POINT/COUNTERPOINT: Renal artery occlusive disease – To treat or not to treat? ASTRAL and CORAL trials show no indication to treat percutaneously. There are still indications to treat renal artery occlusive disease.

Percutaneous treatment of renal artery occlusive disease is unnecessary and should be abandoned, except in pediatric cases.

BY GEORGE HAMILTON, M.D.

This position is supported by findings from both the ASTRAL trial (N. Engl. J. Med. 2009;361:1953-62) and the CORAL trial (N. Engl. J. Med. 2013 Nov. 18 [doi:10.1056/NEJMoa1310753]).

The ASTRAL trial, a prospective, randomized comparison of best medical therapy with and without stent angioplasty in more than 800 patients, was the largest trial to date when it began back in the 1990s. The well-known results showed no difference in time to first renal event, first vascular and cardiovascular events, and overall survival. Furthermore, there was no difference in these outcomes among patients with greater than 90% stenosis, with the exception of a possible difference in mortality, which trended toward improvement among those with high-grade stenosis.

We concluded that revascularization in the vast majority of patients is unlikely to improve hypertension control or renal function, and that renal artery stenosis is not pathophysiologically important. We also concluded that there is no point in screening for asymptomatic disease; this was back when every patient was getting screened, and treated primarily on the basis of finding a renal arterial stenosis.

Finally, we concluded that properly applied best medical therapy alone was an extremely good treatment.

Several flaws in the trial garnered extensive criticism, however, and the more rigidly designed CORAL trial was expected to address them. The findings confirmed those of the ASTRAL trial. In more than 900 patients from 88 centers, there was absolutely no benefit of intervention with respect to primary and secondary outcomes, including among those with high-grade stenosis.

We can now see on the basis of extensive level 1 evidence that when added to comprehensive, multifactorial medical therapy, intervention yielded no benefit.

So are there certain patient groups who might benefit more from intervention? Among listed indications are high-grade stenosis (which doesn’t apply any longer); short history of progressive failure (which is quite rare); ACE-induced renal failure (which is also quite rare); difficult-to-control hypertension (there really is no such thing now, except in a tiny percentage of patients); and – the least challenged indication – flash pulmonary edema. These remaining indications move our interventions into a very high risk group of patients.

The current debate is focused almost entirely on endovascular intervention, but a systematic review showed that there is long-term benefit in terms of renal function and hypertension with open procedures. Although overall there is increased mortality, this risk is minimized – and not significantly different from endovascular procedures – in those having only renal revascularization vs. those having concomitant aortic procedures. So open surgery remains a possible treatment option, indeed a recent level 1 study comparing stenting and open surgery, showed better long-term results with open surgery (J. Vasc. Surg. 2009;49:667-75). The authors concluded that surgical reconstruction remains the gold standard in treating renal artery stenosis. Although national data suggest an overall mortality of about 10%, it is much lower at specialist, high-volume centers with mortality rates similar to those of stent angioplasty.

Renal stenting is not a low-risk procedure. In all-comers the complication rates, serious complication rates, and mortality rates are significant with short-term equivalence between focused renal arterial surgery and percutaneous intervention.

Returning to the debate, are either methods of revascularization appropriate? Probably not.

Even in flash pulmonary edema, there is little evidence to support revascularization. Few papers exist suggesting a benefit of revascularization in reduction of flash pulmonary edema, but the patient numbers were small, and there was no benefit in terms of preservation of renal function.

The history of evolution and evaluation of the role of renal revascularization is remarkably similar to that of renal denervation, initially and with considerable conviction thought to be a cure for hypertension. However, when properly assessed by prospective randomized comparison there was found to be absolutely no benefit.

So, given the considerable objective evidence from two major trials and revisiting the basics of the pathophysiology of atherosclerotic renovascular disease, to expect benefit from treating the osteal component of renal artery occlusive disease is at best naive, in my opinion. There remains little clinical evidence of benefit for any indication, with the possible exceptions of ACE-induced renal failure and possibly flash pulmonary edema in the presence of bilateral renal arterial stenoses.

Dr. Hamilton is a professor at the Royal Free London Hospital, University College London, United Kingdom.