Diagnosis of acute heart failure in CT pulmonary angiography: feasibility and accuracy

OBJECTIVES: To evaluate the feasibility and accuracy of diagnosing acute heart failure (HF) with CT pulmonary angiography (CTPA) in emergency department patients. METHODS: In this retrospective single-center study, we evaluated 150 emergency department patients (mean age 65 ± 17 years) undergoing CTPA with a fixed scan (100 kVp) and contrast media protocol (60 mL, 4 mL/s) who had no pulmonary embolism (PE). Patients were subdivided into training cohort (n = 100) and test cohort (n = 50). Three independent, blinded readers measured the attenuation in the right ventricle (RV) and left ventricle (LV) on axial images. The ratio (HU(ratio)) and difference (HU(diff)) between RV and LV attenuation were calculated. Diagnosis of acute HF was made on the basis of clinical, laboratory, and echocardiography data. Optimal thresholds, sensitivity, and specificity were calculated using the area under the curve (AUC) from receiver operating characteristics analysis. RESULTS: Fifty-nine of the 150 patients (40%) were diagnosed with acute HF. Attenuation measurements showed an almost perfect interobserver agreement (intraclass correlation coefficient: 0.986, 95%CI: 0.980–0.991). NT-pro BNP exhibited moderate correlations with HU(ratio) (r = 0.50, p < 0.001) and HU(diff) (r = 0.50, p < 0.001). In the training cohort, HU(ratio) (AUC: 0.89, 95%CI: 0.82–0.95) and HU(diff) (AUC: 0.88, 95%CI: 0.81–0.95) showed a very good performance to diagnose HF. Optimal cutoff values were 1.42 for HU(ratio) (sensitivity 93%; specificity 75%) and 113 for HU(diff) (sensitivity 93%; specificity 73%). Applying these thresholds to the test cohort yielded a sensitivity of 89% and 89% and a specificity of 69% and 63% for HU(ratio) and HU(diff), respectively. CONCLUSION: In emergency department patients undergoing CTPA and showing no PE, both HU(ratio) and HU(diff) have a high sensitivity for diagnosing acute HF. KEY POINTS: • Heart failure is a common differential diagnosis in patients undergoing CT pulmonary angiography. • In emergency department patients undergoing CT pulmonary angiography and showing no pulmonary embolism, attenuation differences of the left and right ventricle have a high sensitivity for diagnosing acute heart failure.