title: Frequency of late potentials on signal-averaged electrocardiograms during thallium stress testing in coronary artery disease.
abstract: Late potentials detected by signal-averaged electrocardiography (SAECG) are an important noninvasive indicator identifying patients with previous myocardial infarction at risk for developing ventricular tachycardia. The role of myocardial ischemia in the development of late potentials is undefined. This study attempts to determine if late potentials on SAECG can be produced during scintigraphically proven ischemia. A signal-averaged electrocardiogram was obtained before and immediately after single-photon emission computed tomography thallium exercise testing in 51 patients. Reversible ischemia was documented in 25 cases with no significant changes in the parameters of SAECG; patients with previous myocardial infarction (n = 10) also had no significant changes from baseline. Multivariate analysis with respect to reversible ischemia and previous myocardial infarction was unrevealing. Patients with late potentials at baseline (n = 10) who developed reversible ischemia (n = 5) had a shorter QRS duration than those with late potentials at baseline and no reversible ischemia. The data indicate that exercise-induced scintigraphically proven ischemia does not alter SAECG even in the presence of previous myocardial infarction. Patients with late potentials at baseline may actually have a shortened QRS duration during reversible ischemia as opposed to the expected lengthening of the QRS.
authors.affiliation: United States Air Force Medical Center, Wright-Patterson Air Force Base, Ohio.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lenihan
authors.forename: E
authors.initials: E
authors.lastname: Coyne
authors.forename: B
authors.initials: B
authors.lastname: Feldman
authors.forename: R
authors.initials: R
authors.lastname: Black
authors.forename: G
authors.initials: G
authors.lastname: Collins
mesh_terms: D003327:Coronary Disease / Q000175:diagnosis* / Q000209:etiology; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D013794:Thallium Radioisotopes; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D013794:Thallium Radioisotopes