Preventing the Unpreventable? Rotational Angiography for the Prevention of Contrast-Induced Nephropathy

J INVASIVE CARDIOL 2010;22:432–433

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“An ounce of prevention is worth a pound of cure.” — Benjamin Franklin Contrast-induced nephropathy (CIN) is the third leading cause of acute kidney injury, accounting for approximately 11% of cases.¹ CIN has been associated with a significant increase in morbidity and mortality following percutaneous coronary intervention (PCI). Furthermore, those patients who develop CIN and need hemodialysis have a very poor prognosis, with a 2-year survival rate of 2 Known risk factors for CIN include advanced age, preexisting renal insufficiency, diabetes mellitus, hypertension, congestive heart failure and the concomitant use of nephrotoxic drugs. There is no effective treatment to reverse CIN, hence prevention of CIN is of utmost importance, with identification of patients at high risk for this complication and implementation of preventive measures being a cornerstone of therapy. Many measures including diuretics, mannitol, dopamine, atrial natriuretic peptide, endothelin receptor antagonists, fenoldopam and prophylactic hemodialysis have failed to show a benefit in randomized, controlled studies, while sodium bicarbonate infusion and N-acetylcysteine have shown conflicting results in recently published studies.^3,4 Removal of contrast material once it reaches the coronary sinus and before it enters the general circulation has been postulated as a potentially novel mechanical method of reducing CIN, but is still being evaluated.^4,5 Only adequate saline hydration and limiting the total dose of radiographic contrast material below the maximum radiographic contrast dose (5 ml x body weight [kg]/serum creatinine [mg/dl]) have consistently shown to decrease the incidence of CIN.^6,7 Cardiac resynchronization therapy (CRT) has become in the last decade an adjunctive treatment for patients with medically refractory heart failure symptoms, severe left ventricular systolic dysfunction and an interventricular conduction delay. Clinical trials of CRT have consistently demonstrated improvement in heart failure symptoms and a reduction in recurrent hospitalizations for heart failure exacerbation. Studies also suggest that CRT may have a beneficial effect, reducing all-cause mortality. In order to properly implant the left ventricular lead, the coronary sinus is cannulated and a biplane occlusive venogram is performed, which helps visualize the great cardiac vein and its branches. A lateral branch of the great cardiac vein is usually identified as the target vessel and standard over-the-wire technique is used to deploy the left ventricular lead. While small amounts of contrast are used to perform the coronary sinus venograms, larger amounts of contrast may be used while trying to find and cannulate the coronary sinus. A retrospective analysis by Cowburn and colleagues at the Mount Sinai Hospital in Toronto assessed the incidence of CIN following CRT. From 68 patients who underwent 73 CRT procedures, 10 patients (14%) developed CIN despite the use of prophylactic acetylcysteine in 9 of them, 3 of these patients required hemofiltration and 1 patient subsequently died of complications.⁸ As in previous studies conducted in patients undergoing PCI, those with worse baseline renal function were at a higher risk of developing this complication (Figure 1). Although patients who developed CIN received a higher dose of contrast material (208 ± 148 ml vs. 135 ± 111 ml), it was not statistically significant. Interestingly, 3 patients developed CIN despite the use of very small amounts of contrast material (Journal, Al Fagih⁹ et al report the feasibility of using rotational coronary sinus occlusive venography to limit the total dose of radiographic contrast during CRT lead implantation. Rotational angiography uses an automated, high speed, C-arc gantry movement while swinging over the patient’s body and obtaining numerous angiographic projections, and thus overcomes many of the limitations of standard angiography. Rotational angiography is a powerful imaging tool for the evaluation of coronary anatomy, resulting in the use of 33% less contrast media and 31% less radiation, without losing the possibility to obtain precise, efficient and fast characterization of the coronary anatomy.¹⁰ In the present study, a total of 30 consecutive patients with severely reduced left ventricular function on optimal medical therapy undergoing CRT implantation were enrolled in the study. Coronary sinus anatomy was adequately visualized in all patients by rotational angiography starting at 45º left anterior oblique and terminating at 0º antero-posterior view, using only 5–8 ml of contrast while using an occlusive balloon. The mean baseline creatinine level was 105 ± 43.75 µmol/l (1.19 ± 0.5 mg/dl). The mean contrast dose administered was 14.76 ± 6.8 ml, which is significantly lower when compared to the previous study by Cowburn et al. There were no periprocedural complications. A major limitation of this study is the small sample size and the lack of data regarding post-procedural creatinine levels. We will have to presume that none of these patients developed CIN by current definitions. Procedural time and radiation dose delivered were not reported. A randomized, controlled trial with a larger sample size would be needed to confirm the validity and reproducibility of these results and to test the hypothesis that reducing contrast dose during CRT by implementing rotational coronary sinus occlusive venography would decrease the incidence of CIN in a high-risk patient population. So what can we conclude at the moment regarding the use of rotational coronary sinus occlusive venography during CRT? The advent of newer imaging technologies in the last decade have helped reduce the amount of contrast used in the catheterization and electrophysiology laboratories, while at the same time obtaining high-quality images. However, this technology is already being surpassed by three-dimensional (3-D) rotational angiography of the heart and surrounding structures which has been supplementing traditional two-dimensional imaging to guide diagnostic and complex electrophysiology interventions. However, increased radiation dose delivered to slender patients and time spent for the 3-D reconstruction are still a source of concern. While these issues are sorted out, prevention of CIN by identifying patients at high risk, implementation of adequate hydration and minimizing contrast dose still comprise the foundation of therapy.

References

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From the Department of Medicine, Division of Cardiovascular Diseases, Stony Brook University Medical Center, Stony Brook, New York. The authors report no conflict of interest regarding the content herein. Address for correspondence: Luis Gruberg, MD, FACC, Department of Medicine, Division of Cardiovascular Diseases, Health Sciences Center, T16-080, Stony Brook, NY 11794-8160. E-mail: luis.gruberg@stonybrook.edu