Renal Stenting for Incidentally Discovered Renal Artery Stenosis: Is There any Outcome Benefit?
Article Outline
- Abstract
- Introduction
- Methods
- Results
- Comparison of Patients with High-Grade RAS with and without PTRAS
- Discussion
- Conclusion
- Acknowledgment
- References
- Copyright
We evaluated whether there was a clinical outcome benefit in patients incidentally discovered to have high-grade renal artery stenosis (RAS) and treated with percutaneous transluminal renal angioplasty and stenting (PTRAS) at the time of angiogram for another indicated procedure. A retrospective chart review was performed on all patients undergoing renal arteriography over 4 years at our academic tertiary-care referral center. Review of catheterization reports was used to identify patients diagnosed with high-grade RAS (reduction of ≥70% luminal diameter by arteriogram). Patients treated with PTRAS were identified. Baseline and postprocedure blood pressure (BP, an average of at least three independent measurements), glomerular filtration rate, serum creatinine, and antihypertensive medication regimen were compared for 12 months of follow-up. Over 4 years, 124 patients underwent renal arteriography and 78 (63%) were diagnosed with high-grade RAS. Fifty-eight patients (74% of those with high-grade RAS) received PTRAS. Patients treated with PTRAS had similar baseline characteristics to those with high-grade RAS with no intervention, with the exception of lower diastolic BP (DBP; 74 ± 11.2 vs. 80 ± 14.2 mm Hg, p = 0.04) and a higher proportion of hyperlipidemia (78 vs. 55%, p = 0.05). Thirty-eight out of 58 PTRAS patients (66%) received sufficient follow-up to assess outcomes. When baseline and postprocedure variables were compared in PTRAS patients with 12-month follow-up, there was a reduction in systolic BP (SBP, 153 ± 20.8 vs. 136 ± 27.2 mm Hg, p = 0.01) and mean arterial pressure (MAP, 103 ± 11.2 vs. 95 ± 14 mm Hg, p = 0.04). When these patients were stratified by those with an increase, decrease, or no change in postprocedure antihypertensive medications, significant reductions in SBP, MAP, and DBP were noted only in the patient population that also had an increase in the number of antihypertensive medications. No differences in renal insufficiency were detected. Patients with high-grade RAS incidentally discovered during arteriography performed for extrarenal disease and treated with PTRAS have a modest reduction in BP, which is significant only in those patients with an increased number of antihypertensive medications postprocedure. Caution must be taken in stenting patients with incidental RAS as outcome benefit may be minimal when compared to medical management only.
Introduction
Atherosclerotic renal artery stenosis (ARAS) is becoming an increasingly recognized entity with the widespread use of noninvasive vascular imaging, cardiac catheterization, and diagnostic arteriography for nonrenal vascular disease. Quite commonly, during angiography for other indications, significant ARAS is discovered and frequently intervened upon, despite nebulous and sometimes contradictory conclusions in the literature regarding the efficacy of such interventions.
The prevalence of renal artery stenosis (RAS) depends on the population screened and the imaging technique used to establish the diagnosis. In a study of 1,459 patients undergoing coronary angiography, concomitant abdominal aortography revealed significant ARAS in 10.8% of patients screened.1 Kalra et al.2 examined the incidence of atherosclerotic renal artery disease in a 5% random sample of the U.S. Medicare population and found that the incidence of atherosclerotic renovascular disease was around 3.7 per 1,000 patient-years.
Given the common practice of imaging the renal arteries during angiography or other imaging procedures, the benefits and risks of intervening on RAS that is discovered incidentally remain enigmatic. The lack of a sufficiently sensitive and predictive functional test to establish a relationship between ARAS, hypertension, and ischemic nephropathy makes the determination of whether to intervene even more difficult.
The objective of this study was to examine all patients who underwent renal arteriography at our institution over a 4-year period and to determine whether an incidentally discovered RAS treated with percutaneous transluminal renal angioplasty and stenting (PTRAS) resulted in an improvement of systemic hypertension, as assessed by blood pressure (BP) and number of hypertensive medications used, and preservation of renal function, as assessed by serum creatinine (SCr) and glomerular filtration rate (GFR).
