Purpose: Although the prevalence of renal artery stenosis in patients with peripheral arterial disease is in the range of 30% to 40%, the role of renal revascularization in patients without severe hypertension or kidney failure is controversial. Duplex scanning is a noninvasive technique that is ideally suited for screening and follow-up of renal artery disease. The purpose of this study was to document the natural history of renal artery stenosis in patients who were not candidates for immediate renal revascularization.
Methods: Eighty-four patients with at least one abnormal renal artery detected by duplex scanning were recruited from patients being screened for renal artery stenosis. Of the 168 renal artery/kidney sides, 29 were excluded (15 prior interventions, 6 nondiagnostic duplex scans, 8 presumed nonatherosclerotic lesions), leaving 80 patients with 139 sides for the follow-up protocol. Renal arteries were classified as normal, less than 60% stenosis, 60% or greater stenosis, or occluded by use of previously validated criteria.
Results: The study group included 36 men and 44 women with a mean age of 66 years who were monitored for a mean interval of 12.7 months. The initial status of the 139 renal arteries was normal in 36, less than 60% stenosis in 35, 60% or greater stenosis in 63, and occluded in 5. Although none of the initially normal renal arteries showed disease progression, the cumulative incidence of progression from less than 60% to 60% or greater renal artery stenosis was 23% +/- 9% at 1 year and 42% +/- 14% at 2 years. All four renal arteries that progressed to occlusion had 60% or greater stenoses at the initial visit, and for those sides with a 60% or greater stenosis, the cumulative incidence of progression to occlusion was 5% +/- 3% at 1 year and 11% +/- 6% at 2 years. The mean decrease in kidney length associated with progression of renal artery stenosis to occlusion was 1.8 cm.
Conclusions: Progression of renal artery stenosis, as defined in this study, occurs at a rate of approximately 20% per year. Progression to occlusion is associated with a marked decrease in kidney length. Whether this natural history can be improved by earlier intervention for renal artery stenosis remains to be determined.