Minimizing Risk of Kidney Injury During Cardiac Evaluation in a Kidney Transplant Patient

Abstract

A 42-year-old Caucasian female with a long history of chronic kidney disease status post living donor-related kidney transplant 18 years prior cautiously underwent angiography as part of her workup for a second kidney transplant due to significantly declining kidney function. Due to successful reduction in contrast volume with the help of a contrast reduction system and hydration, the patient was able to maintain her baseline kidney function and continue evaluation for her transplant surgery without subsequent sequela. 

Introduction

Cardiac risk screening is an often necessary but challenging part of evaluating patients awaiting kidney transplantation due to stage 5 chronic kidney disease (CKD) or end-stage renal disease (ESRD). These patients have a low tolerance to contrast dye, but need good quality images to properly assess their coronary arteries. Research has shown that up to 62% of all kidney transplant candidates have significant coronary artery disease (CAD) despite being low risk or asymptomatic.^1,2 Unfortunately, cardiovascular events are responsible for >50% of all-cause mortality and a leading cause of morbidity after transplantation.^3,4 Furthermore, these patients are also high risk for acute kidney injury (AKI) or contrast-induced nephropathy (CIN), which could lead to dialysis, myocardial infarction (MI), heart failure or mortality. Hydration alone is an insufficient strategy for preventing AKI and CIN.⁵ Therefore, minimizing exposure to contrast media becomes a critical preventative measure.^6,7 This case report presents one such difficult scenario.

Case Report

A 42-year-old Caucasian female with a long history of CKD status post living donor-related kidney transplant 18 years prior was referred from her nephrologist for cardiac evaluation. The patient’s transplanted kidney was becoming increasingly dysfunctional, with gradual rising serum creatinine, and she was experiencing more difficulties controlling her blood pressure, in part related to the kidney dysfunction. She had been experiencing precordial discomfort, shortness of breath with exertion, and palpitations. Other relevant past medical history included obesity, essential hypertension, and diabetes.  

A 12-lead electrocardiogram (EKG) revealed sinus rhythm, occasional premature ventricular contractions (PVCs), and no acute changes. Transthoracic echocardiogram (TTE) showed normal left ventricular systolic function and wall motion with an estimated ejection fraction of 55-60%. A Lexiscan stress Cardiolite myocardial perfusion scan was recommended to evaluate for myocardial ischemia.  Results were interpreted by three physicians and demonstrated a significant reversible perfusion defect in the inferior wall of the left ventricle. To complicate matters, the patient was in the process of undergoing evaluation for repeat kidney transplantation due to worsening renal function. Nephrology and interventional cardiology discussed findings and the decision to continue with diagnostic coronary angiogram without left ventriculogram was made hesitantly. Concerns regarding contrast usage and volume were addressed and it was decided to proceed using the DyeVert Plus Contrast Reduction System (Osprey Medical).  

On the day of the procedure, the patient’s serum creatinine (SCr) was 3.56 mg/dL, estimated glomerular filtration rate (eGFR) was 14 as calculated by the MDRD equation⁸, and estimated creatinine clearance (CrCl) was 27.7 ml/min based on the Cockcroft-Gault calculation⁹. The patient was hydrated with normal saline at 150 ml/hour for just over three hours prior to the procedure. This rate was maintained during the 30-minute procedure, and continued for four hours post procedure. Additionally, a maximum contrast volume threshold of 42 ml was calculated based on the Gurm ratio¹⁰, an established tool for determining contrast dose based on patient’s renal function. Visipaque 320 (GE Healthcare) contrast media was used for the procedure. 

Right radial access was used, and despite difficulty selecting both right (RCA) and left (LCA) coronary arteries, the overall procedure time was 34 minutes with a total contrast dose delivered to the patient of 46.1 ml. The total contrast saved was 49.1 ml (51.5%). Ultimately, while the total contrast volume was 109.9% of the pre-determined threshold, both nephrology and interventional cardiology were pleased with the results. Without the contrast reduction system, total contrast volume delivered to the patient would have been 95.2 ml, or 6.8 times her eGFR. Image quality and our ability to assess the RCA (Figure 1) as well as the LCA (Figure 2) were maintained, despite significant contrast volume reduction. 

The patient’s coronary arteries showed no CAD, and the patient was discharged home the same day after post-procedure hydration. A serum creatinine was obtained three days post procedure, showing no change from the pre-catheterization labs. No adverse events were reported, and the patient was recommended to continue her evaluation for her second renal transplant. 

