Predictors of Non-Obstructive Coronary Artery Disease in Patients Undergoing Elective Coronary Angiography

Background: Appropriate patient selection for coronary angiography (CAG) is essential to minimize the unnecessary risk of morbidities and exposure to radiation and iodinated contrast. This becomes even more relevant in low-to-middle-income settings where most health expenditures are out-of-pocket due to lack of medical insurance. We determined predictors of non-obstructive coronaries (NOC) in patients undergoing elective CAG. Methods: CathPCI Registry®, single-center data was extracted for 25,472 patients who had CAG over an eight year period. After excluding patients for compelling conditions or known CAD, 2,984 (11.7%) patients were included in this study. Non-Obstructive Coronaries was defined as <50% left main coronary artery and major epicardial vessel stenosis. Multiple Cox proportional algorithm was employed to report prevalence ratios (PR) of predictors of NOC along with 95% confidence interval. Results: Mean age of patients was 57.9 ± 9.7 years, 23.5% were women. Preprocedural non-invasive testing (NIT) was performed in 46% of the patients; of which 95.5% reported to be positive but only 67.3% were stratified as high risk. Of 2,984 patients undergoing elective CAG, 711 (24%) had NOC. Predictors of NOC included younger age <50 years (PR: 1.3, CI: 1.0–1.5), Women (1.8, 1.5–2.1), low (1.9, 1.5–2.5) and intermediate risk stratification (1.3, 1.0–1.6) on Modified Framingham Risk Score and inappropriate (2.7, 1.6–4.3) and uncertain (1.3, 1.1–1.6) classification of CAG on Appropriate Use Criteria. Patients with heart failure as an indication of CAG (1.7, 1.4–2.0) and No NIT or positive low risk NIT (1.8, 1.5–2.2) were more likely to have NOC. Conclusion: Approximately one out of four patients undergoing elective CAG had NOC. Yield of diagnostic catheterization can be improved by adjudicating NIT especially in younger patients, women, patients with heart failure as an indication of CAG, patients classified as inappropriate on Appropriate Use Criteria and patients categorized as low or intermediate risk on MFRS.