New More Accurate Complication Prediction Indicator for Patients with Hypertrophic Cardiomyopathy

A new indicator has been developed to more accurately predict the risk of cardiovascular complications in patients with hypertrophic cardiomyopathy.

Professor Kim Hyung-kwan of the Department of Cardiology at Seoul National University Hospital, along with Professors Hwang In-chang of Bundang Seoul National University Hospital and Choi Yoo-jung of Korea University Guro Hospital, conducted a joint study analyzing the risk of cardiovascular complications based on left ventricular global longitudinal strain (LV-GLS) values in hypertrophic cardiomyopathy patients with a left ventricular ejection fraction (LVEF) of 50-60%. The research team found that in patients with an LVEF of 50-60%, those with an absolute LV-GLS value of 10.5% or less had a 2.5 times higher risk of cardiovascular death compared to patients whose LV-GLS exceeded 10.5%. The left ventricular ejection fraction refers to the ratio of blood volume ejected from the left ventricle into the aorta relative to the blood volume received by the left ventricle. The left ventricular global longitudinal strain indicates the degree to which the length of the left ventricle shortens along the longitudinal axis during heart contraction. A larger absolute value is evaluated as stronger contractility.

Professor Hyungkwan Kim of Seoul National University Hospital (from the left), Professor Inchang Hwang of Bundang Seoul National University Hospital, Professor Yujeong Choi of Korea University Guro Hospital

Hypertrophic cardiomyopathy is a rare and intractable genetic disease characterized by thickening of the heart muscle and decreased cardiac contractility. According to existing clinical guidelines, an LVEF of 50% or higher measured by echocardiography is considered normal, while 50% or lower is defined as end-stage heart failure.

In a previous study by the research team published in June, patients with hypertrophic cardiomyopathy and an LVEF of 50-60% were defined as having a low-normal type, and it was reported in the academic community that their long-term cardiovascular prognosis was poor. However, the study did not provide answers as to which patients within the low-normal LVEF group had worse prognoses.

The research team followed 349 patients with low-normal LVEF (50-60%) for a median of 4.1 years and analyzed the association between cardiovascular complication risk and another echocardiographic parameter, LV-GLS, to conduct a detailed risk analysis. The results showed that 7.4% (26 patients) died from cardiovascular diseases, including sudden cardiac death. The cutoff value for LV-GLS, which serves as a criterion for cardiovascular death risk, was an absolute value of 10.5%.

When the absolute LV-GLS value exceeded 10.5%, an independent correlation was observed where increasing this value was associated with a lower risk of cardiovascular death. Patients with reduced contractility assessed by LV-GLS (absolute value ≤ 10.5%) had a 2.54 times higher risk of cardiovascular death, including sudden death, compared to those with preserved contractility (LV-GLS > absolute value 10.5%). The research team explained that these results demonstrate the usefulness of the ‘LV-GLS value’ in predicting mortality and evaluating prognosis in low-normal type hypertrophic cardiomyopathy patients with an LVEF of 50-60%.

The research team stated, "This study is significant because it identified an indicator that can select high-risk groups for cardiovascular death among low-normal type (LVEF 50-60%) hypertrophic cardiomyopathy patients, who are classified as having relatively normal myocardial function but have a high risk of heart failure and cardiovascular death."

The results of this study were published online in August in the European Heart Journal - Cardiovascular Imaging, the international journal of the European Society of Cardiology.

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