Prediction of left ventricular dilatation with thallium-201 SPET imaging after primary angioplasty in patients with acute myocardial infarction

Progressive ventricular dilatation is an important prognostic factor in patients with acute myocardial infarction. We evaluated clinical, angiographic, echocardiographic and thallium-201 single-photon emission tomography (SPET) imaging variables predictive of the change in left ventricular volume during a 7-month follow-up period after primary angioplasty in patients with acute myocardial infarction. Thirty-six patients with first acute myocardial infarction treated with primary angioplasty within 12 h of onset underwent ²⁰¹Tl SPET imaging (5.8±2.1 days after angioplasty). Changes in left ventricular volume were assessed over the 7-month period. The left ventricle dilated significantly after angioplasty (P<0.001). Multivariate analysis revealed that the number of segments with ²⁰¹Tl uptake <40% of peak activity was a single independent predictor of increase in end-diastolic volume index between 1 week and 7 months (R²=0.41, P<0.001). The presence of two or more segments with ²⁰¹Tl uptake <40% predicted an increase in end-diastolic volume index of ≥6 ml/m² with positive and negative predictive values of 85% (17/20) and 75% (12/16), respectively. It is concluded that, following primary angioplasty in patients with acute myocardial infarction, the extent of myocardial infarction assessed by ²⁰¹Tl SPET can identify those who will develop ventricular dilatation during the subsequent 7 months.