Abstract 13150: Effect of Cardiac Hybrid 15o-water Pet/ct Imaging Upon Downstream Referral for Invasive Coronary Angiography and Revascularization Rate

Abstract

Background: Hybrid 15O-water positron emission tomography (PET)/CT-based coronary angiography (CTCA) imaging for the diagnosis of coronary artery disease (CAD) provides complementary information on coronary anatomy and myocardial perfusion in a single scan session. The aim of the present study is to assess the impact of PET/CTCA imaging on referral for invasive coronary angiography (ICA) and revascularization rate.

Methods: A total of 375 patients (mean age 58 ± 10 years, 192 men) without a previous history of CAD underwent hybrid 15O-water PET/CTCA imaging. Downstream treatment strategy within a 60-day period after hybrid PET/CTCA imaging for ICA referral and revascularization procedures (percutaneous coronary intervention or coronary artery bypass surgery) was assessed. CTCA examinations were classified as showing non-obstructive CAD (< 50% luminal narrowing), equivocal (borderline test result / poor image quality) or obstructive CAD (≥ 50%), while the PET perfusion images were classified into normal or abnormal.

Results: Based on CTCA imaging, 182 (49%) patients displayed nonobstructive CAD. Alternatively, 16 (9%) of the patients with nonobstructive CAD on CTCA had abnormal myocardial perfusion imaging (MPI). Only 10 (5%) patients with nonobstructive CAD on CTCA were referred for ICA, which were all negative. An equivocal CT study was noted in 80 (21%) patients, with 56 (70%) having normal MPI. Referral rate for ICA was 18% (normal MPI) and 71% (abnormal MPI). Interestingly, no revascularizations were performed in the presence of an equivocal CT in combination with normal MPI, while 59% of those with an abnormal MPI were revascularized. CTCA indentified obstructive CAD in 113 (30%) patients accompanied in 59 (52%) patients with abnormal MPI. Referral rate for ICA in this group was 57% for normal MPI and 88% in the group with abnormal MPI, compared with revascularization rates of 26% and 72%.

Conclusion: Hybrid cardiac 15O-water PET/CTCA imaging impacts clinical decision making with regard to referral for ICA and subsequent myocardial revascularization procedures. Particularly, in the presence of an equivocal or abnormal CTCA, MPI acts as an arbiter to guide a judicious referral to the catheterization laboratory and revascularization strategy.