Reduction in renal function after renal arteriography and after renal artery angioplasty

A prediction model of contrast-associated acute kidney injury in patients with hypoalbuminemia undergoing coronary angiography

BACKGROUND

Risk stratification is recommended as the key step to prevent contrast-associated acute kidney injury (CA-AKI) among at-risk patients following coronary angiography (CAG) and/or percutaneous coronary intervention (PCI). Patients with hypoalbuminemia are prone to CA-AKI and do not have their own risk stratification tool. Therefore, this study developed and validated a new model for predicting CA-AKI among hypoalbuminemia patients CAG/PCI.

METHODS

1272 patients with hypoalbuminemia receiving CAG/PCI were enrolled and randomly allocated (2:1 ratio) into the development cohort (n = 848) and the validation cohort (n = 424). CA-AKI was defined as an increase of ≥0.3 mg/dL or 50% in serum creatinine (SCr) compared to baseline in the 48 to 72 h after CAG/PCI. A prediction model was established with independent predictors according to stepwise logistic regression, showing as a nomogram. The discrimination of the new model was evaluated by the area under the curve (AUC) and was compared to the classic Mehran CA-AKI model. The Hosmer-Lemeshow test was conducted to assess the calibration of our model.

RESULTS

Overall, 8.4% (71/848) patients of the development group and 11.2% (48/424) patients of the validation group experienced CA-AKI. A new nomogram included estimated glomerular filtration rate (eGFR), serum albumin (ALB), age and the use of intra-aortic balloon pump (IABP); showed better predictive ability than the Mehran score (C-index 0.756 vs. 0.693, p = 0.02); and had good calibration (Hosmer-Lemeshow test p = 0.187).

CONCLUSIONS

We developed a simple model for predicting CA-AKI among patients with hypoalbuminemia undergoing CAG/PCI, but our findings need validating externally.

TRIAL REGISTRATION

http://www.ClinicalTrials.gov NCT01400295 , retrospectively registered 21 July 2011.

A Comparison of Nephrotoxicity of Contrast Medium in Elderly Patients who Underwent Renal or Peripheral Arterial Vascular Intervention

OBJECTIVE

To compare the nephrotoxicity of iodixanol in elderly patients who underwent a renal artery intervention (RAI) with those who underwent an other peripheral vascular intervention (OPI).

METHODS

Three hundred fifty-four consecutive patients (>60 years old) received iodixanol during RAI (n=150) or OPI (n=204). The level of serum creatinine (SCr) was measured at the baseline, 24 hours, 48 hours, 72 hours and 1 month after intervention.

RESULTS

Within 72 hours after the intervention, the adjusted mean of the peak SCr increase was 11.22 umol/L 〔95% confidence interval (CI): 9.21-13.24〕 in the RAI group and 12.40 umol/L (95%CI: 10.7-14.09) in the OPI group. The difference in the peak SCr increase was -1.17 umol/L (95%CI: -3.94-1.60; p=0.406). Contrast-induced nephropathy occurred in 26 patients (17.3%) of the RAI group and in 27 patients (13.2%) of the OPI group (p=0.286). Patients who underwent an RAI showed no increased risk for contrast-induced nephropathy in comparison with patients who underwent an OPI 〔adjusted odds ratio (OR)=1.108; 95%CI: 0.540-2.273; p=0.780〕.

CONCLUSION

The nephrotoxic effect of iodixanol in elderly patients who underwent RAI or OPI was comparable.

Impact of female gender on frequency of contrast medium-induced nephropathy: post hoc analysis of dialysis versus diuresis trial

BACKGROUND

Of patients exposed to contrast medium (CM), 10% will develop contrast medium-induced nephropathy (CIN). Many studies have assessed potential risk factors for CIN. There are limited date concerning the influence of gender on frequency of CIN.

METHODS

From January 2001 to July 2004, a prospective trial was performed to compare different treatments for CIN prevention. Creatinine levels (72 hours) were assessed, as well as in-hospital and long-term outcome. CIN was defined as in an increase of > or =25% or >0.5 mg/dL compared with baseline creatinine. The frequency of CIN in women and men was determined retrospectively.