Methods
Patient Selection
This was a retrospective chart review of patients at the University of California, San Diego Medical Center (UCSDMC) who underwent renal angiography during a 4-year period between the years 2000 and 2004. Institutional review board approval was obtained. Patients were identified by International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) code 88.45 for arteriography of the renal arteries. All inpatients and outpatients undergoing contrast renal angiography were included in the study. Exclusion criteria were age <18 years and a diagnosis of fibromuscular dysplasia.
Clinical Evaluation
Demographic data consisting of age, sex, and race were recorded, as were comorbidities (Table I). Clinical parameters including systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and SCr were recorded for both the pre- and postangiography periods. Our study design required a minimum of three separate BP readings from three separate occasions both pre- and postprocedure for a patient to be included in the final outcome analysis. Any patients not meeting these criteria were considered to have incomplete follow-up. BP values were taken from those documented in the chart from clinic visits. As an indirect measure of GFR, the Modification of Diet in Renal Disease Study (MDRD) prediction equation was used.3 In addition to requiring only four patient variables (SCr, age, race, sex) to estimate GFR, the MDRD equation has been suggested to provide a better estimate of GFR than the Cockcroft-Gault formula.3
Table I. Baseline characteristics of the study population undergoing renal angiography over 4 years
| Parameter | Sample sizea | Value |
|---|---|---|
| Patient profiles | ||
 Mean age, years (range) | 69 (24-93) | |
| Male sex (%) | 124 | 60 (45) |
| Caucasian (%) | 74 (60) | |
| Comorbidities (%) | ||
| DM | 38 (32) | |
| CHF | 33 (28) | |
| Unstable angina | 120 | 44 (37) |
| Stroke | 23 (19) | |
| Flash pulmonary edema | 5 (4) | |
| Hyperlipidemia | 86 (72) | |
| On hemodialysis (%) | 124 | 5 (4) |
| Clinical profiles | ||
| Mean SBP, mm Hg ± SD | 151 ± 22.7 | |
| Mean DBP, mm Hg ± SD | 122 | 77 ± 13.3 |
| Mean MAP, mm Hg ± SD | 101 ± 14.4 | |
| Mean SCr, mg/dL (range) | 123 | 1.2 (0.5-7.4) |
| Mean GFR,b mL/min/1.73m2 (±SD) | 118 | 53 ± 25.5 |
| High-grade RAS diagnosis at angiogram (%) | 78 (63) | |
| Unilateral RAS | 57 (46) | |
| Bilateral RAS | 124 | 21 (17) |
| Received PTRAS | 58 (47) | |
| Unilateral PTRAS | 50 (40) | |
| Bilateral PTRAS | 8 (6) | |
| Medication profiles | ||
| Number of antihypertensive medications (%) | ||
| None | 14 (11) | |
| One | 20 (16) | |
| Two | 39 (31) | |
| Three | 124 | 31 (25) |
| Four | 11 (9) | |
| Five | 3 (2) | |
| Information not available | 6 (5) | |
| Number of different classes of antihypertensive medications (%) | ||
| No medications | 14 (11) | |
| One | 124 | 20 (16) |
| Two | 45 (36) | |
| Three | 28 (23) | |
| Four | 12 (10) | |
| Information not available | 6 (5) | |
an <124 means that the parameter evaluated was only available for that number of patients out of the entire study population of 124 patients. |
bModification of Diet in Renal Disease (MDRD) prediction equation for GFR: GFR = 186.3 × (Pcr)−1.154 × (age)−0.203 × 1.212 (if black) × 0.742 (if female). |
The antihypertensive medication(s) of each patient both pre- and postangiography was recorded. The total number of antihypertensive medications and the number of different classes of antihypertensive agents used by each patient were determined.
Assessment of RAS and Renal Imaging
A diagnosis of high-grade RAS was defined as a ≥70% reduction in renal artery diameter based on contrast angiographic finding. The presence of unilateral and bilateral RAS was also accounted for. The indication(s) for angiography was recorded.
Follow-Up
Patient charts were reviewed for a total of 12 months postangiography, and data points were abstracted. Clinical variables including SBP, DBP, MAP, SCr, and estimated GFR were averaged for the duration of follow-up.
