Predictors of coronary angiography in patients with idiopathic dilated cardiomyopathy: the Washington, DC Dilated Cardiomyopathy Study.

Although a number of clinical and demographic factors have been associated with the performance of angiography in cardiac patients, clinical studies of idiopathic dilated cardiomyopathy (DCM) have often excluded patients who have not undergone coronary angiography to rule out coronary artery disease (CAD). To examine the impact of this diagnostic criterion on population-based studies of idiopathic DCM, we examined characteristics of probable cases of DCM who did or did not have a recorded history of angiography. The cases (n = 129) were ascertained from five medical centers in the Washington, DC metropolitan area over the period 1 July 1990 through 29 February 1992. All of these cases had evidence of ventricular dilation and hypokinesis, with a left ventricular ejection fraction of less than 40%. Cases with a history of known CAD, congenital heart disease, valvular heart disease, or secondary cardiomyopathy were excluded. Sixty-two (48%) of the cases had a recorded history of angiography. Age, educational level, diabetes, alcohol use, insurance status, and type of hospital were significantly associated with angiography in bivariate analysis (p < 0.05). Diabetes and hypertension were inversely associated with history of angiography among black cases, and positively associated with angiography among whites. In logistic regression analysis, age was the strongest independent predictor of angiography (p < 0.025). The associations with educational attainment and alcohol use were of borderline significance (p < 0.10). Thus, in epidemiologic studies of idiopathic DCM, particularly in biracial populations, the exclusion of cases who have not undergone angiography may bias risk estimates and result in the underestimation of incidence and prevalence.