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The article presents a study which examined the use of reperfusion therapy in reducing infarct size (IS) in patients with acute myocardial infarction (AMI). It cites clinical trials investigating mild hypothermia using endovascular cooling catheter as supplementary therapy in AMI. A description of the methodology used in assessing the study population, image analysis and creatine kinase (CK) and troponin T is included.

Abstract: Introduction: Cardiogenic shock is the main cause of death in patients hospitalized due to an acute myocardial infarction. Mild hypothermia reduces metabolism and could offer protective effects for this condition. The aim of our study was to investigate if mild therapeutic hypothermia would improve outcome and hemodynamic parameters in an ischemic cardiogenic shock pig model. Methods: Twenty-five pigs (40–50kg) were anesthetized and a normothermic temperature of 38°C was established utilising an endovascular cooling catheter in a closed-chest model. A Swan-Ganz catheter was placed in the pulmonary artery. Hemodynamic parameters were continuously monitored and blood gases were sampled every 30min. Ischemia was induced by inflation of a PCI balloon in proximal LAD for 40min. Sixteen pigs that have fulfilled predefined shock criteria were randomized to hypothermia (n =8), or normothermia (n =8). Hypothermia (33°C) was induced after onset of reperfusion by using an endovascular temperature modulating catheter and was maintained until termination of the experiment. Results: The pigs in the hypothermia group were cooled to <34°C in approximately 45min. 5/8 pigs in the normothermia group died while all pigs in the hypothermia group survived (p <0.01). Stroke volume and blood pressure were significantly higher in the hypothermia group (p <0.05), whereas heart rate was significantly lower in the hypothermia group (p =0.01). Cardiac output did not differ among the groups (p =0.13). Blood gas analysis revealed higher mixed venous oxygen saturation, pH, and base excess in the hypothermia group indicating less development of metabolic acidosis (p <0.05). Conclusions: In this pig model, mild therapeutic hypothermia reduces acute mortality in cardiogenic shock, improves hemodynamic parameters and reduces metabolic acidosis. These findings suggest a possible clinical benefit of therapeutic hypothermia for patients with acute cardiogenic shock. [Copyright &y& Elsevier]

Objectives: The aim of this study was to confirm the cardioprotective effects of hypothermia using a combination of cold saline and endovascular cooling. Background: Hypothermia has been reported to reduce infarct size (IS) in patients with ST-segment elevation myocardial infarctions. Methods: In a multicenter study, 120 patients with ST-segment elevation myocardial infarctions (<6 h) scheduled to undergo percutaneous coronary intervention were randomized to hypothermia induced by the rapid infusion of 600 to 2,000 ml cold saline and endovascular cooling or standard of care. Hypothermia was initiated before percutaneous coronary intervention and continued for 1 h after reperfusion. The primary end point was IS as a percent of myocardium at risk (MaR), assessed by cardiac magnetic resonance imaging at 4 ± 2 days. Results: Mean times from symptom onset to randomization were 129 ± 56 min in patients receiving hypothermia and 132 ± 64 min in controls. Patients randomized to hypothermia achieved a core body temperature of 34.7°C before reperfusion, with a 9-min longer door-to-balloon time. Median IS/MaR was not significantly reduced (hypothermia: 40.5% [interquartile range: 29.3% to 57.8%; control: 46.6% [interquartile range: 37.8% to 63.4%]; relative reduction 13%; p = 0.15). The incidence of heart failure was lower with hypothermia at 45 ± 15 days (3% vs. 14%, p < 0.05), with no mortality. Exploratory analysis of early anterior infarctions (0 to 4 h) found a reduction in IS/MaR of 33% (p < 0.05) and an absolute reduction of IS/left ventricular volume of 6.2% (p = 0.15). Conclusions: Hypothermia induced by cold saline and endovascular cooling was feasible and safe, and it rapidly reduced core temperature with minor reperfusion delay. The primary end point of IS/MaR was not significantly reduced. Lower incidence of heart failure and a possible effect in patients with early anterior ST-segment elevation myocardial infarctions need confirmation. (Efficacy of Endovascular Catheter Cooling Combined With Cold Saline for the Treatment of Acute Myocardial Infarction [CHILL-MI]; NCT01379261) [ABSTRACT FROM AUTHOR]