Outcome Assessment
Primary outcomes were hypertension control as assessed by reduction of BP and number of antihypertensive medications in all patients with an angiographic diagnosis of high-grade RAS who received PTRAS compared to those who received no intervention.
Secondary outcomes were improvement of renal insufficiency as assessed by both SCr and GFR after PTRAS.
Statistical Analysis
Baseline frequencies of clinical characteristics of the study population were gathered with descriptive analysis. Comparison between the two groups consisting of all patients with high-grade RAS managed with PTRAS and all patients with high-grade RAS managed without PTRAS was performed using a two-sided Student's t-test for continuous variables and Pearson's chi-squared test for dichotomous variables. Comparison between pre- and postclinical variables on all high-grade RAS patients who received PTRAS was performed by two-tailed paired t-test. All reported values required a p ≤ 0.05 for statistical significance. Statistical analysis was performed with SPSS software (SPSS Inc., Chicago, IL).
Results
Study Population and Follow-Up
Over 4 years, 131 patients underwent contrast renal angiography (Fig. 1). A total of seven were excluded: five were excluded secondary to a diagnosis of fibromuscular dysplasia and an additional two because of incomplete charts. Our final study population consisted of a total of 124 patients. A diagnosis of high-grade RAS (≥70%) was established in 78 patients (63%). Fifty-eight (74%) out of the 78 patients diagnosed with high-grade RAS underwent PTRAS. Of all patients undergoing PTRAS, 38 (66%) had sufficient follow-up during the 12 months postprocedure to allow assessment of clinical outcome. Twenty patients (34%) had inadequate follow-up and were excluded from the outcome analysis.
Fig. 1
Overview of the entire study population, demonstrating the distribution of patients undergoing renal angiogram.
For the 124 patients undergoing renal angiography, the primary indication listed for the procedure was coronary ischemia and/or congestive heart failure in 48%, peripheral vascular disease in 6%, unclear in 6%, and suspected RAS in 40% (Fig. 2). When the group of 124 patients was analyzed by all indications listed in the operative report, 19% had a single indication of RAS for the renal angiogram (Fig. 3). Examination of those patient charts revealed that a diagnosis of RAS was made on prior imaging done as an indication for extrarenal disease. Therefore in essence these lesions were incidental and were included in our study.
Fig. 2
Primary indication for angiography as listed on the procedural operative note (n = 124).
Fig. 3
Distribution of renal angiograms by all indications listed in the operative note (n = 124). 19% of patients had a single indication of RAS listed on the procedure note; however, RAS was detected incidentally during prior imaging for extrarenal disease. HTN, hypertension; CAD, coronary artery disease; CRI, chronic renal insufficiency; PVD, peripheral vascular disease.
Baseline Characteristics
Demographic and clinical characteristics of the study population are listed in Table I. Variables not available for all patients were not counted in the sample size used in final calculations. A total of 78 patients were diagnosed with high-grade RAS. Fifty-seven patients had unilateral RAS and 21 had bilateral RAS. Five patients, 4% of the total study population, were on hemodialysis at the time of the renal angiogram. Only one out of these five patients had a diagnosis of high-grade RAS, which was unilateral. None of the five patients on hemodialysis underwent PTRAS.
Comparison of Patients with High-Grade RAS with and without PTRAS
Of the 78 patients diagnosed with high-grade RAS by renal angiography, 58 were treated with PTRAS (Table II). Baseline characteristics of all patients with high-grade RAS were compared between those receiving PTRAS and those who did not (Table II). The two groups were similar in age, sex, race, antihypertensive medications, GFR, SCr, and most comorbidities. A higher proportion of patients in the stented group had a history of hyperlipidemia (p = 0.05). Although there was no significant difference between the groups in SBP and MAP, patients who were not stented had a slightly higher mean DBP (80 ± 14.5 vs. 74 ± 11.2 mm Hg, p = 0.04).
