Prognostic impact of mitral L-wave in patients with hypertrophic cardiomyopathy without risk factors for sudden cardiac death

Hypertrophic cardiomyopathy (HCM) with severe diastolic dysfunction is a major cause of heart failure and sudden cardiac death (SCD) associated with lethal arrhythmia. Although various risk factors for cardiac events have been reported in HCM patients, previous studies have reported that some HCM patients exhibit either no risk or a low risk of SCD experienced cardiac events. The mid-diastolic transmitral flow velocity curve (mitral L-wave) is an echocardiographic index of left ventricular compliance, and it has been reported as one of the parameters of advanced diastolic dysfunction assessed noninvasively. However, little is known about the association between the mitral L-wave and long-term clinical outcomes in HCM patients without SCD risk factors. Between July 2005 and February 2016, 112 patients were diagnosed with HCM and 96 patients without risk factors were enrolled. After excluding 3 patients whom we could not detect L-wave more than once, 93 patients (mean age 57.7 ± 13.1 years, 33 females) were divided into the following two groups, according to the presence or absence of the mitral L-wave: Group L (+) (with the mitral L-wave) and Group L (−) (without the mitral L-wave). The correlations between the mitral L-wave and rates of cardiac events were investigated. The mitral L-wave was present in 14 (15.1%) patients [Group L]. During the follow-up period [4.7 (2.9–7.5) years], patients experienced 7 cardiac events. Kaplan–Meier survival analysis showed that the event-free rate was significantly lower in Group L (+) than in Group L (−) (log-rank P = 0.002). Additionally, in multivariate analysis, L-wave positivity was identified as independent predictors of cardiac events. Existence of the mitral L-wave can predict cardiac events, even in HCM patients without SCD risk factors.