Endovascular therapeutic hypothermia may help prevent radiocontrast nephropathy (RCN), a cause of kidney failure, according to the results of a clinical feasibility trial presented at the recent American Heart Association's Scientific Sessions 2006 in Chicago.
Radiant Medical, Inc., a private medical technology company developing endovascular temperature therapy products, sponsored the COOL RCN (COOLing to Prevent RadioContrast Nephropathy in Patients Undergoing Diagnostic or Interventional Catheterization) Pilot Trial, a feasibility study conducted at eight international medical centres. The study was designed to evaluate the feasibility of preventing RCN, an acute decline in kidney function after the administration of contrast agents, in high-risk patients. Patients were treated with the new Radiant Medical endovascular temperature therapy system, a venous heat exchange catheter that enables very rapid induction of mild hypothermia and rewarming.Thirty patients with pre-existing renal insufficiency (creatinine clearance 20-50 mL/min) and scheduled for an angiography, angioplasty, and/or stenting procedure were enrolled in the study. Using the Radiant Medical system, patients were rapidly cooled to 33-34 degrees C prior to administration of contrast agent. Serum creatinine (SCr) was measured at 24, 48 and 72-96 hours. The primary endpoint was development of RCN, defined as a rise in SCr > 25% from baseline.In this study, only 10% of patients cooled with the Radiant Medical system developed RCN. The expected incidence of RCN was estimated at 40%, based on a previous study (CONTRAST) of patients with a similar risk profile. The 75% reduction in occurrence of RCN was accompanied by a favourable safety profile, where no cooled patients required dialysis.Gregg W. Stone, M.D., Professor of Medicine and the Director of Cardiovascular Research and Education at Columbia University Medical Centre, and Chairman of The Cardiovascular Research Foundation, presented the study findings on behalf of the investigators. "The COOL RCN pilot study results suggest that mild systemic hypothermia may be an effective approach to prevent contrast nephropathy. RCN is a common complication of contrast dye administration in high-risk patients and it is associated with a significant morbidity and mortality," said Dr. Stone.In recent years, several different preventive therapies for RCN have been investigated with mixed results. Patients with pre-existing renal insufficiency and/or diabetes are at particularly high risk of developing RCN after cardiac catheterization. Unfortunately, heart disease and kidney disorders frequently go hand and hand, so a large number of patients requiring cardiac catheterization have renal insufficiency or diabetes and could benefit from an adjunctive therapy to reduce the risk of RCN.Kenneth G. Hayes, President and CEO of Radiant Medical stated, "This finding adds another potential use to a growing list of clinical applications of endovascular therapeutic cooling with our new state-of-the-art technology. The latest generation of our heat exchange system cools patients very rapidly, taking less than 20 minutes to reach 33 degrees C, enabling easy incorporation of the therapy into the cath lab procedure."Enrolment has begun in the pivotal phase of the COOL RCN Trial, a prospective, randomized, multicentre clinical trial designed to evaluate the safety and effectiveness of endovascular cooling for preventing RCN in high- risk patients. The pivotal study is being conducted at 35 international sites and will enrol 400 patients randomized to mild systemic hypothermia or control. (Source: American Heart Association's Scientific Sessions : Columbia University Medical Centre : December 2006.)