The effect of transdermal glyceryl trinitrate, a nitric oxide donor, on blood pressure and platelet function in acute stroke

Background and Purpose: Hypertension is a common medical complication in ac ute stroke and is associated with a poor outcome. However, no large trials have assessed the effect of lowering blood pressure (BP) on outcome, and it remains unclear how BP should be managed in acute stroke. We assessed, in a double-blind randomised controlled trial, whether the nitric oxide (NO) d onor glyceryl trinitrate (GTN, a known systemic and cerebral vasodilator), would lower BP and alter platelet function. Methods: Thirty-seven patients with recent (<5 days) ischaemic or haemorrhagic stroke were randomised by m inimisation to 12 days of daily treatment with transdermal GTN or matching placebo patches. Twenty-four-hour ambulatory BP was measured before and dur ing GTN treatment at days 0, 1 and 8. Platelet aggregation and expression o f adhesion molecules were assessed at the same time points. Functional outc ome (Rankin scale) and case fatality were assessed at 3 months. Analysis wa s by intention-to-treat. Results: GTN significantly lowered BP by 13.0/5.2 mm Hg at day 1 and 9.3/5.0 mm Hg at day 8. The lesser reduction at day 8 th an day 1 suggests that tolerance to GTN was developing. Non-significant fal ls of 0.9/0.6 and 3.8/0.0 mm Hg occurred at days 1 and 8, respectively, in the placebo group. GTN had no effect on heart rate, or platelet aggregation or expression of platelet adhesion molecules, including glycoproteins la, lb, llla and P-selectin. Additionally, GTN did not alter case fatality or d ependency, although the study was not powered for these outcomes. Conclusio ns: Transdermal GTN, an NO donor, lowered BP by 5-8%, a clinically signific ant and relevant, but not excessive, degree in patients with acute stroke. However, GTN had no effect on platelet aggregation or expression of adhesio n molecules. Since NO donors increase cerebral blood flow in patients with acute ischaemic stroke, GTN may be an appropriate drug for testing the effe ct of lowering BP on functional outcome. Copyright (C) 2001 S. Karger AG, B asel.