Abstract 158: Transient Hypothermia During the Acute Phase of Myocardial Infarction Dramatically Reduces Scar Size, Prevents Left Ventricular Dilation and Remodeling, and Preserves Cardiac Function
Background: While hypothermia (H) induced by the non-invasive ThermoSuit apparatus (convective-immersion cooling) acutely reduced myocardial infarct (MI) size in our experimental models, the long term effects of transient hypothermia on MI scar size, left ventricular (LV) remodeling, and LV function are largely unknown. Therefore we assessed the long term effects of transient H in our chronic rat MI model.
Methods: Rats were randomized to normothermic (N) or H groups (n=14 in each group). Rats were subjected to 30 minutes coronary artery occlusion and reperfusion for 6 weeks. For H therapy, rats were placed into the ThermoSuit apparatus at 2 minutes after the onset of coronary artery occlusion, and were taken out of the apparatus when the core body temperature reached 32°C (in ~8 minutes) and were then allowed to rewarm.
Results: After 6 weeks of recovery, rats treated with H demonstrated markedly reduced scar size (expressed as % of left ventricular area H, 9 ± 2%; N, 27 ± 3%; p < 0.001), and thicker anterior LV wall (H, 1.67 ± 0.08 mm; N, 1.13 ± 0.05 mm; p < 0.001); decreased postmortem left ventricular volume (H, 0.45 ml ± 0.04; N, 0.6 ± 0.03 ml; p = 0.028); and better LV fractional shortening (H, 37 ± 3%; N, 19 ± 2%; p = 0.0002) and LV ejection fraction (H, 68 ± 3%; N, 48 ± 3%; p = 0.0006) by echocardiography. Figure A and B show representative slices of hearts stained with picrosirius red staining. Muscle cells stain yellow while scar area with collagen stains red, showing reduced collagen deposition in H versus N.
Conclusions: Rapid, transient non-invasive surface cooling with the ThermoSuit apparatus in the acute phase of MI decreased scar size by 68%, attenuated adverse post-infarct left ventricular dilation and remodeling, and improved cardiac function in the chronic phase of experimental MI. This is the first study to show that H induced by the ThermoSuit has long lasting and dramatic beneficial effects on cardiac morphology and function post MI.
Author Disclosures: W. Dai: None. M.J. Herring: None. S.L. Hale: None. R.A. Kloner: Research Grant; Modest; Stealth Peptides. Research Grant; Significant; Significant. Speakers Bureau; Modest; Pfizer. Speakers Bureau; Significant; Modest. Honoraria; Modest; Pfizer. Honoraria; Significant; Modest. Consultant/Advisory Board; Modest; Stealth Peptides. Consultant/Advisory Board; Significant; Significant.
- © 2014 by American Heart Association, Inc.