Increased risk for sICH
In all, 628 patients were included in the study. The ASA groups included 310 patients, and the no-ASA groups included 318 patients. In all, 332 participants received heparin, and 296 received no heparin.
The demographic characteristics were well balanced between groups. The population’s median age was 73 years, and about 53% were men. The median baseline NIHSS score was approximately 15. About 74% of patients received IV thrombolysis. The median baseline Alberta Stroke Program Early CT Scan score was 9.
The investigators observed a slight shift toward worse outcome in the ASA group, compared with the no-ASA group (adjusted OR, 0.91). In addition, the ASA group had a significantly increased risk for sICH, compared with the no-ASA group (14% vs. 7.2%; aOR, 1.95).
Patients in the ASA group were less likely to have good functional outcome (mRS of 0 to 2; aOR, 0.76), and the mortality rate tended to be higher.
The researchers found a nonsignificant shift toward a worse functional outcome in the heparin group, compared with the no-heparin group (aOR, 0.81). The risk for sICH was significantly higher in the heparin group, compared with the no-heparin group (13% vs. 7.4%; aOR, 2.00).
Patients in the heparin group were also less likely to have a good functional outcome (aOR, 0.78), and there was a nonsignificant increase in risk for death among those patients.
The rate of sICH was 11% in the group that received low-dose heparin; it was 26% in the group that received moderate-dose heparin (aOR, 6.05). The mortality rate was 23% in the low-dose group and 47% in the moderate-dose group (aOR, 5.45).
There was no significant interaction between ASA and heparin on the primary outcome and on sICH occurrence.
‘A unique trial’
“MR CLEAN-MED is a unique trial because it investigated a widely used treatment but until now without any proof of effectiveness,” said Dr. van der Steen. The researchers expect that their findings will have a strong impact on the management of patients with acute ischemic stroke. They suggest that the administration of antithrombotic agents during EVT be avoided.
“We consider it probable that the increased risk of sICH explains at least a part of the nonsignificant shift towards a worse functional outcome,” co-investigator Bob Roozenbeek, MD, PhD, a neurologist at the Erasmus Medical Center, said in an interview. “However, to make more definite statements, we will have to do more in-depth analyses.”
It remains unclear whether the periprocedural use of lower dosages of antithrombotic agents or of a single bolus of heparin could be safe and effective, said Dr. van der Steen.
To gain insight into these questions, the investigators will evaluate the effect of the medications and dosages examined in this trial on primary hemostasis and coagulation activity in the trial population. They also plan to examine the effect of primary hemostasis and coagulation activity on risk for sICH and functional outcome.
Enhancing the effectiveness of thrombectomy for acute ischemic stroke continues to be an important goal for stroke therapy, said Mark Fisher, MD, professor of neurology and pathology and laboratory medicine at the University of California, Irvine, who commented on the findings for this news organization.
At least three strategies are available: The use of ancillary antithrombotic medications, neuroprotection, and modulation of the vasoconstrictive properties of the microcirculation.
“Results of MR CLEAN-MED argue against the antithrombotic strategy,” said Dr. Fisher. “The alternate strategies remain viable, and results of interventions using those approaches are awaited with great interest.”
The study was funded by the CONTRAST consortium, which is supported by the Netherlands Cardiovascular Research Initiative and the Brain Foundation Netherlands. Funding also was provided by Stryker, Medtronic, and Cerenovus. Dr. van der Steen and Dr. Fisher have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.