The law of surprise: temporal variation and seasonality of acute aortic syndromes: a single-centre epidemiologic cohort analysis spanning 20 years

Abstract Background and aims Acute aortic syndromes (AAS) represent life-threatening cardiovascular emergencies characterized by high mortality rates despite rapid intervention. Global epidemiological data indicate substantial variance in incidence. Longitudinal single-centre data over extended periods are limited but crucial for understanding diagnostic, demographic, and systemic factors influencing admission trends.(1). This study aimed to analyze annual and seasonal variation trends of AAS over a 20-year period in a single maximal care centre and explore potential chronological and environmental contributors to this variation. Methods This retrospective cohort study evaluated 403 patients admitted with a confirmed diagnosis of AAS between 2005 and 2025 at the University Hospital Erlangen, Germany. All diagnoses were established via computed tomography angiography (CTA) and confirmed intraoperatively. Annual, quarterly, and monthly surgical volumes were calculated, and temporal trends were analyzed using Poisson and negative binomial regression models. Admission rates during public holidays and school vacations were also evaluated. Results Over the 20-year observation period, a steady increasing trend in the annual number of AAS cases was observed, peaking in 2017. Analysis of quarterly distributions revealed a statistically significant dominance of cases in the fourth quarter (Q4: October–December; p < 0.05) compared to the second (Q2) and third (Q3) quarters. Monthly analysis demonstrated a prominent peak in October (incidence rate ratio [IRR] = 1.85 vs. June, p < 0.05). Conversely, fixed public holidays and school vacations were associated with statistically significant reductions in daily admission counts ( p < 0.05), with the lowest relative case counts observed during the Christmas vacation period (IRR: 0.40–0.50). Conclusion The case counts of acute aortic syndromes exhibits significant temporal and seasonal variation, characterized by a distinct late-autumn and early-winter peak, alongside significant declines during institutional vacation periods. These findings suggest that acute cardiovascular events are heavily modulated by cyclical environmental and socio-systemic factors.