The Management of Renal Artery Stenosis: An Alternative Interpretation of ASTRAL and CORAL

Abstract

To assess the literature on intervention for renal artery stenosis (RAS), with special emphasis on the last two and largest randomized trials, the ASTRAL and CORAL trials. A review of renal physiology, pathology, and pathophysiology of RAS and a critical analysis of the randomized trials. Published literature for renal physiology and RAS were assessed. Renal physiology, renal intervention, and the limitations and challenges of both ASTRAL and CORAL are analysed. The last two reported, and largest randomized trials of percutaneous renal artery intervention for RAS were the ASTRAL and the CORAL trials; both generated much debate and much controversy, however both trials had methodological shortcomings, and assumed a simplistic approach to renal physiology. Both trials were hampered by slow recruitment, and there were protocol changes to accommodate, and CORAL was not powered for subgroup analysis. The primary outcome measure for ASTRAL was the reciprocal of serum creatinine levels and CORAL a complex composite endpoint of cardiovascular or renal events. In ASTRAL, 25% of patients had normal renal function and 40% almost normal renal function; and in CORAL, 50% of the cohort had either no renal failure, or were Stage I or Stage II CKD, (i.e. eGFR of >60mls/min/1.73m(2)). In ASTRAL, 41% of patients had a stenosis of <70%; and an interim analysis of 611 patients (of 947 enrolled) in CORAL revealed that 55% had <70% renal artery stenosis. Best evidence still supports intervention for patients with RAS of >80% with a significant trans-lesional pressure gradient; difficult to control blood pressure with more than three antihypertensives, especially in younger patients; and those with truncal rather than ostial stenosis; patient with a rapid deterioration of renal function; flash pulmonary oedema; and post-transplant RAS.