Clinical Briefs

Hypertension and the Risk of Thrombolytic Therapy

Source: Aylward PE, et al. Ann Intern Med 1996; 125:891-900.

Small studies have suggested that the risk of intracerebral hemorrhage is greater with t-PA than it is with streptokinase in acute MI patients with elevated blood pressure. Thus, Aylward et al assessed the GUSTO-1 database of 41,000 acute MI patients to determine the effect of previous hypertension and elevated blood pressure at study entry on the outcomes of thrombolytic therapy with ateplase and streptokinase. Prior cerebral vascular events, but not hypertension, were excludsion criteria. If the patients initial blood pressure was greater than 200/100 mmHg the treating physician could lower it before giving thrombolytic therapy. Less than 1% of subjects had systolic BPs greater than 200, and less than 10% had diastolic pressures greater than 100. The rate of stroke and intracerebral hemorrhage increased as systolic BP increased, being 3.4% at more than 175 mmHg vs. 1.2% at less than 124 mmHg. Ateplase increased the total stroke rate vs. streptokinase (3.6% vs 3.0%) in patients with systolic BP over 175, but mortality was reduced (4.3% vs 7.8% at 30 days) as was disabling stroke plus death (4.9% vs 8.9%). In low-risk patients with SBP greater than 175 (class I, no prior MI) mortality was low (4.3%) as was total stroke (4.1%). History of hypertension increased the risk of all complications of MI, but there was not a differential effect of the two thrombolytic agents. Thus, a history of hypertension should not influence the decision to use thrombolytics in acute MI. Higher entry SBPs decreased the risk of death but increased the risk of stroke. The increased stroke risk was markedly higher in patients with SBP over 175 who received ateplase, but the combined end point of death and disabling stroke was lower than with streptokinase. Although these data would favor ateplase vs. streptokinase regardless of entry SBP, in a small subgroup (2% of this study) at low-risk of death, with high SBP at entry, the risk of stroke with ateplase may outweigh the small survival benefit. This study did not address the issues of the role of initial treatment of high BP, nor the advisability of primary angioplasty in such patients.—mhc