INTERACT: Aggressive BP Lowering Reduces Hematoma Growth in ICH

Caroline Cassels

April 04, 2008

April 4, 2008 — Drastically lowering blood pressure after intracranial hemorrhage (ICH) reduces hematoma growth, is well tolerated, and could improve patient outcomes, a new pilot study suggests.

The Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage (INTERACT), a randomized trial of 404 ICH patients, found that intensive antihypertensive treatment resulted in a 22% greater reduction in hematoma volumes compared with recommended standard treatment.

"Because intravenous treatment to lower blood pressure is relatively straightforward, is not hazardous, and is of low cost, if applied widely these effects could translate into major absolute benefits," the authors write.

Published online April 5 in Lancet Neurology, the study was recently presented at the American Stroke Association International Stroke Conference in New Orleans and reported by Medscape Neurology & Neurosurgery at that time.

Considerable Uncertainty

Led by Craig Anderson MD, PhD, from the George Institute for International Health, in Sydney, Australia, the study's aim was to reduce the considerable uncertainty surrounding the effects of lowering elevated blood pressure after ICH by assessing the safety and efficacy of this intervention.

According to Dr. Anderson, hypertension is a cause of ICH and is also very common at the acute stage of illness. However, all of the guidelines for blood pressure control in acute stroke, including ICH, are based on nonrandomized, observational data. Therefore, doctors are uncertain of how to handle it.

The study included 404 patients who experienced spontaneous ICH and at trial entry had the diagnosis confirmed on computerized tomography (CT) within 6 hours of symptom onset.

Patients were randomly assigned to receive intensive blood pressure lowering based on a titrated protocol of routinely available intravenous agents to a target systolic blood pressure of 140 mm Hg or to a less intensive treatment targeted to a systolic blood pressure of 180 mm Hg, based on American Heart Association guidelines.

The study's primary end point was proportional change in hematoma volume at 24 hours. At 24 hours, investigators found hematoma growth in the intensive-treatment group was 13.7%, vs 36.3% in the nonintensive group.

Best Evidence To Date

Importantly, there were no differences between the 2 groups in numbers of adverse effects or in any of the secondary clinical outcomes, including death, disability, physical and mental functioning, or quality of life in survivors at 90 days.

The researchers note that these results support going forward with INTERACT2, a new trial that will determine the effects of intensive blood pressure lowering on clinical outcomes in 2800 patients with ICH.

In an accompanying editorial, Mustapha Ezzeddine, MD, from the University of Minnesota, in Minneapolis, says INTERACT "represents the best evidence to date of the safety of such an intervention."

Furthermore, he notes, while many questions — such as whether these results are generalizable to other stroke patients and how early and how long blood pressure needs to be controlled — remain unanswered. However, he said, results from INTERACT 2 will help resolve some of these questions and, most important, determine impact on patient outcomes.

The study was funded by the National Health and Medical Research Council of Australia.

Lancet Neurol. 2008; Published online April 5, 2008


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