Ambient particulate matter exposure and acute type A aortic dissection: A retrospective time-stratified case-crossover study in northern Italy

ims: Ambient particulate matter triggers acute cardiovascular events, but its relationship with acute type A aortic dissection is poorly characterised in Europe. We examined whether ambient PM2.5 and PM10 concen- trations were associated with Stanford type A acute aortic dissection (AAD) in northern Italy. Methods: We performed a retrospective, single-centre, time-stratified case-crossover study of 40 patients with confirmed Stanford type A AAD (2018-2022). Case days were compared with referent days on the same weekday within the same month and year. Daily mean PM2.5 and PM10 concentrations from the fixed Piacenza-Parco Montecucco urban-background monitoring station in Piacenza were evaluated for the same calendar day and a 30-day window including the index day. Separate conditional logistic regression models were adjusted for ambient temperature. Results: A doubling of same-day PM2.5 was associated with increased odds of a case day (adjusted OR 4.78, 95% CI 1.61-14.29; nominal p = 0.005). Associations in the same direction were observed for 30-day PM2.5 and for PM10 in both windows. Estimates were imprecise and correlated and should be considered exploratory. Conclusion: In this selected cohort, higher same-day and 30-day particulate concentrations were associated with Stanford type A AAD case days. Larger multicentre studies using individual-level and strictly pre-event exposure estimates are required before clinical or public-health inferences can be drawn.