Vitamin C improves baroreflex sensitivity in chronic heart failure but has no effect on arterial stiffness

Background: Baroreflex sensitivity (BRS) is impaired in patients with chronic heart failure (CHF) and is a strong predictor of cardiac death. We hypothesised that vitamin C (VC) would acutely improve BRS in CHF patients by reducing arterial stiffness. Methods: 38 CHF patients were studied. 20mls of saline was injected into a venous cannula and baseline measurements of BRS and arterial stiffness performed. 30 mins later subjects were randomised to either 2g VC (20mls) or 20mls saline intravenously. Repeat measurements were performed. BRS was assessed from the ECG and blood pressure (Finapres) using spontaneous sequence analysis. Arterial stiffness was measured using the SphygmoCor (PWV Medical) system to give augmentation index (AIx). Results: Data expressed as mean ±SEM. Both groups had similar baseline BRS (8.6 ± 1.9 v 8.1 ± 0.6 ms/mmHg) and AIx (17.6 ± 2.8 v 13.0 ± 6.8%). BRS significantly improved in those who received VC compared to saline (Δ BRS 2.0 ± 0.7 v -0.5 ± 0.9 ms/mmHg; p=0.04). There was no significant change in AIx from baseline in either group (Δ AIx 2.9 ± 0.6 v 1.6 ± 1.2%; p=0.9). Conclusion: We show a significant improvement in BRS after an intravenous bolus of VC in CHF patients. VC has been shown to improve endothelial function both acutely and chronically in CHF. Despite this we did not demonstrate any measurable change in arterial stiffness. It is possible that VC has its beneficial effect through a direct action of a reduction of free radicals on baroreceptor nerve endings. This result raises the possibility of a novel therapy to reduce cardiac death in CHF.