Abstract 2833: Magnetic Resonance Imaging Characterization of Peri-Infarct Zone Remodeling following Reperfused Myocardial Infarction
Background: Clinical studies using delayed enhanced magnetic resonance imaging (de-MRI) suggest the peri-infarct zone (PIZ) contains a mixture of viable and non-viable myocytes and is associated with greater susceptibility to ventricular tachycardia induction and adverse cardiac outcomes. However, data characterizing the temporal formation and remodeling characteristics of the PIZ do not exist. We hypothesized that the PIZ undergoes spatial/temporal changes in parallel with structural ventricular remodeling following reperfused myocardial infarction (MI).
Methods: Ten mini-pigs underwent coronary occlusion followed by reperfusion. Functional and de-MRI studies were performed prior and at five time points after MI induction. Custom signal density threshold algorithms based on the remote myocardium were applied to define the infarct core and PIZ region.
Results: LVEDV increased from 34.7. ± 2.2 ml to 47.8± 3.0 ml (day 3 and week 12, respectively; p<0.001). The size of infarct scar expanded by 14% and thinned by 56% from day3 to 12 weeks (p=0.004 and p<0.001, respectively). Though, there was no change in total scar volume (11.0±0.8 ml and 9.2±1.2 ml, day 3 and week 12, respectively; p=NS), the PIZ volume showed significant changes over 12 weeks (figure⇓) parallel to the structural remodeling of the left ventricle. After the initial post-MI edema subsided the PIZ decreased further by 54% from day 10 to week 12 (p=0.04)
Conclusions: The PIZ is dynamic and decreases in volume following reperfused MI. Remodeling characteristics of the PIZ may provide mechanistic insights into the development of life-threatening arrhythmias and sudden cardiac death post-MI.