Cardiac abnormalities in First Degree relatives of unexplained Cardiac arrest Victims
METHODS AND RESULTS: 398 first degree family members (186 UCA, 212 SUD relatives; mean age 44+ 17 years) underwent extensive cardiac workup including ECG, SAECG, exercise testing, cardiac imaging, Holter monitoring and selective provocative drug testing with epinephrine or procainamide. Genetic testing was performed when a mutation was identified in the UCA survivor or when the diagnostic workup revealed a phenotype suggestive of a specific inherited arrhythmia syndrome. The diagnostic strength was classified as definite, probable or possible based on previously published definitions. Cardiac abnormalities were detected in 120/398 patients (30.2% with 67/398 having a definite or probable diagnosis (17% including longQT Syndrome (13% CPVT (4% ARVC (4% and Brugada syndrome (3% The detection yield was similar for family members of UCA and SUD victims (31% versus 27% P=0.59) Genetic testing was performed more often in family members of UCA patients (29% versus 20%;P=0.03) Disease causing mutations were identified in 20/398 relatives (5% The most common pathogenic mutations were RyR2 (2% SCN5A (1% and KNCQ1 (0.8%