Increased fluid accumulation, reduced physical activity and heart rate variability during national holidays in patients with cardiac implantable electronic devices.

AIMS: The higher incidence of myocardial infarction (MI) during national holidays could be caused by overindulgence of food and beverages, potentially straining the heart of vulnerable individuals. Monitoring decreased thoracic impedance by cardiac implantable electronic devices (CIED) can be used for detection of fluid accumulation. We aimed to assess the relationship between cardiac metrics and national holidays in patients with CIED.

METHODS AND RESULTS: Patients with CIED-based impedance monitoring at a tertiary care hospital in Sweden were screened. Patients were included if they had data for at least one holiday (Christmas, New Year, or Midsummer) between June 2015 and January 2020. Thoracic impedance, heart rate variability, and activity during the holiday were compared with baseline values, defined as the average of 3 days preceding Christmas and Midsummer. Clinical characteristics were obtained from medical records. In total, 96 patients (82% men, age 69 ± 10 years, 92% ICD, 78% CRT, 72% with LVEF < 40%) were included, which provided data for 649 patient-holidays. During Christmas Day, New Year's Day, and Midsummer Day combined, impedance decreased by a mean of 1.1 Ohm [95% CI 0.7-1.6, P < 0.001], heart rate variability decreased by a mean of 8.0 ms [4.9-11.2, P > 0.001] and daily activity by a mean of 40 min [35-45, P < 0.001]. One ventricular tachycardia event requiring shock therapy was documented during the holiday.

CONCLUSION: A transient decrease in thoracic impedance, heart rate variability, and physical activity was observed during national holidays, potentially contributing to the higher incidence of MI during holidays.