Table II. Comparison of baseline characteristics of high-grade RAS patients by intervention
| PTRAS group (n = 58) | No intervention group (n = 20) | Student's t-test P | Pearson's chi-squared p | |
|---|---|---|---|---|
| Demographic | ||||
| Age, years (±SD) | 72.6 ± 9.1 | 69.4 ± 16.8 | 0.28 | |
| Female sex (%) | 34 (57) | 9 (45) | 0.29 | |
| Race (%) | ||||
| Non-Hispanic, white | 38 (66) | 13 (65) | 0.72 | |
| Black | 3 (5) | 2 (10) | ||
| Latino/Hispanic | 9 (16) | 3 (15) | ||
| Asian | 4 (7) | 2 (10) | ||
| Clinical characteristics preprocedure | ||||
| Mean SBP, mm Hg (±SD) | 150 ± 20.5 | 152 ± 25.9 | 0.69 | |
| Mean DBP, mm Hg (±SD) | 74 ± 11.2 | 80 ± 14.5 | 0.04 | |
| MAP, mm Hg (±SD) | 99 ± 12.4 | 104 ± 16.8 | 0.15 | |
| Antihypertensive medication regimen (%) | ||||
| No medication | 4 (7) | 4 (20) | 0.44 | |
| One medication | 11 (20) | 3 (15) | ||
| Two medications | 16 (29) | 8 (40) | ||
| Three medications | 16 (29) | 4 (20) | ||
| Four medications | 5 (9) | 1 (5) | ||
| Five medications | 3 (6) | 0 (0) | ||
| Antihypertensive regimen by number of different medication classes (%) | ||||
| No medication | 4 (7.3) | 4 (20) | 0.35 | |
| One class | 11 (20) | 3 (15) | ||
| Two classes | 19 (35) | 9 (45) | ||
| Three classes | 13 (23.6) | 3 (15) | ||
| Four classes | 8 (15) | 1 (5) | ||
| Mean calculateda GFR,b mL/min/1.73 m2 (±SD) | 50 ± 25.5 | 57 ± 22.1 | 0.29 | |
| SCr (±SD)c | 1.5 ± 0.67 | 1.5 ± 1.2 | 0.89 | |
| Coexisting conditions (%) | ||||
| Diabetes mellitus | 17 (30) | 5 (26) | 0.74 | |
| Congestive heart failure | 20 (36) | 5 (26) | 0.46 | |
| Unstable angina | 20 (36) | 4 (21) | 0.24 | |
| Stroke | 11 (20) | 7 (37) | 0.13 | |
| Flash pulmonary edema | 3 (5) | 1 (5) | 0.99 | |
| Hyperlipidemia | 45 (78) | 11 (55) | 0.05 | |
an = 55. |
bModification of Diet in Renal Disease (MDRD) prediction equation for GFR: GFR = 186.3 × (Pcr)−1.154 × (age)−0.203 × 1.212 (if black) × 0.742 (if female). |
cn = 57. |
Outcomes
Two-thirds of the patients receiving PTRAS for high-grade RAS had sufficient follow-up over the 12 months at our institution to assess clinical outcome (Fig. 1). The baseline and post-PTRAS clinical parameters were compared for the 38 patients who received follow-up (Table III). Mean pre- and postprocedure SBP, DBP, MAP, SCr, and GFR were compared over the 12-month period.
Table III. Clinical outcomes of patients diagnosed with high grade RAS and receiving PTRAS over 12 months of follow-up (n = 38)
| Baseline | 12 months after PTRAS | p | |
|---|---|---|---|
| Mean SBP, mm Hg (±SD) | 153 ± 20.8 | 136 ± 27.2 | 0.01 |
| Mean DBP, mm Hg (±SD) | 78 ± 10.1 | 76 ± 25.4 | 0.67 |
| Mean MAP, mm Hg (±SD) | 103 ± 11.2 | 95 ± 17 | 0.04 |
| GFR, mL/min/1.72 (±SD) | 50 ± 26.7 | 50.9 ± 27.1 | 0.34 |
| SCr, mg/dL (±SD) | 1.5 ± 0.69 | 1.5 ± 0.68 | 0.64 |
There was no statistically significant difference between pre- and post-PTRAS GFR (50 ± 26.7 vs. 50.9 ± 27.1 mL/min/1.73 m2, p = 0.34) or SCr (1.5 ± 0.69 vs. 1.5 ± 0.68 mg/dL, p = 0.64). At 12-month follow-up there was a reduction in mean SBP from 153 ± 20.8 to 136 ± 27.2 mm Hg, reaching statistical significance (p = 0.01). There was also a similar significant reduction in MAP from 103 ± 11.2 to 95 ± 17 mm Hg (p = 0.04). There was no significant reduction in DBP (78 ± 10.1 vs. 76 ± 25.4 mm Hg, p = 0.67).
