Assessment of reperfused acute myocardial infarction with two-phase contrast-enhanced helical CT: prediction of left ventricular function and wall thickness

Purpose: To investigate whether two-phase contrast material-enhanced computed tomographic (CT) findings serve as predictors of changes in left ventricular (LV) function and wall thickness (WT) after acute myocardial infarction (MI) and successful angioplasty.

Materials and methods: Ethics committee approval and informed consent were obtained. In 58 patients (51 men and seven women; mean age, 62 years +/- 12 [standard deviation]) who had experienced an acute MI and undergone successful angioplasty, two-phase (acquisitions at 45 seconds and 7 minutes) contrast-enhanced CT was performed in the acute (mean interval between treatment and CT, 37 hours +/- 4) and intermediate (mean interval, 28 days +/- 4) periods and for long-term (mean interval, 12 months +/- 4) follow-up. CT images were reviewed for an early perfusion defect (ED) at 45 seconds and for late enhancement (LE) and a residual perfusion defect (RD) at 7 minutes. Myocardial enhancement patterns and WT were assessed, and LV ejection fraction (LVEF) and percentage decrease in WT were calculated. The patient group was subdivided into three groups according to enhancement pattern: Group 1 included patients with LE but no ED or RD; group 2, patients with ED and LE but no RD; and group 3, patients with ED, LE, and RD. Fisher exact testing was used to measure categorical response. Paired and unpaired t tests were used for comparison between two groups (points); Tukey-Kramer multiple comparison and repeated-measures analysis of variance were used for comparisons between the three groups. P < .05 was considered to indicate a significant difference.

Results: In group 3 (n = 36), WT in infarcted area was significantly reduced at the intermediate and long-term CT examinations (P < .001). At the intermediate and long-term examinations, percentage decrease in WT was greater in group 2 (n = 10) than in group 1 (n = 12) (P < .05 for intermediate and P < .001 for long-term examination) and was greatest in group 3 (P < .001 for both examinations). LVEF was poorest in group 3 and best in group 1.

Conclusion: Two-phase contrast-enhanced CT proved useful in predicting LV functional recovery and WT in patients who had experienced acute MI and undergone successful angioplasty.