Endogenous nitric oxide in patients with chronic heart failure (CHF): relation to functional impairment and nitrate-containing therapies.

We assessed the levels of exhaled nitric oxide (eNO) in patients with chronic heart failure (CHF) according to the functional impairment and the use of nitrate-containing agents. Forty patients (age 55+/-9 years) were classified according to the NYHA classes I-II (n=18, group 1) and classes III-IV (n=22, group 2), and to the use of nitrate-containing drugs (Nitrate+, Nitrate-). Twenty-two healthy age-related subjects served as controls (group 3). Respiratory function, symptom-limited incremental cycloergometry and resting eNO concentration at peak (FENOp) or plateau (FENOpl) of the single-breath exhalation curve were assessed in all subjects. FENOpl was significantly lower in patients than in controls (7.8+/-2.7 and 10.6+/-2.8 ppb, respectively, P<0.005) and lower in most severe CHF patients (7.1+/-2.6 and 8.8+/-2.7 ppb in group 2 and group 1, respectively, P<0.05). A significant correlation between peak V'O(2), Watts and FENOpl (r=0.42, P<0.013 and r=0.46, P=0.008, respectively) was found. Independent of NYHA class, Nitrate+ showed higher FENOp levels than Nitrate- patients (36.9+/-15.7 vs. 28. 1+/-15.1 ppb, P<0.05). Resting eNO was lower in the most compromised CHF patients and was significantly related to exercise capacity. Nitrate-containing agents might influence the levels of eNO in these patients.