JOURNAL CLUB: ASTRAL

There has been a lot of debate regarding renovascular hypertension/kidney disease and the benefits of revascularization vs. medical therapy. The much anticipated ASTRAL trial has just been published in the NEJM November 12, 2009. However, many questions remain unanswered.

Briefly, this was a randomized, multi-center, unblinded trial of 806 patients with atherosclerotic renovascular disease assigned to either medical therapy or revascularization with medical therapy (403 in each arm) followed over an average of 34months. Primary outcome was renal function as measured by reciprocal of creatinine and secondary outcomes were BP, time to renal and CV events, an mortality. No significant difference was found between the two arms in any outcomes, but 23 patients had complications associated with revascularization, including 2 deaths and 3 amputations.

The study design was based on "equipoise", or true uncertainty about which arm would do better. This, of course, is very subjective. Those thought to benefit from revascularization were excluded. The problem with this is that no one clearly knows who would benefit. Such assumptions are based on small studies looking at such things as degree of stenosis, resistive indices on duplex, hypertension control, renin/aldo levels, degree and rate of decline of renal function, and so forth. To have these patients undergo revascularization may therefore be considered "standard of care", and perhaps this is why a design of this nature was performed (ie. to include these patients would be "unethical").

It should also be noted that ~40% of patients had stenosis less than 70% in both arms, and unilateral RAS was included in a study where the primary outcome looked at renal function (although their posthoc analysis of severe bilateral stenosis or severe unilateral stenosis of solitary kidney also showed no difference).

We must be careful on how we interpret studies. This is a step in the right direction to draw a conclusion, but by no means should this be seen as anything definitive...