Quantification of Seasonal Variation in Daily Physical Activity in Individuals with Heart Failure and Implantable Cardioverter Defibrillator/Cardiac Resynchronisation Therapy Devices.

Purpose: Understanding seasonal variation of daily physical activity (PA) in patients with heart failure (HF) has important implications for planning and interpretation of clinical trials, but the presence and magnitude of this seasonal variation in daily PA have yet to be established. The purpose of the present study was to determine the presence and magnitude of seasonal variation in daily PA in community-dwelling individuals with HF using several analytic approaches.

Methods: Retrospective chart review of patients with HF and Medtronic implantable cardioverter defibrillator/cardiac resynchronisation therapy (ICD/CRT) devices. Data included in analyses (autocorrelation, analysis of covariance, one-way analysis of variance) were clinical characteristics, the patient activity measure of daily PA from the ICD/CRT devices, temperature and hours of daylight over the 1-year period of 1 November 2017-31 October 2018.

Results: One hundred and sixty-eight patients were included. Visual analysis and autocorrelation demonstrated seasonal variation in daily PA. Daily PA seasonal difference between winter and summer months was 0.4 hours per day/24 minutes per day/2.8 hours per week/14.9%. This seasonal effect on daily PA is significantly greater in those with ≤8 comorbid conditions and an overall activity level of >2.2 hours per day compared to those with multiple comorbidities and low overall activity (0.7 versus 0.1 hours per day, respectively).

Conclusions: The present study affirms the seasonality of daily PA in a cohort of patients with HF and ICD/CRT devices and reveals a disproportionate seasonal effect on those with fewer comorbidities and higher overall activity levels. Seasonal variation should be accounted for when interpreting change in daily PA in clinical practice and when designing and interpreting results of clinical trials investigating interventions to improve daily PA.