Stents in medicine Angioplasty

Atherosclerotic carotid stenosis is responsible for 10% of ischaemic strokes but until recently there has been uncertainty about the benefit of treating carotid stenosis. However, two randomised controlled trials, the North American Symptomatic Carotid Endarterectomy Trial (NASCET)l and the European Carotid Surgery Trial (ECST),' have now convincingly established the benefit of carotid endarterectomy in preventing strokes in symptomatic patients. Both trials showed that the very high rate of stroke in patients with recently symptomatic severe carotid stenosis of 70% or more treated medically was significantly reduced by surgery. However, surgery has disadvanges including the use of general anaesthesia, damage to cranial and superficial cutaneous nerves from the incision, and problems from the scar. Carotid percutaneous transluminal angioplasty (PTA) avoids these disadvantages, can be used to treat surgically inaccessible lesions, and involves a shorter hospital stay. Interest has therefore developed in using PTA, with or without stenting, in the carotid artery, although neither technique has gained general acceptance because of uncertainty about the risks and benefits. The main concern is that carotid PTA may result in a stroke at the time of the procedure.' 4 This may be caused by the guidewire or balloon catheter dislodging thrombus or a fragment ofthe atherosclerotic plaque, which embolises to the cerebral circulation. PTA also causes dissection which may occlude the vessel lumen, resulting in critical cerebral ischaemia, or promote thrombus formation and cerebral embolism.' 4Despite these risks, a number of centres in Europe and North America have excellent early results of carotid PTA, although there are very few data on long-term outcome. Data on carotid angioplasty, available from several series totalling over 500 patients, give a similar rate of procedure-related stroke or death during carotid PTA as found as a result of carotid surgery in NASCET and ECST. The mean stroke rate at the time of the procedure for all the published carotid PTA series together is 1.5% for minor or non-disabling stroke and 2.1% for major stroke or death, resulting in an overall rate of 3.6%.' Other potential complications of carotid PTA include groin haematoma and reaction to contrast used during the procedure. Another concern about carotid PTA is that re-stenosis may result in symptom recurrence which, in the case of embolic stroke could be catastrophic for the patient. Re-stenosis after peripheral and coronary PTA may be associated with significant symptoms. However, claudication and angina are primarily related to a reduction in flow, while cerebral ischaemia from carotid stenosis is usually thromboembolic. Re-stenosis after carotid PTA may remain asymptomatic if it produces a smooth vessel lumen and embolisation does not occur. Our current knowledge about the shortand long-term safety and efficacy of carotid PTA is limited by the lack of data from randomised controlled trials of carotid PTA versus carotid endarterectomy. The patients in the published series may have been highly selected with respect to degree of stenosis, eccentricity ofthe lesion, comorbidity from other pathology and so on, making it impossible to compare the low immediate complication rate of carotid PTA with surgery. There is no long-term follow-up of the efficacy of the procedure. The results from the only on-going trial, the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), in which the majority of patients have had simple angioplasty without stenting,6 should be available early in 1998. Until data from randomised trials are available, cerebrovascular PTA will remain an experimental procedure.