Dose-response relationship of cardiorespiratory fitness with incident atrial fibrillation

The dose-response association between cardiorespiratory fitness and risk of atrial fibrillation (AF) is still not well known. Therefore, we performed a comprehensive meta-analysis to investigate the dose-response association between cardiorespiratory fitness and incident AF. We performed a comprehensive search in the databases of PubMed, Cochrane library, and Ovid from inception through August 2019. A one-stage robust error meta-regression method was used to summarize the dose-response association between cardiorespiratory fitness and AF. A total of 9 studies were included in this meta-analysis. In the categorical analysis, compared with the lowest level of cardiorespiratory fitness, both the intermediate (RR = 0.68, 95% CI 0.57-0.82) and highest (RR = 0.60, 95% CI 0.51-0.72) levels of cardiorespiratory fitness were associated with a decreased risk of AF. In the dose-response analysis, per 1 metabolic equivalent increase in cardiorespiratory fitness was associated with a decreased risk of AF (RR = 0.91, 95% CI 0.86-0.95). There was an inverse relationship between cardiorespiratory fitness and risk of AF with evidence of linearity (Pnon-linearity = 0.43). Current evidence suggests that there is an inverse relationship between cardiorespiratory fitness and risk of AF, manifesting as a higher level of cardiorespiratory fitness is associated with a decreased risk of AF.