VECTORCARDIOGRAPHIC EVALUATION OF MYOCARDIAL INFARCT SIZE - DEPARTUREPARAMETERS ARE SUPERIOR TO CONVENTIONAL SPATIAL PARAMETERS

To determine whether the departure parameters derived from a ''departu re loop'' of a vectorcardiogram are more accurate than conventional sp atial parameters in evaluating myocardial infarct size, 74 patients wi th first-onset myocardial infarction (MI) were studied. The correlatio n between the departure parameters (amplitudes in scalar leads of the departure loop) and the percent defect volume of thallium myocardial s cintigrams (%DV) was compared with that of the spatial parameters (mag nitude, azimuth, and elevation of the original QRS loop). In anterosep tal MI, the amplitude of a 20-msec vector in the z-axis and the azimut h of a 30-msec vector (H30) were significantly correlated with %DV (r= 0.783, p<0.001 and r=0.572, p<0.05). In anteroseptal MI with involveme nt of the lateral wall, the amplitude of a 30-msec vector in the x-axi s and H30 showed significant correlation with %DV (r=0.802, p<0.001 an d r=0.772, p<0.01). In inferior and inferoposterior MI, the amplitude of a 30-msec vector in the y-axis and the elevation of a 30-msec vecto r were significantly correlated with %DV (r=0.920, 0.891, p<0.001 and r=0.871, 0.678, p<0.01, respectively). In conclusion, the departure pa rameters are more accurate than the spatial parameters for evaluation of myocardial infarct size.