COOLing as an Adjunctive Therapy to Percutaneous Intervention in Patients With Acute Myocardial Infarction - COOL-MI
The goal of the COOL-MI trial was to evaluate the safety and effectiveness of treatment with endovascular cooling in patients with acute myocardial infarction (AMI).
Treatment with endovascular cooling will be safe and will be associated with a reduction in infarct size in patients with AMI.
Patients Enrolled: 392
Mean Follow Up: 30 days
Mean Patient Age: Mean 60 years
AMI within six hours (anterior MI or inferior MI with reciprocal changes)
Prior MI within one month; cardiogenic shock; and hypersensitivity to hypothermia, buspirone, or meperdine; inferior vena cava filter in situ
Efficacy: Infarct size at 30 days; safety: MACE at 30 days
ST resolution, left ventricular ejection fraction by SPECT, and creatine kinase-MB
Patients with an AMI were randomized to endovascular cooling (n=177) or control (percutaneous coronary intervention [PCI] alone; n=180). Patients were awake during the cooling procedure and were cooled to a target temperature of 33°C. Following the cooling, patients underwent PCI.
Buspirone (60 mg orally); meperidine used to reduce shivering
Endovascular cooling was well tolerated and was completed in 94.3% of patients, with 72% of patients reaching target cooling temperature; only 1% discontinued cooling therapy due to shivering. Time from symptom onset to hospitalization was 237 minutes in the cooling arm and 238 minutes in the control arm, and time from door to balloon was 110 minutes and 92 minutes, respectively. Post-procedure TIMI flow grade 3 rates were 90% in the cooling arm and 95% in the control arm (p=NS), and myocardial blush grade 3 rates were 29% and 33% (p=NS), respectively.
There was no difference in the primary endpoint of infarct size at 30 days between the cooling arm and control arm (cooling 14.1% vs. control 13.8%, p=0.45). However, in an analysis restricted to patients with anterior MI who were cooled to <35°C, cooling was associated with a significantly smaller infarct size compared with controls (9.3% vs. 18.2%, p=0.05). There was no difference in 30-day major adverse cardiac events (MACE) (6.2% vs. 3.9%, p=0.45) or mortality (3.4% vs. 2.2%, p=0.71), or occurrence of ventricular tachycardia or fibrillation (17.5% vs. 20.0%, p=NS).
Among patients with AMI undergoing PCI, treatment with endovascular cooling was not associated with a reduction in the primary endpoint of infarct size compared with control, but was associated with a reduction in infarct size in the subset of patients with an anterior MI cooled to <35°C at the time of PCI.
While the overall trial results did not meet the prespecified primary endpoint, the finding in the anterior MI patients cooled to <35°C at time of PCI provides important information for future investigation. Prior animal studies have demonstrated that hypothermia reduces infarct size. The present trial is the first randomized, multicenter trial to assess the effectiveness of endovascular cooling in AMI patients.
Presented at the 2003 Transcatheter Cardiovascular Therapeutics conference, by William O’Neill, MD
Keywords: Temperature, Tachycardia, Ventricular, Inferior Wall Myocardial Infarction, Shivering, Hypothermia, Hospitalization, Stents, Percutaneous Coronary Intervention
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