Survival after stenting of severe atherosclerotic ostial renal artery stenoses

How should we define appropriate patients for percutaneous transluminal renal angioplasty treatment?

Renovascular hypertension (RVH) is one of the most common causes of secondary hypertension and can result in resistant hypertension. RVH is associated with an increased risk for progressive decline in renal function, cardiac destabilization syndromes including "flash" pulmonary edema, recurrent congestive heart failure, and cerebrocardiovascular disease. The most common cause of renal artery stenosis (RAS) is atherosclerotic lesions, followed by fibromuscular dysplasia. The endovascular technique of percutaneous transluminal renal angioplasty (PTRA) with or without stenting is one of the standard treatments for RAS. Randomized controlled trials comparing medical therapy with PTRA to medical therapy alone have failed to show a benefit of PTRA; however, the subjects of these randomized clinical trials were limited to atherosclerotic RAS patients, and patients with the most severe RAS, who would be more likely to benefit from PTRA, might not have been enrolled in these trials. This review compares international guidelines related to PTRA, reevaluates the effects of PTRA treatment on blood pressure and renal and cardiac function, discusses strategies for the management of RVH patients, and identifies factors that may predict which patients are most likely to benefit from PTRA.

Impact of Percutaneous Revascularization on Left Ventricular Mass and Its Relationship to Outcome in Hypertensive Patients With Renal Artery Stenosis

BACKGROUND

We investigated the effects of percutaneous transluminal renal angioplasty on left ventricular (LV) mass, and the impact of LV mass reduction on outcomes.

METHODS

A total of 144 hypertensive patients with renal artery stenosis (RAS) (mean age 69 years; 22.2% fibromuscular dysplasia (FMD)) who underwent angioplasty were included. Echocardiography was performed at baseline and after 1 year, and patients were thereafter followed up for a median of 5.6 years for primary composite outcomes.

RESULTS

In both the FMD and atherosclerotic stenosis (ARAS) groups, LV mass decreased after angioplasty, but the decrease in LV mass index (-15.4 ± 18.3% vs. -0.8 ± 27.8%, P < 0.01) as well as the regression rate of LV hypertrophy was greater in FMD. Multiple logistic regression analysis indicated that FMD (odds ratio (OR) 2.94, P < 0.01), severe RAS (≥90%) (OR 2.94, P < 0.05), and higher LV mass index at baseline (OR 2.94 for 1 SD increase, P < 0.001) were independent predictors of LV mass index decrease of at least 20%. The primary composite outcomes occurred in 45 patients (31.3%). In FMD, lower LV mass index after 1 year (hazard ratio 2.81 for 1 SD increase, P < 0.05) or regression of LV mass (hazard ratio 0.75 for 5% decrease, P = 0.054) showed a tendency to be associated with better outcomes; however, these associations were not found in ARAS.

CONCLUSIONS

Hypertensive patients with ARAS have less regression of LV mass in response to angioplasty than those with FMD, and LV mass regression is less useful as a surrogate marker of outcomes especially in ARAS.

Percutaneous transluminal renal angioplasty of global kidney ischemia improves renal function and blood pressure

Background

Renal artery stenosis (RAS) can lead to hypertension and renal failure. Nevertheless, its treatment by percutaneous transluminal renal angioplasty (PTRA) remains controversial. It is unknown, whether patients with global kidney ischemia (GKI), that means patients with bilateral RAS or RAS with a single functioning kidney, may benefit from PTRA or not.

Methods

We retrospectively analyzed 93 patients with RAS (25 bilateral or single functioning kidney) undergoing PTRA. Patients had refractory hypertension (≥3 medications). Blood pressure, antihypertensive drugs and serum-creatinine were compared pre-/post-intervention and at 1 year’s follow-up.

