PET can determine stroke risk

Is carotid occlusion an independent predictor?

Investigators from Washington University in St. Louis, recently studied 81 patients who had suffered a stroke or a transient ischemic attack to determine whether a subgroup of people with carotid artery occlusion have an independent risk factor for suffering a subsequent stroke.1 Using positron emission tomography (PET), they measured which of the participants were in stage II hemodynamic failure, an indication that the brain is not receiving enough oxygenated blood to function normally. The ability to pinpoint those in hemodynamic failure allows researchers to determine who may most likely have carotid artery occlusion, which increases a person’s chances of having a stroke. A majority of people with occlusion may not know they have it because they do not experience symptoms.

The researchers found that of the 81 patients, 39 had stage II hemodynamic failure on one side of the brain and 42 did not. The researchers determined that subgroup of 39 was six times more likely to suffer an overall stroke and more than seven times more likely to suffer a stroke on one side of the brain than those who did not have stage II hemodynamic failure.

Following the patients for four years, the researchers found that stroke occurred in 12 out of 39 patients in the subgroup but only three out of 42 patients who were not. Eleven of 39 patients in the subgroup suffered stroke on one side of the brain while only two out of 42 not in the subgroup suffered a stroke on one side.

"Although this study establishes that stage II hemodynamic failure is a strong predictor of subsequent stroke in patients with symptomatic carotid occlusion, it cannot establish the mechanism for these subsequent strokes," the researchers write. "The demonstration of hemodynamic failure at baseline does not necessarily prove that all subsequent strokes are hemodynamically mediated."

An accompanying editorial states that the study provides potentially important information that may help reopen the previously closed door on surgical therapy for carotid artery occlusion.2

References

1. Grubb RL, Derdeyn CP, Fritsch SM, et al. Importance of hemodynamic factors in the prognosis of symptomatic carotid occlusion. JAMA 1998; 280:1,055-1,060.

2. Adams HP. Editorial: Reopening A Closed Door? JAMA 1998; 280:1093-1094.