Prognostic value of PET derived coronary flow reserve: should we correct for resting perfusion product?

Abstract

Abstract Introduction Positron emission tomography (PET) myocardial perfusion imaging (MPI) derived coronary flow reserve (CFR) is an important risk-stratifying tool to tailor management of patients with coronary artery disease. Resting myocardial blood flow (MBF) is positively correlated to the product of resting heart rate and systolic blood product (resting pressure product – RPP), and can in turn lead to lower CFR in the setting of normal stress MBF. Purpose We aimed to assess the comparative incremental prognostic value of uncorrected to RPP-corrected CFR in predicting incident events. Methods Consecutive patients who had clinically indicated PET MPI were included. Patients were followed from the date of imaging to incident major adverse cardiovascular event (MACE: inclusive of all-cause death, myocardial infarction, admission for heart failure and late revascularization – percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) >90 days after imaging). Results The study population consisted of 2,893 patients with clinically indicated PET MPI (mean age 67 (±12), 53% male, 41% Caucasian). Cardiovascular risk factors were prevalent (88% hypertensive, 80% dyslipidemic, 47% diabetics, 18% ever smoking). After a mean follow-up of 8±7 months, 250 patients (8.6%, 10.7 per 1000 person-year) experienced MACE (90 D/38 MI/51 PCI/11 CABG/113 HF). Both uncorrected and corrected CFR were independently associated with incident MACE (HR 0.38, 95% CI 0.29–0.51, p<0.001 and 0.61, 95% CI 0.50–0.76, p<0.001 respectively). A comparison of model incremental prognostic value showed the model with uncorrected CFR had a statistically higher Harrell's C (0.76 vs 0.77, p=0.23). Conclusion Our findings showed that the prognostic value of CFR was preserved even in the setting of high resting blood pressure or heart rate. This suggests that correction for RPP should be selective. Funding Acknowledgement Type of funding sources: None.