Bahar M. Beaver, MD
Patients with ischemic stroke or transient ischemic attack (TIA) due to intracranial atherosclerosis often have disease in other vascular territories within the body. As neurologists, we prescribe secondary preventive agents for these patients following a stroke, in hopes of decreasing their risk for future vascular events. In this article, Mirjam Heldner et al. set out to better delineate the relationship between atherosclerosis in other vascular beds and the intracerebral vasculature and how the number of vascular territories effected impacts patients’ overall risk of recurrent vascular events.
In a population-based study, the authors sampled patients from a pool of 92,728 patients in Oxfordshire, United Kingdom (part of the OXVASC study) who had a stroke or TIA from 2000 to 2014. The authors investigated patients who had symptomatic disease in their coronary and/or peripheral vasculature in addition to their stroke/TIA. Additionally, they compared atherosclerotic risk factors (hypertension, hypercholesterolemia, diabetes, smoking) among patients and correlated these with the severity of systemic vascular disease. These patients underwent thorough clinical evaluation and were followed up at 1, 6, 12, 60, and 120 months for identification of any further vascular events. Statistical analysis compared the number of atherosclerotic risk factors to the number of vascular territories affected, as well as the rate of recurrence or prevalence of symptomatic vascular disease.
Out of 2,554 patients with either ischemic stroke or TIA, 72.1% had single-territory disease, 23.8% had double-territory disease, and 4.1% had triple-territory disease. The authors found that those with the highest number of atherosclerotic risk factors were more likely to have disease in multiple vascular beds — with double-territory disease having more risk factors than single-territory disease, and triple-territory disease having more risk factors than double-territory disease and single-territory disease. Of all the risk factors mentioned above, triple-territory disease was more strongly associated with hypercholesterolemia. Though patients who had double- or triple-territory disease were more likely to be on intensive secondary prevention agents (antiplatelets, statins, antihypertensives, etc.), the authors found that these patients remained at higher risk for further vascular events regardless of their preventive treatment. Interestingly, patients with stroke/TIA plus peripheral vascular disease had a higher risk for future events than those with stroke/TIA and coronary artery disease. Furthermore, those with triple-territory disease had higher risk of recurrent ischemic stroke.
In this study, Heldner et al. demonstrate that although physicians tend to focus on controlling individual risk factors for patients with vascular disease, it is actually the number of effected territories that better correlate with risk of recurrent vascular events, rather than the individual atherosclerotic risk factors themselves. Though we have a strong foundation of literature on the various contributing factors to systemic atherosclerosis, there is yet work to be done regarding effective preventive measures. The authors of this study propose that perhaps we need to adjust our secondary prevention guidelines to address the number of vascular territories with symptomatic atherosclerosis in each individual patient.
For the time being, however, we will continue to use the current secondary prevention guidelines for cholesterol, blood pressure, blood glucose, and smoking, until we have more concrete information on how systemic atherosclerosis can be better managed.
