QRST CHANGES DURING AND AFTER PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY

This study reports preliminary results on 45 patients who underwent pe rcutaneous transluminal coronary angioplasty (PTCA); 120-lead data (in cluding the Iii-lead standard electrocardiogram [ECG]) were recorded b efore, during, and after balloon inflation. Twenty-one patients underw ent PTCA for left anterior descending coronary disease, 13 for right c oronary artery disease, and 10 for left circumflex; 1 patient had comb ined left anterior descending and right coronary artery disease. In ea ch patient, voltage data recorded during the various phases of the pro cedure were compared with the patient's own baseline data. In 18 patie nts, 120 leads were also recorded 24 hours after PTCA. In this study, the usefulness of the standard 12-lead ECG was investigated in locatin g the coronary artery being occluded, in elucidating the mechanisms of the QRS changes, and in identifying changes occurring 24 hours after completion of the procedure. Results indicate that the observation of ST elevation in the 12-lead ECG may lead to ambiguous interpretation. Also, limiting observation to ST-T patterns alone instead of including QRS changes further hampers correct identification of the involved ve ssel. QRS modifications during inflation are interpreted as conduction disturbances, although other mechanisms are evoked: study of surface maps may contribute to the understanding of these mechanisms. Changes present 24 hours later are visible in the standard leads, but again, i n the absence of the thoracic potential distribution, these are diffic ult to interpret. These changes were different from those observed aft er cessation of inflation at the end of the procedure. It is hypothesi zed that next-day changes may reflect reperfusion injury and/or repres ent myocardial stunning. Presence of injury and reversibility of chang es require further investigation Also, biochemical markers such as cre atine kinase-MB mass, creatine kinase-MB activity, myoglobin, and trop onin-T may help elucidate the significance of these findings.