LAUSR

Life threatening arrhythmias (LTA) can trigger sudden cardiac death, or provoke implantable cardioverter defibrillator (ICD) discharges that escalate morbidity and mortality. Longitudinal myofibrils predominate in the subendocardium which is uniquely sensitive to arrhythmogenic triggers. To test the hypothesis that mitral annular systolic velocity (S'), a tissue Doppler index of LV long-axis systolic function, might predict lethal arrhythmias irrespective of LVEF. We analysed data from diverse ICD and cardiac resynchronization therapy defibrillator (CRT-D) patients at 2 London centres. Channelopathies were excluded. S' was averaged from medial and lateral mitral annuli velocities. Primary outcome was time to sustained ventricular tachycardia (VT) or fibrillation (VF) needing device therapy. In 302 patients (mean age 68 years, LVEF 32%, 77% male, 52% ischemic, 35% primary prevention, and 53% CRT-D), median S' was 5.1 (IQR: 4.0–6.2) cm/s and lower in CRT-D than ICD subjects. After a median follow-up of 15 months, 56 (19%) subjects had LTA and those who did had a lower S' than those who did not (4.6±1.4 cm/s vs. 5.4±1.7 cm/s, P=0.003-Fig A). Each 1cm/s lower S' correlated to a 43% increased risk of LTA (HR: 0.70, 95% CI: 0.57–0.87, P=0.001) independently of age, gender, β-blocker use, centre, ICD use and LVEF. Adding S' to the baseline model improved net reclassification (P=0.02) implying incremental utility (Fig B). An S' ≤5.6cm/s was the best cut-off, conferring a 2.4-fold higher LTA risk than an S'>5.6 cm/s (95% CI: 1.17–4.37, P=0.02–Fig C). A lower S' forecasts an enhanced probability of LTA in cardiac device recipients irrespective of LVEF, and could be used to titrate medical, device and ablative therapies to mitigate future arrhythmic risk.