Simple clinical scores to predict blood pressure and renal function response to renal artery stenting for atherosclerotic renal artery stenosis
Key words: atherosclerotic renal artery stenosis, blood pressure and renal function improvement, prediction models, responders
CC BY-NC-SA 4.0
Simple clinical scores to predict blood pressure and renal function response to renal artery stenting for atherosclerotic renal artery stenosis
CC BY-NC-SA 4.0
Introduction: There are no systematic tools to predict blood pressure (BP) or renal function (RF) improvement after stent‑assisted percutaneous transluminal angioplasty (PTA) for atherosclerotic renal artery stenosis (ARAS).
Objectives: This study aimed to develop simple, clinically applicable scores based on preprocedural clinical and renal ultrasonography parameters in order to predict BP and RF improvement following ARAS‑PTA.
Patients and methods: A total of 202 patients who underwent ARAS‑PTA were categorized as RF responders (eGFR increase ≥11 ml/min/1.73 m2) or BP responders (systolic and diastolic BP decrease ≥20 mm Hg and ≥5 mm Hg, respectively) at 12 months following ARAS‑PTA. The variables associated with the RF or BP response in univariable analysis were included in a multivariable logistic regression model. Point‑based response scales were developed proportionally to odds ratios in each of the 2 models to embrace the maximum score of 10.
Results: The BP response to ARAS‑PTA was 93.3% in the high‑probability category (6–10 points), 66.7% in the medium‑probability category (3–5 points), and 25.3% in the low‑probability category (0–2 points), with the preprocedural variables of systolic BP ≥145 mm Hg (3 points), diastolic BP ≥83 mm Hg (4 points), PTA of a single functioning kidney (2 points), and bilateral PTA (1 point). The RF response was 77.3% in the high‑probability category (8–10 points), 33% in the medium‑probability category (4–7 points), and 10.9% in the low‑probability category (0–3 points) for serum creatinine levels >122 μmol/l and eGFR >30 ml/min/1.73 m2 (3 points), index kidney length >98 mm (3 points), renal artery end‑diastolic velocity >1.1 m/s (2 points), and arterial resistive index <0.74 (2 points).
Conclusions: Models of favorable BP and RF response may improve patient selection for ARAS‑PTA. Further insights are expected from prospective validation.
What's new?
Current guidelines on atherosclerotic renal artery stenosis (ARAS) revascularization (stent‑assisted percutaneous transluminal angioplasty [PTA]) offer little aid in clinical decision making. No baseline clinical, parameter‑based scores for the assessment of the response to treatment have been established yet. Based on a detailed evaluation of a large ARAS‑PTA patient cohort, we developed clinical scores to predict blood pressure and renal function response following ARAS revascularization. These simple scores may serve as useful tools to guide clinicians in patient selection for ARAS‑PTA.
Introduction
Atherosclerotic renal artery stenosis (ARAS) is a relatively frequent disease, especially in older patients or those with either coronary or extracoronary athero‑occlusive disease.1-3 Some patients benefit from ARAS revascularization, but the intervention (stent‑assisted percutaneous transluminal angioplasty [PTA]) is not routinely recommended.4-6 The results of randomized controlled trials of ARAS revascularization have been largely neutral in terms of blood pressure (BP) and / or renal function (RF) improvement, as compared with best medical therapy (BMT).4,7,8 Clinical series focused on BP and RF outcomes in selected patients have reported improved BP control in up to 65% of patients and RF improvement in approximately 30% to 40% of patients.4,9,10
Identifying responders to the treatment—prior to ARAS‑PTA—poses the major problem.11 There are no clinical scores or decision making trees that would guide clinicians on patient selection either for BMT or PTA plus BMT. In consequence, guidelines addressing patient selection for ARAS‑PTA are vague and leave clinicians without clear guidance.12
The issue is of clinical importance, as improvement in BP and RF translates into reduced risk of cardiovascular events.4,6,13-15 We noted that an increase in the estimated glomerular filtration rate (eGFR) by at least 11 ml/min/1.73 m2 as well as systolic and diastolic BP decrease by 20 mm Hg and 5 mm Hg or greater, respectively, following PTA for ARAS, are related to cardiovascular death or stroke risk reduction over 5 years.16
Therefore, the aim of the present study was to develop clinically applicable scores incorporating routine preprocedural parameters to predict BP and RF response following PTA for ARAS.
Patients and methods
Study population
From January 2003 to December 2018, 202 patients with ARAS (60% to 99% lumen diameter stenosis on quantitative angiography) underwent PTA for ARAS provided that they had presented with accelerated or refractory hypertension on at least 3 antihypertensive drugs and / or RF impairment. Exclusion criteria were nonatherosclerotic renal artery stenosis, nondiagnostic renal ultrasonography, and lack of informed consent to participate in the study.
