Differences in the Occurrence of Carotid Transient Ischemic Attacks Associated With Antiplatelet Aggregation Therapy

Twenty-six of 117 consecutive patients with a provisional diagnosis of transient ischemic attacks answered the following criteria: (1) transient hypofunction of an area supplied by a branch of an internal carotid artery, (2) no evidence of infarction, (3) carotid and vertebral arterial systems visualized angiographically, (4) cerebral blood flow and metabolism studies performed, (5) followed a minimum of three months, (6) other causes of transient dysfunction had been ruled out, and (7) no carotid arterial system surgery. Only six (23%) had occlusion greater than 50% and 21 (81%) had evidence of irregularity or ulceration of an atherosclerotic plaque in the appropriate internal carotid artery. It was noted in retrospect that 15 of the patients were treated with aspirin (300 mg b.i.d.) and 11 were not. No difference in ultimate infarction or death was noted, but only two (13%) of those treated with aspirin had an additional attack compared to nine (82%) of those who had no aspirin. These findings suggest that fibrin-platelet emboli may be a major contributor to transient ischemic attacks in the carotid circulation. The authors stress that this is a retrospective study and its importance is to further support the need for prospective studies before antiplatelet aggregating drugs are used indiscriminately.