Possible Triggers and Temporal Patterns of Implantable Cardioverter Defibrillator Discharges: A Preliminary Study

Abstract

The present study investigated: (1) mental and physical activities as possible triggers of implantable cardioverter defibrillator discharges; and (2) the temporal patterns of those di scharges in order to provide the rationale for a larger~sca le study.Retrospecti ve interviews of patients with coronary artery disease and implantable cardioverter defibrillators were conducted to determine frequency of discharges and timing of discharges as well as specific circumstances surrounding those discharges. The interview also collected information regarding the usual activity levels of the patients to serve as control or baseline data. The case-crossover method was used to approach the data of 32 patients who were interviewed. Over a two-year period, 20 of the 32 patients had experienced discharges. Elevated Mantel-Haenszel estimates of relative risk were found for high physical exertion, sexual activity, high mental activity, tension or stress, and anger, but these elevated risks were statistically non-significant given this small sample size. Chi-square analysis of a circadian pattern of discharges was statistically non-significant, but there was evidence of a seasonal variation in number of discharges ("t}= 9.00, p=O.029). This seasonal pattern revealed a peak prevalence of incidents during the winter months and a smaller peak during summer months.