Significance of ST alternans during percutaneous transluminal coronary angioplasty.

Repolarisation ST alternans was observed during percutaneous transluminal coronary angioplasty (PTCA) in nine patients. Six had ST alternans on surface electrocardiogram (ECG) while three patients developed ST alternans only on intracoronary ECG recordings. The pattern of occurrence of ST alternans in successive inflations varied. Ventricular arrhythmias occurred in 6 of 28 (21.42%) of inflations associated with ST alternans while in a control group of 50 patients undergoing PTCA who did not have ST alternans, ventricular arrhythmias were noted in only 6 of 342 inflations (1.75%; p < 0.001). It is suggested that ST alternans is a regional ischemic phenomenon.