Emergency department visits and hospitalizations after a diagnosis of angina with no obstructive coronary artery disease (ANOCA).

Introduction: Angina with no obstructive coronary artery disease (ANOCA) presents diagnostic and treatment challenges, significantly burdening healthcare resources. This study assessed emergency department (ED) visits and hospitalizations and factors associated with these outcomes following ANOCA and stable angina (SA) with obstructive coronary artery disease (CAD) diagnoses.

Methods: A retrospective cohort of individuals who had their first invasive cardiac catheterization for chest pain in Alberta from 2002 to 2017 was extracted retrospectively from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) database. Incidence rates (IRs) were calculated for ED visits and hospitalizations, while factors associated with these outcomes were analyzed using Cox models.

Results: Our analysis included 28,881 individuals (ANOCA, 36%). Two-year post-catheterization IRs of ED visits were 100.3-119.3 per 1,000 person-years for ANOCA and increased over time (unstandardized beta coefficient [b]=2.19 per biennium [95%CI 0.83-3.55];p=0.008); for SA with obstructive CAD the IRs were 209.3-240.2 per 1,000 person-years and remained stable (b=-1.83 per biennium [95% CI -5.73 to 1.70]; p=0.25). IRs of hospitalizations were 12.4-25.8 per 1,000 person-years and stable for ANOCA (b=-0.93 per biennium [95% CI -2.49-0.64];p=0.20); for SA with obstructive CAD, they were 106.4-171.4 per 1,000 person-years and decreased over time (b=-9.02 per biennium [95% CI -13.27 to -4.77; p=0.002). A previous history of heart failure was most associated with ED visits (HR= 1.74 [95% CI 1.41-2.14]; p<0.001) and hospitalizations (HR= 2.40 [95% CI 1.82-3.18]; p<0.001) for ANOCA.

Conclusions: ED visits for ANOCA have risen over time while hospitalizations remain stable, indicating a growing burden despite generally lower rates than SA with obstructive CAD. These findings underscore the need for more effective management strategies to address the significant morbidity and resource utilization in ANOCA.