Electromechanical Window Negativity and Arrhythmic Risk in Arrhythmogenic Mitral Valve Prolapse

BACKGROUND: Mitral valve prolapse (MVP) is generally a benign valvular heart disease, but a subset of patients is at particular risk of malignant ventricular arrhythmias (AMVP). OBJECTIVES: The authors evaluated the electromechanical window (EMW) as an arrhythmia-risk marker in (A)MVP (the sum of all MVP and AMVP patients). METHODS: Healthy controls, patients with MVP without ventricular arrhythmia (MVP/-VA), and patients with AMVP with nonsustained (AMVP/nsVA) or sustained ventricular arrhythmia (AMVP/VA) (ventricular arrhythmia >30 seconds) were retrospectively included from 3 centers (derivation cohort). An independent validation (A)MVP cohort was recruited from 2 centers. EMW was calculated blinded from apical Doppler echocardiography by subtracting the QT time from the simultaneous Q-to-aortic-valve closure time (QAoC). RESULTS: In the derivation cohort (31 controls, 31 MVP/-VA, 29 AMVP/nsVA, 14 AMVP/VA), patients with (A)MVP displayed a borderline shorter QAoCc (P = 0.06) and significantly longer QTc than controls (P < 0.0001), resulting in a more negative EMW (-18 ms [-47 to -8 ms]; P < 0.0001). EMW was most negative in patients with AMVP/VA (-71 ms [-177 to -30 ms]). These findings were reproduced in the validation cohort (n = 76 with [A]MVP), albeit at different absolute values. In a pooled receiver-operating characteristic analysis, EMW identified patients with AMVP/VA with an area under the curve of 0.82 (95% CI: 0.73-0.91), significantly outperforming QTc and QAoCc. An EMW threshold of -30 ms was the optimal cutoff (sensitivity: 0.71; specificity: 0.83). EMW was independently associated with AMVP/VA status and improved model performance in addition to established risk parameters. CONCLUSIONS: EMW is markedly negative in patients with AMVP/VA, reflecting electromechanical discordance. Thus, EMW emerges as a promising risk-associated marker in (A)MVP.