- Incidence of acute aortic dissection tended to spike on cold days while the incidence of aortic aneurysm rupture increased the day after, an observational study from Tokyo suggested.
- These findings add to the growing evidence of a relationship between low ambient temperatures and aortic emergencies.
- The excess risk posed by the cold temperatures appeared to disproportionately affect older adults in the study.
The likelihood of an acute aortic dissection (AAD) or aortic aneurysm rupture quickly spiked following days of cooler ambient temperatures, according to a large study from Tokyo.
Extremely cold days, with temperatures below the first percentile (2.8°C or 37.04°F), were associated with significantly higher odds of AAD (OR 2.86, 95% CI 1.95-4.19) and aortic aneurysm rupture (OR 2.39, 95% CI 1.16-4.93) after adjusting for multi-day temperature trends, indicating that the finding is not explained by short-term temperature drops.
As for the timing, the increased risk of AAD was highest the day of a cold spell, whereas the highest risk for aortic aneurysm ruptures more typically lagged by 1 to 2 days, reported Takahiro Jimba, MD, PhD, of the University of Tokyo, and colleagues in the European Journal of Preventive Cardiology.
Moreover, there was a continuous relationship between temperature and these aortic emergencies, such that the lowest risk was observed at a balmy 30.5°C (86.9°F) and rose steadily with cooler weather.
"Overall, we confirmed an immediate cold-related increase in AAD risk, consistent with previous reports, and further demonstrated a delayed cold-related increase in the risk of aortic aneurysm rupture," the authors wrote.
During the study period, the median daily average temperature in Tokyo was 17.2°C (63.0°F); the city is said to share a similar climate to Washington, D.C.
Previous studies have already linked low temperatures to aortic emergencies and deaths, with reports from Japan, China, Brazil, and Germany, among others.
An AAD is a rare but life-threatening and painful tear in the intimal layer of the aorta that leads to the separation of the aortic wall layers. An aortic aneurysm rupture is a significant tear through all of the layers of the aorta wall, often occurring at the site of a large aneurysm. Age is a risk factor for both AAD and aortic aneurysm rupture, leading to a rising prevalence in an aging population.
Jimba and colleagues suggested that the difference in timing between AADs and aortic aneurysm ruptures after a cold spell reflects distinct pathophysiological processes. "Sustained hemodynamic stress, neurohumoral activation, and vascular inflammation induced by cold exposure may underlie aneurysm rupture, although further investigation is warranted," they wrote.
"Nevertheless, our findings clarify the impact of temperature exposure on [aortic emergencies] and offer practical implications for climate-informed prevention," they added. "Specifically, clinicians should emphasize patient education on temperature and blood pressure control during cold climate, particularly among those at risk, such as individuals with unruptured aortic aneurysms."
This observational study used data from the Tokyo CCU Network Database, a prospective registry covering 76 major hospitals in the Tokyo metropolitan area. The researchers included 8,371 people with AAD (median age 70 years, 59.8% men) and 2,064 with aortic aneurysm rupture (median age 78 years, 68.9% men) who were admitted from January 2013 to December 2019.
The risks of both AAD and aortic aneurysm rupture were significantly higher in the oldest patients (age ≥75 years).
"Although prior time-stratified case-crossover studies focusing on middle-aged populations found no significant age interaction, studies including older adults (>75 years) demonstrated an interaction effect, supporting heightened vulnerability in this age group," Jimba and colleagues wrote.
They acknowledged the need to validate these findings in other cohorts and noted that the official recorded ambient temperature in Tokyo may not fully reflect individual exposures.
Disclosures
The study was supported by the Tokyo Metropolitan Government.
Jimba had no disclosures. A study co-author reported a research grant from Pfizer.
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