The 38 patients with high-grade RAS who both received PTRAS and had follow-up were stratified into three groups consisting of those who postprocedure had (1) an increase (n = 16), (2) no change (n = 12), or (3) a decrease (n = 10) in hypertensive medications (Fig. 4). A statistically significant reduction in SBP, DBP, and MAP was only noted in the group that also had an increase in post-PTRAS antihypertensive medications (p < 0.05).
Fig. 4
Comparison of baseline and 12 months: A SBP, B DBP, and C MAP in 38 patients with high-grade RAS who underwent PTRAS as stratified into three groups consisting of those having an increase (n = 16), a decrease (n = 10), or no change (n = 12) in their postprocedure antihypertensive medications. A statistically significant reduction in SBP, DBP, and MAP was demonstrated only in the group that also had a postprocedural increase in antihypertensive medications (*p < 0.05).
Twenty-one (17%) of the total patients in our study population had a diagnosis of bilateral RAS (BRAS, Table IV). Five patients received no intervention, eight received unilateral PTRAS, and eight received bilateral PTRAS. Of the total 21 patients angiographically diagnosed with BRAS, only three had sufficient follow-up over the 12 months postprocedure. For those three patients having BRAS and receiving PTRAS, clinical outcomes were compared at baseline and over the 12 months after the procedure (Table V). There was no difference between the groups in terms of mean SBP (145 ± 12.7 vs. 134 ± 10.1 mm Hg, p = 0.24), mean DBP (67 ± 20.5 vs. 63 ± 12.1 mm Hg, p = 0.66) and mean MAP (92 ± 15.4 vs. 86 ± 8.7 mm Hg, p = 0.45) when comparing baseline to 12-month follow-up, respectively.
Table IV. Subset of patients with BRAS
| Sample size (n) | Proportion of interest (%) | |
|---|---|---|
| Patients with BRAS | 124 | 21 (17) |
| BRAS no intervention | 21 | 5 (24) |
| BRAS + unilateral PTRAS | 21 | 8 (33) |
| BRAS + bilateral PTRAS | 21 | 8 (33) |
| Patients with 12-month follow-up | 21 | 3 (13) |
Table V. Clinical outcomes of patients diagnosed with BRAS and receiving PTRAS over 12 months of follow-up (n = 3)
| Baseline | 12 months after PTRAS | p | |
|---|---|---|---|
| Mean SBP, mm Hg (±SD) | 145 ± 12.7 | 134 ± 10.1 | 0.24 |
| Mean DBP, mm Hg (±SD) | 67 ± 20.5 | 63 ± 12.1 | 0.66 |
| Mean MAP, mm Hg (±SD) | 92 ± 15.4 | 86 ± 8.7 | 0.45 |
Discussion
ARAS has come to increased attention with the liberal use of advanced diagnostic imaging and vascular interventional techniques. Hansen et al.,4 in a longitudinal, prospective, population-based study among elderly participants in the Cardiovascular Health Study, showed that hemodynamically significant renovascular disease, as defined by ≥60% RAS or occlusion by renal duplex sonography, was present in 6.8% of this elderly free-living cohort. It is estimated that as much as 25% of patients undergoing routine coronary angiography and 50% of patients undergoing peripheral angiography will have evidence of atheromatous RAS.5 Although ARAS is an important cause of renovascular hypertension and ischemic nephropathy, its anatomic presence does not always prove functionality. To date, there is no established method that can reliably identify patients whose renal function is at risk from atherosclerotic renal vascular occlusive disease and which of those will benefit from catheter or surgical intervention. Therefore, the incidental finding of atherosclerotic renal disease in the older patient undergoing evaluation for extrarenal disease remains a management dilemma. Several observational studies argue against the routine interventional treatment of incidentally discovered RAS.6, 7, 8 Collectively, these reports suggest that in the absence of bilateral RAS or stenosis of a solitary functioning kidney, an incidental lesion that is left untreated rarely progresses to uncontrolled hypertension or renal failure. In our retrospective series of 124 patients undergoing contrast angiography, 63% had evidence of high-grade RAS (≥70%) that was discovered on evaluation of extrarenal disease. When the decision is made to treat renovascular disease, options include medical management, renal artery angioplasty with or without stenting (PTRAS), or surgical revascularization. Despite the apparent high prevalence of ARAS, consensus on diagnosis, treatment, and follow-up is lacking. Most of the available literature addressing these outcomes is based on observational studies; however, there are a few randomized clinical trials (RCTs) that have investigated these end points.