Results

At 1 year after PTRA of patients with GKI, systolic and diastolic blood pressure were significantly reduced compared to patients with unilateral PTRA (systolic: −19.1 ± 10.5 [bilateral] vs. −11.4 ± 12.1 mmHg [unilateral], P < 0.01; diastolic: −10.1 ± 6.8 mmHg vs. −6.3 ± 6.6 mmHg, P < 0.05). The number of antihypertensive drugs was reduced by −0.8 ± 3.0 at 1 year in patients with GKI, while it increased by +0.1 ± 3.5 in the unilateral RAS group (P < 0.001). Furthermore, post-interventional serum-creatinine decreased by −34.6 ± 31.4 μmol/I after of patients with GKI (P < 0.001 vs. baseline). In patients with unilateral PTRA, a non-significant increase in serum-creatinine was observed (+8.3 ± 2 μmol/l).

Conclusion

PTRA in patients with GKI led to improved blood pressure and renal function. A large, well-designed, randomized clinical trial targeting this population is still needed. The benefit of PTRA should be measured with the risks in each patient individually.

Kissing stent management of stenosis of two branches of left renal artery bifurcation: a case report

Background

Secondary hypertension accounts for 5% of all cases of hypertension. Renal artery stenosis is one of the common causes of secondary hypertension. Atherosclerosis and fibromuscular dysplasia are the commonest types of stenosis associated with renal vascular hypertension, with the former accounting for 70–80% of all cases and the latter accounting for 10% of the incidence. The greatest incidence atherosclerosis is in men over the age of 40 years, mostly affecting the proximal part of the renal arteries, whereas fibromuscular dysplasia affects women ranging in age from 30 to 50 years. Currently, possible treatments are medical treatment using blood pressure-lowering drugs, balloon angioplasty with or without stent insertion, and surgery to reconstruct the artery.

Case presentation

We report a case of a 46-year-old Asian woman with stenosis of two branches of renal artery bifurcation treated by percutaneous balloon dilatation and stenting of both branches after referral to our department for a renal angiogram following 8 months of uncontrolled hypertension despite receiving medications. Initially, the patient presented with severe headache and fatigue. She was a known nonsmoker, was not diabetic, and had no history of diabetes in her family. She had no history of atherosclerosis. Apart from high blood pressure, the result of her physical examination was unremarkable. Laboratory investigations revealed normal serum cholesterol, lipid profile, and serum creatinine. She had been attending a hypertension clinic and receiving antihypertensive drugs for the past 8 months on a regular basis under close observation. Despite this treatment and care, her blood pressure remained high at 175/110 mmHg, which the attending doctor concluded to be uncontrolled blood pressure. Initial imaging indicated left renal artery stenosis, and the patient was referred to our department.

Conclusions

For patients with uncontrolled hypertension despite receiving medications, renal Doppler ultrasound should be included in the diagnostic workup for secondary hypertension. Once renal artery stenosis is suspected, renal angiography is highly recommended because the technique is able to accurately diagnose stenosis in the branch arteries, unlike computed tomographic angiography and magnetic resonance angiography. Percutaneous transluminal renal angioplasty is the treatment of choice for renal artery stenosis in patients with renovascular hypertension or renal dysfunction.

Association between renal function and outcomes after percutaneous transluminal renal angioplasty in hypertensive patients with renal artery stenosis

OBJECTIVE

We investigated the impact of renal function on outcomes after percutaneous transluminal angioplasty.

METHODS

A total of 139 hypertensive patients with atherosclerotic renal artery stenosis (mean age, 70 years, 80.6% men) who underwent renal percutaneous transluminal angioplasty were included. Renal function was evaluated on the basis of estimated glomerular filtration rate (eGFR) and albuminuria/proteinuria, and classified into three categories according to eGFR (≥45, 30-44, and <30 ml/min/1.73 m) and albuminuria/proteinuria [normal-to-mild: albumin/creatinine ratio (ACR) less than 3.0, protein/creatinine ratio (PCR) less than 15; moderate: ACR 3.0-30.0, PCR 15-50; severe: ACR > 30.0, PCR > 50 mg/mmol].

