Progression of internal carotid artery stenosis in patients with peripheral arterial occlusive disease
Received 20 September 2008; accepted 24 February 2009.
Objectives
To study the risk factors and rate of progression of asymptomatic carotid stenosis in patients with peripheral arterial occlusive disease.
Methods
Between July 1999 and September 2003, we studied consecutive patients referred to a vascular laboratory for peripheral arterial occlusive disease who had not experienced neurologic symptoms within the previous 3 years. Carotid duplex ultrasound scan (DUS) was performed at baseline and at 6 to 12-month intervals. The internal carotid artery peak systolic velocity (PSV) was used to determine severity of carotid stenosis. Multilevel linear regression modeling (MLM) was used to identify the rate of progression and risk factors for progression.
Results
For 614 consecutive patients, median follow-up by DUS was 30 (2-42) months. Patients were 73 ± 10-years-old, and 62% were men. Mean ankle-brachial index (ABI) was 0.79 ± 0.24. The baseline prevalence of carotid stenosis ≥50% (PSV ≥125 cm/second) was 22%. During follow-up, ipsilateral amaurosis fugax, transient ischemic attacks, and strokes occurred in 3 (0.4%), 7 (1.1%), and 5 (0.8%) patients, respectively. Overall, there was little progression in carotid stenosis. Female gender, low ABI, and smoking were risk factors for progression of disease regardless of severity of carotid stenosis. Patients with ≥50% carotid stenosis were at greatest risk of progression if they continued smoking and were diabetic. Prediction models for progression of carotid stenosis given a baseline PSV and patient risk factors were constructed.
Conclusion
There are few neurologic events in patients with asymptomatic carotid stenosis. The average rate of progression of stenosis over 2 years is not significant but greater in diabetic patients with baseline stenosis >50% who continue smoking. Rescreening by serial DUS should be limited to high-grade stenosis and follow-up performed at an interval of 1-2 years.
aDivision of Vascular Surgery, Guelph General Hospital, Hamilton, Ontario, Canada
bDivision of Vascular Surgery, University of Toronto, Toronto, Ontario, Canada
cDepartment of Medicine, McMaster University, Hamilton, Ontario, Canada
dDivision of Vascular Surgery, McMaster University, Hamilton, Ontario, Canada
Reprint requests: Dr Claudio Cinà, St. Michael's Hospital, University of Toronto, 55 Queen St. East, Suite 308, Toronto, Ontario M5C 1R6, Canada
The study was funded by the Heart & Stroke Foundation of Ontario.
ABSTRACT