1. Patient Selection Indications for Renal Intervention
Joseph C. Babrowicz, Jr., M.D.
Georgetown University Hospital
Division of Vascular Surgery

2. DISCLOSURES
Joseph C. Babrowicz, MD
Honoraria
Endologix

3. Scope of the Problem
Screening DUS suggested RAS (>60%) in 6.8% of Medicare population (mean age 77yrs) (White & Olin, Nat Clin Prac Card Med 2009;6: )
Clinically manifested RAS in medicare pts 0.5% overall and 5.5% with CKD (Dworkin, NEJM 2009;361: )

4. Risk Factors for RAS Late onset Hypertension (age > 55yrs)
Malignant, refractory, resistant HTN
Declining renal function with ACE-I or ARB
Atrophic kidney, size discrepancy >1.5cm
Unexplained renal dysfunction
Flash pulmonary edema
Multivessel CAD
Symptomatic PAD
White & Olin, Nat Clin Prac Card Med 2009;6:

5. Prevalence of RAS in ASCVD
Stroke
Carotid Art Disease
Coronary Art Disease MI
AAA
Lower extremity PAD
10%
19%
6-40%
12%
20-38%
21-49%
Prog Card Dis 2009;52:

6. Rates of Adverse CV Events
With RAS per 1000 pt years
Without RAS per 1000 pt yrs
ASHD
303.9
73.5
PVD
258.6
52.2
CHF
194.5
56.3
CVA or TIA
175.5
52.9
Death
166.3
63.3
Prog Card Dis 2009;52:

7. Evaluation – Screening Suspicion
Onset Stage 2 HTN (BP>160/100 mmHg) after age 50yr or in absence of family history
HTN associated with renal insufficiency (esp if worsens with ACE-I or ARB)
HTN with repeated admit for CHF
Drug resistant HTN ( at least 3 drugs)
Dworkin, NEJM 2009;362:

8. Evaluation - Imaging Test Advantage Disadvantage Duplex ultrasound
Noninvasive
Technician dependent, obesity, bowel gas
CTA
Contrast nephropathy, radiation
MRA
NSF in CKD
DSA
Best anatomical info
Invasive, CIN, radiation
Dworkin, NEJM 2009;362:

9. Evaluation – Adjuncts Resistance Index PSV/EDV in cortical parenchyma
Indication of small vessel renal disease
Possibly predicts response to renal intervention
Data are conflicting
Radermacher et al., NEJM 2007;344:

10. Evaluation - Biomarkers
Renin
Levels altered by many meds
Suppressed by volume expansion
Unreliable in clinical practice
Brain Natriuretic Peptide
Animal study BNP upregulated after cliping renal artery
Silva et al (Circ 2005;111: ) showed decrease BNP after renal artery stenting
More investigation needed
White et al., 2009 NCPCardMed; 6:176-90

11. Evaluation - Invasive Catheter Angiography
Variability in estimating degree of stenosis
Hemodynamic effects develop between 75% and 85% luminal occlusion
Detectable lateralization of renal vein renins at greater than 80% stenosis
Somewhat difficult to define “significant lesion” by imaging only
Textor et al., Prog Card Dis 2009:52,3:

12. Figure 4 Treatment of renal artery stenosis with balloon angioplasty and
stenting
White CJ and Olin JW (2009) Diagnosis and management of atherosclerotic renal artery stenosis: improving patient selection and outcomes Nat Clin Pract Cardiovasc Med doi: /ncpcardio1448

13. Evaluation - Invasive Translesional Pressure Gradient
AHA consensus suggests peak systolic gradient at least 20mmHg or mean gradient at least 10mmHG
Absolute thresholds questioned
Dependent on catheter diameter, aortic pressure, distal vascular bed, renal venous pressure
Perfusion pressure distal to the gradient more important
Pressure wires may provide better information

14. Fractional Flow Reserve
Effective renal perfusion is related to the absolute pressure distal to a stenosis and not the gradient itself
Flow across an artery is proportional to the pressure across the vascular bed and inversely proportional to the resistance of the vascular bed
FFR = Pressure distal/pressure proximal measured after maximal renal hyperemia using a pressure wire
Baseline normal FFR > or = 0.8
White, Prog Card Dis 2009;52:

15. Fractional Flow Reserve
17 patients with refractory HTN and unilateral RAS treated with renal stenting
7 pts FFR < pts normal FFR at baseline
3 month follow up 86% with abnormal FFR had improved HTN compared to 30% for normal FFR group
BP improvement after renal stenting significantly more likely if baseline FFR<0.8
Mitchel et al., Cath Card Int, 2007;69:

16. Management for HTN Randomized Trials
DRASTIC Trial (NEJM )
Scottish Newcastle Group (J Hum Hypertension 1998;12: )
EMMA Group (Hypertension 1998;31: )
ASTRAL Study (NEJM 2009;361: )
Mostly negative results for BP control – 0nly 70% with improved BP, very few cures
Problems - Underpowered, poorly defined medical management, selection biases, crossover, some nonhemodynamically significant lesions, PTA alone

17. Management – Ischemic Nephropathy
Meta-analysis of 10 studies showed serum creatinine levels improve in 25%, no change in 50%, and worsen in 25%
ASTRAL study designed to evaluate renal function showed no worthwhile clinical benefit from revascularization
Some small studies have shown improved renal function
Improvement is best for patients with rapid recent decline in renal function
White et al., Nat Clin Pra Card Med 2009;6:

18. Management – Cardiac Disturbance
RAS can exacerbate coronary ischemia and CHF and make medical management (ACE and ARB) difficult
Khosla et al. (Am J Card 1997;80: )
48 patients with CHF or ACS had renal stent or renal stent and PCI
88% decreased BPs and/or improved symptoms
Renal stent alone had similar outcomes to renal stent/PCI patients suggesting that renal stent was the major factor

19. Management – Cardiac Disturbance
Gray et al. (Vasc Med 2002;7: )
39 patients renal stent for control of CHF
BP improved in 72%
Renal function improved in 51%
Mean number of hospitalizations for CHF fell form 2.4+/-1.4 to 0.3+/-0.7
77% had no further admission at 21 months
Related to decreased renin –angiotensin production and ability to administer ACE and ARB meds

20. Conclusions RAS is an independent predictor of adverse CV events
Percutaneous revascularization for hemodynamically significant RAS and accelerated, resistant, or malignant HTN is reasonable
Percutaneous revascularization is reasonable for RAS and progressive decline in renal function
Percutaneous revascularization is indicated for significant RAS and cardiac disturbance syndromes
Defining significant RAS is difficult and adjuncts like FFR and BNP may improve ability to select good responders