RESULTS

During a median follow-up of 5.4 years, 36.0% of patients developed the primary composite end point, including cardiovascular and renal outcomes. In multivariate Cox regression analysis, eGFR less than 30 (hazard ratio 3.47, P < 0.01) as well as severe albuminuria/proteinuria (hazard ratio 2.63, P < 0.05) was an independent predictor of worse outcome. In the subgroup without events within 1 year after angioplasty (n = 117), the outcome differed among the three renal functional categories at 1 year based on eGFR (log-rank χ = 16.28, P < 0.001) as well as on albuminuria/proteinuria (log-rank χ = 8.30, P < 0.05). At 1 year, 24 patients (20.1%) showed at least 20% decrease in eGFR, and their outcome was worse than that in those with at least 20% increase (n = 23) (hazard ratio 3.50, P < 0.05). Multiple logistic regression analysis indicated that pretreatment moderate-to-severe albuminuria/proteinuria was an independent predictor of at least 20% eGFR decrease (odds ratio 2.82, P < 0.05).

CONCLUSION

Impaired renal function, and in particular, a poor response of eGFR to angioplasty, is associated with worse outcome. Therapeutic effectiveness of renal angioplasty seems to be limited in patients with albuminuria/proteinuria.

Resultados a longo prazo da angioplastia de artérias renais com stent na doença aterosclerótica: revisão sistemática

Resumo A doença renovascular aterosclerótica é a principal causa de hipertensão secundária. A história natural da doença demonstra taxas de progressão de 4 a 12% ao ano. Entre os métodos de tratamento existe a angioplastia com stent de artérias renais; porém, poucos estudos clínicos demonstraram seus resultados a longo prazo. Esta revisão sistemática da literatura se propõe a apresentar os resultados a longo prazo (acima de 24 meses) da angioplastia com stent de artérias renais na doença aterosclerótica em relação à função renal e aos níveis pressóricos no controle da hipertensão. Foi realizada uma ampla pesquisa, utilizando os termos apropriados, nas bases de dados LILACS, EMBASE, SCIELO, Cochrane Library e MEDLINE. De um total de 2.170 referências, apenas sete artigos contemplavam todos os critérios de inclusão. Conclui-se que, a longo prazo, há uma estabilização da função renal, redução dos níveis pressóricos e diminuição do número de classes de medicamentos anti-hipertensivos.

Identification of Factors Associated With Improved Survival After Renal Artery Stenting

Atherosclerotic renal artery stenosis (RAS) is associated with high mortality rates, but large randomized trials have not shown improvement in survival with renal artery stenting. These results suggest that factors other than ongoing renal hypoperfusion are important in determining survival in patients with RAS. Using logistic regression models, we performed a single-center, case-control study that included 188 patients with ≥70% RAS with an average age of 67 ± 10 years, 54% women, 20% black, and 70% smokers; 118 patients (63%) underwent renal artery stenting. A total of 89 patients (47%) died during an average follow-up of 5.1 years. Previous myocardial infarction (MI) (odds ratio 2.6 95% confidence interval [1.4 to 4.7]), left ventricular ejection fraction (LVEF) ≤35% (odds ratio 4.1 95% confidence interval [1.6 to 10.6]), and renal insufficiency were predictors of mortality in this study. The risk associated with LVEF ≤35% and previous MI were additive with mortality of 40%, 54%, and 85%, respectively, with 0, 1, or both these factors. Renal artery stenting was associated with a 43% reduction in mortality in patients with 0 or 1 mortality risk factors (defined as LVEF ≤35%, previous MI, and glomerular filtration rate ≤45 ml/min/1.73 m²) but had no effect on mortality in patients with 2 or 3 mortality risk factors. Systolic blood pressure, diastolic blood pressure, or severity of RAS did not correlate with survival. In conclusion, this retrospective analysis suggests that clinical, in addition to anatomic and physiological, factors should be considered in future studies examining effects of renal artery stenting on survival.

