Thallium-201 lung uptake and peak treadmill exercise first-pass ejection fraction

Increased thallium-201 lung uptake immediately after exercise has been shown (1) to be a marker for extensive coronary artery disease, (2) to correlate with low rest and exercise left ventricular ejection fraction by supine gated blood pool scintigraphy, and (3) to be a powerful independent predictor of future cardiac events. Exercise left ventricular ejection fraction measured during upright exercise by the first-pass technique has also been shown to be a powerful independent prognostic variable. Combined perfusion and exercise left ventricular ejection fraction can be acquired by using the technetium 99m-based myocardial perfusion agents and offers an alternative protocol to stress/redistribution thallium imaging. It is therefore clinically important to understand the relation between exercise lung heart thallium uptake and exercise left ventricular ejection fraction. Accordingly, both these measurements were acquired in 38 patients with documented coronary artery disease who underwent two treadmill exercise studies. Parameters obtained from the first-pass study that are known to affect lung thallium uptake were correlated with exercise lung/heart thallium ratios; lung/heart ratios were used in a model to predict exercise left ventricular ejection fraction values. Exercise left ventricular ejection fraction and peak filling rate showed significant negative correlations with thallium lung/heart ratio, but the first-pass variables examined were not independently predictive of thallium lung uptake. The chance of finding an abnormal thallium lung/heart ratio at exercise LVEF of 40% is only 52%, whereas the chance of finding an abnormal ratio at exercise LVEF of 30% is 74%.(ABSTRACT TRUNCATED AT 250 WORDS)