XDH and idiopathic dilated cardiomyopathy: Administration of the xanthine oxidase inhibitors oxypurinol or allopurinol in patients with chronic heart failure, idiopathic dilated cardiomyopathy, or acute myocardial infarction has been shown to improve LV ejection fraction, myocardial efficiency, endothelial dysfunction, peripheral vasodilator capacity, and blood flow and to reduce plasma B-type natriuretic peptide levels and oxidative stress [37, 312–316].