Continuous vectorcardiographic changes in relation to scintigraphic signs of reperfusion in patients with acute myocardial infarction receiving thrombolytic therapy.
OBJECTIVES. Changes in the electrical activity of the heart reflecting the infarct process can be recorded by continuous vector-ECG, a method which is now clinically available for cardiac supervision. Shifts of the ST-segment and QRS-vector reflect ischaemia and necrosis of the myocardium. Continuous vector-ECG changes were evaluated against myocardial scintigraphy in 18 patients with acute myocardial infarction treated with streptokinase in order to study the impact of improved myocardial perfusion. DESIGN. Myocardial perfusion was analysed with 99Tcm-Sestamibi (Cardiolite, DuPont Scandinavia AB, Kista, Sweden) single photon emission computerized tomography (SPECT). Registrations were performed before and after thrombolysis in order to estimate the amount of myocardium with impaired perfusion initially (threatened myocardium) and the degree of perfusion improvement in this myocardial area. X, Y, Z vectors were registered continuously by Frank leads (Ortivus Medical, Täby, Sweden). QRS-vector difference, and the time to plateau phase and the ST-vector magnitude were used as a measurement of ischaemia and size of the myocardial infarction. RESULTS. In seven out of 11 patients treated within 3 h of onset of symptoms, an improvement in myocardial perfusion in the initially hypoperfused areas was achieved in contrast to none of the seven patients treated > 3 h after onset of pain (P