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Stenting and Medical Therapy for Atherosclerotic Renal-Artery Stenosis

Christopher J. Cooper, M.D., Timothy P. Murphy, M.D., Donald E. Cutlip, M.D., Kenneth Jamerson, M.D., William Henrich, M.D., Diane M. Reid, M.D., David J. Cohen, M.D., Alan H. Matsumoto, M.D., Michael Steffes, M.D., Michael R. Jaff, D.O., Martin R. Prince, M.D., Ph.D., Eldrin F. Lewis, M.D., Katherine R. Tuttle, M.D., Joseph I. Shapiro, M.D., M.P.H., John H. Rundback, M.D., Joseph M. Massaro, Ph.D., Ralph B. D’Agostino, Sr., Ph.D., and Lance D. Dworkin, M.D. for the CORAL Investigators

N Engl J Med 2014; 370:13-22 January 2, 2014DOI: 10.1056/NEJMoa1310753

As a practicing endovascular medicine physician, I’m excited to get Dr. Creager’s take on this. The CORAL study, to start with, was a study that was sponsored by the NHLBI (National Heart, Lung, and Blood Institute), -looking at patients who had greater than 60% stenosis who had resistant hypertension or renal insufficiency and were optimally treated with medical therapy. The patients were given free antihypertensive therapies and statin therapy. And that alone was compared with medical therapy plus renal artery intervention with stenting.

Dr. Creager, can you summarize the take-home message and the results for our audience?

Mark A. Creager, MD: Thank you, Seth. This was an important study. The CORAL study compared these 2 groups, and the primary endpoints were cardiovascular and renal death, hospitalization for congestive heart failure, stroke, myocardial infarction, progressive renal insufficiency, and renal replacement therapy. The trial found that there was no significant difference in this primary composite endpoint between the 2 groups.

That’s an important message: that if we treat our patients with hypertension and renal insufficiency who have concomitant renal artery stenosis with appropriate medical therapy, they will do as well — in terms of cardiovascular and renal endpoints — as those who undergo renal artery stenting.

Dr. Bilazarian: A very strong message that stenting adds nothing, if we take home the short answer that renal stenting adds nothing on top of optimal medical therapy. Previously, enthusiasts for renal stenting criticized studies such as ASTRAL^[3] and STAR^[4] that the patients may not have been optimally chosen and may not have had significant enough renal artery stenosis.

In the CORAL study, we saw yesterday that in a subgroup analysis looking at patients who had greater or less than 80% stenosis, the average was 72% in the whole trial. But those at greater than 80% did not seem to fare any better from this study. They were the same as those at less than 80%. So does this largely close the door to renal stenting for atherosclerotic disease?

Dr. Creager: As implied by your question, one might have anticipated that those individuals with the most severe renal artery stenosis would have been those most likely to benefit. But as you stated, there was no difference between the patients who had a greater than 80% stenosis and those who did not. That really continues to raise questions about the efficacy of renal artery stenting in this population in general.

But it doesn’t entirely close the door. I think it still is very important for all physicians to deal with their patients individually and inform their decisions by the evidence that’s available. But there will be patients who have hypertension and remain refractory despite aggressive and appropriate medical therapy. And in those individuals, one might consider looking for the presence of renal artery stenosis, and if found, treat them.

But keep in mind that in this trial, the group randomized to medical therapy did demonstrate benefit. In fact, they demonstrated a 15-mm Hg (on average) decrease in systolic blood pressure, indicating that before enrollment in the trial they probably were being treated as aggressively as they should be.

My take-home message is: If you have a patient with significant hypertension, make sure you’re implementing guideline-based therapies to bring their blood pressure into appropriate control. And if one is not successful in that case, then consider other options.

Dr. Bilazarian: One of the findings in the study was that at the end of the trial, there was a 2.5-mm Hg blood pressure difference between those with renal stenting and those without renal stenting (both on optimal medical therapy). Did that result surprise you?

Dr. Creager: It did surprise me for the very reason I just alluded to. I think that prior to enrollment in the trial, many of these patients who were treated with 2 or more antihypertensive drugs still might not have been treated aggressively enough with the right doses of these drugs or the right number of drugs to bring their blood pressure down.

In fact, I was pleased to see that an intensive medical regimen could be effective in these patients. And it sends another important message to our medical community that we can do more for these patients.

Dr. Bilazarian: You mentioned in this last answer that there may still be a role for identifying patients with renal artery stenosis. Can you help clarify that for me as a director of the vascular lab at Brigham and Women’s Hospital? As a teacher of postgraduate physicians, help me understand in what situation patients should be evaluated.

Currently, patients who may not have frank resistant hypertension get referrals to duplex ultrasound for assessment. Should that bar be moved up? Or is it only the most refractory patients who should be investigated? Or is it still valuable to know whether a patient has renal artery stenosis with noninvasive testing?

Dr. Creager: The bar does need to be moved without question. But there are several situations. I’ll give you 2 examples. One I mentioned: The patient who continues to have resistant hypertension despite aggressive medical therapy will be one such patient where I’ll be looking for secondary causes. And one of those secondary causes could be renal artery stenosis. So in that individual, duplex ultrasound would be appropriate, and if renal artery stenosis is found, continue the evaluation and treat that patient as the renal artery stenosis is confirmed.