Percutaneous Endovascular Therapy of Renal Artery Stenosis: Technical and Clinical Developments in the past Decade

Renal artery stenosis may initiate or exacerbate arterial hypertension and/or renal insufficiency. During the last decade, technical improvements of diagnostic and interventional endovascular tools have led to more widespread use of endoluminal renal artery revascularization and broader indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Grüntzig in 1978, numerous single-center studies have documented the benefits of percutaneous renal revascularization. In the early 1990s, stent implantation was added to the interventionist's armamentarium for treating renal artery stenosis due to atherosclerosis or fibromuscular dysplasia. The metaanalysis of 3 randomized studies comparing balloon angioplasty with best medical therapy found intervention to be beneficial for blood pressure control but not for preservation of renal function. Despite the absence of randomized studies, there is mounting evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has a positive impact on blood pressure control and renal function. This article summarizes the technical improvements in these endovascular tools during the last decade and gives an overview concerning their clinical impact on renal artery revascularization.

Technological Advances in the Design of Catheters and Devices Used in Renal Artery Interventions: Impact on Complications

Purpose:

To analyze the impact of technical improvements in stent devices and guiding catheters (e.g., reduced device diameter, increased flexibility) on the complication rates associated with percutaneous renal artery interventions.

Methods:

During a 5-year period (1997–2001), 268 consecutive patients (178 men; mean age 67±9 years) had 370 atherosclerotic renal artery stenoses (RAS) ≥70% treated with angioplasty/stenting in 320 procedures. The guiding catheter technique was used routinely until 2000; in 2001, a guiding sheath was used in 29% of cases. From 1997 to 2000, sealing devices were frequently used for sheath removal; during the last year, the sheaths were removed using the Femostop device.

Results:

In 320 interventions, 32 (10%) complications occurred, with a decreasing frequency during the last 2 years (1996/97: 13% [7/53]; 1998: 16% [9/57]; 1999: 15% [11/74]; 2000: 4% [3/70]; 2001: 3% [2/66]). There were 21 (6.6%) local complications, including 4 cases requiring permanent hemodialysis after the intervention and 11 (3.4%) access site complications. No procedure-related death occurred. During the study period, the average sheath diameter was reduced from 8.15±0.76 F to 6.15±0.63 F (p<0.05). Mean procedural time was reduced from 42±13 minutes to 23±11 minutes (p<0.05). The initial heparin dose was reduced from 10,000 to 5000 units.

Conclusions:

In parallel with the use of more flexible catheters and premounted stents of lower profile, the complication rate of renal angioplasty/stenting of atherosclerotic RAS has been reduced significantly during a 5-year period.

Mortality and Renal Replacement Therapy after Renal Artery Stent Placement for Atherosclerotic Renovascular Disease

PURPOSE

To identify risk factors for progression to renal replacement therapy (RRT) and all-cause mortality in patients who underwent renal artery (RA) stent placement for atherosclerotic renal artery stenosis (RAS).

MATERIALS AND METHODS

A retrospective study from June 1996 to June 2009 identified 1,052 patients who underwent RA stent placement. Glomerular filtration rate at time of RA stent placement was estimated from serum creatinine level and divided into chronic kidney disease (CKD) stages 1-5. Univariate and multivariable Cox proportional hazards models were used to determine which factors were associated with each endpoint.

RESULTS

Times to progression to all-cause mortality and RRT were similar for CKD stages 1/2/3A and served as the reference group. In multivariable analysis, high-grade proteinuria (P < .001) and higher CKD stage (5 vs 1/2/3A [P < .001], 4 vs 1/2/3A [P < .001], 3B vs 1/2/3A [P = .02]) remained independently associated with increased risk of progression to RRT. Angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB) use was associated with decreased risk of progression to RRT (P = .03). Higher CKD stage (5 vs 1/2/3A [P < .001], 4 vs 1/2/3A [P = .004]), carotid artery disease (P < .001), diabetes mellitus (P = .002), and high-grade proteinuria (P < .001) remained independently associated with all-cause mortality. Statin use was associated with decreased risk of all-cause mortality (P < .001).

