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Induction of Mild Systemic Hypothermia With Endovascular Cooling During Primary PCI for Acute MI - Induction of Mild Systemic Hypothermia With Endovascular Cooling During Primary PCI for Acute MI
Description:
Primary PCI with or without endovascular cooling for acute MI
Hypothesis:
To evaluate the safety and feasibility of endovascular cooling during primary PCI for acute MI
Study Design
Study Design:
Patients Enrolled: 42
Mean Follow Up: 30 days
Mean Patient Age: 32-83 years
Female: 12
Patient Populations:
Symptom onset <6 hours, chest pain >30 min duration with ST-segment elevation >=1 mm in two contiguous leads. Patients with inferior AMI were required to have >=1 mm reciprocal ST-segment depression in two precordial leads.
Exclusions:
Cardiogenic shock, rescue angioplasty, previous AMI <1 month, Raynaud's disease, hypersensitivity to buspirone or meperidine, treatment with a monoamine oxidase inhibitor in the previous 14 days, bleeding diathesis or coagulopathy, severe hepatic or renal impairment, pregnancy, patient height <1.5 m, or the presence of an inferior vena cava filter.
Primary Endpoints:
MACE at 30 days (death, non-fatal reinfarction, and ischemia-driven TVR)
Secondary Endpoints:
Infarct size per SPECT at 30 days; hemodynamic and electrocardiographic monitoring; vascular or bleeding complications.
Drug/Procedures Used:
Patients with acute MI were randomized to primary PCI with or without endovascular cooling. Cooling was done via a heat-exchange balloon catheter device into the inferior vena cava. PCI was performed once the patient temperature was reduced to a target core temperature of 33°C. Cooling was maintained for 3 h after reperfusion. Oral buspirone and IV meperidine were used to reduce the shivering threshold.
Concomitant Medications:
Aspirin 325 mg; Heparin during the procedure (ACT >250 sec); Coronary stenting, adjunctive thrombectomy, and use of GP IIb/IIIa inhibitors at the operator's discretion.
Principal Findings:
Endovascular cooling was performed in 20 of the 21 patients randomized to this arm (95%) to a mean core temperature at first balloon inflation of 34.7 +/- 0.9°C and a mean duration of cooling of 241 +/- 29 min. Mild shivering occurred during cooling in 9 patients, 4 of which were treated with meperidine and surface warming and 5 of which required a small increase in target core temperature. MACE occurred in 0% vs. 10% of treated vs control patients (p = NS). The median infarct size was 2% in the cooling arm vs 8% in the control arm (p=0.80). No hemodynamic instability or increase in arrhythmia occurred in the cooling arm.
Interpretation:
This trial is the first study to show that endovascular cooling can feasibly and safely be performed as an adjunct to primary PCI for acute MI. Given the small sample size of this study, no statistically significant clinical benefit was observed with the cooling therapy. However, the ongoing "COOLing for Myocardial Infarction" (COOL MI) trial will address the efficacy of cooling as an adjunct to primary PCI in a larger study of acute MI patients. Cooling has been used in other clinical settings to limit ischemic cellular injury such as during cardiopulmonary bypass surgery, organ transplantation, and neurosurgery. It has previously been demonstrated that lowering myocardial temperature reduces metabolic demand in the myocardium at risk and may reduce infarct size. However, prior limitations to mild hypothermia included the inability to conveniently and easily reduce core temperature as well as the inability to prevent shivering in patients. The combination of buspirone and meperidine was used in this study to suppress shivering while the endovascular heat-exchange catheter allowed the core temperature to be reduced without surface cooling (e.g., ice packs or cooling blankets) or highly invasive procedures (e.g., cardiopulmonary bypass or extra-corporeal blood cooling circuits). Given the promising feasibility and safety of this technique, further studies into the clinical efficacy are warranted.
References:
J Am Coll Cardiol 2002;40:1928–34.
Keywords: Buspirone, Vena Cava, Inferior, Myocardial Infarction, Shivering, Angioplasty, Balloon, Coronary, Hemodynamics, Percutaneous Coronary Intervention, Stents, Temperature, Hypothermia, Chest Pain, Meperidine, Cardiopulmonary Bypass, Hypothermia, Induced
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