Is it Time for a New Paradigm in Asymptomatic Severe Aortic Stenosis?

We read with interest the paper by Taniguchi et al. (1), who reported that a strategy of earlier aortic valve replacement (AVR) in patients with asymptomatic severe aortic stenosis (AS) was associated with a lower long-term risk of hospitalization for heart failure or all-cause mortality compared with the strategy currently recommended in clinical practice guidelines, which is to wait for the onset of symptoms before intervention.

Two important issues should be considered regarding the clinical relevance of this study. First, Taniguchi et al. (1), in the collection of baseline clinical information, reported the classic symptoms of angina, syncope, or heart failure as AS-related symptoms. These symptoms are typically the later manifestation of disease and now are seen only in patients who do not receive medical care, fail to report early symptoms, or have an inappropriate surgical delay (2). Second, although the study methods were robust, asymptomatic status was not confirmed by a treadmill exercise test; therefore, it was possible that some symptoms were undetected or unrecognized in some patients due to a sedentary life-style. Among patients with asymptomatic severe AS, cardiopulmonary exercise testing (CPET) provides more sensitive detection of exercise intolerance than the stress test criteria recommended in the guidelines (3).

The American College of Cardiology/American Heart Association guidelines provide a class IIa recommendation for AVR in asymptomatic patients with severe AS who have decreased exercise tolerance on treadmill testing (4). However, nonspecific dyspnea is frequently observed during exercise testing, and differentiating between pathological and physiological breathlessness is sometimes challenging. Aging, a sedentary life-style, obesity, and/or lung disease complicate the interpretation of exercise symptoms. CPET has been proven to have diagnostic and prognostic value in heart failure, and reportedly improves the quantification of exercise cardiopulmonary capacity in valvular diseases (3).

The safety of CPET in asymptomatic AS was recently studied in a cohort of 327 patients. No major adverse events during or after the test were reported (5). Compared with standard exercise testing, CPET can provide additional information about the respiratory status, quality and quantity of efforts, and an estimate of cardiac output in these patients (3). The decision-making process regarding AVR is especially challenging in patients who are either asymptomatic or have equivocal symptoms, and CPET can potentially aid in that decision process. Further research should specifically evaluate the incremental value of CPET over standard exercise tests in a large cohort of asymptomatic patients with severe AS and a normal exercise test (3).

Once severe valve obstruction is present, the most important distinction is between asymptomatic and symptomatic disease. If the symptom status is unclear, CPET may be helpful in revealing under-reported or underestimated symptoms and in predicting the short-term occurrence of symptoms in truly asymptomatic individuals.

• American College of Cardiology Foundation