Importance of Nonobstructive Coronary Artery Disease in the Prognosis of Patients With Heart Failure

OBJECTIVES: This study sought to examine the prognostic significance of nonobstructive coronary artery disease (CAD) in patients with heart failure (HF), as a distinct category apart from those with normal coronary arteries. BACKGROUND: Individuals with HF are often dichotomized into ischemic versus nonischemic categories according to the underlying etiology. This binary classification creates a heterogeneous group, combining individuals with nonobstructive CAD with those with normal coronary arteries under the nonischemic label. METHODS: A cohort of individuals with HF and reduced ejection fraction undergoing invasive coronary angiography was examined and linked to administrative databases for outcomes evaluation. Patients were divided into those with normal coronary arteries, nonobstructive disease, and obstructive disease. The primary outcome was the composite of cardiovascular death, nonfatal acute myocardial infarction, nonfatal stroke, or HF hospitalization. RESULTS: Of 12,814 individuals, 2,656 (20.7%) had normal coronary arteries, 2,254 (17.6%) had nonobstructive CAD, and 7,904 (61.7%) had obstructive CAD. The risk of the primary outcome was increased in the nonobstructive group (hazard ratio HR: 1.17; 95% confidence interval CI: 1.04 to 1.32; p = 0.01) relative to those with normal coronary arteries. Nonobstructive CAD was associated with an increased hazard of cardiovascular death (HR: 1.82; 95% CI: 1.27 to 2.62; p = 0.001) and death of any cause (HR: 1.18; 95% CI: 1.05 to 1.33; p = 0.005). There were no significant differences in the rate of acute myocardial infarction, stroke, or HF hospitalization. CONCLUSIONS: Among HF patients with reduced ejection fraction, the presence of nonobstructive CAD was independently associated with an increased hazard of the primary composite outcome and death of any cause.