Asymptomatic Aortic Stenosis

Aortic stenosis (AS) is the most commonly encountered valvular degenerative pathology in the world, affecting between 2% and 5% of the general population. The prevalence of AS increases with age and can be as high as 4% to 13% in those older than 75 years of age. Although the overall incidence of AS has not dramatically changed over time, the burden of disease has increased because of increased longevity of the population. Even though mitral regurgitation may be more common in population-based studies, the clinical impact of AS is higher. In some registries, it represents about one-third of all patients followed for valvular heart disease but represents nearly half of all patients undergoing valve procedures. The pathogenesis of calcific aortic valve disease is complex and involves an interplay of genetics, lipoprotein processing, inflammation, oxidation, and ossification rates of valve leaflets. This complex and dynamic interaction of causes helps explain some of the variance seen in the rates of progression, hemodynamics, and the effect on ventricular function. Given the heterogeneity of affected patients, guideline documents have largely focused on therapeutic interventions on more advanced disease states.

The importance of symptoms in AS is well-established. Patients with severe symptomatic AS have a median survival of less than 3 years, with early hazard as high as 3% to 6% in the first 6 months. ^, This is the primary reason why current guidelines emphasize symptoms as the primary indication for aortic valve replacement (AVR). ^, However, some observational studies have suggested that a strategy that awaits for symptoms may be suboptimal compared with strategies that recommend early presymptomatic intervention. Reliable markers that predict those who would benefit from an early intervention are not known and some parameters, such as global left ventricular (LV) systolic dysfunction, may be too late in the disease progression and represent an irreversible finding ( Fig. 80.1 ). Finally, therapeutic interventions have historically been limited to surgical aortic valve replacement (SAVR) and its higher initial risks. With the rapidly evolving and lower risk therapeutic intervention now commonly available in transcatheter aortic valve replacement (TAVR), the understanding of overall risk of an early invasive strategy will continue to be reassessed in asymptomatic severe (and potentially even moderate) AS. This individualized risk–benefit analysis will evolve with future clinical trial results and a better understanding of the long-term durability of TAVR versus SAVR valves.

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The interplay between aortic stenosis (AS), symptoms, hemodynamics, and ventricular function underlying some of the challenges in the assessment of AS. In the center of the triangle are the current indications for valve replacement, although many other features around the classic indications, especially in the severe AS section, may portend higher risk and benefit from intervention. BP, Blood pressure; CAD, coronary artery disease; CMRI, cardiac magnetic resonance imaging; CO, cardiac output; CT, computed tomography; ECG, electrocardiography; HFpEF, heart failure with preserved ejection fraction; HFrEF, heart failure with reduced ejection fraction; LV, left ventricular; LVEF, left ventricular ejection fraction.