For several decades, aortic stenosis (AS) has been the most prevalent valvular disease in developed countries, contributing significantly to morbidity, mortality, and a high healthcare burden. Various studies and registries have associated classic cardiovascular risk factors with the development of AS. However, the pathogenesis of degenerative aortic stenosis (DAS) is not yet fully understood, and there is still debate regarding the role of physical exercise and cardiorespiratory fitness (CRF) in its progression. Below, we present a study conducted by the group led by BTS Smenes et al., which, through a prospective registry of a large cohort in Trøndelag County (Norway), explores the association between the need for invasive therapies, such as surgical valve replacement (AVR), CRF, and physical exercise.

Over recent decades, degenerative aortic valve disease has become the most common valvular pathology in our region. This is primarily due to the drastic reduction in the incidence of rheumatic mitral and aortic valvulopathies, along with the progressive aging of the population. Although various factors have been associated with DAS, no treatment exists to halt its progression. The only effective interventions are invasive procedures such as AVR or TAVI. The authors of this study hypothesize an inverse relationship between the need for AVR and both physical training and CRF. Additionally, they will evaluate the association of postoperative mortality with these two variables.

To conduct this analysis, a prospective study was carried out using data collected from the HUNT cohort in Trøndelag since 1984, in which over half of the county’s population participated. Participants were divided into three groups based on weekly physical activity reported in questionnaires: low activity (less than one hour of high-intensity exercise or less than three hours of low-intensity exercise per week), moderate activity (1-3 hours of high-intensity or more than three hours of low-intensity exercise per week), and high activity (more than three hours of high-intensity exercise per week). CRF was also estimated using clinical variables and exercise questionnaires, based on a model developed with over 4,500 patients from the same population who underwent cardiopulmonary exercise testing (HUNT3 Fitness Study). This allowed the population to be divided into quintiles according to estimated CRF. During the prospective follow-up, the relationship between these groups and the need for isolated AVR due to severe AS (defined as a mean echocardiographic gradient greater than 40 mmHg) was analyzed, along with AVR combined with other procedures in a sensitivity analysis. Patients who had undergone other types of cardiac surgery (including AVR due to aortic insufficiency) and those who underwent TAVI were excluded.

A total of 57,214 participants (52.6% women) were included and followed for an average of 17.6 years, with 102 isolated AVRs for AS recorded. The average age at inclusion was 45.6 ± 16 years, and the average age at intervention was 70.1 ± 9.8 years. While no statistically significant association was found between higher reported physical activity and the need for AVR, the authors did observe a 15% reduction in the need for isolated AVR for each estimated MET increment in CRF (HR 0.85; 95% CI 0.73-0.99). Additionally, a lower incidence of this surgery was observed in the groups with higher CRF, with the reduction being statistically significant only in the fifth quintile (HR 0.44; 95% CI 0.23-0.86). Results did not vary when considering the sensitivity analysis that included combined procedures during the surgical act. Similarly, while no differences in survival post-AVR were found based on physical activity groups, a 37% reduction in mortality was observed for each estimated MET increment in CRF, in a statistically significant manner (HR 0.63; 95% CI 0.47-0.83); with a lower risk of mortality post-AVR in the fifth CRF quintile compared to the first (HR 0.06; 95% CI 0.01-0.47).

The authors conclude that the main finding of this study is that estimated CRF is strongly and inversely associated with the risk of AS requiring AVR, and that higher estimated CRF is associated with better postoperative survival.

COMMENTARY:

This is a prospective, observational registry with a very large sample size and extended follow-up, demonstrating a reduced risk of requiring AVR for AS among patients with higher estimated CRF, as well as improved survival in this population when intervention is needed. These data align with other studies that have also associated lower incidence of DAS in subpopulations with greater physical capacity, such as the study published by Laukkanen et al. in a Finnish population. Additionally, within the same “HUNT” cohort analyzed, the same group had already demonstrated lower incidence of coronary artery bypass surgery and improved survival in patients with higher estimated CRF, a pathology that shares several risk factors with DAS.

Conversely, despite the strong association between physical exercise and CRF, no inverse relationship was found between surgery and the subgroup of participants reporting higher activity levels. The authors hypothesize that this could be due, on one hand, to potential overestimation in self-reported physical activity, and on the other, to the possibility that excessive physical exercise may accelerate the progression of DAS, without properly distinguishing this subpopulation within those with more than three hours per week of vigorous activity.

The main limitations of the study are that, as a prospective observational registry, there is no comparator group; physical activity was self-reported rather than measured; and CRF was estimated based on a model developed with a subgroup of the same population rather than measured directly by cardiopulmonary exercise testing. Additionally, aortic valve status at inclusion was unknown, and patients who underwent TAVI were excluded.

Regardless, we can conclude by reinforcing the idea that there is an association between patients’ physical capacity and reduced incidence of AVR as well as improved postoperative survival. Therefore, this aspect, along with the numerous benefits already demonstrated in other areas of cardiovascular disease and beyond, should encourage us to promote physical activity within the general population.

REFERENCE:

Nystøyl BTS, Letnes JM, Nes BM, Slagsvold KH, et al. Cardiorespiratory fitness and the incidence of surgery for aortic valve stenosis-the HUNT study. Eur J Cardiothorac Surg. 2023 Nov 1;64(5). doi: 10.1093/ejcts/ezad322.