Carotid Stenting and Stroke Prevention

To determine if carotid stenting reduces the risk of stroke, surgical and medical therapy trials must be compared to stenting trials, since no data directly comparing the procedures are available. Although this strategy is “a little imperfect,” says William Gray, MD, Associate Professor of Clinical Medicine at Columbia University, “it's all we have.”

These data show that surgery is able to prevent stroke better than medical therapy. Additionally, comments Dr. Gray, “carotid artery stenting has demonstrated equivalent stroke prevention efficacy compared to endarterectomy.” Recently published EVA-3S trial in Europe, however, found higher incidence of stroke in symptomatic patients treated with stenting than with endarterectomy (Jean-Louis Mas et al. NEJM 2006; 355:1660–1671) The TACIT trial, currently under proposal, aims to directly compare medical therapy, endarterectomy and stenting.

Renal Failure Prevention

Progressive renal artery stenosis (RAS) is a problem, according to Chris White, MD, Chairman of the Department of Cardiology and Director of the Ochsner Heart & Vascular Institute in New Orleans, “I think it's actually quite dangerous to sit here and watch RAS progress.” He adds that conservative medical therapy could lead to progression and eventually occlusion. Indeed, in the DRASTIC (Dutch Renal Artery STenosis Intervention Cooperative) trial, balloon angioplasty and medical therapy in RAS lead to 0% and 16% of patients suffering from occlusion, respectively. Finally, occlusion typically leads to renal failure. Renal artery stenosis has high prevalence in patients with coronary artery disease and confers additional mortality, making a case for screening high risk patients undergoing cardiac catherization for presence of renal artery stenosis (White CJ et al. Circulation 2006; 114(17):1892–1895).

Patient selection is important for success in preventing RAS. Murray et al demonstrated that the more rapid the decline in renal function, the more likely the patient is to benefit from revascularization (Murray S et al. Am J Kidney Dis 2002; 39:60). Additionally, to avoid complications, embolic protection devices are recommended (though none of the devices are approved for use in renal arteries).

“Benign neglect of RAS is not benign,” summarizes Dr. White, “you cannot treat patients with medical therapy and assume that because you are controlling the blood pressure you are not losing renal function.”

Aortic Stenting and AAA Rupture Prevention

“Life really changed in September of 1999 when the FDA approved two graft prostheses,” says Alan Lumsden, MD, Professor and Chief of the Division of Vascular Surgery at Baylor College of Medicine in Houston, when referring to the Guidant Bifurcated Endograft and the AneuRx Stent Graft System. Since then, many devices have emerged around the same concept and have shown significant promise.

In the US AneuRx trials, freedom from rupture was 98.4%, and freedom from aneurysm related death was 96.9%. The key to success, says Dr. Lumsden, is patient selection, with the single most important criteria being neck diameter (≤26mm). Problems arise when a patient presents with a short, tapered neck. Therefore, pre-procedure planning involving a CT scan of the abdomen to calculate neck diameter, is critical.

“Good anatomy equals good results when you're treating patients with a stent graft,” says Dr. Lumsden, adding, “We must understand and respect anatomical limits, practice careful follow-up, and understand the nuances of each device.”