Impact of Screening MR Angiography on Referrals for Percutaneous Intervention in Renovascular Disease

Abstract

Concern about contrast- and catheter-induced complications inhibits liberal use of catheter angiography to screen for renal artery stenosis. The authors evaluated the impact on interventional practice growth of offering magnetic resonance angiography (MRA) as an alternative screening test for renovascular disease. A retrospective analysis of 339 patients with renovascular disease identified with MRA from January 1, 1993 through December 31, 1997, and the subsequent utilization of follow-up catheter angiography and/or intervention was performed. The number of patients treated per year with percutaneous techniques for renovascular disease was recorded, and was correlated with screening MRA. The impact of screening MRA on percutaneous management of renovascular disease was evaluated through comparisons of the number of percutaneous procedures performed among the individual years during the 5-year period, and with the number of procedures performed during the 5-year period (1988-1992) immediately preceding 1993, prior to the use of screening MRA. The number of annual screening MRA examinations increased six-fold during the 5-year period, from 17 per year initially to approximately 100 per year for each of the last 3 years. One hundred thirty-five (40%) of screening MRA examinations were positive for renal artery stenosis or occlusion, and 111 (33%) patients had anatomy potentially suitable for percutaneous intervention. Fifty-two patients with positive screening MR angiograms underwent arteriography: 34 underwent renal angioplasty or stent placement, seven had surgery, seven with stenosis determined with MRA had occlusion on catheter angiography, and four had false-positive results of MRA (<50% stenosis). Three additional patients with negative screening MR angiograms were also referred for arteriography, which confirmed the MRA findings. The percentage of positive catheter angiograms was 50% greater among patients with a screening MRA, and the number of renal artery angioplasties performed annually doubled. Moreover, comparison with the 5-year period from 1988 to 1992 (immediately prior to the use of MRA as a screening tool), demonstrates that the average number of renal artery percutaneous procedures performed per year increased nearly 350% from an average of three per year to 15 per year. These findings are entirely attributable to referrals from screening MRA. Marketing of renal artery MRA as a safe, noninvasive outpatient screening technique can lead to improved utilization of catheter angiography in evaluation of renovascular disease, and can secondarily increase the volume of renal artery angioplasty and stent placement procedures for treatment of renovascular disease.