Baroreflex sensitivity changes with calcium antagonist therapy in elderly subjects with isolated systolic hypertension

In order to study the effects of calcium-blocking therapy on cardiovascular homeostasis in elderly subjects with isolated systolic hypertension, we pe rformed a randomised double-blind placebo-controlled crossover study of 6 w eeks therapy with modified-release nifedipine or placebo. Changes with calc ium-blocker treatment in clinic and 24-h blood pressure (BP), heart rate, B P variability, baroreflex sensitivity (BRS) by three methods (Valsalva mano euvre, phenylephrine and sodium nitroprusside injection), and in baroreflex - and non-baroreflex-mediated reflexes (tilt and cold face stimulus) were s tudied in 14 elderly subjects (mean age [+/- SEM] 70 +/- 1 years) with sust ained isolated systolic hypertension (clinic BP 179 +/- 3/85 +/- 1 mm Hg). Clinic systolic BP, but not diastolic BP, was reduced with treatment (by 14 +/- 6 mm Hg, P = 0.03, diastolic BP 4 +/- 3 mm Hg, P = 0.16). Twenty-four hour BP was also reduced by nifedipine treatment (by 18 +/- 3/9 +/- 2 mm Hg , both P < 0.001). Clinic and 24-h heart rate, and daytime BP variability, were unchanged with treatment. BRS was significantly increased during nifed ipine therapy by all three measurement methods (all P < 0.05). With 60 degr ees tilt during active treatment, subjects exhibited a greater heart rate i ncrease (P < 0.01), and a reduced tall in systolic (P < 0.05) and diastolic BP (P < 0.05). Thus despite the arteriosclerosis and reductions in large a rtery compliance described in elderly patients with isolated systolic hyper tension, clinically important improvements in clinic and ambulatory BP and some aspects of cardiovascular homeostasis can be achieved with calcium-cha nnel blocking therapy.