Assessment of microembolization associated with revascularization in acute myocardial infarction: MDCT cardiac perfusion and function study

To use multi-detector computed tomography (MDCT) for assessing the effects of coronary microemboli on pre-existing acute myocardial infarct (AMI) and to compare this pathology to LAD microembolization and occlusion/reperfusion. An angioplasty balloon catheter was placed in the LAD coronary artery of pigs under X-ray guidance. Four animals served as controls without intervention (group A) and an additional 24 animals (8/group) were subjected to microembolization (group B), occlusion/reperfusion (group C) or combination of the two insults (group D). MDCT was used to assess perfusion, LV function and viability. At postmortem, the LV sections were stained with hematoxylin/eosin and triphenyltetrazolium chloride (TTC). Dynamic perfusion and helical cine MDCT demonstrated decline in regional LV perfusion and function, respectively, after all interventions. MDCT showed significant differences in ejection fraction between groups: A = 57.5 +/- A 4.7 %, B = 40.3 +/- A 0.5 % P < 0.05, C = 34.9 +/- A 1.3 % P < 0.05 and D = 30.7 +/- A 1.2 % P < 0.05, while viability MDCT demonstrated differences in enhancement patterns and extents of damage between the groups (B = 9.1 +/- A 0.4 % LV mass, C = 11.9 +/- A 0.7 % and D = 16.2 +/- A 1.2 %, P < 0.05) and extent of microvascular obstruction (MVO) (group C = 3.2 +/- A 1.0 % LV mass versus D = 5.2 +/- A 0.7 %, P < 0.01). DE-MDCT overestimated all types of myocardial damage compared with TTC, but showed a close correlation (r > 0.7). Microscopic examination confirmed the presence of patchy and contiguous necrosis, MVO, edema and calcium deposits. Dynamic and helical cine MDCT imaging can grade LV dysfunction and perfusion deficit, respectively. DE-MDCT demonstrated a large and persistent MVO zone after microembolization of pre-existing AMI. Furthermore, it has the potential to visualize patchy microinfarct, detect perfusion deficits and dysfunction at the border zone after microembolization of pre-existing AMI.