Another example might be an individual who has recurrent acute pulmonary edema that cannot be explained by coronary artery disease or severe left ventricular dysfunction. That’s a patient I would consider working up for bilateral renal artery stenosis. And if found, I would treat. That patient population was really not the type that was included in the CORAL trial. So those are 2 examples.

Dr. Bilazarian: Our current guidelines say that there is a role for renal artery intervention for resistant hypertension, acute pulmonary edema, and declining renal function. It seems like the first of those has been taken off the table. Is there a role in the patient with declining renal function?

Dr. Creager: Well, that’s an important subset of patients, indeed. And I would be evaluating them for the potential causes of declining renal function. If they have renal artery stenosis, I would then initiate aggressive risk factor modification, antiplatelet therapy, and if they’re hypertensive, treat that as well.

But if in spite of that there still is evidence of declining renal function, then there’s a situation of someone who has failed medical therapy, and I would consider evaluating them for a renal artery stenosis. If one were to find, for example, bilateral renal artery stenosis in that patient or a severe stenosis to a single functioning kidney, then, yes, I would consider renal artery stenting in that individual.

Dr. Bilazarian: Great. Thank you for that summary on the trial called CORAL. Let’s move on to the second trial that you moderated. That trial is called ERASE, a study looking at supervised exercise therapy — an abbreviation I wasn’t familiar with: SET — supervised exercise therapy alone or supervised exercise therapy plus intervention of lower-extremity peripheral arterial disease. And that study was called ERASE. It built on an earlier study called CLEVER.^[5] Please summarize the take-home message for the audience in that trial.

Dr. Creager: These were patients with peripheral artery disease and intermittent claudication, and the peripheral artery disease could have affected the aortoiliac system or the femoropopliteal system. The bottom line is that those patients who were randomized to both endovascular intervention and supervised exercise training had a much greater improvement in their walking time as assessed by treadmill testing, and also in quality of life as assessed by a number of instruments, compared with those patients who were just treated with supervised exercise training.

It adds incrementally to what we’ve previously understood. We know that supervised exercise training is extremely effective in improving walking time in patients with intermittent claudication. And as was shown with CLEVER, compared with medical therapy, endovascular intervention — at least in the aortoiliac area — is also associated with improvement in walking time.

So perhaps it’s no surprise that if you put the two together, they’re going to do better. And that’s what the ERASE trial showed.

Dr. Bilazarian: I agree with you. Many times, studies compare one or the other. And, of course, both is better than one or the other. I was happy to see that this trial looked at both.

There is one part of the trial that I had difficulty getting a take-home message from, and I’d love your input. As endovascular medicine physicians, we think in terms of the 3 zones of lower-extremity vascular disease: above the inguinal ligament, the fem-pop system, and then below the knee. Each becomes increasingly difficult, both for acute result as well as for durability. In this trial, half the patients had aortoiliac disease and half had fem-pop disease. Am I right to say that that might make it somewhat difficult to interpret whether the effects of supervised exercise therapy might be different for fem-pop disease or, say, aortoiliac disease, and that the bar for intervention might be lower for aortoiliac disease?

Dr. Creager: That’s a very important question. We don’t know yet what the subset analysis will be between those patients who had aortoiliac disease and underwent randomization and those who had femoropopliteal artery disease. And I’m sure we all await that analysis when it’s available.

Having said that, however, the studies show several things. It underscores the fact that no matter where the lesion is, patients still do better when exercise training is included in their therapeutic interventions. I think those of us who practice vascular medicine recognize the fact that endovascular intervention in the iliac arteries has been extremely successful and durable. And those patients really do benefit. d Our practice pattern and standard of care is to do endovascular intervention in patients with disabling claudication who have aortoiliac disease.

Superficial femoral artery disease, as you implied, is a little bit of a different situation. Those lesions are sometimes more difficult to treat and the durability is not as great. Within the context of this study, durability was pretty good in terms of restenosis. But I still think we need to see the subset analysis to make sure that those patients benefited as much as the entire group.

Dr. Bilazarian: Help us with a take-home message for US-based physicians. This was supervised exercise therapy in-home. We don’t have that available in the United States. Other than adding to our knowledge base, which is, of course, valuable, and being able to impart this knowledge to our patients and show them that this is of value, what other things can we do as a change in our practice to integrate this?

Dr. Creager: Currently we do need changes in healthcare policy, at least as it applies to supervised exercise training. We need reimbursement from CMS (Centers for Medicare & Medicaid Services). We need reimbursement from other third-party payers to provide additional incentive for physicians to recommend supervised exercise training for their patients. Unfortunately, that’s not available. And that’s one reason why patients in this country are not being referred for supervised exercise training. It’s an extremely effective intervention in patients with intermittent claudication.

Dr. Bilazarian: Great. Mark, thanks for joining me and for helping unpack these 2 trials for our audience: the ERASE trial of lower-extremity exercise in PAD patients, and the CORAL trial of renal artery stenting. I think they will add to our knowledge base and hopefully make practice changes in both areas. Thank you again for joining. And thank you for joining us for this program.

SOURCE

http://www.medscape.com/viewarticle/815029?src=emailthis#1