RESULTS

Four hundred twelve patients (67.1 +/- 10.2 years, 68 women) were randomized for different treatment strategies. Univariate analyses identified higher age (p = 0.031), diabetes (p = 0.03), decreased estimated glomerular filtration rate (eGFR) (p < 0.001), lower hemoglobin levels (p = 0.001), use of angiotensin-converting enzyme inhibitors (ACEI) (p = 0.004) and loop diuretics (p = 0.011), the amount of CM given (p < 0.001), and female gender to be associated with the occurrence of CIN within 72 hours. The frequency of CIN within 72 hours after CM administration was significantly higher in women than in men (p = 0.016). When CIN-associated factors were compared between women and men, women were older (69.8 vs. 66.5 years, p = 0.014) and had lower hemoglobin levels (12.6 vs. 13.8 g/dL, p < 0.001) and eGFR (35 vs. 49 mL/min, p < 0.001), suffered more often from diabetes (37% vs. 29%, p = 0.09), and had medication more frequently with loop diuretics (50% vs. 36%, p = 0.036) but not ACEI (56% vs. 57%, ns). The amount of CM given was identical (189 vs. 189 mL, ns). Multivariate analysis found female gender not to be an independent predictor of CIN (odds ratio [OR] 1.48, 95% confidence interval [CI] 0.72-3.02).

CONCLUSIONS

Women are significantly more likely than men to suffer from CIN. This higher rate of CIN was confounded by unfavorable comorbidities, as found by univariate and multivariate analyses.

Embolic protection: Limitations of current technology and novel concepts

Distal embolic event is one of the major limitations of coronary and non-coronary vascular interventions. Balloon and filter-based Embolic Protection Devices (EPDs) are a new class of interventional devices, used to prevent consequential morbidity and mortality of the distal embolic events. Data from first generation EPD supply proof of concept and show approximately 40% reduction in mortality and morbidity, when EPDs are used during saphenous vein grafts (SVGs) interventions. Current limitations of all first generation EPD technology taper their penetration. With breakthroughs in embolic protection technology, it is estimated that, in the near future, EPDs will be used with stenting in all high-risk lesions (SVGs, carotid arteries and acute coronary syndromes), become the standard of care and even be used in low risk cases.

Renal safety of CT angiography and perfusion imaging in the emergency evaluation of acute stroke

BACKGROUND AND PURPOSE

Multimodal CT imaging with contrast-enhanced CT angiography (CTA) and CT perfusion (CTP) is increasingly being used to guide emergency management of acute stroke. However, little has been reported about the safety of intravenous contrast administration associated with these studies in the acute stroke population, including cases in which baseline creatinine values are unknown. We investigated the incidence of contrast-induced nephropathy (CIN), defined as a 25% or more increase in baseline creatinine levels within 72 hours of contrast administration and chronic kidney disease in patients receiving CTA+/-CTP at our regional stroke center.

MATERIALS AND METHODS

We analyzed 198 patients who underwent contrast CT studies for evaluation of acute ischemic or hemorrhagic stroke at our center (2003-2007). Through retrospective chart abstraction, we analyzed serial creatinine levels (baseline to day 3) and later values (>/=day 4) where available. The incidences of CIN and/or chronic kidney disease were documented. After power analysis, CIN and non-CIN groups were compared by using the unpaired t test, Wilcoxon rank sum test, or Fisher exact test.

RESULTS

None of the 198 patients developed chronic kidney disease or required dialysis. Of 175 patients with serial creatinine measurements between baseline and day 3, 5 (2.9%) developed CIN. The incidence of CIN was 2% in patients who were scanned before a baseline creatinine level was available.

CONCLUSION

The incidence of renal sequelae is relatively low in acute stroke patients undergoing emergent multimodal CT scanning. Prompt CTA/CTP imaging of acute stroke, if indicated, need not be delayed in those with no history of renal impairment.

Radiologists’ knowledge and perceptions of the impact of contrast-induced nephropathy and its risk factors when performing computed tomography examinations: A survey of European radiologists

BACKGROUND

The past decade has seen a proliferation in the number of CT procedures. As increasing numbers of elderly patients with multiple comorbidities undergo contrast media (CM)-enhanced procedures, more patients are at risk for contrast-induced nephropathy (CIN).

