Ischemic preconditioning tested in stroke patients

By Eleanor McDermid, Senior medwireNews Reporter

Inducing repeated brief ischemia in the arms may reduce the rate of recurrent stroke in patients with symptomatic intracranial arterial stenosis, a small clinical study shows.

Recurrent stroke rates were just 5.0% after 90 days and 7.9% after 300 days of treatment, compared with 23.3% and 26.7%, respectively, in the control group, report Xunming Ji (Xuanwu Hospital, Beijing, China) and colleagues in Neurology.

Initially, 103 patients entered the study and were randomly assigned to active or control treatment. The device used was designed specifically for the study. It has two tourniquets, similar to blood pressure cuffs, which, once applied, inflate and deflate according to a preprogrammed schedule to induce five cycles of bilateral upper limb ischemia for 5 minutes followed by 5 minutes of reperfusion.

Patients used the device twice a day for 300 consecutive days. In the control group, the device did not induce ischemia, merely recorded heart rate and blood pressure. A total of 103 patients entered the study; however, 35 patients who underwent randomization were excluded, and the analysis was based on the 68 patients who completed treatment and had full follow-up data.

The exclusions were unlikely to affect outcomes, being mostly because the patients refused follow up with single-photon emission computed tomography (SPECT). However, editorialists Brad Zacharia (Columbia University Medical Center, New York, USA) and co-authors say that the researchers should still have performed an intention-to-treat analysis, as "the only way to maintain the statistical and theoretical benefits of randomization."

They say: "Taking these issues into account, it would be difficult to view these findings as broadly applicable without extensive external validation."

Zacharia et al also note that the researchers did not report the degree of stenosis in the two groups, pointing out that an imbalance between patients with more or less than 70% stenosis could have a large effect on the outcome.

Nevertheless, they say: "These results are promising and provide much-needed human data to support the efficacy of ischemic preconditioning in preventing recurrent stroke among patients with symptomatic intracranial arterial stenosis."

SPECT follow up showed improved cerebral perfusion in patients who underwent ischemic preconditioning. By day 90, 31.6% of these patients had improved perfusion relative to baseline, compared with 6.7% of the control group. In keeping with this, 65.8% of patients in the ischemic preconditioning group had achieved an excellent functional outcome by this point (modified Rankin Scale 0-1), compared with 13.3% of the control group.

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