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

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. Sixty-eight AMI patients successfully treated by primary percutaneous coronary intervention underwent Tc-99m-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. 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). 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.