Ventricular remodeling after acute myocardial infarction: Effect of low-intensity laser irradiation

BACKGROUND AND OBJECTIVE: Low-intensity laser irradiation is claimed to enhance wound healing. Healing after myocardial infarction results in ventricular enlargement and wall thinning. If laser treatment accelerated cardiac healing, we speculated that ventricular remodeling would be attenuated. STUDY DESIGN/MATERIALS AND METHODS: In vitro, fibroblasts were irradiated for 1 minute twice a day for 4 days (5 mW; wavelength, 780 nm). One day after infarction, rats were randomly assigned to 5 or 10 mW transdermal irradiation twice a day for 4 days or to sham. One week after infarction, we measured the remodeling parameters; cavity volume, infarct thickness, and vascular structure, and the healing parameters; collagen content and inflammation. RESULTS: Laser-treated fibroblasts occupied more area than controls. Hearts receiving the 10 mW treatment had smaller volumes than sham hearts. Laser treatment reduced infarct thinning and preserved arterial lumen area; however, collagen was not increased and inflammation was inhibited. CONCLUSIONS: Low-intensity irradiation attenuated infarct-associated remodeling. In contrast to expectations from in vitro study, these effects were not a result of enhanced healing.