This study of patients undergoing emergent CT evaluation for symptoms of acute ischemic stroke shows that significant atherosclerotic disease in the carotid arteries does not predict significant atherosclerotic disease in the coronary arteries, vertebral arteries, or aorta. Moreover, our results indicate that, while non-significant atherosclerotic disease tends to be systemic, significant disease tends to be isolated to one of the four types of arteries we evaluated—the carotid arteries, coronary arteries, vertebral arteries, and aorta. When comparing significant disease in the carotid and coronary arteries, we found that 26 of our 79 patients (33%) had significant disease in their carotid, coronary, or both types of arteries. Eight of these 26 patients (30.7%) had significant disease isolated to their carotid arteries and 16 (61.5%) to their coronary arteries. Only 2 of these 26 patients (7.8%) had significant disease in both the carotid and coronary arteries. When evaluating for significant disease in all four types of arteries, we found that 26 of our 79 patients (33%) had significant disease in one type of artery, and only 7 of our 79 patients (9%) had significant disease in more than one type of artery.
These results have clinical implications. While the presence of significant carotid artery disease alone was not an adequate predictor of significant coronary artery disease in our population of patients undergoing emergent evaluation for suspected stroke, 18 of our 79 patients (23%) had significant coronary artery disease, and only 2 of these 18 (11%) had concomitant significant carotid artery disease. Therefore, it is important to image both the carotid and coronary arteries in patients with symptoms of acute stroke. But, these results also indicate that in a patient with significant carotid artery disease, extensive work-up for coronary disease may not be warranted.
The results of this study also have implications for expanding our knowledge of the pathogenesis of atherosclerosis. Atherosclerosis has been viewed as a systemic disease for a number of years.(37
) Our results indicate that while atherosclerosis is a diffuse process, it tends to be significant in one type of artery at a time. This suggests that the progression of atherosclerosis is not synchronous in all arteries but predominates in different arteries in different patients. Previous studies have also shown this propensity for atherosclerosis to be severe in one vascular bed while not in others.(37
) Further studies are required to determine why some patients tend to develop significant atherosclerosis in different arteries. Also, our study design was cross-sectional, and we cannot assess the evolution of time of the severity of atherosclerotic disease; we do not know whether patients with severe disease in one type of artery are more likely to develop severe disease in other arteries, or if severe disease would remain confined in the one type of artery.
There are limitations to the applicability of our results to other patient populations. Our study was conducted in a select group of patients undergoing emergent CT evaluation for suspected stroke. Because of their symptoms, such patients are more likely to have atherosclerotic disease compared to the general population. We felt that it would not be ethical to expose patients without symptoms to the radiation dose associated with our stroke CT protocol. On the other hand, we included all patients referred for a CTA independently on whether their final diagnosis was stroke/transient ischemic attack or not, in order to minimize the selection bias. It is likely that the overall prevalence of atherosclerotic disease would have been higher if we had considered only patients with a final diagnosis of stroke/transient ischemic attack.
Our study was also limited by its sample size; a large-scale study to confirm our results would be useful.
In conclusion, significant atherosclerotic disease in the carotid arteries does not predict significant disease in the coronary arteries, vertebral arteries, or aorta. Significant atherosclerotic disease is more often isolated to one type of artery. On the other hand, non-significant atherosclerotic disease tends to be a systemic process.