Non rate-controlled CT coronary angiography for the exclusion of obstructive coronary artery disease in the assessment of patients referred for transcatheter aortic valve implantation

Abstract

Purpose: Optimal management of concomitant coronary artery disease (CAD) in patients undergoing transcatheter aortic valve implantation (TAVI) is contentious. This study aimed to assess the role of routine non rate-controlled CT coronary angiography (CTCA) in assessing CAD in patients referred for TAVI, thereby potentially precluding the need for invasive coronary angiography (ICA). CTCA in this cohort can be difficult due to the high burden of coronary calcium and the inability to perform standard pharmacological rate control. Methods: All patients underwent an ECG-gated 128-slice calcium score and CT angiogram to assess peripheral vasculature, aortic anatomy, aortic valve calcification and location of the coronary ostia. Coronary artery calcium scores (CACS) and CTCA images were scored by two independent, blinded observers and compared with ICA performed prior to TAVI. Significant coronary stenosis was defined as ≥70% and ICA was deemed the gold standard for true disease status. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated for CTCA at a patient level. Results: 70 consecutive patients referred for consideration of TAVI were studied: 40% male (n=28), mean age 78.9yrs (±7.91), 23% diabetic (n=16). Significant CAD was demonstrated in 30% of ICA studies (1 vessel disease (VD) 20% [n=14], 2VD 8.6% [n=6], 3VD 1.4% [n=1]). The sensitivity, specificity, PPV and NPV of CTCA for the detection of significant coronary stenoses were 57.9% (CI: 33.5% to 79.7%), 87.0% (CI: 75.1% to 94.6%), 61.1% (CI: 35.8% to 82.6%) and 85.4% (CI: 73.3% to 93.5%) respectively. The vast majority of false positive (5/6; 83%) and false negative (6/7; 86%) CTCAs were seen in patients in the highest quartile of CACS (>400). Conclusions: In patients undergoing CT assessment prior to TAVI, non rate-controlled CTCA shows poor sensitivity but good specificity and negative predictive value for the detection of significant CAD. A CAC score >400 may represent a threshold above which invasive angiography is mandated.