Prognostic utility of sestamibi lung uptake does not require adjustment for stress-related variables: A retrospective cohort study

sLHR was determined in 718 patients undergoing 99mTc-sestamibi SPECT stress imaging. sLHR was assessed in relation to demographics, hemodynamic variables and outcomes (mean follow up 5.6 ± 1.1 years).Mean sLHR was slightly greater in males than in females (P < 0.01) and also showed a weak negative correlation with age (P < 0.01) and systolic blood pressure (P < 0.01), but was unrelated to stress method or heart rate at the time of injection. In patients undergoing treadmill exercise, sLHR was also positively correlated with peak workload (P < 0.05) but inversely with double product (P < 0.05). The combined explanatory effect of sex, age and hemodynamic variables on sLHR was less than 10%. The risk of acute myocardial infarction (AMI) or death increased by a factor of 1.7–1.8 for each SD increase in unadjusted sLHR, and was unaffected by adjustment for sex, age and hemodynamic variables (hazard ratios 1.6–1.7). The area under the ROC curve for the unadjusted sLHR was 0.65 (95% CI 0.59–0.71, P < 0.0001) and was unchanged for the adjusted sLHR (0.65, 95% CI 0.61–0.72, P < 0.0001).Stress-related variables have only a weak effect on measured sLHR. Unadjusted and adjusted sLHR provide equivalent prognostic information for prediction of AMI or death.The assessment of myocardial perfusion using radioactive tracers has consistently been shown to provide important prognostic information in patients with known or suspected coronary artery disease [1-3]. A number of additional non-perfusion parameters of left ventricular function have also been described to have prognostic importance, such as transient ischemic cavity dilation (TID) and left ventricular systolic function [4,5]. Increased post-stress 99mTc-sestamibi lung-to-heart ratio (sLHR) has recently been shown to predict cardiac outcomes independent of other clinical and imaging variables [6]. Peak heart rate and use of pharmacologic stress affect post-stress pulmonary uptake of thallium-201, and these factors need to be c