Association between Ambient Temperature and Ventricular Arrhythmias in Patients with Implantable Cardioverter-Defibrillators: A Time-Stratified Case-Crossover Study in China

Ambient temperature has been recognized as an environmental trigger for adverse cardiovascular events. However, its association with ventricular arrhythmias (VAs) in patients with implantable cardioverter-defibrillators (ICDs) remains understudied, particularly in China. We conducted a time-stratified case-crossover study among a cohort of patients with ICDs from 2019 to 2024. Conditional logistic regression models, integrated with restricted cubic splines, distributed lag nonlinear models, and distributed lag linear models, were used to estimate the association between ambient temperature and the occurrence of VAs, adjusting for relative humidity and public holidays. A total of 322 VA events were identified among 1053 patients with ICDs. Only extremely high ambient temperatures were significantly associated with increased probabilities of VA events, which increased by 180% (OR = 2.80, 95% CI: 1.08-7.28) over 1 day and 196% (OR = 2.96, 95% CI: 1.06-8.30) over 2 days compared with the incidence at reference temperatures. Subgroup analyses suggested that females, older patients, and those residing in the monsoon climate zone might be more susceptible to high-temperature risks. This investigation into the role of ambient temperature in VAs in patients with ICDs provides insights into its highly complex relationships and emphasizes the need for additional research and public health interventions.