Associação da gravidade clínica no desempenho físico mediada pela modulação autonômica cardíaca em pacientes com insuficiência venosa crônica: um estudo transversal

Abstract

Chronic venous insufficiency (CVI) is characterized by abnormal function of the venous system of the lower limbs, which generates an imbalance in blood flow and compromises venous return to the heart. CVI causes several health problems, including physical performance. However, in addition to this component, it is suggested that CVI has an impact on cardiovascular health as the clinical worsening of the disease occurs, in which such a condition may possibly affect the autonomic nervous system, demonstrated through cardiac autonomic modulation (CAM), where such a condition is still uncertain in the literature. Thus, the possible mediation function of cardiac autonomic function in the association between clinical severity of CVI and physical performance requires further discussion. Thus, the objective of this study was to verify the impact of clinical severity of CVI on physical performance using CAM as a mediator. This is a cross-sectional, prospective, observational study with patients with CVI with clinical severity classified by the clinical-etiology-anatomic-pathological (CEAP) classification of C3-C6, of both sexes, aged 18 years or older. To assess physical performance, handgrip strength, the 6-minute walk test (6MWT), and the Short Physical Performance Battery (SPPB) were analyzed. To analyze MAC, the heart rate variability (HRV) technique was used. Logistic regression analysis was used to identify statistically significant variables in clinical severity, MAC, and physical performance, and mediation analysis was used to analyze the impact of clinical severity of CVI on physical performance using MAC as a mediator. For all statistical analyses, p-value >0.05 was considered. The study included 110 patients, with a mean age of 59 ± 11 years, the majority of whom were female (69%) and had CEAP C6 (31%). The results showed that only the pNN50 indicator in the multivariate model showed a statistically significant association (OR 1.01; 95% CI 1.00-1.03; p = 0.015). Regarding the mediation analysis, only the parameters of MAC Mean RR, RMSSD, pNN50, SDNN and LF/HF ratio presented a mediating role in the variables of physical performance of the 6MWT, tandem balance, total balance score, usual gait speed, total sit-to-stand score and total SPPB score. Therefore, physical performance was altered by clinical severity with MAC playing a mediating role in both parasympathetic and sympathetic parameters. Therefore, we suggest the development of future studies that address the use of this evaluation method longitudinally in order to observe the evolution of the study variables throughout different stages.