99mTc-MIBI SPECT assessment of the effects of aneurysm resection on the left ventricular morphology

99mTc-MIBI SPECT is a widely used myocardial perfusion investigation technique, but few data are available concerning its use to assess the morphological characteristics of a left ventricular aneurysm (LVA) before and after LVA resection.

Pre- and postoperative rest 99mTc-MIBI SPECT images were analysed in order to characterize the features of LVAs and the changes in the 3D scintigraphic parameters after apical LVA resection in 6 patients. In the middle horizontal slice an angle was defined to quantify the apical divergence associated with the LVA. After resection, the changes in the divergence angles (DA) were measured as were the changes in the left ventricular volumes (LVV) by volumetric calculations. The mean DA decreased from an average of 38.50 degrees +/- 11.32 degrees preoperatively to 24 degrees +/- 11.84 degrees postoperatively (p = 0.03). The mean LVV also decreased significantly: from 443 +/- 87 ml to 317 +/- 74 ml (p = 0.003). The resectable LVAs were associated with a very low isotope uptake in the apical segments (< 20% relative activity). A DA < 20 degrees was also characteristic of anatomical LVA in all patients. A regression curve plotting divergence angle and the number of left ventricular segments below 20% relative activity showed a significant correlation between them (r = 0.86, p = 0.003).

The significant decreases of DA and LVV after resection reflect favourable morphological changes in the left ventricle (reverse remodelling). We consider 99mTc-MIBI SPECT a useful method for apical LVA detection, it allows an analysis of the morphological (and indirectly the functional) results of the surgery.