CONCLUSIONS

Patients with atherosclerotic RAS who undergo RA stent placement and have high-grade proteinuria and CKD stage 3B/4/5 have increased risk of progression to RRT. Patients with high-grade proteinuria, CKD stage 3B/4/5, carotid artery disease, or diabetes have increased risk for all-cause mortality after renal artery stent placement. Patients receiving ACEI/ARBs have a decreased risk of progression to RRT, and patients receiving statins have a decreased risk of all-cause mortality.

Risks for mortality and renal replacement therapy in atherosclerotic renovascular disease compared with other causes of chronic kidney disease

AIM

Patients with atherosclerotic renovascular disease (ARVD) have an increased risk for death and likelihood of initiating renal replacement therapy (RRT) compared with the general population. No data exist to describe prognosis in ARVD compared with other causes of chronic kidney disease (CKD). We compare patient outcomes between ARVD and other causes of CKD.

METHODS

Patients were selected from two prospective observational cohort studies of outcome in ARVD and CKD. Multivariate Cox regression was used to compare risk for RRT and death (both prior to and following initiation of RRT) between patients with ARVD and other causes of CKD.

RESULTS

Of 1472 patients (563 (38%) ARVD, 909 (62%) non-ARVD), 242 (16%) progressed to RRT and 640 (44%) died over a median follow-up period of 4.1 (2.4-5.6) years. Patients with ARVD had an increased risk for death (HR 1.5 (1.2-1.8), P < 0.001) but not for RRT (HR 1.0 (0.7-1.4), P = 0.9). The largest increase in risk for death was observed relative to renal limited diseases, e.g. pyelonephritis (HR 2.4 (1.3-4.5), P = 0.004) and interstitial/infiltrative disease (HR 2.2 (1.3-4.5), P = 0.02). Following initiation of RRT, patients with ARVD had a significantly increased risk for death compared with patients without ARVD (HR 3.3 (2.2-5.0), P < 0.001).

CONCLUSIONS

Patients with ARVD as a cause of CKD have an increased risk for death both prior to and following initiation of RRT. Further work should seek to identify modifiable risk factors relevant to prognosis.

The benefit of renal artery stenting in patients with atheromatous renovascular disease and advanced chronic kidney disease

BACKGROUND

Around 16% of all patients who present with atheromatous renovascular disease (ARVD) in the United States undergo revascularization. Historically, patients with advanced chronic kidney disease (CKD) have been considered least likely to show improvement in renal functional terms, or survival. We aimed to investigate whether differences in outcomes after revascularization compared to medical management might be observed in ARVD patients if stratified by their CKD classes.

METHODS

Two prospective cohorts, a UK center with a traditionally conservative approach, and a German center who undertook a proactive revascularization approach, were compared. An improvement in renal function was defined as > 20% renal improvement at one year's follow-up. To improve validity and comparability, revascularized patients in the UK center were also used within analyses,

RESULTS

347 (UK conservative group), 89 (UK revascularized group), and 472 (German center) patients were included in the analysis. When subdivided by CKD stage, patient ages between the two centers were comparable. Improvements in renal function were observed in twice as many patients who underwent revascularization as compared to medical treatment, particularly in the latter CKD stages, 15.2 (German revascularization) vs. 0% in CKD 1-2, 12.2 (UK), and 32.8 (German) revascularization vs. 14.1% in CKD3, and 53.1 and 53.8 vs. 28.3 in patients with CKD 4-5. The improvements in eGFR were 10.2 (16) and 8.1 (12.5) ml/min/year in the German and UK revascularized groups, respectively, vs. -0.05 (6.8) ml/min/year in the medical cohort in CKD 4-5. Improvements in blood pressure control were noted at 1 year overall and within each CKD category. Multivariate analysis revealed that revascularization independently reduced the risk of death by 45% in all patients combined (RR 0.55, P = 0.013).

