Low temperature and cold spells on arrhythmia onset: An individual-level case-crossover study in Minhang District, Shanghai, China

Low temperatures and cold spells have recently been associated with various diseases. However, the effects of these conditions on arrhythmia onset remain insufficiently explored. We investigated the association between low temperatures, cold spells, and the risk of arrhythmia. A time-stratified case-crossover design was employed using outpatient records from 25,957 arrhythmia cases in Minhang District, Shanghai, China, between January 2017 and December 2019. Cold spells were defined using multiple temperature thresholds (P10, P7.5, P5, P2.5) and durations (≥2, ≥3, and ≥4 consecutive days). Conditional logistic regression models incorporating distributed lag non-linear model (DLNM) estimated the association between low temperatures, cold spells, and arrhythmia onset, considering lag periods up to 14 days. The cumulative relative risk over lags of 0–14 days for low ambient temperatures was 1.837 (95 % CI: 1.357–2.486), whereas for cold spells, it was 1.198 (95 % CI: 1.020–1.407). Stratified analyses revealed that cold spells were associated with a higher risk of other cardiac arrhythmias compared to atrial fibrillation and flutter, while low temperatures raised the risk of atrial fibrillation and flutter more than other cardiac arrhythmias. Both males and younger patients were more susceptible to cold spells and low temperatures, although the difference was not statistically significant. This study offers robust evidence that low temperatures and cold spells increase the risk of arrhythmia onset. • Low ambient temperatures were associated with an elevated risk of arrhythmia. • Cold spells, defined by multiple temperature thresholds and durations, were associated with arrhythmia onset. • Male patients appeared more susceptible to cold-related arrhythmia risk. • Exposure–response analysis revealed a nonlinear increase in arrhythmia risk with decreasing temperature.