The Cervical Artery Dissection in Stroke Study (CADISS-NR) trial concluded that there was no difference in secondary stroke prevention provided by antiplatelet and anticoagulant agents in patients with carotid or vertebral artery dissections.¹ It is important to note that the mean time of treatment after symptom onset was 10.8 days (SD 7.0, range 1–31 days) in this study.

Extensive published data^2,3 and my personal experience show that most strokes develop within the first 7 days after brain ischemia and the rate of stroke thereafter is very low. In addition, strokes are uncommon in patients whose presentation does not include brain ischemia (neck pain, Horner syndrome, compression of nerve roots, or lower cranial nerves). These patients were included in the trial. In CADISS-NR, only 2 patients had strokes within 3 months.

In the meta-analysis included in the report, almost all of the patients were enrolled beyond 5 days after onset. Physicians must not take the results of this trial and the meta-analysis to conclude anything about treatment during the very acute period after brain symptom onset. This time period was not a part of the trial or the meta-analysis. When brain infarction develops in the acute stage, it is almost always explained by embolism of red erythrocyte-fibrin thromboemboli.⁴ This pathogenesis would predict that acute anticoagulation would be more effective than antiplatelets during the first week and experience has shown that acute anticoagulation is effective.⁵

Author Response

Dr. Caplan raises an important point: Some studies suggest that the risk of recurrent stroke in patients with cervical dissection is highest in the first few days after initial clinical symptoms. For this reason, the ongoing randomized arm of CADISS is recruiting patients within 7 days of symptom onset. The nonrandomized arm, the results of which are included in our current report, included patients who were ineligible for the randomized arm. Fifty-three of the 88 patients were included in the nonrandomized—rather than the randomized—arm because they were recruited later than 7 days after first symptoms. However, even in the remaining 35 (with some recruited on the first day after presentation), the risk of recurrent stroke was not high.

Convincing arguments can be made as to whether anticoagulants or antiplatelets may be more effective in preventing recurrent stroke in cervical dissection. However, whether anticoagulants or antiplatelets will be more effective during the acute phase can only be answered by randomized trials such as CADISS.