Relationship between infarct size and severity measured by gated SPECT and long-term left ventricular remodelling after acute myocardial infarction.

PURPOSE: After acute myocardial infarction (AMI), left ventricular (LV) remodelling may occur despite successful reperfusion. This study aimed to investigate by gated single photon emission computed tomography (SPECT) the long-term evolution of myocardial perfusion and LV function after AMI and to identify the predictors of LV remodelling. METHODS: Sixty-eight AMI patients successfully treated by primary percutaneous coronary intervention underwent (99m)Tc-sestamibi gated SPECT at 1 month (baseline) and over 6-month follow-up after the acute event. LV remodelling was defined as 20% increase in LV end-diastolic volume at follow-up. RESULTS: At baseline, patients with remodelling (n = 14) showed larger (infarct size 29.3 ± 7.8%) and more transmural (infarct severity 0.28 ± 0.10) infarctions, and reduced LV ejection fraction (35.4 ± 5.6%), but similar LV volume indexes, compared to patients without remodelling (n = 54) (infarct size 20.8 ± 14.4%, p < 0.05, infarct severity 0.40 ± 0.11, p < 0.001, ejection fraction 44.5 ± 9.2, p < 0.001). At stepwise multivariate regression analysis, infarct severity showed the best predictive value for predicting LV remodelling (F = 5.54, p < 0.05). Using the thresholds identified by receiver-operating characteristic curve analysis, infarct size and severity detected patients with remodelling with 75% accuracy and 95% negative predictive value. Infarct resorption (defined as the defect size difference between follow-up and baseline) was comparable between patients with (-4.4 ± 8.4%) and without remodelling (-6.8 ± 9.4%) (p = NS). CONCLUSION: Perfusion parameters assessed by gated SPECT in the subacute phase after successfully treated AMI correlate with changes in functional parameters at long-term follow-up. Infarct severity is more effective than infarct size, but both are helpful for predicting LV remodelling.