Diagnostic and prognostic value of ambulatory electrocardiographic monitoring.

To evaluate the diagnostic and prognostic value of continuous ambulatory ECG (AECG) monitoring, we studied 124 patients with chest pain syndromes by stress myocardial perfusion scintigraphy (MPS) and AECG. MPS was classified as normal or with fixed or reversible defects involving one or more than one vascular territory. Positive AECGs were divided into those with mild (< or = 1.5 mm), moderate (1.5 to 2.5 mm), and severe (> or = 2.5 mm) ST segment displacement. Among 61 patients with a negative AECG, 93% had limited ischemia or normal scintigraphic studies. All 24 patients with moderately or severely positive AECGs had reversible defects on MPS. Among those with severely positive AECGs, nine (75%) had multivessel scintigraphic ischemia. Severe ST segment depression on AECG was highly related to multivessel perfusion defects and to a large amount of myocardium in jeopardy. A negative AECG generally indicated limited or absent ischemia and thus a more benign prognosis. Induced symptoms and the daily ischemic burden were not related to the severity of induced AECG or MPS abnormalities. AECG may provide independent information as to the severity and related risk of ischemia.