BACKGROUND:
Efficacy of xanthine oxidase inhibitors on the improvement of cardiac performance is not clearly defined. This study was designed to study the efficacy of allopurinol on the improvement of left ventricular ejection fraction (LVEF) in patients with chronic heart failure.

METHODS:
A randomized, double blind, placebo controlled clinical trial was performed on two groups of patients suffered from class II to III heart failure of New York Heart Association classification. 16 cases were in intervention group who intake allopurinol (100 mg/day in the first three days, 200 mg/day in the second three days and 300 mg/day for one month); 15 cases were in control group and intaked placebo like case group. Left ventricular ejection fraction was measured by echocardiography with Simpson's method and compared before and after the intervention.

FINDINGS:
The mean of LVEF before and after intervention, in case group were 38.8±9.9 and 41.9±9.7 respectively (p<0.05); and in control group were 37.05±5.7 and 37.1±5.6 respectively (p>0.05). In intervention group EF was increased 3.1% from base level.

CONCLUSION:
Allopurinol can be effective in improvement of cardiac performance. However its clinical use for heart failure patients needs to be approved by more trials, in various situations and longer periods.

KEY WORDS:
Heart failure, left ventricular ejection fraction, xanthine oxidase inhibitors, allopurinol, clinical trial.