Diiodothyropropionic acid (DITPA) is a thyroid hormone analog that is currently 
in phase II clinical trials. However, there have not been any studies to 
comprehensively analyze its effect on myocyte morphology. In addition, long-term 
studies with DITPA have not been done. This study compares the effects of DITPA 
with L-thyroxine (T4) on chamber remodeling, cardiac function, cellular 
morphology, cardiac blood flow, and protein expression. Normal and 
cardiomyopathic hamsters were treated with T4 or DITPA for 2 months. At the end 
of the treatment, echos, hemodynamics, coronary blood flow, cell morphology, and 
protein expression data were collected. Both T4 and DITPA treatment reduced 
chamber diameter during diastole, suggesting attenuated chamber dilatation in 
cardiomyopathic hamsters. Wall thickness also tended to increase, which was 
supported by cell morphology data in which DITPA significantly increased 
cross-sectional growth of myocytes specifically in the minor dimension, which is 
oriented transmurally. T4 and DITPA also increased myocardial blood flow both at 
baseline and after maximal dilation. This suggests there was increased 
angiogenesis or reduced loss of arterioles. Both T4 and DITPA had beneficial 
effects on chamber remodeling, which was most likely due to beneficial changes 
in cell shape and improved vascular supply.