Oral vitamin C improves carotid baroreflex sensitivity in chronic heart failure

Baroreflex sensitivity (BRS) is reduced in chronic heart failure (CHF) and is associated with an adverse prognosis. Oxidative stress may be implicated via reduced arterial compliance and/or direct effects on bare-receptor nerve endings. We investigated the effects on baroreflex sensitivity of treatment with the antioxidant vitamin C in CHF. 10 patients with CHF were studied. Integrated BRS was measured using spontaneous sequence analysis of a 10 minute recording of blood pressure and ECG, and arterial BRS evaluated using a carotid neck collar. BRS was recorded at baseline, 1 month after treatment with oral vitamin C 2g bd, and in a subset of 5 patients repeated 6 weeks after stopping treatment. Baseline BRS was measured in 10 age-matched controls for comparison. Both spontaneous and carotid BRS were significantly reduced in the patients compared to the controls (7.3±3.0 vs 13.3±5.2 ms/mmHg, p=0.005, and 0.9±0.6 vs 2.9±2.1 ms/mmHg, p=0.01 respectively). After treatment with vitamin C there was a significant improvement in carotid BRS (0.9±0.6 to 1.7±1.1, p=0.04) but no change in spontaneous BRS (7.3±3.0 to 7.8±3.3, p=0.54). In the subgroup re-evaluated after discontinuing treatment, carotid BRS deteriorated (1.7±0.8 to 1.1±0.7, p=0.02), but spontaneous BRS remained unchanged (8.5±4.9 to 10.1±8.8. p=0.68). Treatment with the antioxidant vitamin C results in an improvement in carotid arterial baroreflex sensitivity in patients with CHF which is reversed 6 weeks after stopping therapy. There is no effect on integrated BRS assessed by spontaneous sequence analysis.