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Persistent thallium-201 defect: can clinical, electrocardiographic and exercise hemodynamic variables predict defect normalization with reinjection?

This study was designed to assess the contribution of clinical, electrocardiographic and exercise hemodynamic variables to the prediction of normalization on resting reinjection scintigraphy of persistent thallium-201 (201Tl) myocardial perfusion defects seen with exercise and 2- to 4-hour delayed (redistribution) imaging. To evaluate this contribution, we studied 159 consecutive patients with persistent 201Tl myocardial perfusion defects on routine exercise and 2- to 4-hour-delayed scintigrams at the University of Rochester Medical Center who were classified as having moderate or greater ischemic normalization (group 1, n = 76) or minimal to no ischemic normalization (group 2, n = 83) by reinjection scintigraphy. Multiple logistic regression analysis with backward elimination was used to model the effects of clinical, electrocardiographic and exercise hemodynamic data on the odds ratio of a normalized defect. No difference was observed in the two groups with regard to gender, angina on exertion, rate-pressure product, exercise duration, resting or exertional ischemic ST changes on electrocardiogram, presence of Q waves or left ventricular hypertrophy on baseline electrocardiogram, or total number of stress thallium defects (2.8 +/- 1.5 segments). No single variable or combination of variables discriminated between groups 1 and 2 by logistic regression analysis. We conclude that defect normalization seen on resting 201Tl myocardial perfusion scintigraphy is prevalent in patients with persistent defects on routine exercise and delayed myocardial perfusion scintigraphy, and was not predictable from available clinical, electrocardiographic and exercise hemodynamic variables.