Right ventricular dysfunction detected by gated scintiphotography in patients with acute inferior myocardial infarction.

Twenty-seven patients with acute myocardial infarction not complicated by cardiogenic shock and ten normal volunteers were studied with gated cardiac blood pool scans. The ratio right vetricular area/left ventricular area (RVA/LVA) determined from the left anterior oblique end-diastolic scans was examined. The ratio was 1.11 +/- .06 in the normal volunteers. In patients with anterior infarction the ratio fell to 0.75 +/- .12 (P less than .05) due to left ventricular enlargement. In those with inferior infarction the ratio was 1.12 +/- .23 which was greater than in those with anterior infarction (P less than .05) due to enlargement of both the left and right ventricles. Six patients with cardiogenic shock, three with inferior and three with anterior infarction were studied. The three with anterior infarction had left ventricular enlargement and a decrease in the ratio of RVA/LVA to 0.62 while the three with inferior infarction had an increase in the ratio to 2.05 suggesting right ventricular dilatation and dysfunction. These studies suggest a high incidence of right ventricular dysfunction in patients with inferior myocardial infarction.