Mitral Valve Disease Common in East Asian Patients With Hypertrophic Cardiomyopathy

Among East Asian patients with hypertrophic cardiomyopathy (HCM), mitral valve (MV) disease is common, with the major type being nonobstructive. Meanwhile, in patients with obstructive HCM, mitral regurgitation (MR), systolic anterior motion (SAM), and mitral annular calcification (MAC) are more common. These are the findings of a single-center, retrospective cohort study published in the Journal of the American Association.

HCM is a genetic disorder characterized by asymmetric left ventricular (LV) hypertrophy, as well as a broad clinical and morphologic spectrum. MV disease is observed frequently in patients with HCM. Data on the prognostic implications of MV disease and its progression in individuals with HCM remain scarce, however. For the study, conducted at Yonsei University College of Medicine in Seoul, Korea, researchers evaluated the prognostic implication of MV disease and its progression in East Asian patients with HCM.

A total of 1193 patients who had been diagnosed with HCM in a single-center HCM registry between January 2005 and December 2016 were identified. An HCM diagnosis was based on “echocardiographic demonstration of a hypertrophied, nondilated LV in the absence of another cardiac or systemic disease that could produce a comparable magnitude of LV hypertrophy.” Following the exclusion of some patients, a total of 1185 individuals were ultimately included in the study. A total of 667 patients who received follow-up echocardiograms after 3 to 5 years were evaluated as well.

The mean age for participants was 60; 67% of the patients were men. The participants were classified into 2 groups, according to the presence of LV outflow tract (LVOT) obstruction: obstructive HCM (group 1; n=104) and nonobstructive HCM
(group 2; n=1081).

In this study, LVOT obstructive was defined as “peak pressure gradient of the LVOT [of] ≥30 mm Hg on continuous-wave Doppler echocardiogram at rest or with physiologic provocation.” The progression of MR was defined as “the increase of at least 1 grade.” Clinical outcomes included a composite of cardiovascular death, heart failure hospitalization, MV surgery or septal myectomy (SM), and heart transplantation.

Overall, 23.5% (278 of 1185) of the participants exhibited at least mild MR on indexed electrocardiograms. Among patients with obstructive HCM, MR, SAM, and MAC all were more often reported. Over 7.0 years of follow-up, the presence of MR was independently associated with poor clinical outcomes (hazard ratio [HR], 1.60; 95% CI, 1.07-2.40; P =.023).

Based on follow-up echocardiograms performed 3 to 5 years later, 10.0% (67 of 667) of individuals in this analysis demonstrated MR progression, which was independently associated with a poor prognosis (HR, 2.46; 95% CI, 1.29-4.71; P =.007).  

Several study limitations warrant mention. There are some situations where it may be a challenge to quantify MR in individuals with HCM — particularly when LVOT obstruction exists. Also, not all of the participants underwent provocation tests for the diagnosis of HCM, which could be linked to the underdiagnosis of obstructive HCM in this analysis. Further, participants with HCM were recruited from a tertiary hospital only, and individuals who had already undergone SM or MV surgery were excluded, which might create selection bias.

The researchers concluded, “The presence and progression of MR is a prognostic factor in the occurrence of poorer clinical outcomes; therefore, careful assessment of MV functional abnormalities and detailed evaluation of MV anatomical features are needed to predict subsequent complications in patients with HCM.”