Researchers at the Deutsches Herzzentrum (German Heart Center) and the 1. Med. Klinik at Klinikum rechts der Isar (Rechts der Isar University Hospital), both in Munich, investigated, for the first time, the cardiac and renal tolerance of contrast media with different osmolarities in a high-risk group of patients with chronic renal failure undergoing percutaneous coronary intervention .
Since the NEPHRIC study, in which an iso-osmolar contrast medium showed a better renal tolerance in diabetics compared with a hyperosmolar contrast medium, the discussion concerning contrast-induced nephropathy (CIN) has divided the experts. Proponents of iso-osmolar contrast media consider the blood isotonicity and the resulting lack of osmotoxicity of these to be the reason for the better tolerance demonstrated in a number of clinical trials, where the protection of impaired kidneys is concerned. Opponents of this theory, likewise, cite clinical trials that did not indicate any significant differences in the renal tolerance of the contrast media used.
Patients with impaired renal function also suffer more frequently from coronary heart disease. Coronary interventions in these patients are often complex and require high doses of contrast media, which puts a lot of strain on the heart and kidneys. CIN is an independent mortality risk factor in these patients and a significant risk factor for cardiovascular events, says Dr. Rainer Wessely, Associate Professor of Cardiology at the Technical University of Munich.
In light of this, the CONTRAST study (COntrast media and NephroToxicity following coronary Revascularization by AngioplaSTy) investigated in patients of very advanced age and with severe coronary heart disease, whether the iso-osmolar contrast medium IODIXANOL also exhibits a superior renal tolerance in this constellation in comparison with the hyperosmolar contrast medium IOMEPROL. The patients, whose renal function was already compromised, were administered higher-than-normal quantities of contrast medium of around 360 ml on average during percutaneous coronary intervention (PCI), due to the complexity of the procedures.
Included in the study were 324 patients with moderate to severe impairment of renal function (SCr Â‰Â¥1.5 mg/dl or eGFR <60 mL/min/1.73m2), who underwent percutaneous coronary intervention with IODIXANOL 320 (VISIPAQUETM) or IOMEPROL 350 (ImeronÂ®). The patients were carefully hydrated intravenously both before and after the procedure (1 ml/kgBW/h 0.9% NaCl).
The CIN rate in the IODIXANOL patients was 20% lower than the CIN rate in the IOMEPROL arm of the study (22.2% vs. 27.7%). The difference was, however, not statistically significant (p=0.25). No significant differences were shown in the maximum increase in the serum creatinine level (IODIXANOL 0.19 mg/dl vs. IOMEPROL 0.21 mg/dl, p=0.53) or in the proportion of patients requiring dialysis after the procedure (1.9% vs. 0.6%, p=0.31).
The clinical endpoints of the study, such as heart attack, death and repeat percutaneous coronary intervention in the target lesion within 90 days also revealed no differences between the different contrast media.
The preliminary results of the study, which Dr. Wessely presented at the Annual Conference of the American College of Cardiology in Chicago, throw up a number of questions regarding the alleged superior renal tolerance of the iso-osmolar IODIXANOL compared with the class of low-osmolar contrast media. The results initially appear to contradict current guidelines and the earlier studies cited at the beginning. Subgroup analyses, however, have shown significant differences in favour of the iso-osmolar IODIXANOL, while the hyperosmolar comparative product IOMEPROL did not perform significantly better in any subgroup analysis, states Dr. Wessely. These and other analyses still underway are certainly of importance for in-depth interpretations of the study. For the first time, the results of the CONTRAST study could provide us with an understanding of up to what morbidity level or in what morbidity constellation isoosmolar contrast media could potentially offer greater renal tolerance than hyper-osmolar contrast media.