BACKGROUND Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden cardiac death (SCD) in young individuals, largely due to ventricular arrhythmias, which may be associated with electrical disturbances from pathologic myocardial changes.

OBJECTIVES The purpose of this study was to investigate electromechanical mismatches in patients with HCM and the relationship between electromechanical mismatches and life-threatening events (LTEs).

METHODS We performed a retrospective review of patients (age 1-80 years) diagnosed with HCM. Electromechanical mismatch was evaluated using the electromechanical window (EMW), defined as the interval between the Q wave and aortic valve closure minus the QT interval.

RESULTS We enrolled 458 patients (mean age 52.4 ± 18.8 years). When the EMW of patients with HCM was compared to that of age-/sex-matched normal controls, EMW was more negative in patients with HCM than in normal controls (-51 ± 35 ms vs 7 ± 19 ms; P <.001). LTEs occurred in 25 patients (5.5%). EMW was more negative in patients with LTEs than in those without (-77 ± 33 ms vs -42 ± 31 ms; P <.001). The cutoff value of EMW to identify patients with LTEs was -54 ms, and the c-index of EMW was 0.726. EMW less than -54 ms, unexplained syncope, pediatric onset, and extreme left ventricular hypertrophy were significant risk factors for LTEs on multivariate analysis.

CONCLUSION EMW was more negative in patients with HCM than in healthy individuals, and profound EMW negativity was an independent risk factor for LTEs. EMW can be useful for risk stratification of SCD in patients with HCM.