A randomised, factorial trial to reduce arterial stiffness independently of blood pressure: proof of concept? The ‘VaSera’ trial testing dietary nitrate and spironolactone

Aim\ud To test if spironolactone or dietary nitrate from beetroot juice could reduce arterial stiffness as aortic pulse wave velocity (PWVart), a potential treatment target, independently of blood pressure. \ud Methods\ud Daily spironolactone (≤50mg) versus doxazosin (control ≤16mg) and 70mL beetroot juice (‘Beet-It’ ≤11mmol nitrate) versus nitrate-depleted juice (placebo; 0mmol nitrate) were tested in people at risk or with type-2 diabetes using a double-blind, 6-month factorial trial. Vascular indices (baseline, 12, 24 weeks) were cardiac-ankle vascular index (‘CAVI’), a nominally pressure-independent stiffness measure (primary outcome), pulse wave velocity (PWVart) secondary, central systolic pressure and augmentation. Analysis was intention-to-treat, adjusted for systolic pressure differences between trial arms.\ud Results \ud Spironolactone did not reduce stiffness, with evidence for reduced CAVI on doxazosin rather than spironolactone (mean difference [95% confidence intervals]; 0.25[-0.3, 0.5] units, p=0.080), firmer for PWVart (0.37[0.01, 0.7] ms-1, p=0.045). There was no difference in systolic pressure reduction between spironolactone and doxazosin (0.7[-4.8, 3.3]mmHg, p=0.7). Circulating nitrate and nitrite increased on active versus placebo juice, with central systolic pressure lowered -2.6[-4.5, - 0.8]mmHg, p=0.007 more on the active juice, but did not reduce CAVI, PWVart, nor peripheral pressure. \ud Change in nitrate and nitrite concentrations were 1.5-fold [1.1-2.2] and 2.2-fold [1.3, 3.6] higher on spironolactone than on doxazosin respectively; both p