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 99mTc-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.