7. Spargias K, Alexopoulos E, Kyrzopoulos S. Ascorbic acid prevents contrast-mediated nephropathy in patients with renal dysfunction undergoing coronary angiography or intervention. Circulation.110(18)2837-42
In this study, a team of Greek researchers studied the use of vitamin C in patients with renal insufficiency (creatinine >1.2) undergoing coronary catheterization or intervention to determine if it prevented contrast-mediated nephropathy (CMN). Although the etiology of CMN is unknown, ischemic insults to the renal medulla and free radical release have been implicated. Since vitamin C has been shown in animal studies to attenuate nephropathy when administered with known renal toxins, a similar effect was postulated when administered with IV contrast.
Two hundred and twenty patients electively admitted for coronary catheterization or intervention were randomized to placebo or to receive 3 grams of vitamin C 2 hours prior to the dye load followed by 2 gm that night and the morning after. The two groups were balanced for presence of hypertension, diabetes, tobacco use, and use of commonly prescribed medications. Intravenous hydration was given to all at variable rates depending on left ventricular ejection fraction. The catheterization team chose the type of contrast agent. Creatinine was measured at baseline (up to 3 months prior to dye load) and 2-5 days afterwards. CMN was defined as a rise in total serum creatinine by 0.5 mg/dL or by 25%. Using these criteria, 9% of the vitamin C group developed CMN as opposed to 20% in the controls (NNT 9; 95% CI: 5-53). Logistical regression was performed to account for differences in age, initial serum creatinine, or both, and always yielded significant differences. The treatment group was slightly older, had higher rates of isoosmolar contrast administration (reno-protective), and had slightly higher baseline creatinines, so the true protective effect was thought even higher than reported.
This study is limited by small sample size, an overwhelmingly male patient base (90%), and the suspected presence of atherosclerotic heart disease in all patients. The amount and rate of delivery of contrast was not noted. The vitamin C preparation used was not described, implying that all preparations were bioequivalent. No mention was made of whether these results could be extrapolated to other procedures involving contrast. Given the low cost and high tolerability of vitamin C, however, further studies would certainly be welcome.
8. Yadav J, Wholey M, Kuntz R, et al. Protected carotid-artery stenting versus endarterectomy in high-risk patients. NEJM.2004;351:1493-1501.
Carotid angioplasty has been available for the past decade, but, due to possible complications such as plaque embolization and stent compression, the procedure had been limited to patients unsuitable for surgical endarterectomy. Recently, the introduction of crush-resistant nitinol stents and emboli protection devices has made the procedure safer. This study was designed to test the hypothesis that angioplasty and stenting is not inferior to endarterectomy. Three hundred and thirty-four patients at 29 centers had either a symptomatic carotid lesion greater than 50% or asymptomatic lesion greater than 80% and were deemed to be suitable candidates for either carotid endarterectomy or angioplasty. Patients were then randomized to one of the treatment groups. Surgeons, cardiologists, or interventional radiologists performed angioplasty. The primary endpoint was a composite of death, stroke, or MI within 30 days of the procedure, or death or stroke between 31 days and one year.
Secondary endpoints were the need for revascularization and cranial-nerve palsy at one year. During the first month after procedure, 4.8% of patients in the stent group and 9.8% of patients in the surgical group reached the primary endpoint. In the subsequent year, 12.2% of stent patients and 20.1% of surgical patients reached the primary endpoint (absolute risk reduction of 7.9, CI 0.7-16.4 and NNT 14). Cranial nerve palsy at one year was 0% vs. 4.9% in the stent vs. surgical group. Need for revascularization at one year was 0.6% vs. 4.3% for stent vs. surgical group. Although this study was designed to show the non-inferiority of angioplasty vs. carotid endarterectomy in patients deemed suitable for either procedure, it actually was statistically significant for superiority of stenting. It also implied a lower complication rate in terms of cranial nerve palsy and the need for revascularization at one year made the procedure safer. This study was designed to test the hypothesis that angioplasty and stenting is not inferior to endarterectomy. Three hundred and thirty-four patients at 29 centers had either a symptomatic carotid lesion greater than 50% or asymptomatic lesion greater than 80% and were deemed to be suitable candidates for either carotid endarterectomy or angioplasty. Patients were then randomized to one of the treatment groups. Surgeons, cardiologists, or interventional radiologists performed angioplasty. The primary endpoint was a composite of death, stroke, or MI within 30 days of the procedure, or death or stroke between 31 days and one year.