AN INCREMENTAL EVALUATION OF THE DIAGNOSTIC-VALUE OF THALLIUM SINGLE-PHOTON EMISSION COMPUTED TOMOGRAPHIC IMAGING AND LUNG HEART RATIO CONCERNING BOTH THE PRESENCE AND EXTENT OF CORONARY-ARTERY DISEASE/

Background. The goal was to assess the incremental diagnostic value of thallium single-photon emission computed tomographic (SPECT) imaging and lung/heart ratio (LHR) over other clinical and exercise electrocar diographic (EGG) variables concerning the presence and extent (three v essel/left main) of coronary artery disease. Methods and Results. Mult ivariable logistic regression analysis that used an incremental study design was applied to clinical, exercise test, SPECT, LHR, and cathete rization data from 323 patients with suspected coronary disease. The f ollowing variables were evaluated as predictors of presence and extent of disease: clinical (age, sex, symptoms, diabetes, and smoking), exe rcise ECG (millimeters of ST segment depression, slope of ST segment d epression, peak heart rate, change in systolic blood pressure, and met abolic equivalents of the task), and thallium (defect reversibility an d intensity of hypoperfusion and LHR). Discrimination and incremental value were assessed by receiver operating characteristic (ROC) curve a nalysis. SPECT imaging (segment hypoperfusion score) was an independen t predictor of both presence and extent of disease (p < 0.0001) irresp ective of the percent stenosis criterion used. However, it added signi ficant incremental diagnostic information over clinical and exercise E CG data only concerning presence (e.g., ROC curve areas: presence of d isease - clinical plus exercise ECG = 83 +/- 2 vs clinical, exercise E GG, plus SPECT = 87 +/- 2, p < 0.001; extent of disease - clinical plu s exercise ECG = 83 + 4 vs clinical, exercise EGG, plus SPECT = 85 +/- 3, p = 0.11). Thallium LHR was an independent predictor of both prese nce and extent of disease (p < 0.05), but the incremental information added to SPECT data did not reach statistical significance (e.g., ROC curve areas: presence of disease - SPECT = 87 +/- 2 vs SPECT plus LHR = 88 +/- 2, p = 0.24; disease extent - SPECT = 85 +/- 2 vs SPECT plus LHR = 86 +/- 2, p = 0.24). However, when combined, LHR and SPECT data had significant incremental value over clinical and exercise ECG data alone concerning extent of disease (e.g., ROC curve areas: clinical pl us exercise ECG = 83 +/- 4 vs clinical, exercise EGG, SPECT and LHR = 86 +/- 3, p = 0.04). Conclusion. SPECT thallium imaging variables are independent predictors of both presence and extent of coronary disease . However, they have significant incremental value over clinical and e xercise ECG data concerning only presence of disease. Thallium LHR is an independent predictor of both presence and extent of disease but ad ds only a small insignificant amount of incremental diagnostic informa tion over SPECT data. However, there was significant incremental value to the addition of LHR to SPECT data concerning extent of disease.