Discussion

There is currently no collective strategy for cardiac risk assessment amongst CKD and ESRD patients waiting for kidney transplantation. Some guidelines recommend myocardial perfusion imaging, while others recommend no cardiac workup if a patient has stable renal function. This leaves greater subjectivity and difficulty in determining the level and degree to which patients require cardiac screening or invasive testing prior to kidney transplantation.

In general, screening patients, increasing hydration, and contrast minimization are the only preventative measures currently part of the clinical society guidelines for the prevention of AKI in CKD patients undergoing cardiac angiography.¹¹ For high-risk patients with multiple or multifactorial issues, screening has limited applicability and becomes more of a balancing act of risks. Hydration protocols vary widely among and within institutions, and are frequently not followed consistently or at all. Therefore, limiting contrast exposure becomes the most attainable action for minimizing risk. However, despite intentions to use careful observation and manual efforts to reduce contrast during angiography, most physicians don’t reduce contrast. A recent study by Amin et al found that AKI rates and contrast volumes vary greatly among physicians, and that physicians typically didn’t use any less contrast with patients at higher risk for AKI.¹²

Renal preservation and AKI prevention become even more challenging in the face of unstable kidney function. The ratio of total contrast volume to creatinine clearance has been shown to be a predictive factor for both AKI and neuropathy requiring dialysis.¹³ Per clinical studies in real-world populations, the incidence of AKI and contrast volume has an almost linear relationship.^12,13 In addition, CIN occurs at a greater frequency and is more severe in patients with impaired renal function.¹ Moreover, the prevalence of cardiovascular risk factors in renal transplant candidates is high and has been shown to result in an incidence rate of post-transplant cardiovascular events of 40%.³ The occurrence of any AKI event is costly to both the patient and the hospital, and is best avoided by all means possible.¹⁴

Upon seeing impressive results in a previous case with a patient at-risk for AKI, it was prudent to utilize the DyeVert Plus system in this case. Contrast reduction is especially important in high-risk patients. However, for this young lady with CKD stage 5 who has spent most of her life trying to avoid dialysis, contrast minimization was vital. Her nephrologist was very concerned about contrast volume during coronary angiography, and so it was imperative to reduce her contrast dose as much as possible. Certainly, this was a catch-22. Her transplant team would not proceed with evaluation with a positive stress test, but performing catheterization poses risk of CIN. In this case, a successful outcome can be attributed to a multidisciplinary approach, adequate peri-procedure hydration, vigilant real-time monitoring of contrast use along with a pre-procedure calculated contrast volume threshold, and reducing the patient’s contrast volume as much as clinically possible. Also of note, the patient was obese, and, in retrospect, the inferior perfusion defect on the stress and resting myocardial perfusion imaging was felt to be secondary to diaphragmatic attenuation artifact.  

Conclusion

When a diagnostic cardiac angiogram is required in a high-risk renal transplant candidate, steps need to be taken to ensure the protection of the patient’s remaining kidney function. Society guidelines are clear that hydration and minimizing contrast delivery to the patient are the only measures that reduce the risk of AKI. The DyeVert Plus Contrast Reduction System is a safe and effective tool for limiting total contrast volume with the aim of preserving kidney function, in addition to careful patient screening and adequate hydration. 

References

1. Ramphul R, Fernandez M, Firoozi S, et al. Assessing cardiovascular risk in chronic kidney disease patients prior to kidney transplantation: clinical usefulness of a standardised cardiovascular assessment protocol. BMC Nephrol. 2018 Jan 8;19(1):2. doi: 10.1186/s12882-017-0795-z.
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12. Amin AP, Bach RG, Caruso ML, et al. Association of variation in contrast volume with acute kidney injury in patients undergoing percutaneous coronary intervention. JAMA Cardiol. 2017 Sep 1; 2(9): 1007-1012.
13. Gurm HS, Seth M, Mehran R, et al. Impact of contrast dose reduction on incidence of acute kidney injury (AKI) among patients undergoing PCI: a modeling study. J Invasive Cardiol. 2016 Apr; 28(4): 142-146.
14. Koulouridis I, Price LL, Madias NE, Jaber B. Hospital-acquired acute kidney injury and hospital readmission: a cohort study. Am J Kidney Dis. 2015 Feb; 65(2): 275-282.

¹WakeMed Heart and Vascular, WakeMed Heart Center, Raleigh, North Carolina; ²North Carolina Nephrology Associates, Cary, North Carolina

Disclosures: The authors report no conflicts of interest regarding the content herein.

Dr. Jimmy Locklear can be contacted at jimlock7@aol.com.

Dr. Kevin Lee can be contacted at kmlee4@gmail.com.