OBJECTIVES

To understand whether radiologists are sufficiently aware of the incidence, impact and risk factors of CIN, and whether they are taking sufficient measures to prevent CIN among patients undergoing CT.

MATERIALS AND METHODS

A telephone or online survey was conducted in 2005 with 509 radiologists from 10 European countries. Participants had a minimum of 3 years' experience and performed at least 50 CT scans per week.

RESULTS

Most (88%) radiologists believed that CIN is an important issue. While 45% identify that a patient is experiencing CIN when the serum creatinine level increases >25% (0.5mg/dL) from baseline within 48h, the remainder used criteria that might lead to significant under-diagnosis. Most (72%) radiologists believed that CIN is associated with increased morbidity; 56% did not believe that it is associated with increased mortality. Most respondents agreed that pre-existing renal impairment (97%), dehydration (90%) and diabetes (89%) were risk factors for CIN; however, 26%, 30% and 46%, respectively, did not identify advanced age, CM dose or congestive cardiac failure as risk factors. Only 7% of radiologists thought they were always made aware of CIN associated with their cases and 28% never consulted a nephrologist to discuss patients at risk of CIN or who had developed CIN.

CONCLUSION

There is highly variable awareness of the definition, impact and risk factors for CIN among European radiologists. Data regarding the importance of CIN in CT are limited. Improved efforts are required to better educate radiologists and referring physicians and to institute appropriate protocols to identify at-risk patients and prevent CIN.

Risk prediction of contrast-induced nephropathy

In order to make appropriate decisions about clinical management, it is important for physicians to be able to stratify patients according to their risk for contrast-induced nephropathy (CIN). The most important risk marker for nephropathy after exposure to iodinated contrast media is preexisting renal impairment. The risk of CIN is elevated and becomes clinically important in patients with chronic kidney disease characterized by an estimated glomerular filtration rate <60 mL/min per 1.73 m(2). In patients with renal impairment, diabetes mellitus amplifies the risk of CIN and complicates postprocedure management. Other markers associated with an increased risk of CIN include cardiovascular disease, periprocedural hemodynamic instability, use of nephrotoxic drugs, and anemia. The effect of risk factors is additive, and the presence of multiple risk factors in the same patient can create a very high risk for CIN and acute renal failure requiring dialysis. Risk models incorporating baseline and periprocedural characteristics have been developed using data from large databases of percutaneous coronary intervention patients. These schemes are potentially valuable, but at present the most practical approach to risk prediction is based on a simple model incorporating renal function and diabetes mellitus.

Contrast medium use

Various properties of iodinated contrast media (osmolality, ionic versus nonionic, and viscosity) may contribute to contrast-induced nephropathy (CIN). Therefore, the choice of contrast medium affects the risk for CIN. There is good evidence that low-osmolar contrast media are less nephrotoxic than high-osmolar contrast media in patients at increased risk for CIN who receive intra-arterial iodinated contrast. Current evidence suggests that nonionic isosmolar contrast presents the lowest risk for CIN in patients with chronic kidney disease (CKD), particularly in those patients with diabetes mellitus. Intra-arterial administration of contrast media may be associated with a greater risk for CIN above that observed with intravenous administration. The use of gadolinium or CO(2) as alternative contrast media to avoid the risk of nephrotoxicity cannot be substantiated by clinical trials and therefore cannot be recommended. Most studies show that, within a class, higher volumes (>100 mL) of iodinated contrast medium are associated with a higher risk for CIN. However, in patients at high risk, such as those with CKD and diabetes, even small volumes of contrast medium can have adverse effects on renal function.

Nephropathy induced by contrast media: pathogenesis, risk factors and preventive strategies

With the increasing use of contrast media in diagnostic and interventional procedures, nephropathy induced by contrast media has become the third leading cause of hospital-acquired acute renal failure. It is also associated with a significant risk of morbidity and death. The current understanding of the pathogenesis indicates that contrast-medium nephropathy is caused by a combination of renal ischemia and direct toxic effects on renal tubular cells. Patients with pre-existing renal insufficiency, diabetes mellitus and congestive heart failure are at highest risk. Risk factors also include the type and amount of contrast medium administered. Therapeutic prevention strategies are being extensively investigated, but there is still no definitive answer. In this article, we review the current evidence on the causes, pathogenesis and clinical course of contrast-medium nephropathy as well as therapeutic approaches to its prevention evaluated in clinical trials.

