"Renal artery stenting remains the most appropriate intervention in selected patients with significant renal artery stenosis," says Robert Kerlan, M.D., chief of Interventional Radiology at UCSF Medical Center.

 

Clarifying studies' confusing results

Though the recent STAR and ASTRAL trials failed to show benefits from renal artery interventions compared with optimal medical management in a relatively unselected group of patients, Kerlan and vascular surgeon Jade Hiramoto, M.D., agree that when a renal artery stenosis becomes hemodynamically critical — or is likely related to a worsening of the patient's hypertension — revascularization is usually the most appropriate intervention.

"The studies were a legitimate response to indiscriminate use of renal artery stenting, but they don't tell the whole story," says Hiramoto, who conducts research on vascular surgery outcomes. "The problem is that it is really difficult to randomize people who have significant renal artery lesions combined with drug-resistant hypertension, yet these are the patients that really stand to benefit from revascularization."

Stratifying patients

Kerlan and Hiramoto say that the decision on revascularization depends on careful assessment of the patient and the lesion, with the latter typically done using noninvasive CT imaging or ultrasound. Physicians can then match the patient with a therapy that meets the patient's anatomy and overall medical condition.

• Patients who have renal artery lesions with less than 70 percent narrowing should be treated first with medical therapy.
• "Young people with hypertension and fibromuscular dysplasia typically do quite well with balloon angioplasty," says Kerlan.
• Patients who experience a sudden worsening of hypertension or renal functioning after a prolonged stable period should be evaluated immediately to determine whether there is a significant lesion. If there is, these patients are good candidates for revascularization.
• The data are less clear on what the optimal treatment is for patients with greater than 70 percent stenosis, but with stable renal function and blood pressure.
• For patients with greater than 70 percent stenosis and a complicating condition (see sidebar), revascularization should be the primary option.

"If these patients [who require revascularization] are younger and in good condition, surgical revascularization is generally more appropriate because it is more sustainable," says Hiramoto.

But renal artery disease mostly afflicts older patients, smokers, and those with significant coronary or pulmonary disease. "For such patients, renal artery stenting is the best option — and is often lifesaving," says Kerlan.

Finally — whether the choice is surgery or stenting — because revascularization procedures can be technically challenging, referral to experienced clinicians optimizes the chances for success.

Candidates for renal artery revascularization

Refer patients for renal revascularization when they have hemodynamically significant lesions greater than 70 percent and underlying conditions that include one or more of the following:

• Significant flash pulmonary edema
• Acute renal insufficiency
• Severe drug-resistant hypertension

To contact Dr. Jade Hiramoto, call (415) 353–4366.

To contact Dr. Robert Kerlan, call (415) 353–1300.

 

Heart & Vascular Center News, Winter 2010 Index