Non-Invasive Testing Cannot Identify A Typical Substrate For Life-Threatening Re-Entry Vts In Athletes

Introduction: Two electroanatomical (EA) scar pattern for VT from the RV have been identified: a dominant subtricuspid and an isolated epicardial RVOT scar, typical for endurance athletes with inferior axis VT. The latter pattern may not be identified by non-invasive testing. Methods: Consecutive symptomatic patients (pts) with scar-related re-entry VT from the RV, who underwent endocardial ± epicardial EA mapping (2006–2015) were included. Non-invasive evaluation included medical, family and endurance training history, ECG, Holter, exercise test, imaging studies (echocardiography, cardiac MR, CT), and genetic testing (NGS for 55 genes). Endurance training >6 hours/week, >5 years qualified as endurance athlete. Results: Among 57 pts (48 ± 15 years, 83% male, 95% Caucasian) 46 (81%) had a dominant subtricuspid scar; 6/46 presented with OHCA, 11/46 had (pre)syncope, 26/46 palpitations. All had features suggestive for structural heart disease (SHD); T-wave inversion (TWI) >V2 in 17 (37%), prolonged TAD 25/35, epsilon waves 10 (21%), wall motion abnormalities (WMA) on echocardiography / CMR 27 (59%), and 25/45 (56%) had an ARVC associated pathogenic mutation. Based on non-invasive testing the diagnosis was definite ARVC in 33 (72%), borderline ARVC in 3 (7%), cardiac sarcoidosis in 5 (11%), scar of unknown origin in 4 (9%) and myocarditis in 1 (2%). All 11 pts with isolated RVOT scar were endurance athletes (15 [IQR 10 – 20] hours/week for 13 [IQR 10-18] years; 9/11 (82%) presented with exercise related palpitations including syncope in 6 (55%). All had spontaneous LBBB/inferior axis VT Only 1 had increased TAD, 2 (18%) TWI V1-V2, but none TWI > V2, epsilon waves, WMA, or a pathogenic mutation. Based on non-invasive testing the diagnosis was idiopathic RVOT VT in 8/11 (81%) and possible SHD based on additional minor criteria in 3. Catheter ablation was successful in 10/11 (91%), none had VT recurrence during 30 ± 37 months. Conclusion: The majority of endurance athletes with isolated RVOT scar has no features for SHD on non-invasive testing and may be misdiagnosed as idiopathic VT. Considering the potentially life threatening VT EA mapping should be considered in symptomatic athletes.