Our results confirm that flosequinan improves exercise duration in patients with chronic heart failure. They suggest that this observed beneficial effect is independent of any change in large artery distensibility and that in the presence of ACE inhibitors, this improvement may be independent of any vasodilating action of flosequinan. Although this study confirms the beneficial symptommatic effects of flosequinan in chronic cardiac failure, clinical trials have subsequently demonstrated an overall increase in mortality in patients treated with 100 mg flosequinan daily. This has resulted in the withdrawl of flosequinan from routine clinical use.