In the only prospective RCT comparing percutaneous transluminal angioplasty (PTA) to surgical revascularization for renovascular disease, Weibull et al.9 demonstrated that although surgical revascularization had higher patency rates, improvement in blood pressure and renal function did not differ between the two groups. van de Ven et al.,10 in an RCT, compared PTA with PTRAS in patients with ostial atherosclerotic RAS ≥50%; and although PTRAS had significantly better technical success rates at 6-month follow-up, there was no change in SCr or number of antihypertensive medications between the groups.
An interesting issue that follows is that of how percutaneous interventions compare with medical management alone. A systematic review of the available data provided by the Cochrane Database suggests that there are insufficient data to conclude that balloon angioplasty is superior to medical therapy in patients with medically controlled blood pressure.11 A significant portion of this analysis came from the contribution of three RCTs comparing percutaneous treatment with medical treatment of renovascular hypertension.12, 13, 14 The Essai Multicentrique Medicaments vs. Angioplastie (EMMA) Study Group randomly assigned 49 patients with unilateral ARAS to angioplasty versus medical treatment alone.12 At 6-month follow-up there was no statistically significant difference in BP between groups, although the angioplasty group required a reduced amount of antihypertensive medications. The Scottish and New Castle Renal Artery Stenosis Collaborative Group randomly assigned 55 patients with ≥50% RAS to either angioplasty or medical management.13 They noticed a modest reduction in SBP when compared to medical therapy alone; however, this benefit was limited to patients with bilateral RAS. There was no difference in renal function as assessed by SCr. The largest prospective study to date is the Dutch Renal Artery Stenosis Intervention Cooperative (DRASTIC), which randomized 106 patients with RAS ≥50% to either angioplasty or medical management.14 Based on an intention-to-treat analysis, at 1 year there were no significant differences in BP, medication, and/or renal function.
These studies point out that, at best, percutaneous angioplasty has a modest effect on hypertension, with possible negligible effects on renal function when compared to medical management alone. Although these are randomized trials, caution must be taken as sample size is modest and they may lack sufficient power to detect subtle differences.
The outcomes of these studies serve as a basis for the interpretation of our study. In our series of 124 patients over 4 years undergoing renal angiography, 63% were diagnosed with high-grade RAS and 74% of these received an intervention in the form of PTRAS. The patients who received a stent were similar in terms of baseline characteristics to those patients not stented. The only exception is that stented patients had a higher proportion of hyperlipidemia and a lower mean DBP. Of the 58 patients who received PTRAS, only 66% had sufficient follow-up during the subsequent 12 months after the procedure to assess study outcomes. This lower than expected number is likely a testament to our gap in understanding how these patients should be managed and the lack of consensus as to how they should be followed up.
When pre- and postprocedure clinical parameters of patients with adequate follow-up undergoing PTRAS were compared, a statistically significant reduction in SBP and MAP was noted. There was no significant reduction in DBP, GFR, or SCr. When these patients were stratified by medication group, only those who also had a postprocedure increase in their antihypertensive medications had significant reductions in SBP, DBP, and MAP. This would suggest that the improvement in BP was due to an increase in medication rather than PTRAS. The etiology of hypertension in this subgroup of patients may not have been renovascular in nature. Another possibility to explain the lack of effect of PTRAS on hypertension is restenosis after stenting. The use of follow-up imaging in our patient population was scarce, which precluded further investigation of this; however, the presence of significant restenosis would also be considered a failure of intervention.
