Sex differences in the change in cardiorespiratory fitness and quality of life following exercise training in adults with atrial fibrillation: a systematic review and meta-analysis
Authors: Vidal Almela S , Marcal I R , Wong J , Terada T , Nguyen B O , Joensen A M , Bittman J , Mills M T , Prud'homme D , Reed J L 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Public Institution(s). Main funding source(s): University of Ottawa Heart Institute.
Patients with atrial fibrillation (AF) often have poor cardiorespiratory fitness (CRF), quality of life (QoL) and mental health. Improving CRF through exercise training is an important AF management target associated with lower hospitalization and mortality rates. Emerging research indicates smaller CRF increases in females than males following exercise training. Yet, this has not been examined in those with AF. The primary aim was to compare changes in CRF (estimated or directly measured as peak oxygen consumption [VO2peak, mL O2/kg/min]) following exercise training between females and males with AF. We hypothesized that females would experience smaller CRF improvements. Secondary aims compared changes in functional capacity (6-minute walk test [6MWT] distance), QoL (SF-36), anthropometric and hemodynamic measures, and anxiety and depression (Hospital Anxiety and Depression Scale).

Methods
This review adhered to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines and was registered with PROSPERO (#CRD42022302310). Five electronic bibliographic databases were searched to identify published and unpublished studies up to January 2022, with prospective cohort and experimental designs, implementing exercise training of any form ≥4 weeks, in adults with AF. When eligible studies did not segregate results by sex, authors were contacted to obtain their sex-specific data. Random-effects meta-analyses were performed to synthesize the measures of effect (i.e. mean difference [MD] in the changes between sexes following exercise).

Results
Our search identified 9,398 studies. Sex-specific data were obtained from 18/60 eligible studies (see Table 1), with 868 participants enrolled in an exercise training program (29% females, F: 69±7, M: 66±8 years old). Exercise interventions lasted between 6 weeks to 1 year and used mainly aerobic training of light to high intensity, 2 to 5 days/week. The change in VO2peak did not differ between sexes (MD=+0.25, 95% CI=−1.13 to +1.62 mL O2/kg/min, p=0.724; I²=33%, see Figure 1). There were no differences in changes in functional capacity (MD=−7.11, 95% CI=−22.56 to +8.34 m, p=0.367; I²=66%); Physical Component Summary (MD=+0.82, 95% CI=−1.72 to +3.36 points, p=0.526; I²=49%) and Mental Component Summary (MD=+1.03, 95% CI=−1.68 to +3.75 points, p=0.456; I²=46%) scores of the SF-36; body mass index (MD=−0.13, 95% CI=−0.94 to +0.68 kg/m², p=0.756; I²=0%); anxiety (MD=+0.22, 95% CI=−1.33 to +1.77 points, p=0.782; I²=39%) and depression (MD=-0.01, 95% CI=−1.64 to +1.63 points, p=0.995; I²=60%). Smaller reductions in SBP were found in females than males (MD=+3.11, 95% CI=0.14 to 6.09 mmHg, p=0.040, I²=42%).

Conclusions
This review addressed the lack of sex-based analyses in previous exercise studies in AF. We did not observe smaller changes in CRF in females. However, the underrepresentation of females in research continues to hinder establishing clear conclusions in sex-specific research.