Identification of Left Ventricle Failure on Pulmonary Artery CTA: Diagnostic Significance of Decreased Aortic & Left Ventricle Enhancement.

Abstract

This study aimed to identify findings on non-ECG-gated CT pulmonary angiography (CTPA) indicating decreased left ventricle (LV) systolic function, later confirmed by echocardiogram. After obtaining institutional review board approval, review was performed of emergency department (ED) patients who had CTPA and follow-up echocardiogram within 48h, over 18months. Patients with pulmonary embolus, suboptimal CTPA, arrhythmias or pericardial tamponade were excluded. One hundred thirty-seven patients were identified and divided into cases (LVEF <40%, n=52) and controls (LVEF >50%, n=85). Two reviewers performed these analyses: measurement of enhancement in main pulmonary artery (MPA), LV, and aorta; subjective enhancement of LV and aorta (Ao) relative to MPA using a four-point Likert scale; contrast transit time (TD) to trigger CTPA and LV short & long axis dimensions. When available, the most recent N-terminal pro-B-type natriuretic peptide (NT-proBNP) level was recorded. Decreased aortic and LV subjective enhancement were the best predictors of LV systolic dysfunction. For Ao/MPA ratio, an optimal cutoff value of 0.20 resulted in a sensitivity of 0.54 and specificity of 0.93 (AUC=0.83, 0.78-0.88 95% CI). A threshold of 86.7HU for Ao enhancement resulted in a sensitivity of 0.68 and specificity of 0.90 (AUC=0.82, 0.77-0.88 95% CI). A LV short axis diameter of more than 54.3mm had a sensitivity of 0.62 and specificity of 0.98 (AUC=0.88, 0.83-0.92 95% CI). For the LV long axis diameter, a cutoff of 87.5mm resulted in a sensitivity of 0.66 and specificity of 0.84 (AUC=0.78, 0.72-0.84 95% CI). With bolus timing, cases had a longer TD (13.4 vs. 10.4s, p<0.0001). Unsuspected LV systolic dysfunction can be recognized on a CTPA by identification of decreased aortic enhancement, LV enlargement and increased TD. This has important diagnostic implications for the patient presenting with shortness of breath, chest pain, or dyspnea.