Purpose: In two-phase contrast enhanced CT (CE-CT), early defect (ED), late enhancement (LE), and residual defect (RD) are observed in acute myocardial infarction (AMI). However, the changes of these enhancement patterns during healing process have not been elucidated yet. Purpose was to investigate the change of the enhancement patterns after reperfusion therapy, and to investigate whether these changes can predict clinical outcome in one year by two-phase CE-CTs.
Methods and Materials: Materials consisted of 56 pts with successfully reperfused AMI. Pts underwent ECG-gated two-phase CE-CT after injection of contrast medium, at 45 sec and 7 min later. All patients received conventional biplane left ventriculography (LVG) immediately after primary reperfusion therapy, 1-mo and 1-year. End-diastolic and end-systolic volumes (EDV, ESV) and ejection fraction (EF) were assessed by the LVGs. Two-phase CE-CT was performed at 48-hr, 14-days, 1-mo and 1-year. End-diastolic short axial images were used to analyze myocardial enhancement patterns. Wall thickness (WT) was also measured in infarct and opposite normal areas, then % of reduction of wall thickness (WT%-decrease) was generated by the formula á(WTa -WTt)÷WTa)´100%ñ (a; 48-hr, t;14-days, 1-mo and 1-year).
Results: Perfusion patterns were classified into three groups at 48 hr. There were 16 Gr-1 (16/56), who showed ED(-),RD(-) and LE(+/-). There were 21 Gr-2 (21/56), who showed ED(+),RD(-) and LE(+). There were 19 Gr-3 (19/56), who showed ED(+), RD(+) and LE(+). In Gr-1, in all patients LE disappeared at 14-days, 1-mo and 1-year. In Gr-2, ED disappeared and only LE remained (®Gr-1) at 1-mo and LE also disappeared (®Gr-1) at 1-year. In Gr-3, RD disappeared in 12/19 at 1-mo (®Gr-2) and LE disappered at 1-year (®Gr-1) The other 7/19 remained in Gr-3. EDV, ESV and EF were not significantly different among the three groups at 48-hr. At 1-mo, ESV and EF in Gr-1 became smaller than those of Gr-3. In Gr-1, EF significantly improved. In Gr-2, EF did not significantly improve at 1-month but improved at 1-year. In Gr-3, EF deteriorated both 1-mo and 1-year. Especially in Gr-3, patients with RD at 1-mo (7/19) significantly deteriorated from 45±13% to 30±11%. WT%-decrease in Gr-3 was the highest and the lowest in Gr-1 at 1-year.
Conclusion: Myocardial perfusion pattern on CE-CT changes dynamically in healing stage. Perfusion pattern can predict clinical outcome of AMI after reperfusion therapy.
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