We appreciate the critical analysis regarding our study provided by Lacalzada-Almeida et al., in which they highlight their experience in the use of cardiopulmonary exercise testing (CPET) in patients with aortic stenosis (AS).

In their study, Lacalzada-Almeida et al.1 found a higher percentage of abnormal CPET results—defined by symptoms and electrocardiographic and blood pressure changes—in patients with severe or paradoxical low-gradient AS than in patients with moderately severe AS. No differences were found in the peak oxygen consumption (pVO2) or the VE/VCO2 slope between these 3 groups. This may be explained by the limited population included and possible selection bias, as the authors point out, by excluding patients with inconclusive symptoms attributable to AS. In addition, a nonnegligible percentage of patients reached an RER <1.1, which could lead to erroneous analyses if submaximal CPET parameters were not taken into account.1

Currently, CPET is the only objective tool available to estimate myocardial oxygen consumption, ventilatory efficacy, and muscle performance on exertion, information of value to determine the cause of a patient's symptoms.2 Hence, we propose CPET use in patients with asymptomatic severe AS, as many of them are falsely asymptomatic because of several concurrent factors, such as advanced age, frailty, obesity, and others.2 pVO2 values <20mL/kg/min and VE/VCO2 slope values >30 are pathological and imply a higher risk of adverse events on follow-up, as described by Guazzi et al.3 in the first published report proposing an algorithm for the study of valve disease with CPET.

Thus, our group proposes an objective algorithm to identify these falsely asymptomatic patients using CPET. In the absence of randomized studies, we believe it could be a useful instrument for this purpose.