Issues in renovascular disease and ischemic nephropathy: beyond ASTRAL

Whereas atherosclerotic renal artery stenosis is recognized to accelerate hypertension and threaten kidney function, recent trials indicate that many patients can be managed primarily with antihypertensive drug therapy without renal revascularization. These trials have been criticized for many reasons, including inclusion of large groups with only minor vascular occlusive disease.

Although moderate stenosis is associated with preserved oxygenation within both cortex and medulla, severe disease is demonstrably associated with reduced oxygenation that can be identified using blood oxygen level-dependent magnetic resonance. Fewer clinical procedures to revascularize stenotic kidneys likely will be followed by advanced occlusion with loss of function. Experimental studies confirm that poststenotic microvascular injury is magnified in the presence of atherosclerosis, activating local inflammatory and fibrogenic pathways in the kidney. Even without restoring renal blood flow, experimental studies with endothelial progenitor cells indicate that recovery of renal vascular structures and function may be possible.

The short-term prospective trials to date remain at odds with observational studies indicating improved blood pressure, stabilization of renal function, and improved management of some patients with congestive heart failure. Nephrologists will need to balance optimizing medical therapy for complex patients with renovascular disease and identifying those most likely to benefit from renal revascularization on an individualized basis.