ASTRAL (Angioplasty and stent for renal artery lesions) – “possibly the most debated trial that’s not yet published!” – raises as many questions as it answers, according to Mark Downes, Kent and Canterbury Hospital, UK.
The trials of renal artery percutaneous transluminal angioplasty and/or stenting are generally weak, Downes told delegates at the 31st CX Symposium, held in London this April.
The bulk of these studies compare angioplasty to medical therapy in renal artery stenosis. There are a number of studies, he said, “but they all contain small numbers, and they all are flawed in that there was significant cross-over between trial groups, compromising the results. In fact, in the DRASTIC trial, 22 out of 50 patients crossed over between the two trial groups.”
Downes observed also a lack of consistency in endpoints in these trials, whether monitoring of hypertension or renal function. “Despite this poor level of evidence, in vast parts of the world – the developed world – this has still resulted in a change of practice from simple angioplasty to renal artery stenting.”
Downes referred to the prospective cohort study presented at the Leipzig Interventional Course, Germany, January 2009, by Thomas Zeller, Albert-Ludwigs-University Freiburg, Germany, and to the ODORI register presented at the CX Symposium just a day earlier. Both of these studies produced useful data broadly supporting the use of stents in the renal artery, but do not provide the level one evidence that Downes holds to be lacking.
Although data from the ASTRAL trial is still undergoing peer review prior to publication in a reputable journal, the results have been widely disseminated at conferences around the globe, and have been the subject of much discussion, Downes observed.
“But – there’s always a ‘but’! – recruitment started in 2000, so that’s actually nine years ago.” Downes said that just 403 patients were recorded as receiving stents in that time, across 58 centres: “That’s two patients per centre, per year. I think that’s something that needs to be answered.”
He also questioned whether ASTRAL’s findings – particularly with regard to mortality, morbidity, and other complications – are relevant, given that guide wires and stents have radically changed over the last ten years.
“Although not yet published, I too question the relevance of the ASTRAL study, as it has been presented at meetings. The main concern is the low inclusion rate, as mentioned. Either the centres have had too low volumes to permit a reasonable quality, or a very small proportion of eligible patients were included. In both cases that affects the potential to generalise from these findings. Another concern is the fact that there seem to have been no pressure measurements prior to dilatation/stenting, which may result in nonsígnificant stenoses being treated, thus diluting the possible effect of treatment.” – Martin Björck, Uppsala, Sweden