CHICAGO — Hemofiltration is the first and only strategy for the prevention of contrast-induced nephropathy that rises to the standard of proven efficacy, Dr. Peter A. McCullough said at the annual meeting of the Society for Cardiovascular Angiography and Interventions.
This is a very recent development. When the international multidisciplinary expert consensus panel of which Dr. McCullough is a member met late last year to consider whether they could endorse any adjunctive drug or mechanical therapies to reduce the risk of contrast-induced nephropathy (CIN), they concluded they could not. No adjunctive therapy had demonstrated consistent evidence of efficacy in at least two randomized trials.
That changed a few months later, however, when Dr. Giancarlo Marenzi and his coworkers at the University of Milan published a randomized trial that involved 92 patients with chronic kidney disease who were assigned to intravenous hydration with isotonic saline for 12 hours before and after iodinated contrast exposure (controls), 12 hours of intravenous hydration before contrast exposure followed by 18–24 hours of hemofiltration after, or hemofiltration for 6 hours before and again for 18–24 hours after, contrast exposure.
CIN occurred in 40% of controls, 26% of patients who got postcontrast hemofiltration, and just 3% of those with both pre- and postcontrast hemofiltration. Of patients in the control arm, 30% required hemodialysis, as did 10% in the postcontrast hemofiltration arm and none in the pre- and postcontrast hemofiltration group.
In-hospital mortality was 20% among controls, 10% with postcontrast hemofiltration, and 0% with full-course hemofiltration (Am. J. Med. 2006;119:155–62).
What particularly impressed Dr. McCullough was that this was the Milan group's second and confirmatory positive trial involving hemofiltration for prevention of CIN; the first was published in the New England Journal of Medicine (2003;349:1333–40).
Hemofiltration is an expensive blood-washing technology. “There is something about this hemofiltration procedure—that is, putting the patient on hemofiltration in a planned and coordinated way before contrast exposure and again afterward—that seems to avert de novo acute renal failure requiring dialysis, as well as mortality,” said the cardiologist, who is chief of the division of preventive medicine at William Beaumont Hospital in Royal Oak, Mich.
In considering potential adjunctive therapies for prevention of CIN, the panel agreed the best they could come up with was a list of potentially beneficial agents, none of which have been validated as effective. This list includes theophylline, ascorbic acid, statins, and prostaglandins. “The single best study is for vitamin C in preventing contrast-induced nephropathy,” according to Dr. McCullough.
The statin study, from Henry Ford Hospital in Detroit, involved nearly 30,000 patients with serum creatinine measurements before and after contrast exposure. Those on a preprocedural statin had an adjusted 13% lower relative risk of developing CIN (Am. J. Med. 2005;118:843–9).
The panel also developed an evidence-based list of potentially detrimental agents, including endothelin receptor blockers, mannitol, and furosemide.
On the basis of the favorable preliminary results with vitamin C, pharmaceutical companies are now developing proprietary advanced oxidants as potential adjunctive agents for prophylaxis against CIN.
Other potential future approaches under active investigation, Dr. McCullough said, include renal cooling, high-flow diuresis, the use of ultra-low contrast loads in conjunction with more sensitive imaging techniques, and development of nontoxic contrast agents.