CONCLUSIONS

Although this study has significant methodological limitations, it does shows that percutaneous renal revascularization can improve renal function in advanced CKD (stages 4-5), and that this can provide a survival advantage in prospective analysis.

Predicting blood pressure response after renal artery stenting

BACKGROUND

Although technical success of renal artery stenting (RAS) is high and adverse events are infrequent, clinical success (improved blood pressure and renal function) and durability have been less predictable. Identifying those patients who will respond to RAS could improve overall outcomes of the procedure.

METHODS

This was a retrospective analysis of all patients who underwent RAS for treatment of renovascular hypertension (RVH) between 2001 and 2007 at Dartmouth-Hitchcock Medical Center. The primary outcome measure was blood pressure improvement or cure as judged by American Heart Association criteria. Estimated glomerular filtration rate (eGFR), number of antihypertensive medications, and survival were evaluated as secondary outcomes. Univariate and multivariate analyses were performed to identify factors associated with blood pressure improvement at the last follow-up.

RESULTS

During the 6-year period, 129 patients (179 renal arteries) underwent stent placement for RVH. Procedural complications occurred nine patients (7.0%). Average length follow-up was 1.5 years. Follow-up data were obtained in 122 patients (95%). At last follow-up, there were significant improvements in systolic blood pressure (161 vs 144 mm Hg, P < .001), diastolic blood pressure (80 vs 73 mm Hg, P < .001), and number of antihypertensive medications (3.1 vs 2.8, P = .034). The eGFR was improved in 16% of patients, stable in 60%, and worse in 24%. By multivariate analysis, a baseline eGFR <40 mL/min/1.73 m2 (odds ratio, 1.6; 95% confidence interval [CI], 1.0-2.9; P = .02) and female gender (OR, 1.3; 95% CI, 1.0-2.1; P = .04) were independent predictors of failure to achieve blood pressure improvement. By 2 and 4 years of follow-up, sustained blood pressure improvement was present in 67% of patients with a baseline eGFR of > or = 40 mL/min/1.73 m2 and in 31% of patients with a baseline eGFR <40 mL/min/1.73 m2. During 2 years of follow-up, survival was similar between patients with sustained blood pressure response and those without.

CONCLUSION

Patients treated for RVH who have a baseline eGFR of > or = 40 mL/min/1.73 m2 demonstrate a better response to RAS at each follow-up interval, with a significant difference at 2 to 4 years, compared with patients with an eGFR <40 mL/min/1.73 m2.

Critical review of indications for renal artery stenting: do randomized trials give the answer?

Significant renal artery stenosis (RAS) is a well accepted cause of deterioration of arterial hypertension and of renal insufficiency. Just recently, more interest has been focused on the impact of RAS on structural heart disease and patient survival. Technical improvements of diagnostic and interventional endovascular tools have lead to a more widespread use of endoluminal renal artery revascularization and extension of the indications for this type of therapy during the past 2 decades. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Grüntzig, numerous single centre studies have reported the beneficial effect of percutaneous transluminal renal angioplasty, and since the early 1990's stenting of renal artery stenosis caused either by atherosclerosis or fibromuscular dysplasia. However, none of the so far published or presented randomized controlled trials (RCT) could prove a beneficial outcome of RAS revascularization compared with medical management. As a result of these negative trials including the recently presented ASTRAL trial, referrals to endovascular renal artery revascularization went down and moreover, reimbursement of these procedures became a matter of debate. This article summarizes the background and the limitations of the so far published and still ongoing controlled trials. Moreover, we discuss why well-designed registries might give important insight on the impact of endovascular revascularization of hemodynamically relevant atherosclerotic RAS.

