Identification of Patients With Heart Failure From Test Bolus of Computed Tomography Angiography in Patients Undergoing Preoperative Evaluation for Transcatheter Aortic Valve Replacement.

PURPOSE

Identify a measurable parameter from test bolus of computed tomography angiography that can differentiate aortic stenosis patients with normal systolic function from those with heart failure and reduced ejection fraction (HFrEF).

MATERIALS AND METHODS

This retrospective study included patients (undergoing evaluation for transcatheter aortic valve replacement) who had retrospective electrocardiogram-gated cardiac computed tomography angiography using test bolus. The measured variables were time to peak contrast enhancement in the pulmonary artery (PAtime), in the ascending (AsAotime) and descending aorta (DsAotime). From these, the pulmonary transit time (PTT: difference between time to peak enhancement in the ascending aorta to peak enhancement in the main pulmonary artery), aortic transit time (ATT: difference between time to peak enhancement in the descending aorta to time to peak enhancement in the ascending aorta) and DsAotime-PAtime were also calculated. Biventricular volumes and function were calculated.The subjects were classified on the basis of ventricular ejection fractions: normal (EF>50%), midrange (EF 40% to 50%), and HF patients with reduced EF (EF<40%). Continuous variables were compared between all groups using ordinary 1-way analysis of variance, while sex was compared using the Fisher exact test. The unpaired t tests were used to compare between the normal and HF groups. Receiver operating characteristic analysis was used in predicting decreased cardiac function (EF<40% vs. EF>50%).

RESULTS

AsAotime and PTT were significant predictors of low biventricular EF when controlling for sex and body mass index (AsAotime: odds ratio=0.74 [95% confidence interval=0.61-0.91], P=0.005; PTT: odds ratio=0.64 95% confidence interval=0.46-0.88], P=0.006). A threshold of 23 seconds for AsAotime resulted in 72.1% sensitivity and 71.4% specificity, and 79.1% sensitivity and 64.3% specificity for DsAotime.

CONCLUSIONS

The time to peak contrast enhancement from the test bolus images correlates with cardiac function. Decreased biventricular systolic dysfunction can be predicted if the time to peak contrast enhancement is >23 seconds in the ascending or descending aorta.