Allopurinol in Patients With Refractory Angina to Improve Ischemic Symptoms

Inclusion Criteria: * Clinical diagnosis of stable angina in functional class (CCS) ≥ 2 for at least three months in patients taking maximally tolerated doses of at least three classes of antianginal agents * Documentation of myocardial ischemia by any provocative functional test (exercise test, stress echocardiogram, myocardial perfusion scintigraphy or cardiac resonance) * Signature of the Informed Consent Form Exclusion Criteria: * Left ventricular dysfunction defined by LVEF \< 30% on transthoracic echocardiogram * Significant concomitant valve disease * Chronic renal failure stage 4 or 5 (GFR \< 30mL/min/1.73m2 calculated by the MDRD equation * Significant liver dysfunction (Child-Pugh class C) or MELD value ≥ 15 calculated from creatinine, total bilirubin, and INR values * Current use of warfarin * Prior use of allopurinol within three months of randomization * Pregnant and lactating women