Future prognostic models of clinical outcomes following ischemic stroke should consider reperfusion in addition to recanalization, as the time to maximum reperfusion index had the highest accuracy for predicting a good outcome, according to a study published online May 28 in Radiology.

“This study emphasized the importance of reperfusion over recanalization for prediction of clinical and imaging outcomes in ischemic stroke,” wrote Armin Eilaghi, PhD, of University of Western Ontario, London, Ontario, Canada, and colleagues.

Recanalization and reperfusion have been shown to be strongly associated with imaging and clinical stroke outcomes, explained the authors. However, recanalization may not result in reperfusion due to arterial reocclusion or distal thrombus embolization, they noted. Previous studies have suggested reperfusion status has superior predictive value over clinical time and radiologic parameters.

To assess a predictive model including reperfusion indices, Eilaghi and colleagues conducted baseline CT perfusion less than 4.5 hours after stroke symptoms, follow-up CT perfusion within 24 hours and five-to-seven day MRI exams in 114 patients. Recanalization status was determined at follow-up CT angiography.

Results showed that reperfusion indices were significantly higher in patients with recanalization than in those without, and reperfusion, defined as restoration of time to maximum volume of 59 percent or greater, is strongly associated with good clinical outcome on the 90-day modified Rankin scale with an odds ratio of 18.771. “Recanalization was not significantly associated with outcome on multivariate analysis, whereas reperfusion index, baseline [National Institutes of Health Stroke Scale], and age remained significant,” wrote Eilaghi and colleagues.

Time to maximum reperfusion index had the high accuracy for good outcomes, with an area under the receiver operating characteristic curve of 0.70, according to the authors.

The authors also reported that, among those with recanalization, patients with positive reperfusion status had higher salvaged penumbra and lower total infarct volume and infarct growth.

“Our results strengthened the assertion that reperfusion provides tissue-level information rather than gross vessel level occlusion status, which ignores the effect of supporting collaterals and the effects of interstitial pressure on perfusion,” wrote Eilaghi and colleagues. “Importantly, we demonstrated that recanalization occurred without reperfusion, which highlighted the need to consider both recanalization and reperfusion.”