Coronary computed tomography angiography (CTA) enables non-invasive detection of coronary atherosclerosis and obstructive coronary artery disease (CAD). In turn, positron emission tomography angiography (PET) myocardial perfusion imaging (MPI) enables detection of hemodynamically significant coronary artery stenoses and myocardial ischemia. In hybrid imaging, data from coronary CTA and PET MPI are combined providing complementary information about coronary anatomy and physiology.

We have comprised an observational retrospective registry of patients who have been imaged in Turku PET Centre with a hybrid imaging protocol due suspected obstructive CAD.

We evaluated sex differences in disease profile and outcomes after hybrid imaging. We found that women have lower prevalence of ischemic CAD and lower rate of adverse events (unstable angina pectoris, myocardial infarction, death). Importantly, hybrid imaging predicted outcomes equally in women and men. We also investigated the incremental value of PET imaging over CTA in predicting short- and long-term outcomes. PET MPI improved the prediction of adverse events beyond CTA imaging for the first 4 years of follow-up. After this period MPI did not add prognostic power over CTA. This illustrates the complementary nature of anatomic and functional imaging in the prediction of outcome in patients with suspected CAD.

Above this, we collected blood samples from the registry patients and assessed the predictive power of the 3 most promising polygenic risk scores (PRS) in prediction of coronary atherosclerosis and obstructive CAD. We found that the addition of PRS to classical clinical risk factors did not clinically significantly improve the predictive accuracy for either coronary atherosclerosis or obstructive CAD, indicating that current PRSs are not justified for clinical routine for CAD.