Clinical efficacy of PTCA and identification of restenosis: evaluation by serial body surface potential mapping. We used serial body surface potential mapping (BSPM) with the departure map technique to evaluate the clinical efficacy of percutaneous transluminal coronary angioplasty (PTCA) in various pathophysiologic stages of coronary artery disease, and to detect restenosis. The BSPM was performed prior to, 1 week after, and 1 month after PTCA. A follow-up coronary angiography was performed 3 to 6 months after PTCA, and BSPM was also performed at the same time. The results of BSPM were compared with those of thallium-201 single-photon emission computed tomography (Tl-201 SPECT) and radionuclide ventriculography. After PTCA, BSPM showed a significant reduction in the departure area, the Tl-201 SPECT also showed a significant reduction in the extent and severity scores, and the left ventricular ejection fraction improved significantly. In the cases with restenosis, the departure area, which had decreased in size after PTCA, showed an increase in size. After successful re-PTCA, the size of the departure area again became smaller. We concluded that BSPM, which is a simple, noninvasive, and inexpensive method, is useful in the evaluation of the clinical efficacy of PTCA and in the detection of restenosis after successful PTCA. 