RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY OF SUPPLEMENTAL ORAL L-ARGININE IN PATIENTS WITH HEART-FAILURE

Background Patients with heart failure have reduced peripheral blood f low at rest, during exercise, and in response to endothelium-dependent vasodilators. Nitric oxide formed from L-arginine metabolism in endot helial cells contributes to regu lation of blood flow under these cond itions. A randomized, double-blind crossover study design was used to determine whether supplemental oral L-arginine can augment peripheral blood flow and improve functional status in patients with moderate to severe heart failure. Methods and Results Fifteen subjects were given 6 weeks of oral L-arginine hydrochloride (5.6 to 12.6 g/d) and 6 weeks of matched placebo capsules in random sequence. Compared with placebo , supplemental oral L-arginine significantly increased forearm blood f low during forearm exercise, on average from 5.1 +/- 2.8 to 6.6 +/- 3. 4 mL . min(-1). dL(-1) (P<.05). Furthermore, functional status was sig nificantly better on L-arginine compared with placebo, as indicated by increased distances during a 6-minute walk test (390 +/- 91 versus 42 2 +/- 86 m, P<.05) and lower scores on the Living With Heart Failure q uestionnaire (55 +/- 28 versus 42 +/- 26, P<.05). Oral L-arginine also improved arterial compliance from 1.99 +/- 0.38 to 2.36 +/- 0.30 mL/m m Hg (P<.001) and reduced circulating levels of endothelin from 1.9 +/ - 1.1 to 1.5 +/- 1.1 pmol/L (P<.05). Conclusions Supplemental oral L-a rginine had beneficial effects in patients with heart failure. Further studies are needed to confirm the therapeutic potential of supplement al oral L-arginine and to identify mechanisms of action in patients wi th heart failure.