All patients provided informed consent before enrollment in accordance with the requirements of the local ethics committee (KBET/392/B/2003). The study was performed in line with the principles of the Declaration of Helsinki.
Blood pressure and renal function evaluation
Data were collected on patient admission to the department, prior to any intervention, immediately after signed informed consent was obtained from the patients.
Blood pressure was measured according to the guidelines published by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (the seventh report).17 Hypertension was defined as systolic and / or diastolic BP ≥140 mm Hg and ≥90 mm Hg, respectively. Blood pressure evaluation was based on an average of 2 BP measurements performed in a patient in a sitting position, within 5‑minute intervals during separate outpatient office visits that followed optimization of pharmacotherapy.
Fasting blood samples, including serum creatinine, were taken upon admission. Renal function assessment including serum creatinine levels and eGFR was performed prior to PTA. The value of eGFR was estimated from the Modification of Diet in Renal Disease (MDRD) formula, according to the following equation: MDRD = 175 × creatinine [mg/dl]−1.154 × age [years]−0.203 × 0.742 [if female].
Assessment of renal flow parameters and the kidneys on Doppler ultrasonography
Doppler ultrasonography was performed in a supine and / or left or right lateral position, depending on which renal artery was assessed. The examination was performed by 2 operators, using a high‑resolution ultrasonograph (TOSHIBA APLIO [Canon Medical Systems GmbH, Neuss, Germany] with a 3.5–5‑MHz probe). The assessment included the following parameters: systolic velocity in the aorta, peak systolic and end‑diastolic velocity (EDV) in the index renal artery, the renal‑aortic ratio, the resistive index (RI) in the renal artery, the intrarenal RI, acceleration time, and the pole‑to‑pole kidney length of the index and contralateral kidneys.
Renal artery stenting
The PTA procedure was described in detail elsewhere.16 In brief, PTA was performed according to the standard protocol. All patients received dual antiplatelet therapy before the procedure, which was continued for 3 months after PTA, and then, single antiplatelet therapy was continued indefinitely. The choice of stent type and route of vascular access was left at the operator’s discretion. A distal embolic protection device was used during a single procedure.
Follow‑up examinations
Follow‑up including the evaluation of clinical symptoms, BP, and RF was conducted before discharge and at 6 and 12 months following PTA. The protocol for BP measurement and RF evaluation was the same as that used before PTA.
The study patients were categorized as responders or nonresponders in 2 categories: responders versus nonresponders in terms of BP or eGFR. Cutoff values for responders were defined as a systolic and diastolic BP reduction of at least 20 mm Hg and 5 mm Hg or greater, respectively, or an eGFR increase greater than 11 ml/min/1.73 m2 and adopted from the previously published study on the reduction of cardiovascular death, myocardial infarction, or stroke risk following PTA for ARAS.16 Nonresponders were defined as patients showing no improvement in systolic or diastolic BP or eGFR.
Statistical analysis
Continuous variables were presented as mean (SD), and categorical variables were expressed as numbers and percentages. Differences between mean values were verified using the t test and the analysis of variance, and categorical variables were compared using the χ2 test for independence, as appropriate. The normal distribution of the analyzed variables was determined by the Shapiro–Wilk test.
Construction of models for the prediction of blood pressure and renal function improvement after percutaneous transluminal angioplasty
Step 1: BP and RF outcomes were analyzed as a dichotomous variable (responder versus nonresponder).
The potential independent prognostic markers of BP and RF response during the follow‑up period were established based on clinical, Doppler ultrasonography, and angiographic variables by univariable analysis (table 1).
OR (95% CI) | P value | OR (95% CI) | P value | |
Angiographic and procedural data | ||||
Doppler ultrasonography parameters | ||||
- Przewlocki T, Kablak‑Ziembicka A, Kozanecki A, et al. Polyvascular extracoronary atherosclerotic disease in patients with coronary artery disease. Kardiol Pol. 2009; 67: 978‑984.
- Masta Q, Beutler JJ. The prevalence of atherosclerotic renal artery stenosis in risk groups: a systematic literature review. J Hypertension. 2009; 27: 1333‑1340. | Crossref
- Przewlocki T, Kablak‑Ziembicka A, Tracz W, et al. Prevalence and prediction of renal artery stenosis in patients with coronary and supraaortic artery atherosclerotic disease. Nephrol Dial Transplant. 2008; 23: 580‑585. | Crossref
- Caielli P, Frigo AC, Pengo MF, et al. Treatment of atherosclerotic renovascular hypertension: review of observational studies and a meta‑analysis of randomized clinical trials. Nephrol Dial Transplant. 2015; 30: 541‑553. | Crossref
- Van der Niepen P, Persu A. Long‑term cardiovascular outcome after renal revascularization. Pol Arch Intern Med. 2019; 129: 735‑737. | Crossref
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