Antithrombotic Therapy for Cerebrovascular Disorders: Differential Diagnosis of Stroke

A large, multicenter stroke data bank project recently reported a 19% prevalence of cardioembolic stroke, based on carefully defined clinical criteria. The prevalence of presumed cardioembolic stroke varied between 13 and 34% at the 4 centers participating in this study, suggesting either patient population differences or intercenter variability in application of diagnostic criteria. Others have recently reported that 15% of carotid TIAs and 16-21% of consecutive strokes/TIAs are of cardioembolic origin. Among younger patients with ischemic stroke/TIA, 23-27% are presumed due to cardiogenic emboli. In aggregate, recent clinical studies continue to suggest that about 1 stroke in 6 is cardioembolic. This amounts to an estimated 80,000 strokes annually in the United States, with billions of dollars spent in acute care, rehabilitation, and long-term care. Cardioembolic strokes are, on average, associated with greater functional impairment and higher early absolute mortality (11-21%) than those due to cerebrovascular mechanisms. Here

The impact of cardioembolic brain ischemia both on individuals with heart disease and from a public health perspective is far from inconsequential.
Lack of validated, reliable clinical diagnostic criteria for cardioembolic stroke hampers individual patient management and challenges the accuracy of prevalence estimates. The likelihood of identifying a potential cardioembolic source for brain ischemia clearly depends on how thoroughly patients are evaluated and what lesions are accepted as potentially cardioembolic. In recent reports, about 30% (range, 22-39%) of patients with ischemic stroke/TIA will have a potential cardiac source of embolism, but about one third (range, 17-48%) of these patients will have concomitant cerebrovascular atherosclerosis that could also be responsible for brain ischemia. Bogouss-lavsky and colleagues performed cerebral arteriography in 50 TLA patients with a potential cardioembolic source and reported significant ipsilateral atherosclerosis in 19 (38%); minimal or no atherosclerosis was present in the remainder. Olsen et al studied 21 stroke patients who had either AF and/or AMI and found 4 (19%) with severe ipsilateral atherosclerosis, 3 (14%) with minimal atherosclerosis, and 15 (67%) with no atherosclerosis. Cerebral arteriography is reliable in diagnosing atherosclerosis for subocclusive lesions of larger arteries; cervical carotid occlusions are usually attributed to cerebrovascular atherosclerosis but can be due to occult cardiogenic embolism in up to 20% of cases. Clearly, the presence of a potential cardioembolic source alone does not establish the stroke mechanism.