Translating Population-Based Epidemiology into Clinical Recognition of Coronary Artery Spasm: Prevalence, Incidence, and Geographic-Seasonal Variation in Taiwan.

Background: Coronary artery spasm (CAS) is a reversible cause of myocardial ischemia, infarction, and sudden cardiac death. Often under-recognized and influenced by ethnicity, geography, and environment, CAS requires population-level data. This study examined nationwide CAS epidemiology in Taiwan by age, sex, region, and season. Methods: This cross-sectional population-based study used the Taiwan National Health Insurance Research Database (2004-2018). Diagnosis-coded CAS was operationalized using ICD-9-CM code 413.1 or ICD-10-CM code I20.1 recorded on at least three outpatient encounters or one inpatient encounter. Age- and sex-standardized prevalence and incidence were calculated, and temporal, geographic, and seasonal variations assessed. Results: Among 27,974 patients with diagnosis-coded CAS, the mean age at diagnosis was 57.9 years, with nearly equal sex distribution (49.7% female). In 2018, the age-standardized prevalence was 35.1 per 100,000 population, with comparable rates in men (35.4) and women (34.8 per 100,000). The incidence was 11.5 per 100,000 in both sexes. Both prevalence and incidence increased linearly from 2004 to 2018 (p < 0.001), peaked at ages 75-79 years, and then declined. Geographic analysis revealed the highest disease burden in central Taiwan, particularly in Taichung City, Changhua County, and Yunlin County. Seasonal analysis showed a clear pattern, with incidence peaking in winter (December-February) and spring (March-May), and notably lower counts in summer and autumn. Conclusions: From 2004 to 2018, CAS prevalence and incidence increased in Taiwan, affected both sexes similarly, peaked at ages 75-79 years, and were highest in central western regions during winter and spring. These findings may improve CAS recognition and resource allocation.