Professor Duk-Hyun Kang’s Team of Asan Medical Center Conducts Long-Term Follow-Up of 1,000 Patients with Severe Mitral Regurgitation

Early Surgery Group Shows 82 Percent Lower Risk of Cardiac-Related Death Compared to Observation Group

Published in ‘Circulation’, the World’s Leading Journal in Cardiovascular Medicine

▲ Professor Duk-Hyun Kang of the Division of Cardiology at Asan Medical Center

Mitral regurgitation is a condition in which the mitral valve, located between the left ventricle and left atrium of the heart, does not close properly, causing blood to flow back into the left atrium when the left ventricle contracts. If left untreated, it can progress to heart failure or even death. However, many patients with severe mitral regurgitation show no symptoms, leading to ongoing debate in the medical community regarding the optimal timing of surgery.

In response, a Korean research team recently reported findings showing that patients with severe mitral regurgitation benefit from early surgery, even in the absence of symptoms, as it improves long-term survival.

The research team led by Professor Duk-Hyun Kang of the Division of Cardiology at Asan Medical Center and Professor Sung Ji Park of the Division of Cardiology at Samsung Medical Center conducted a long-term follow-up of more than 1,000 Korean patients with severe mitral regurgitation who had no symptoms. The study found that patients who underwent early mitral valve repair surgery had an 82 percent lower risk of cardiac-related death compared to those who were observed and later underwent surgery only after developing symptoms.

Severe mitral regurgitation caused by structural abnormalities of the valve requires treatment with mitral valve repair or replacement surgery. Until now, there has been ongoing debate in the medical community on whether patients with severe mitral regurgitation should undergo early surgery in the absence of symptoms, or wait until signs such as shortness of breath or impaired heart function appear before proceeding with surgery.

This study is particularly significant as it followed more than 1,000 patients over a period of 20 years, demonstrating that early mitral valve repair reduces the risk of death even in asymptomatic cases of severe mitral regurgitation, thereby suggesting a more effective treatment strategy.

The study findings were recently published in ‘Circulation’ (impact factor 38.6), the world’s leading cardiovascular journal officially issued by the American Heart Association.

The research team conducted a follow-up study of 1,063 patients treated at Asan Medical Center and Samsung Medical Center between 1996 and 2016 for severe mitral regurgitation without symptoms. The patients were observed for more than 20 years, with an average follow-up of 12 years. All patients had been diagnosed with severe mitral regurgitation through echocardiography, and their left ventricular function was preserved at the time of diagnosis.

Of these patients, 545 underwent mitral valve repair surgery within six months of enrollment in the study. The remaining 518 patients were initially managed with observation and later underwent surgery only after developing symptoms or experiencing deterioration in left ventricular function.

When comparing the success rates of mitral valve repair surgery between the two groups, the early surgery group showed a success rate of 97 percent, while the observation group showed 84 percent. The surgical mortality rate was 0 percent in the early surgery group and 0.8 percent in the observation group. These findings suggest that surgery performed in the absence of symptoms is less technically challenging, leading to more successful outcomes. In contrast, surgery performed after symptoms appear or heart function declines results in reduced success rates.

During the average follow-up period of 12 years, cardiac-related mortality was 1.7 percent in the early surgery group and 10.3 percent in the observation group, confirming that early surgery reduced the risk of death by 82 percent. The 20-year cumulative cardiac mortality was 5.6 percent in the early surgery group and 17.4 percent in the observation group, showing that the survival benefit of early surgery was sustained over the long term.

Overall mortality was 13.4 percent in the early surgery group and 22.3 percent in the observation group, indicating that early surgery reduced the risk of death from all causes by approximately 34 percent.

Hospitalization due to heart failure occurred in 2.4 percent of the early surgery group compared with 9.1 percent of the observation group. New-onset atrial fibrillation was reported in 13.4 percent of the early surgery group and 17.2 percent of the observation group. These results demonstrate that early surgery not only improves survival but also enhances quality of life.

He added, “Not all patients with severe asymptomatic mitral regurgitation are candidates for early surgery. The patient’s surgical risk must be low, and factors such as whether the medical institution performing the surgery has a mitral valve repair success rate of above 95 percent should be carefully considered.”