The benefits of fixed-dose combination isosorbide dinitrate plus hydralazine (ID/H) in African-Americans with heart failure (HF) were established by the African-American Heart Failure Trial (A-HeFT), which was terminated early because of a significant survival benefit of ID/H. The Extension to A-HeFT trial (X-A-HeFT), designed to make ID/H available for ethical reasons after A-HeFT termination, afforded an opportunity to further observe responsiveness and compliance with ID/H. In total 198 patients completing the A-HeFT took ID/H for an additional 209 +/- 116 days. Their age (57 +/- 13 years), cause and duration of HF, and HF medications were not different from all A-HeFT patients. New York Heart Association class at X-A-HeFT baseline was > or =III in 51% of patients versus 100% of all patients at A-HeFT baseline, remained unchanged in most patients, improved in 24%, and worsened in only 9% during X-A-HeFT. The average number of ID/H tablets taken during X-A-HeFT was 3.7 +/- 1.8 per day with compliance averaging 87 +/- 25%. The most common adverse events, headache (34%) and dizziness (16%), were less than in patients taking ID/H in A-HeFT, with only 6% discontinuations for adverse events. The 6% annualized mortality rate in X-A-HeFT was the same as for ID/H in A-HeFT. There were no statistically significant differences in baseline characteristics or outcomes in X-A-HeFT patients analyzed according to their A-HeFT randomization. In conclusion, these results confirm the good compliance, tolerability, and responsiveness, with low mortality and improved symptoms, during treatment with ID/H observed in A-HeFT.