Low ambient temperature and sudden temperature drop increases the incidence of acute aortic dissection: a retrospective analysis from the northeast region of China.

Background: Acute aortic dissection (AAD) is a cardiovascular catastrophe with substantial early mortality. Although ambient cold has been implicated as a trigger, existing evidence derives predominantly from temperate and subtropical settings. Populations enduring protracted severe winters-a hallmark of cold temperate zones-remain underrepresented, leaving the cardiovascular hazard of sustained extreme cold poorly defined. Methods: In this retrospective time-stratified case-crossover study, we analyzed 1 384 patients with AAD admitted to a tertiary cardiovascular center in Harbin, China-a city in the cold temperate zone of Northeast Asia with a harsh continental monsoon climate. Meteorological data (2014-2023) were interrogated using distributed lag non-linear models combined with conditional logistic regression to quantify exposure lag-response relationships between daily mean temperature and temperature change between neighboring days (TCN) with the AAD onset. Results: A near-linear increase in AAD risk was observed with decreasing daily mean temperature, with minimum morbidity at 25.9 °C. Extreme cold (-23.4 °C, 1st percentile) raised the risk significantly within 3 days. A pronounced risk elevation followed temperature drops between consecutive days-a decline of 9.2 °C was associated with a RR of 9.57 (95% CI 1.21-75.76). In contrast, temperature rises conferred protection. These effects were accentuated in winter and during the period of centralized indoor heating. Conclusion: In a cold temperate region marked by severe winters, both low ambient temperature and abrupt cooling act as potent environmental triggers for AAD. These findings call for enhanced clinical awareness and tailored preventive measures during cold exposure in such climates.