Atheroemboli during renal artery angioplasty: An ex vivo study

OBJECTIVE

We hypothesized that atheroemboli released during renal angioplasty could be responsible for the modest functional result of renal angioplasty even after anatomic reduction of renal artery stenosis. To test this hypothesis, we enumerated and sized fragments released during ex vivo angioplasty and stenting of human renal artery atherosclerotic specimens removed during aortorenal endarterectomy.

METHODS

Thirty-three intact aortorenal atheroma specimens (16 pairs with adjacent aortic atheroma and one specimen with a single renal artery orifice) were removed from 17 patients with renal artery occlusive disease who underwent renal artery endarterectomy. specimens. Endarterectomy specimens were removed with a ring of aortic plaque and "fitted" with a polytetrafluoroethylene "adventitia". Ex vivo angioplasty was technically successful in 31 of the 33 specimens and was performed by using a 0.018-inch guidewire and 3.0-mm and 5.0-mm angioplasty balloons inflated for 30 seconds at 15 atmospheres pressure. Stenting was performed with either a 5-mm or 6-mm self-expanding Wallstent. Each artery was flushed with 20 mL of saline after guidewire placement, each angioplasty, and stent placement. The effluent was collected for analysis for counting with either a microscope (size >100 microm) or a Coulter counter (size <100 microm). The number and size of embolic fragments in the effluent collected after each manipulation was recorded.

RESULTS

Each manipulation of the specimens, including simply advancing the guidewire through the atherosclerotic lesion, released thousands of fragments. The numbers of fragments in each size category increased with decreasing particle size. Positioning and deploying the Wallstent released an additional bolus of fragments similar to that released after balloon angioplasty.

CONCLUSIONS

Ex vivo renal angioplasty releases thousands of atherosclerotic fragments of sufficient size to create vascular occlusions and initiate significant renal parenchymal damage. The results of renal angioplasty procedures could be improved by placing distal protection devices to prevent atheroembolization.

CLINICAL RELEVANCE

Athero-emboli produce a local arteritis in the kidney and could cause substantial damage to the renal parenchyma. This report explores the quantity of athero-emboli released during ex vivo angioplasty and stenting of renal atheroma specimens. The number of emboli found in this ex vivo study suggest that the use of protection devices may be advisable to protect the end organ, as done with angioplasty of the carotid artery. Of necessity, this was an ex vivo study and direct application to the clinical setting will need further study. Fortunately, multi-center trials examining the value of protection devices are currently in progress.

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.

Long-term follow-up after renal artery stenting

BACKGROUND

Renal artery stenosis may cause secondary arterial hypertension and lead to end-stage renal disease. Percutaneous transluminal angioplasty with stent implantation (PTRAS) allows effective and consistent treatment with a high technical success rate. The present trial focuses on the morphological and clinical results as assessed at a long-term follow-up (FU) visit. The main goals were assessment of the restenosis rate and evaluation of arterial hypertension and renal function.

PATIENTS AND METHODS

40 patients who had undergone successful stenting of a main renal artery were prospectively enrolled. At the FU visit, all patients underwent a risk-factor assessment, evaluation of arterial blood pressure and serum creatinine, and multi-detector computed tomography angiography (CTA).

RESULTS

Median FU was 3.3 years. Hyperlipidemia was present in 67.5% of the patients, current cigarette smoking in 35% and diabetes mellitus in 15%. All patients still suffered from arterial hypertension but, compared with the pre-interventional situation, arterial hypertension was improved in 37.5%. Serum creatinine was increased in 25% of patients, mean creatinine level was 1.3 +/- 0.4 mg/dl. Hemodynamically relevant restenosis was detected by observer 1 in five patients and by observer 2 in six patients, giving restenosis rates of 12.5% and 15%, respectively, after the median FU period. Both observers detected three additional relevant stenoses in the contralateral main renal arteries.

CONCLUSIONS

PTRAS gives excellent morphological long-term results. However, the clinical long-term outcome regarding arterial hypertension and renal function is only moderate.