September 19, 2014 — According to a new study, peritoneal hypothermia is feasible for patients who have suffered ST-segment elevation myocardial infarction (STEMI). However, the procedure was associated with an increased rate of adverse events without reducing infarct size. These findings were reported at the 26th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium earlier this week.
Rapid reperfusion is essential to improve survival after the onset of myocardial injury in STEMI patients, but a significant proportion of patients experience sizeable losses of ventricular function despite reperfusion. Induction of hypothermia as a means of reducing infarct size has been previously explored using multiple methods to establish rapid hypothermia. However, many methods of inducing hypotheremia are not fast enough to ensure adequate cooling before percutaneous coronary intervention (PCI). Peritoneal lavage has been used to rapidly facilitate hypothermia for decades and has a well-established safety profile for the diagnosis of blunt abdominal injury in patients with trauma and for the treatment of accidental hypothermia, end-stage renal disease and cancer.
VELOCITY was a multicenter randomized trial that sought to determine the feasibility, safety and efficacy of systemic hypothermia induced by peritoneal lavage in patients with STEMI prior to primary PCI. The primary safety endpoint was the 30-day rate of death, reinfarction, ischemia-driven target vessel revascularization, major bleeding, sepsis, pneumonia, peritonitis, severe arrhythmia or renal failure. The primary efficacy endpoint was infarct size assessed by cardiac magnetic resonance imaging (MRI) after 3-5 days.
A total of 54 patients were randomized at seven centers to the hypothermia group (n=28) and the control group (n=26). Hypothermia was successfully initiated in 96.3 percent of patients and the median temperature at first balloon inflation was 34.7 degrees Celsius, indicating rapid cooling had been accomplished. Median door-to-balloon times in the hypothermia and control groups were 62 and 47 minutes, respectively (p=0.007). Both groups underwent primary PCI using standard techniques and adjunct pharmacology as per local standard of care.
The primary composite safety endpoint occurred in six (21.4 percent) patients in the hypothermia group driven by three stent thrombosis events. No patients in the control group experienced stent thrombosis or any adverse events (p=0.02 for comparison). Infarct size (as a percentage of left ventricular mass) was 17.2 percent in the hypothermia group and 16.1 percent in the control group (p=0.54).
“The establishment of peritoneal hypothermia before primary PCI in patients with STEMI was feasible, but did not reduce infarct size,” said lead investigator Gregg W. Stone, M.D., professor of medicine at Columbia University College of Physicians and Surgeons and director of cardiovascular research and education at the Center for Interventional Vascular Therapy at New York-Presbyterian Hospital/Columbia University Medical Center.
“The time to achieve the goal temperature prolonged door-to-balloon time modestly, and the procedure was associated with adverse events including stent thrombosis. These findings have implications not only for the peritoneal approach to hypothermia, but also raise general questions about the utility of systemic hypothermia to reduce infarct size. A large scale, appropriately powered trial is clearly needed to determine whether the rapid induction of mild systemic hypothermia reduces infarct size and improves clinical outcomes in patients with STEMI undergoing primary PCI,” said Stone.
The VELOCITY trial was funded by a grant from Velomedix Inc. Stone reported serving as a consultant to Velomedix.
For more information: www.crf.org, www.tctconference.com