PTA for Intracranial Atherosclerotic Stenoses
abstract & commentary
Sources: Marks MP, et al. Outcome of angioplasty for atherosclerotic intracranial stenosis. Stroke 1999;30:1065-1069.
Percutaneous transluminal angioplasty (pta) has been used widely and successfully to treat atherosclerotic stenoses in the coronary and peripheral circulations, but has been used only in a limited fashion in the extra- and intracranial cerebrovascular circulation. PTA has not been popular in the cerebral circulation because of concerns about arterial rupture and distal embolization.
Marks and colleagues evaluated efficacy and long-term outcome of PTA treating symptomatic intracranial atherosclerotic stenoses. They reviewed all intracranial PTAs performed at Stanford University Medical Center during a five-year period from 1992-1997. Included were 23 patients with fixed symptomatic intracranial stenoses treated solely by elective PTA. Thirty patients who underwent intracranial PTA for etiologies other than atherosclerosis, such as vasospasm or in the setting of acute stroke, were excluded, as were patients with tandem extracranial and intracranial disease who underwent PTA at both sites.
The 20 men and three women in the treatment group were aged 31-84 years (mean age = 62 years). Thirteen patients had lesions in the posterior circulation (8 vertebral artery, 4 basilar artery, and 1 posterior cerebral artery). In all but one patient who had a small, tortuous basilar artery, the stenotic lesion was crossed with an angioplasty balloon. An additional patient suffered fatal rupture of the middle cerebral artery at the time of angioplasty. In the remaining 21 patients (91%), PTA resulted in an improvement in stenosis: mean estimated stenosis before PTA was 91.5% (range, 60-95%), immediately after PTA mean stenosis fell to 40.5% (range, 0-75%) in 22 patients. In one patient, thrombosis at the site of internal carotid angioplasty occurred one hour after PTA but was successfully treated with intra-arterial tPA and the patient suffered no neurological sequelae.
The 21 patients who had successful angioplasties were followed for 16-74 months (mean, 35 months). Two deaths unrelated to cerebrovascular disease occurred in the follow-up group. There were two strokes in a territory appropriate to the angioplasty and three strokes overall in the series, therefore, the annual stroke rate was 3.2% in the territory of the angioplasty and 4.8% for all strokes. Marks et al conclude that although intracranial angioplasty can be performed with a high degree of technical success, it is still a high-risk procedure that in general should be reserved for patients who continue to be symptomatic despite appropriate medical therapy.
Commentary
The stated purpose of this retrospective study was to report on the clinical outcome and follow-up stroke rate after PTA for intracranial stenosis. Marks et al could not establish the long-term potency rates for the various intracranial sites of angioplasty, since none of their patients had repeat imaging studies of the cerebral circulation carried out. No doubt in the future, prospective studies of patients after PTA using MR angiography and transcranial Doppler techniques will supply this important information.
Marks et al also did not compare the annual stroke rate of their post-PTA patients with that of a control group treated with the best medical therapy; therefore, the natural history of intracranial stenotic lesions must be derived from the control groups of other studies. In the EC/IC Bypass Study (EC/IC Bypass Study Group. N Engl J Med 1985;313:1191-1200; Bogousslavsky J, et al. Stroke 1986;17:1112-1120) nonsurgically treated patients with atherosclerotic stenoses in the intracranial internal carotid or middle cerebral arteries had an annual stroke rate of 8-10% in those vascular territories. Patients in the WASID study (WASID Study Group. Stroke 1998;29:1389-1392) with posterior circulation intracranial stenoses treated with medical therapy had annual stroke rates in the same territory of the stenotic artery that were 8% for the vertebral artery and 11% for the basilar artery. Therefore, the approximately 3% per annum stroke rate in the territory of the artery of angioplasty in the present series compares favorably with those data.
Now that angioplasty of intracranial arteries can be performed with a high degree of technical success, the need for a controlled, randomized study to compare its efficacy with that of medical therapy alone is obvious. —jjc
The annual stroke rate for patients with basilar stenosis treated medically is approximately:
a. 3%.
b. 5%.
c. 10%.
d. 15%.
e. 25%.
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