Ten-Year Follow Up Results Reported, Building on the 2019 NEJM Study That Reshaped Global Guidelines

“Aortic Stenosis Progresses Even Without Symptoms, Early Surgery Recommended Upon Diagnosis”

Professor Duk-Hyun Kang of the Division of Cardiology at Asan Medical Center Publishes Third Study in NEJM, Bringing Asan Medical Center’s Total to Ten

▲ Professor Duk-Hyun Kang of the Division of Cardiology at Asan Medical Center is providing care for a patient with asymptomatic severe aortic stenosis.

Severe aortic stenosis, a representative cardiac disease in older adults, was first shown in 2019 to benefit from early surgery even in the absence of symptoms. While these findings have been widely incorporated into clinical treatment guidelines, the long term effects of early surgical intervention had not been clearly established.

A research team led by Professor Duk-Hyun Kang of the Division of Cardiology at Asan Medical Center has recently reported that the benefits of early surgery in patients with asymptomatic aortic stenosis are sustained for more than 10 years.

The study was selected as a Late Breaking Clinical Trial at the recent American College of Cardiology Annual Meeting held in New Orleans, and was published on March 25 in the New England Journal of Medicine, widely regarded as a leading global authority in clinical medicine.

The New England Journal of Medicine, with an impact factor of 78.5, surpasses that of Nature (48.5) and Science (45.8), and is widely regarded as one of the most authoritative medical journals influencing clinical practice guidelines worldwide. The current study has drawn significant attention from cardiovascular experts across the globe.

With this publication, Professor Duk-Hyun Kang has achieved the distinction of publishing his third paper in the New England Journal of Medicine. He first published in the journal in 2012 with a study on infective endocarditis, and in 2019 demonstrated for the first time the safety of early surgery in patients with asymptomatic severe aortic stenosis.

Despite limited research support for valvular heart disease, Professor Duk-Hyun Kang personally authored all three studies as corresponding author and successfully published them in the New England Journal of Medicine, an achievement that is exceptional not only in Korea but also worldwide.

Aortic stenosis is a condition in which the aortic valve becomes calcified due to aging and fails to open properly. As the population continues to age, it has emerged as a representative chronic disease with a steadily increasing number of patients.

The primary symptoms of severe aortic stenosis include dyspnea, chest pain, and syncope. However, one in three patients with severe aortic stenosis remains asymptomatic and is often diagnosed incidentally through echocardiography. Even in the absence of symptoms, there is a risk of sudden cardiac death, making early diagnosis essential.

The standard treatment for severe aortic stenosis is aortic valve replacement, a procedure in which the damaged valve is replaced with a prosthetic valve such as a mechanical or bioprosthetic valve. However, in patients with severe but asymptomatic aortic stenosis, the optimal timing of surgery has long been a subject of global debate due to the lack of clear criteria. Owing to concerns about procedural risks, a conservative strategy had been recommended, involving careful monitoring and delaying surgery until symptoms develop.

However, in 2019, a study led by Professor Duk-Hyun Kang, published in the New England Journal of Medicine, demonstrated that early surgery in patients with severe aortic stenosis, even in the absence of symptoms, significantly reduces cardiovascular mortality. In addition, a large scale clinical trial published in 2025 by an international research group confirmed the safety and efficacy of early intervention using transcatheter aortic valve replacement.

Accordingly, global clinical guidelines have incorporated recommendations to perform early aortic valve replacement within two months of diagnosis, even in asymptomatic patients with severe aortic stenosis. However, it remained unclear whether the mortality reduction benefits of early surgery would be sustained for more than a decade, given concerns regarding the long-term durability of prosthetic valves and the risks associated with lifelong anticoagulation therapy.

To address this, Professor Duk-Hyun Kang‘s research team conducted a long term follow up study of 145 patients with asymptomatic severe aortic stenosis, defined by an aortic valve area of 0.75 cm² or less, between July 2010 and April 2015. Among them, 73 patients underwent early surgery, while 72 patients received conservative management, and all were followed for more than 10 years.

Patients in the early surgery group underwent aortic valve replacement within two months of diagnosis, whereas those in the conservative management group received surgery only after the onset of symptoms during the follow up period.

Over a mean follow up period of 12 years, the incidence of operative mortality or cardiovascular death was 24% in the conservative management group, compared with 3% in the early surgery group, demonstrating a significant difference. All cause mortality was also reduced by nearly half, occurring in 32% of patients in the conservative group and 15% in the early surgery group also reduced all-cause mortality.

Hospitalization due to heart failure occurred in 19% of patients in the conservative management group, whereas no such cases were observed in the early surgery group. The rate of repeat aortic valve replacement was 6% in the conservative group and 4% in the early surgery group, showing no significant difference.

In addition, statistical analysis of mortality risk over time revealed that at 10 years, the incidence of operative mortality or cardiovascular death was 19% in the conservative management group, compared with just 1% in the early surgery group. Notably, among patients in the conservative group, 74% had either undergone aortic valve replacement or died at 5 years, and this figure increased to 97% at 10 years.

Meanwhile, since publishing its first paper in the New England Journal of Medicine in 2003, the Asan Medical Center Heart Institute has steadily produced a total of 10 publications covering coronary artery disease, valvular heart disease, and arrhythmias.

These achievements have had a significant impact on clinical practice worldwide, contributing to the development of treatment guidelines followed by cardiovascular specialists across the globe. Publishing 10 papers in the New England Journal of Medicine as a single institution represents the highest record in Korea and is a rare and distinguished accomplishment even on a global scale.