Aims: Loop diuretics are essential for the treatment of chronic heart failure (CHF) but short-acting diuretics are reported to induce sympathetic nervous system (SNS) activation. This study was performed to compare therapeutic effects of two loop diuretics, long-acting azosemide and short-acting furosemide, using (123)I-metaiodobenzylguanidine ((123)I-MIBG) scintigraphy.
Methods and results: Twenty-two patients with New York Heart Association class II-III heart failure and left ventricular dysfunction, who required treatment with a loop diuretic, were included. In this crossover study, 11 patients were randomized to azosemide treatment first and the remaining 11 patients to furosemide. Treatments were administered for 6 months and then patients were crossed over to the second treatment. (123)I-MIBG scintigraphy was performed before and 6 months after the start of treatment with each loop diuretic. Early and delayed images were obtained 20 min and 4 h after administration of (123)I-MIBG, respectively; and the heart/mediastinum (H/M) ratio and washout rate (WR) were measured. In addition, left ventricular ejection fraction (LVEF), levels of brain natriuretic peptide (BNP), and norepinephrine were measured before and 6 months after the start of treatment. No differences were observed between the two groups in terms of concomitant medication, cause of heart failure, H/M ratio, WR, BNP, norepinephrine, or LVEF. The azosemide group exhibited a significant increase in delayed image H/M ratio, and a significant decrease in WR and norepinephrine after the final administration compared with the furosemide group.
Conclusion: This study indicates that azosemide suppresses SNS activation compared with furosemide in patients with CHF, suggesting that long-acting loop diuretics may have more beneficial effects on the prognosis of CHF.