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Survival Following Renal Artery Stent Revascularization:
Four-year Follow-up
July 2004
Patients with atherosclerotic renal artery stenosis have higher mortality compared to age and sex-matched controls in the general population.1-4 The risk of all cause death is increased 3.3 fold while the cardiovascular death is increased 5.7 fold.3
Survival following renal artery revascularization has not been systematically evaluated. The observations range from excellent survival following surgical revascularization,5 to adverse outcome following renal artery stenting in patients with abnormal baseline serum creatinine,6 to better survival limited only to patients whose renal function improved following successful renal artery angioplasty.7 However, the available data is retrospective and sample size is small.
The objective of our study was to supplement the existing survival data (and cause of death) in patients undergoing renal artery stenting for atherosclerotic renal artery stenosis and drug refractory hypertension.
Methods
This is a retrospective evaluation of 72 consecutive patients who underwent renal artery stent revascularization for suspected renovascular hypertension. All patients had blood pressure > 140/90 mmHg despite 2 anti-hypertensive drugs and angiographic renal artery stenosis (> 70% diameter stenosis). The procedures were performed between September 1998 and September 2001 at a single institution.
Patients were followed up by telephone and hospital medical record review. The date and cause of death was obtained from medical record and death certificate. Kaplan-Meier survival curves were obtained for all patients and pre-defined subgroups (renal failure, systolic dysfunction, bilateral renal artery stenosis, gender, diabetes, coronary artery disease and ethnic group). A Cox regression hazard model and Log-rank (Mantel-Cox) were used to assess the impact of these variables on survival. Cox regression hazard model was applied to the following pre-assigned variables: diabetes, baseline serum creatinine > 1.5 mg/dl, ejection fraction 3 mg/dl, or CHF requiring hospitalization within 2 months of surgery).9 Cambria et al retrospectively analyzed 139 patients undergoing surgical renal artery revascularization. They found 52% survival at 5 years in patients with baseline serum creatinine > 2 mg/dL.10
There are very few reports evaluating survival in patients with atherosclerotic renal artery stenosis following percutaneous renal artery revascularization. Pickering et al. studied 55 patients with renovascular hypertension and azotemia in whom renal angioplasty was attempted (successful in 45 patients). They found better survival in patients who had improvement of renal function after successful renal artery angioplasty.7
Dorros et al. analyzed 163 patients who underwent renal artery stent revascularization. The overall survival at 3 years was 74 ± 4%. Renal dysfunction and diabetes adversely affected survival. Three year survival in patients with baseline serum creatinine of 2mg/dl , the three-year survival was only 51 ± 8%. Risk ratio for patients with creatinine > 1.5 mg/dl was 5 while for diabetics it was 2.56.
In our study, the overall 4-year survival was 83%, which is comparable to the published surgical data (and better than the percutaneous revascularization data). Additionally, in our group of patients, the procedure-related death was 1% compared to 6% operative mortality in surgical revascularization.11
Cardiovascular causes accounted for 90% of out-of-hospital deaths in our series of patients. This is consistent with previously published reports.3,9 The prevalence of co-morbidities in non-survivors was significantly higher than in survivors. Renal dysfunction was present in 60% of the deceased patients (mean creatinine 2.4 mg/dl) and left ventricular dysfunction in 90%. Diabetics had lower survival than non-diabetics but this difference did not reach statistical significance. When Cox proportional hazard model was applied to pre-assigned variables, baseline serum creatinine of > 1.5 mg/dl, male gender, left ventricular ejection fraction
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