A New Radionuclide Method for Detecting Right Ventricular Involvement in nferior Acute Myocardial Infarction: Tc-99m SESTAMIBI Gated SPECT Imaging

This study sought to determine the value of a new method for visual and quantitative assessment of right ventricular involvement (RVI) in patients with inferior acute myocardial infaretion using Tc-99m Sestamibi gated SPECT imaging which allows simultaneous assessment of left ventricular perfusion and function. The study comprised 14 patients with inferior myocardial infaretion suspected of having RVI and 16 normal subjects. Diagnosis of RVI was confirmed with hemodynamic studies and a proximal right coronary artery lesion was detected on angiography in all 14 patients. After normal hemodynamic results were attained (mean 6th day), echocardiography and gated SPECT imaging were performed on the same day. In normal subjects, mean left ventricular end-systolic (ES) maximal counts w as 138± 13/pixel whereas right ventricular ES maximal counts was 48±8/pixel on circumferential profile analysis. The maximal value of color scale, assigned to highest counts of the left ventricle, was set to a value corresponding to the maximal right ventricular activity allowing clear visualisation of right ventricular in all cases. Perfusion was graded on a 5-point score (O=normal; 4=absence of tracer uptake), wall motion on a 4- point score (O=akinesis/dyskinesis; 3=normal) and systolic thickening on a 4-point score (O=absence of thickening; 3=normal) on ES images. A perfusion score ~2 and wall motion abnormality score ::; ı were defined as RVI. This method detected RVI in all 14 patients (100%). Moreover, quantitative analysis of segments with RVI revealed a significant reduction of Sestamibi uptake (m ean 1 9±6 counts/pixel) when compared to the lower limit of normal ES uptake (33 counts/pixel) (pKeywords: Acute myocardial infarction, myocardial perfusion imaging, SestaMIBI