Early Aortic Valve Surgery Versus Watchful Waiting Strategy in Severe Asymptomatic Aortic Regurgitation

Introduction:

Aortic regurgitation (AR) is the third most frequent valvular heart disease in Western countries affecting rather young patients, mostly men. The degenerative process on the trileaflet aortic valve is the main cause of AR, followed by a congenital valve disease, typically bicuspid aortic valve. The high prevalence of bicuspid aortic valve in the general population which is frequently associated with aortic dilatation, another important cause of AR, can explain the unusual distribution of significant AR mainly among the population of males in their average 5th decade. Infective or rheumatic endocarditis and aortic dissection are less frequent reasons for AR.

Hemodynamically significant AR leads to volume and pressure overload of the left ventricle (LV). Severe LV dilatation and moderate LV hypertrophy are the main compensatory mechanisms that help to maintain cardiac output and relieve the increased LV wall stress. Doubling the cardiomyocyte size is accompanied by an increase in extracellular volume, including multiplying collagen fibres and increasing the volume of the non-collagen extracellular matrix. Untreated severe AR leads to advanced LV remodeling and LV dysfunction causing the development of heart failure.

The only appropriate treatment for chronic haemodynamically significant AR is aortic valve surgery. The indications for AR surgical treatment are summarized in the 2021 ESC/EATS Guidelines for the management of the valvular disease. Class I indications of aortic valve surgery are based on the presence of symptoms of heart failure (exertional dyspnoea, chest tightness) and/or presence of severe LV remodelling (LV ejection fraction ≤50% or LV end-systolic diameter (ESD) >50 mm or LV ESD Index >25 mm/m2 in patients with small body size). There is increasing evidence that patients undergoing surgery at such an advanced stage of the disease have already irreversible myocardial damage. There is also evidence that surgical risk in a relatively younger and low-risk population has decreased with novel surgical techniques and perioperative care, including aortic valve-sparing surgery with documented excellent long-term effects. Concerning these facts, it might be reasonable to shift the surgical treatment towards an earlier stage of the disease.

Available evidence including our study suggests higher clinical accuracy of cardiac magnetic resonance (CMR)-derived AR quantification than that of the guidelines-based echocardiographic (ECHO) Integrative approach (12-14). Severe AR defined as regurgitation fraction (RF) >33% and/or regurgitant volume (RV) >44 ml with LV dilatation defined as LV end-diastolic volume index (LVEDVI) >123 ml/m2 present the most accurate marker of early disease progression requiring surgery in a median of 399 (IQR 209) days (unpublished data).