Importance of the distance and velocity of electrical forces in the diagnosis of inferior wall healed myocardial infarction: a vectorcardiographic study.

The vectorcardiograms of 41 patients with angiographically proved inferior myocardial infarction (MI) and 51 normal subjects were analyzed to determine whether it is the time (in milliseconds) or the distance (in millivolts) of the initial superiority directed forces of ventricular depolarization that is increased more by inferior MI, and whether parameters derived from both the initial superior time and distance can be used to detect inferior MI. The 10 best individual and the 10 best paired criteria for inferior MI involve superior distance, either alone or used in the calculation of average velocity (in volts per second), and the product of initial superior time and distance (in millivolts per second). The 2 best individual criteria for inferior MI are: inferior velocity more than 0.0065 V/s (sensitivity 71%, specificity 100%) and superior distance more than 0.39 mV (sensitivity 68%, specificity 100%). These diagnostic performances are superior to those of the best criterion that involves only the duration of the initial superior forces, i.e., initial superior time longer than 28 ms (sensitivity 49%, specificity 98%) (chi 2 = 8.42, p less than 0.005 and chi 2 = 6.31, p less than 0.025, respectively). Initial superior distance and parameters calculated from both initial superior distance and time are better vectorcardiographic criteria for inferior MI than are criteria that involve only initial superior time.