Metabolic Status and Atrioventricular Block Risk: The Role of Physical Activity.

Background: The relationship between metabolic status as a possible risk factor and predictor of response to moderate-to-vigorous physical activity (MVPA) in atrioventricular block (AVB) remains unclear.

Methods: A total of 82,365 UK Biobank participants without a history of AVB or pacemaker implantation, and who were involved in accelerometer work-up, were chosen for the study population. Metabolic status was classified into two categories, healthy and unhealthy, using modified criteria for metabolic syndrome from the International Diabetes Federation. We used the multivariable Cox proportional model to assess the associations between metabolic status and primary outcome (composite of second-degree AVB or third-degree AVB) or secondary outcomes (each component in the primary outcome and AVB-related pacemaker implantation). The relationship between MVPA min/week and the primary outcome in each metabolic status category was assessed using restricted cubic splines.

Results: Of the 82,365 participants, the mean age was 62.3 years, and 44.1% were men. In total, 299 primary outcome events occurred during the 6.1-year follow-up. Compared to metabolically healthy participants, metabolically unhealthy participants had a 58% higher risk of the primary outcome (hazard ratio (HR): 1.58, 95% confidence interval (CI): 1.25-2.00; < 0.001). This pattern was consistent for second-degree AVB (HR: 1.59, 95% CI: 1.12-2.27; = 0.010), third-degree AVB (HR: 1.50, 95% CI: 1.12-2.03; = 0.008), and AVB-related pacemaker implantation (HR: 2.25, 95% CI: 1.44-3.52; < 0.001). Increased MVPA provided statistically significant protection against the primary outcome only in metabolically unhealthy participants, with a threshold of 830 min/week.

Conclusions: Generally, in the middle-aged population, metabolically unhealthy participants had a statistically significantly higher risk of second- or third-degree AVB and AVB-related pacemaker implantation than metabolically healthy participants. However, MVPA reduced the risk of second- or third-degree AVB in the metabolically unhealthy participants, though the effect was attenuated with excessive MVPA. From this perspective, identifying and encouraging exercise in metabolically unhealthy individuals is essential. Due to its observational nature, future research should verify the preventive effects of increased MVPA on conduction block in populations with metabolic abnormalities through randomized controlled trials. Moreover, the biological mechanisms and safety of the protective effects of excessive MVPA require further verification.