Radionuclide quantification of infarct size. Comparison of polar and transaxial slices methods with Tc99m sestamibi and Thallium-201. A study in patients with acute anterior myocardial infarction

Abstract

Aim:The aim of this study was to compare left ventricular ejection fraction (LVEF) obtained by equilibrium radionuclide angiography (ERNA) and echocardiography (US) in patients with severe left ventricular (LV) disfunction. Methods:Fourty patients (12 women, 28 men, mean age of 55Ϯ14 years) with severe left ventricular disfunction selected to cardiac transplantation were studied. All patients had moderate to severe functional limitations (New York Heart Association functional class III or IV). After in vivo labelling of erithrocytes with 444 to 555 MBq of technetium-99m, gated scintigraphic study was acquired with detector in left anterior oblique position with a 15°caudal tilt, during 500 cardiac cycles. Automatic processing was used. In the same week a two dimensional echocardiography was performed and LVEF was assessed using the modified biplane Simpson's rule. The reproducibility was determined from duplicate measurements with reposition in between. Linear regression analysis and evaluation of statistical differences (Bland Altman) between both methods were obtained. Results: ERNA showed a coefficient of variation of 6%, which is smaller than the coefficient of variation obtained by US. We found a moderate good correlation between both results (Rϭ0,83 ; SEEϭ0,05). Bland Altman plot did not show any direction bias and for a 95% confidence interval the differences between LVEF obtained with EARN and with US were within [Ϫ10%; ϩ10%]. Conclusions: ERNA has higher reproducibility than US and should be preferred for follow up measurements. Differences found between both methods are acceptable but should be considered for clinical purpose.