Four years of follow-up renal function and survival data were obtained on 544 patients who underwent 714 successful renal artery stenosis (RAS) stent revascularizations. The mean serum creatinine (SCr) was unchanged at 4 years (1.6+/-1.0 mg/dl versus 1.6+/-0.9 mg/dl). The 2-year paired comparison analysis revealed no change in the reciprocal of the SCr (1/SCr), when compared with baseline or 1-year follow-up values. Simple linear regression analysis revealed flat post-procedure trend line slopes within all patient subsets, which implied renal functional stabilization. The 4-year mortality rate was 20%; variables directly affecting survival were presence of 1 or 2 kidneys, whether 1 or 2 renal arteries were stenotic [survival: unilateral 87%, bilateral 80%, and solitary kidney 60% (p<0.05)], as well as the degree of renal dysfunction [normal renal function patients had a significantly better (p<0.05) survival (88%) than those with moderate (60%) or severe dysfunction (47%)]. Surprisingly, medication controlled blood pressure (BP) patients fared worse than those with poorly controlled BP (56% versus 70%, respectively; p<0.05), with the worst outcomes in controlled BP patients with bilateral disease compared to poorly controlled BP patients (35% versus 69%, respectively; p<0.05).
Conclusion: Renal function remained stable following stent revascularization for RAS, and survival was adversely affected by the variables of unilateral or bilateral RAS, presence of one/two kidneys, renal function impairment and medically controlled BP. These data underscored the premise that the malignant nephropathy associated with RAS was more likely to be segmental than uniform, and resulted from recurrent debris embolization from the obstructing lesion rather than persistent ischemia. Thus, a randomized stent revascularization trial utilizing an embolic protection device, coupled with an effort to collect retrospective preoperative SCr values, may be able to demonstrate post-stent functional stabilization, halting of progressive functional deterioration and, potentially, improvement in survival.