Alternans of the ST segment in variant angina. Incidence, time course and relation to ventricular arrhythmias during ambulatory electrocardiographic recording.

The ST alternans was recorded during at least one ischemic attack with ST elevation in nine of 65 patients with variant angina. The magnitude and duration of ST elevation during ischemic attacks were significantly greater in patients with than in those without ST alternans. It always appeared during the occlusion phase and disappeared during the reperfusion phase of ischemic attacks. In patients with episodic ST alternans, the ischemic attacks showed a greater ST elevation and a longer duration in the presence of ST alternans than in its absence. The incidence of occlusion phase ventricular arrhythmias was greater in patients with than in those without ST alternans; the incidence of reperfusion phase ventricular arrhythmias was similar in the two groups. The ST alternans always preceded the onset of occlusion phase arrhythmias. Thus, in variant angina, ST alternans represents an index of the severity of ischemia and a precursor of ventricular arrhythmias.