QT interval shortening and ST elevation in intracoronary ECG during PTCA

Percutaneous transluminal coronary angioplasty (PTCA) can provide a unique model of transient and reversible myocardial ischemia. The aim of this study was to assess the serial changes in QT interval during elective PTCA‐induced transient ischemia. The serial changes in QT interval before, during, and after PTCA of the left anterior descending artery (LAD) were measured in patients who showed ST elevation in intracoronary electrocardiogram. Twelve consecutive patients who showed ST‐segment elevation during PTCA‐induced ischemia in anterior precordial leads of the electrocardiogram (ECG) were enrolled in the present study. Target lesions for PTCA were all in the LAD. There were six patients with angina pectoris, two with non‐Q‐wave infarction, and four with Q‐wave myocardial infarction. During balloon inflation, QT_c interval shortened in both intracoronary ECG (ic‐ECG) (0.472±0.013 vs 0.436±0.014) and surface ECG (0.462±0.012 vs 0.438±0.011). However, a significant shortening of the QT interval was more rapidly observed in the ic‐ECG (20 s) than in the surface ECG (40 s). We conclude that the QT interval in both ic‐ECG and surface ECG becomes shortened in PTCA‐induced myocardial ischemia, and that the ic‐ECG might be a good probe for detecting survived viable myocardium in the infarcted zone.