Although currently there is no test that predicts which patients would benefit most from PTRAS, perhaps clinical benefit would be most apparent in those patients with a strong history of malignant hypertension, worsening renal function, and flash pulmonary edema. The threshold for intervention in our patient population may have improved if the stenosis was shown to affect renal function by captopril renography or after an increase in SCr following standardized angiotensin-converting enzyme inhibition. Patients with RAS of a solitary functioning kidney or bilateral RAS may receive maximal benefit. We identified 21 patients with bilateral RAS. Sixteen of these received PTRAS, but only three had sufficient 12-month follow-up. Outcome analysis revealed that there was no significant difference in pre- and postprocedural BP. Caution must be taken in interpreting these data as this was a comparison of a relatively small sample size. Only analysis of a larger representative population with BRAS would enable assessment of the outcome of intervention in this group.
Although a retrospective analysis with a modest sample size, our results show that patients with incidentally discovered RAS receiving PTRAS had a small benefit in BP reduction. This benefit was confounded by the fact that these patients also had an increase in postprocedure antihypertensive medical treatment.
In addition to the limitations inherent to a retrospective single-institution chart review, our study had some other drawbacks. There is the potential for selection bias as those patients who gained no improvement from intervention were more likely to require additional clinical follow-up and to be represented in our study population.
Conclusion
A significant proportion of patients undergoing angiography for cardiovascular or peripheral arterial occlusive disease will have an incidental anatomic diagnosis of RAS. In our series, PTRAS of these lesions resulted in significant reduction in BP only in a subgroup of patients who also had an increase in postprocedure antihypertensive medication use. No improvement in renal insufficiency was noted. In this patient population PTRAS is less likely to provide clinical benefit. At present, the management of incidental RAS is controversial and our data do not support the routine practice of renal angioplasty and stenting.
We thank Paul Shragg at the University of California, San Diego Medical Center's General Clinical Research Center for his assistance with statistical analysis.
References
- The prevalence and clinical predictors of atherosclerotic renal artery stenosis in patients undergoing coronary angiography. Heart Vessels. 2004;19:275–279
- Atherosclerotic renovascular disease in United States patients aged 67 years or older: risk factors, revascularization, and prognosis. Kidney Int. 2005;68:293–301
- . Prediction equations to estimate glomerular filtration rate: an update. Curr Opin Nephrol Hypertens. 2001;10:785–792
- Prevalence of renovascular disease in the elderly: a population based study. J Vasc Surg. 2002;36:443–451
- . ABC of arterial and venous disease: renal artery stenosis. BMJ. 2000;320:1124–1127
- . Incidental renal artery stenosis in peripheral vascular disease: a case for treatment?. Kidney Int. 2001;59:1480–1483
- The natural history of incidental renal artery stenosis in patients with aortoiliac vascular disease. Am J Med. 2000;109:642–647
- Outcomes of atherosclerotic renal artery stenosis managed without revascularization. Mayo Clin Proc. 2000;75:437–444
- Percutaneous transluminal renal angioplasty versus surgical reconstruction of atherosclerotic renal artery stenosis: a prospective randomized study. J Vasc Surg. 1993;18:841–850
- Arterial stenting and balloon angioplasty in ostial atherosclerotic renovascular disease: a randomised trial. Lancet. 1999;353:282–286
- . Balloon angioplasty versus medical therapy for hypertensive patients with renal artery obstruction. Cochrane Database of Systematic Reviews. 2003;3;CD002944
- Blood pressure outcome of angioplasty in atherosclerotic renal artery stenosis: a randomized trial. Essai Multicentrique Medicaments vs. Angioplastie (EMMA) Study Group. Hypertension. 1998;31:823–829
- Randomised comparison of percutaneous angioplasty vs. continued medical therapy for hypertensive patients with atheromatous renal artery stenosis. Scottish and Newcastle Renal Artery Stenosis Collaborative Group. J Hum Hypertens. 1998;12:329–335
- The effect of balloon angioplasty on hypertension in atherosclerotic renal-artery stenosis. Dutch Renal Artery Stenosis Intervention Cooperative Study Group. N Engl J Med. 2000;342:1007–1014
PII: S0890-5096(08)00095-2
doi:10.1016/j.avsg.2007.12.022
© 2008 Annals of Vascular Surgery Inc. Published by Elsevier Inc All rights reserved.
