The significance of T-loop change in Frank's lead exercise electrocardiography.

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Thirty-one patients with angina pectoris and 15 patients with myocardial infarction who performed exercise test by Master's double two-step test have been longitudinally followed up for 4-10 years. Exercise electrocardiogram was taken by Frank's lead and T loop was constructed in frontal and horizontal planes from 3 scalar tracings recorded at a paper speed of 100 mm/sec. ST vector was determined at 100 msec from the beginning of Q wave and the line connecting 2 ST vectors before exercise and at the point of the maximal ST change after exercise was determined as ST exercise vector. To indicate width of the T loop, the length to width ratio (L/W) was used and the change of width of the T loop induced by exercise was expressed by a ratio of L/W between before exercise and at the maximal change in frontal and horizontal planes. In cases having ST exercise vector of 0.1 mV or more the magnitude or the direction of the ST exercise vector alone has little prognostic value and widening of the T loop in addition to the ST exercise vector of 0.1 mV or more occurring after exercise was a predictive sign of poor prognosis and no widening of the T loop was a predictive sign of good prognosis.