Assessment of ejection fraction of the right and left ventricles in patients with acute myocardial infarction by magnetic resonance imaging

Right and left ventricular function in acute myocardial infarction (AMI) was assessed by ECG-gated magnetic resonance imaging (MRI) in 64 patients and 8 volunteers. Five short axis images for intrinsic cardiac long-axis of the left ventricle were obtained at 9 msec and 309 msec after the R wave as end-diastole and end-systole. Right and left ventricular volumes were measured by Simpson's rule. The intraobserver variabilities in right and left ventricular ejection fraction (RVEF: r=0.94, LVEF: 0.89) were excellent. The interobserver variabilities in RVEF (r=0.61) and LVEF (r=0.77) were fair. LVEF, but not RVEF, was significantly reduced in patients with AMI. Among left ventricular dysfunction (LVEF≤40%) patients, 50% exhibited right ventricular dysfunction (RVEF≤40%). Among patients without left ventricular dysfunction, only 12% exhibited right ventricular dysfunction. In left ventricular and biventricular dysfunction compared with control, the left ventricular end-diastolic volume index increased (65±10 ml/m2, 68±12 ml/m2 vs 54±8 ml/m2), the end-systolic volume index increased (40±16 ml/m2, 43±7 ml/m2 vs 18±1 ml/m2), and the right ventricular end-diastolic volume index decreased (52±13 ml/m2, 53±20 ml/m2 vs 65±8 ml/m2). MRI can thus be used to assess ventricular systolic function. Since patients with left ventricular dysfunction revealed a high incidence of right ventricular dysfunction, an interaction between the left and right ventricles may occur in ventricular dysfunction. (author)