Renal Cortical Thickness as a Predictor of Renal Function and Blood Pressure Status Post Renal Artery Stenting

Renal artery stenting is a widely performed procedure for atherosclerotic renal artery stenosis. It is very important to identify patients that will benefit from this procedure as this may involve potential risk and complications. Our study is a retrospective analysis aimed at evaluation of mid-pole renal cortical thickness at the time of stenting and correlating with renal function and blood pressure after the procedure. A total of 48 procedures were done on 31 patients evaluated in this study. The change in SBP was greater for the abnormal group compared to the normal group (-1.49 mmHg vs. -0.98 mmHg, P = 0.7813). The change in DBP was greater for the abnormal group compared to the normal group (-0.68 mmHg vs. 0.04 mmHg, P = 0.3809). The change in odds of having a GFR in higher categories was greater for the abnormal group compared to the normal group (OR =1.23 vs. 1.05, P = 0.3085). Our study did not show a significant association of renal cortical thickness and outcomes of BP and GFR following stenting of atherosclerotic renal artery stenosis. However, we did find a greater improvement in BP and GFR in patients with abnormal cortical thickness compared to those with normal cortical thickness.

Factors Influencing the Need for Target Vessel Revascularization After Renal Artery Stenting

PURPOSE

To provide additional insight into factors that may be associated with the need for target vessel revascularization (TVR) following de novo renal artery stenting during long-term follow-up.

METHODS

A retrospective chart and database review was conducted to analyze the progress of all patients with de novo symptomatic renal artery stenosis who underwent stent-supported angioplasty under the auspices of the Single Operator, Single Center, Renal Stent Retrospective Study (SOCRATES). The records review identified 782 patients who were enrolled in the study between 1993 and 2004; after excluding 34 (4.5%) patients (lost to follow-up or inadequate data), 748 consecutive patients (412 women; mean age 70.7+/-9.7 years, range 37-92) were suitable for longitudinal analysis. The need for TVR was based on strict clinical criteria (> or =20% rise in serum creatinine, worsening hypertension, and/or recurrent flash pulmonary edema), and all patients underwent multidisciplinary evaluation before stenting and during follow-up.

RESULTS

Follow-up spanned a mean 45.8+/-26.5 months. TVR was needed in 88 (10.03%) of 877 arteries and was best predicted by patient age < or =67 years (OR 2.91, p=0.0001), stent diameter < or =5.0 mm (OR 2.31, p=0.001), solitary functioning kidney (OR 2.01, p=0.048), history of lower extremity peripheral artery disease (OR 1.87, p=0.008), and antecedent history of stroke (OR 1.73, p=0.026).

CONCLUSION

Renal artery stenting appears to be durable, with only 10% of stented arteries requiring TVR during clinically-based long-term follow-up. Arteries with a final stent diameter < or =5.0 mm were more than twice as likely to need TVR, as were patients with a solitary kidney. The authors acknowledge that clinical recurrence is not a surrogate for ultrasound surveillance after renal artery stenting, so prospective controlled trials will be needed to determine risk factors for restenosis.

Impact of the Rapid-Exchange Versus Over-the-Wire Technique on Procedural Complications of Renal Artery Angioplasty

PURPOSE

To investigate whether the use of rapid-exchange (RX) systems adds to the safety of percutaneous renal artery procedures compared to the conventional over-the-wire (OTW) technique.

METHODS

The interventional registry in our department was interrogated to identify patients who underwent plain balloon angioplasty and/or stent implantation for >60% renal artery stenosis and intractable hypertension or decreasing renal function between 1998 and 2004. In this time period, 63 consecutive patients (36 men; mean age 67 years, range 57-80) underwent 78 renal artery angioplasty procedures. The first 46 procedures were done using a transfemoral OTW technique via 7-F sheaths; the following 32 procedures were performed with an RX system via a transfemoral 6-F access. Duration of fluoroscopy, amount of contrast agent, course of serum creatinine, and complications were compared between OTW and RX approaches.

