive (n=24), and both-negative (n=3) ( Figure A ). Among the 4 groups, no significant difference was noted in the factors that could influence the development of VF, such as QTc, late potential, familial history of sudden cardia death, or serum levels of electrolytes. During a median follow-up of 38 months, VF recurred in all groups except the both-negative group, of which 13 cases had appropriate ICD shocks to terminate fatal VAs. When we analyzed the 16 patients with Brugada-like ECG pattern (34%) separately, no VF episode was noted in the CAS-alone or both-negative group throughout the study period. Kaplan-Meier analysis showed that the CAS-alone group was at lower risk for OHCA recurrence as compared with the Brugada syndrome group (log-rank test, P=0.036) ( Figure B ). Conclusions: These results indicate that among OHCA survivors, those with CAS-alone and without Brugada syndrome in the dual induction tests may be at low risk for recurrent sudden death and ICD firing.