Author + information
- Thomas Keeble1,
- Marko Noc2,
- Grigoris Karamasis1,
- Beata Sredniawa3,
- David Erlinge4 and
- Michael Holzer5
COOL AMI EU Pilot Trial was a multicenter, prospective, randomized controlled pilot trial to assess safety and efficacy of intravascular therapeutic hypothermia (TH) as an adjunctive therapy to Primary PCI (PPCI) in conscious patients with anterior ST-elevation myocardial infarction (STEMI). We recently reported a numerical yet non-significant 7.1% absolute and 30% relative reduction in infarct size in the TH treatment group. We now report the effect of hypothermia upon microvascular obstruction (MVO) and ejection fraction (EF) at 4-6 and 30 days.
50 conscious patients with anterior STEMI and symptom duration <6 hours were recruited and randomized to PPCI + TH or PPCI alone. TH was induced using the ZOLL Proteus intravascular temperature management system and rapid infusion of 1L of cold normal saline, with a target temperature of 32oC. MVO was measured by cardiac magnetic resonance (cMR) at 4 to 6 days post-MI. An MVO area larger than 3.9% of LV mass has been shown to independently predict clinical outcomes, thus we assessed the proportion of patients with extensive MVO (>3.9%) between hypothermia and control patients. EF was measured by cMR at both 4-6 and 30 days.
50 patients were randomized; 22 patients in the TH group and 23 patients in the control group completed cMR follow up. Mean age was 58 years, and 86% were men. At reperfusion, mean intravascular temperature for the TH group was 33.6 +/- 1oC. The incidence (binary) of MVO was high and not different in both groups (74% vs. 77%, p=0.79). The proportion of patients with a MVO >3.9% was 11% in the TH group and 23% in the control group (50% relative reduction; p=0.30). Patients with extensive MVO showed reduced EF at 4-6 days (34% versus 43%, p=0.01). The number of patients with EF <35% at 30 days was numerically lower in those that had received TH (6% vs 24%, p=0.19).
In the COOL-AMI Pilot Trial, therapeutic hypothermia was associated with a 50% numerical reduction in the incidence of extensive MVO, which led to improved EF in these patients. These results hold promise for improved clinical outcomes in patients with STEMI treated with hypothermia, and warrant a pivotal trial powered for efficacy.
CORONARY: Acute Myocardial Infarction