RESULTS

Duration of fluoroscopy (median 13.1 versus 11.1 minutes, p=0.099) and primary technical success (94% versus 97%, p=0.64) were not significantly different between the OTW and RX approaches, but significantly less contrast agent was needed with the RX system (median 215 versus 140 mL, p<0.001). Complications, all minor, occurred significantly more often with the OTW (11/46, 24%) compared to the RX system (2/32, 6%; p=0.040) and included misplaced stents, prolonged severe hyper/hypotension, transient renal impairment, and puncture site complications. In particular, the rates of increased serum creatinine within 24 hours were higher in the OTW patients compared to the RX group (20% versus 3%, respectively, for >25% increase [p=0.041] and 9% versus 0% for >50% increase [p=0.087]).

CONCLUSIONS

Rapid exchange systems seem to add to the safety of percutaneous renal artery interventions. This likely may be due to a variety of causes, including lower doses of contrast medium, shorter duration of fluoroscopy, and smaller device diameters.

Percutaneous endovascular therapy of renal artery stenosis: technical and clinical developments in the past decade

Renal artery stenosis may initiate or exacerbate arterial hypertension and/or renal insufficiency. During the last decade, technical improvements of diagnostic and interventional endovascular tools have led to more widespread use of endoluminal renal artery revascularization and broader indications for this type of therapy. Since the first renal artery angioplasties performed by Felix Mahler and Andreas Gruntzig in 1978, numerous single-center studies have documented the benefits of percutaneous renal revascularization. In the early 1990s, stent implantation was added to the interventionist's armamentarium for treating renal artery stenosis due to atherosclerosis or fibromuscular dysplasia. The meta-analysis of 3 randomized studies comparing balloon angioplasty with best medical therapy found intervention to be beneficial for blood pressure control but not for preservation of renal function. Despite the absence of randomized studies, there is mounting evidence that stenting of hemodynamically relevant atherosclerotic renal artery stenosis has a positive impact on blood pressure control and renal function. This article summarizes the technical improvements in these endovascular tools during the last decade and gives an overview concerning their clinical impact on renal artery revascularization.

Stent-Supported Angioplasty of Severe Atherosclerotic Renal Artery Stenosis Preserves Renal Function and Improves Blood Pressure Control:Long-term Results From a Prospective Registry of 456 Lesions

PURPOSE

To report a prospective study evaluating the long-term impact of stent-supported angioplasty on renal function and blood pressure control.

METHODS

In a 6-year period, 456 hemodynamically significant de novo renal artery stenoses > or =70% were treated in 340 consecutive hypertensive patients (223 men; mean age 66+/-10 years, range 44-84) with or without impaired renal function. Baseline data on serum creatinine (sCr), intrarenal resistance index, ambulatory 24-hour blood pressure monitoring, and documentation of the number and dose of antihypertensive drugs were compared to values obtained during follow-up. The primary endpoint was a 10% decrease in sCr; the glomerular filtration rate and changes in blood pressure control were additional outcome measures.

RESULTS

During a mean follow-up of 34+/-20 months, sCr decreased significantly from 1.45+/-0.87 to 1.39+/-0.73 mg/dL (p=0.048). In 34% of the patients, sCr decreased >10%, 39% were unchanged, and 27% had an increase >10%. Glomerular filtration rate increased from 59+/-26 to 62+/-26 mL/min/1.73 m(2) (p=0.6). Systolic, diastolic, and mean blood pressure measurements significantly improved immediately after the intervention (132/72/93 versus 144/79/102 mmHg at baseline, p<0.0001) and remained improved during follow-up (p<0.0001). Blood pressure control was improved in 46%, unchanged in 43%, and deteriorated in 11%. Baseline sCr, bilateral intervention, percent diameter stenosis, and 3-vessel coronary disease were independent predictors of improved renal function during follow-up; the number of antihypertensive drugs taken before the intervention predicted improved blood pressure control.

CONCLUSIONS

Stent-supported angioplasty of renal artery stenoses preserves renal function and improves blood pressure control in a broader spectrum of patients than previously thought.