Prevalence and Angiographic Severity of Obstructive Coronary Artery Disease in Patients Presenting with a Dilated Cardiomyopathy Phenotype: A Retrospective Single-Center Cohort Study

Background and Objectives: Identification of obstructive coronary artery disease (CAD) in patients presenting with a dilated cardiomyopathy phenotype is clinically important because it may influence etiologic classification, prognosis, and subsequent management. However, real-world angiography-based data on the prevalence and angiographic severity of obstructive CAD in this setting remain limited, particularly in regional single-center cohorts. Materials and Methods: This retrospective single-center cohort study included consecutive patients presenting with a newly diagnosed dilated cardiomyopathy (DCM) phenotype of initially unknown etiology who underwent first-time diagnostic invasive coronary angiography at St. Marina University Hospital, Varna, Bulgaria, between January 2010 and December 2025. Obstructive CAD was defined as stenosis >70% in a major epicardial coronary artery with a reference vessel diameter >2.5 mm. Patients were categorized as having non-obstructive or no significant coronary stenoses, single-vessel disease, two-vessel disease, or three-vessel disease. Additional descriptive analysis assessed severe occlusive coronary lesions, defined as chronic total occlusions or subtotal stenoses. The primary endpoint was the prevalence of obstructive CAD. Secondary analyses included angiographic disease extent, vessel-level coronary involvement, severe occlusive lesions, and coronary revascularization. Results: A total of 107 patients were included. Mean age was 55.4 ± 10.9 years, and 97 patients (90.7%) were male. Obstructive CAD was identified in 19 patients (17.8%; 95% confidence interval [CI], 11.7–26.1%), whereas 88 patients (82.2%) had non-obstructive or no significant coronary stenoses. Among patients with obstructive CAD, 3 (15.8%) had single-vessel disease, 4 (21.1%) had two-vessel disease, and 12 (63.2%) had three-vessel disease. Severe occlusive coronary lesions were present in 10 of 19 patients (52.6%); 8 (42.1%) had at least one chronic total occlusion and 5 (26.3%) had at least one subtotal stenosis. Conclusions: In this retrospective single-center cohort of patients presenting with a dilated cardiomyopathy phenotype and referred for coronary angiography, obstructive CAD was present in fewer than one in five patients. In contrast, most had non-obstructive or no significant epicardial coronary stenoses. However, when obstructive CAD was present, three-vessel disease and severe occlusive lesions were frequent. These findings indicate that obstructive epicardial CAD was uncommon in this selected angiography-referred cohort while underscoring the clinical role of coronary angiography when an ischemic or mixed etiology is clinically suspected.