Key result
Seasonal temperature shifts are linked to a ~0.4-hour daily physical activity difference in HF device patients.
Why the study?
Seasonal variation affects daily physical activity, but its impact on individuals with heart failure and ICD/CRT devices has not been investigated.
Observational (n=16)
Effect estimate: median difference 0.39 hours (r=0.71)
p-value: p=0.004
May warrant seasonal adjustment when interpreting device activity data in HF; leaves open effects on outcomes and need for targeted trials.
BACKGROUND: Previous studies indicate that seasonal variation affects daily physical activity (PA), but none have investigated this relationship in individuals with heart failure (HF) who also have implanted cardioverter defibrillators and cardiac resynchronization therapy (ICD/CRT) devices. The purpose of the present study was to determine if seasonal variation in temperature affects daily PA in patients with HF and ICD/CRTs. PATIENTS AND METHODS: Secondary analysis of data from 16 subjects with HF and Medtronic® ICD/CRT devices enrolled in a randomized trial investigating interventions to improve daily PA. Due to the rolling study enrollment, daily PA data for all subjects were not available for the entire time frame and were divided into two groups. Determination of seasonal variation of daily PA was determined using visual analysis of daily PA plotted with average temperature, autocorrelation, visual analysis of seasonal subseries plots and boxplot analysis, as well as Wilcoxon signed-rank tests. RESULTS: Subjects 1-8 demonstrated the greatest differences in daily PA during periods of seasonal transition whereas subjects 9-16 demonstrated the greatest variation in daily PA with greatest seasonal temperature difference. Wilcoxon signed-rank testing of the lowest and highest months for daily PA revealed median differences of 0.30 (p = 0.050) and 0.36 hours (p = 0.036) for subjects 1-8 and 9-16, with effect sizes of 0.69 and 0.74, respectively. CONCLUSIONS: Seasonal variation in mean temperature appears to affect daily PA in individuals with HF and ICD/CRT devices by a magnitude of 0.30-0.36 hours, which may need to be accounted for in future research investigating interventions to improve daily PA.
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Shoemaker et al. (2016) conducted an observational in Heart failure with implanted cardioverter defibrillators and cardiac resynchronization therapy (ICD/CRT) (n=16). Seasonal variation in temperature vs. Low vs high activity seasons (temperature variation) was evaluated on Difference in daily physical activity between seasonal high and low months (median difference 0.39 hours (r=0.71), p=0.004). Seasonal variation in mean temperature significantly altered daily physical activity in patients with heart failure and ICD/CRT devices, showing a median difference of 0.39 hours between seasons.
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