Stenting versus surgery-lessons from the heart to the brain
Atherosclerosis, or clogging up arteries, causes more deaths and more suffering than any other cause worldwide, most commonly in the form of heart attacks and strokes. Blocking of coronary arteries in the heart causes a spectrum of disease from angina to heart attacks, while blockages in cerebral arteries in the brain cause mini-strokes (transient ischaemic attacks or TIAs) and strokes. How best to prevent further strokes and heart attacks (secondary prevention) has occupied medical research for 40 years. There are similarities in the disease process and treatment strategies and lessons from the heart are proving useful in the brain.
Thrombolysis uses clot-busting drugs very soon after the heart attack or stroke to reduce the risk of further events. In both heart attacks and strokes, this treatment is now well-established as long as it is delivered within the narrow time window (12 hours for heart attacks and 4.5 hours for stroke). Evidence from randomised trials was 7 years later in the case of stroke, compared with heart attacks, and the data from meta-analysis has been even slower .
In both heart and brain, surgery is possible to remove or bypass the area of the blood vessel that is worst affected by atherosclerosis.
Coronary artery bypass surgery (CABG) uses a strip of vein or artery to bypass the section of narrowed vessel. An alternative strategy is to insert “stents” to keep the narrowed section patent and allow blood flow. Coronary stents have been adopted across the world for the last 20 years, at the expense of CABG for several reasons, including patient preference, shorter hospital stay, physician preference and stent-company lobbying. Meta-analysis has shown that in the case of multi-vessel disease, CABG is at least as good as stenting, and perhaps even better. Stents had been widely adopted despite inadequate long-term follow-up data, and despite inadequate trial data.
It was not long before stents started to be used in the arteries to the brain as well. However, it seems that the same caution needs to be used with stents in the brain circulation as in the heart. A recent randomised controlled trial of carotid endarterectomy (stripping away the clot from the wall of the artery) versus carotid stents in 1700 patients, concluded that carotid endarterectomy should remain the treatment of choice for patients suitable for surgery. Another analysis from the same trial showed that new lesions on MRI scan (suggesting stroke) were 3 times more likely after carotid stent versus carotid surgery. Data presented at the American Stroke Association last week from a similar North American trial suggests that the two treatments are near equal. Until proper long-term trial data and proper consensus is reached, let us hope that carotid stents are not rolled out with the same zeal as coronary stents.