Non-obstructive coronary artery disease (NOCAD) is a common finding on coronary angiography. Our goal was to evaluate the long-term prognosis of NOCAD patients with stable angina (SA).
The study cohort consisted of 7478 NOCAD patients with normal EF (≥ 50%), and SA who underwent coronary angiography between 1995 and 2012. We compared NOCAD patients (stenosis< 50%) with 10,906 patients with stable obstructive CAD (≥ 50%). The primary endpoint was all-cause mortality. Secondary endpoints included repeat angiography, progressive CAD, and PCI. A second comparison group consisted of 7344 patients with NOCAD presenting with an ACS. Rates of all-cause mortality of NOCAD ACS patients were compared to NOCAD SA patients.
Median follow-up time was 6.5 years. NOCAD patients had a lower risk of all-cause mortality compared to CAD patients (HR CAD vs. NOCAD 1.33 (1.19-1.49); p < 0.001). This was driven by patients with normal coronary arteries (HR CAD vs. normal 1.63 (1.36-1.94), p < 0.001), whereas patients with minimal disease (> 0% and < 50%) were at similar risk as CAD patients (HR CAD vs. minimal 1.08 (0.99-1.29), p = 0.06). In NOCAD patients, the strongest predictors of all-cause mortality were age and minimal disease. SA patients with NOCAD had low rates of repeat angiography (7.3%), future CAD (2.3%) and PCI (1.7%). NOCAD ACS patients had a 41% increase in all-cause mortality risk compared to NOCAD SA patients (HR 1.41 (1.25-1.6), p < 0.001).
This study underlines the importance of minimal CAD, as it is not a benign disease entity and portends a similar risk as stable obstructive CAD.