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INTERACT: Antihypertensives slowed hematoma growth
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Patients who lowered their blood pressure substantially after having an acute intracerebral hemorrhage had reduced ongoing hemorrhage than patients who received less aggressive antihypertensive therapy.
Researchers in the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial (INTERACT) wrote that aggressive antihypertensive therapy showed short-term benefits on hematoma growth parameters without being associated with major hazard on safety or clinical outcomes over 90 days of follow-up. Craig Anderson, MD, PhD, professor of stroke medicine and clinical neuroscience at the University of Sydney, Australia, presented the results of the pilot phase of INTERACT at the International Stroke Conference in New Orleans.
Intensive treatment effective
Anderson and colleagues from various sites in Australia, Asia and the United States enrolled 404 patients with acute intracerebral stroke from 44 hospitals in China, Korea and Australia. Patients were enrolled in either an intensive antihypertensive treatment arm using a protocol for available intravenous agents or a less-intensive antihypertensive arm based on American Heart Association guidelines. The primary outcome was the proportional change in hematoma volume at 24 hours. The systolic BP target for the intensive treatment group was 140 mm Hg; for the less-intensive treatment group, 180 mm Hg.
Treatment was administered no longer than six hours after the acute hemorrhage. The researchers observed average diferences in systolic BP of 13.3 mm Hg (P<.0001) in the intensive group compared with the guideline treatment groups over the first hour after randomization. In addition, patients in the intensive treatment group had a mean proportional reduction in hematoma size of 22.6% (95% CI, 0.6-44.5%) compared with the guideline group. The frequency of major hematoma formation was also lower in the intensive treatment group by 36% (95% CI, 0-59). Researchers reported no serious adverse events or poor outcomes evidenced at 90 days in the intensive treatment group.
“The study results have shown that early rapid lowering of elevated BP in the setting of primary intracerebral hemorrhage is clinically feasible and not associated with excessive hazard with careful monitoring of the patient,” Anderson told Cardiology Today. “Further, the effects of the treatment appear to reduce the amount of ongoing bleeding in the brain, which may translate into a better outcome for the patient. At this stage, these data do not call for a change in clinical practice or an update of clinical guidelines.”
Anderson cautioned, however, that the study population was small and results are limited in applicability. The researchers are set to enroll 2,500 patients in the main phase of the INTERACT trial this year.
“The effects [of intensive antihypertensive therapy] are modest, and we were unable to detect a clear signal on clinical outcomes,” Anderson said. “Given that intravenous antihypertensives are cheap and widely available, small relative effects could translate into large, absolute benefits if it’s widely adopted. In order to test this, however, a large-scale clinical trial well powered to substantial endpoints is needed.” – by Eric Raible
It is no surprise that people with lower BP would have some benefit, because in the acute setting, the extent of the bleeding is related to some extent to the height of the BP. So that makes sense at least as an acute remedy. What is more important is that once we have dealt with the acute episode and the bleeding is stabilized, it is very important to make sure that BP is tightly controlled thereafter and also to obviously try to prevent further events from occurring.
– Michael Weber, MD
Cardiology Today Editorial Board member
For more information:
- Anderson C. INTERACT: Results of the vanguard pilot phase. Session XIII. Presented at: the International Stroke Conference; Feb. 20-22, 2008; New Orleans.