Dynamic factor analysis of seasonal variation in daily physical activity in individuals with heart failure and implanted cardiac devices.

BACKGROUND:The purpose of the present study was to determine the presence and magnitude of seasonal variation in daily physical activity (PA) in those with heart failure (HF). METHODS:Retrospective study and dynamic factor analysis (DFA) of Patient Activity data from Medtronic implanted cardioverter defibrillator and cardiac resynchronization devices (ICD/CRTs). RESULTS:In a data set of 435 patients, distinct states/trends were identified by DFA including a classic, sinusoidal pattern of seasonal variation and a pattern of decline over the course of 12 months, which were associated with specific clinical characteristics. Overall, model fitting was good. CONCLUSIONS:Those with low comorbidities, better NYHA Class, higher BMI, no hospitalization, and male sex demonstrated greater seasonal variation of at least 40 min per day between winter (lowest PA) and spring/summer (highest PA). Those with female sex and hospitalization demonstrated overall downward trajectories of approximately 40 and 80 min, respectively, over the course of the year.