Four Risk Factors for Reoperation Identified Through 20 Year Follow Up of 337 Patients Undergoing Mitral Valve Repair

Professor Joon Bum Kim of Department of Thoracic and Cardiovascular Surgery at Asan Medical Center stated, “For low risk patients, mitral valve repair rather than valve replacement is the optimal treatment.”

▲ (From left) Professors Joon Bum Kim and Kitae Kim of the Department of Thoracic and Cardiovascular Surgery at Asan Medical Center

Rheumatic heart disease is caused by chronic inflammation of the heart valves as a complication of rheumatic fever. As inflammation persists, the valves become thickened and stiff, leading to stenosis in which the blood flow pathway narrows, or regurgitation in which the valve fails to close properly. Such valvular dysfunction places excessive strain on the heart and can progress to heart failure, often necessitating surgical treatment.

Until now, mitral valve replacement using a prosthetic valve has been regarded as the standard treatment for patients with rheumatic disease accompanied by advanced valvular degeneration. Although mitral valve repair, which preserves the patient’s native valve as much as possible, offers advantages such as preservation of left ventricular function and minimization of anticoagant therapy, long-term evidence regarding the durability of the repaired valve has been limited.

A research team led by Professors Joon Bum Kim and Kitae Kim of the Department of Thoracic and Cardiovascular Surgery at Asan Medical Center analyzed 337 patients who underwent rheumatic mitral valve repair between 2000 and 2022 and found that, among low risk patients without risk factors such as concomitant pulmonary hypertension, the reoperation rate within 20 years was only 1 percent.

The findings of this study are significant in that, through more than 20 years of long-term follow up, they not only demonstrated that mitral valve repair is a highly effective and safe treatment option for patients with rheumatic disease, but also provided scientific evidence to support individualized surgical strategies.

The research team conducted a long-term follow up of 337 patients who underwent mitral valve repair for rheumatic heart disease at Asan Medical Center between January 2000 and February 2022, with a mean follow up period of 15 years and a maximum of 22 years.

The study found that the overall 20-year survival rate among all patients was 78.9 percent, while the cumulative incidence of mitral valve reoperation was 4.5 percent at 10 years and 12.7 percent at 20 years. In addition, the researchers identified four independent risk factors associated with an increased risk of mitral valve reoperation: moderate or greater mitral stenosis, pulmonary hypertension indicated by a tricuspid regurgitation velocity greater than 3.4 m/s, anterior leaflet augmentation, and chordal procedures.

Patients who underwent anterior leaflet augmentation, in which tissue is added to a valve leaflet contracted by rheumatic inflammation, or chordal procedures to reconstruct the chordae tendineae that support the valve, were found to have a relatively higher risk of reoperation. This is because the need for such procedures reflects more extensive valve damage and more advanced disease severity.

When patients were stratified according to the number of these risk factors, the differences in outcomes became even more pronounced. Among low risk patients with no risk factors, the risk of reoperation within 20 years was only 1 percent. In contrast, the rate was 12.7 percent in those with one risk factor and 33.6 percent in the high risk group with two or more risk factors.

In cases where the mitral valve is replaced with a bioprosthetic valve, most patients require reoperation by 20 years due to the limited durability of the tissue valve. The research team explained that mitral valve repair, even in the high-risk group, showed a 20 year reoperation risk of 33.6 percent, indicating superior long term durability compared with bioprosthetic valves and suggesting that it may serve as an alternative that overcomes the limitations of prosthetic valve replacement.

This study suggests that the long term success of mitral valve repair can be predicted based solely on the preoperative condition of the valve and the presence of concomitant pulmonary hypertension. Given that rheumatic disease often affects younger patients, the findings are particularly meaningful in that they provide scientific evidence showing that, for low risk patients, valve repair that preserves the native valve is more advantageous than valve replacement, which requires lifelong anticoagulation therapy.

Joon Bum Kim of the Department of Thoracic and Cardiovascular Surgery at Asan Medical Center stated, “Rheumatic heart disease has long raised concerns regarding the long term durability of mitral valve repair due to the extensive nature of valvular damage. However, through this study, we confirmed that in low risk patients, mitral valve repair remains stable for more than 20 years and represents the optimal treatment option.”

Kitae Kim of the Department of Thoracic and Cardiovascular Surgery at Asan Medical Center stated, “By applying an independent risk factor model that predicts the likelihood of mitral valve reoperation, we can establish the most appropriate surgical strategy tailored to each patient, whether repair or replacement. This approach is expected to contribute to improving the long term prognosis of patients with rheumatic heart disease.”

The study was recently published in ‘The Journal of Thoracic and Cardiovascular Surgery’, a leading international journal in the field of thoracic surgery, with an impact factor of 5.2.

▲ Professor Joon Bum Kim of the Department of Thoracic and Cardiovascular Surgery at Asan Medical Center is examining a patient with rheumatic heart disease who underwent mitral valve repair.