13N-ammonia PET/CT stress myocardial blood flow compared to fractional flow reserve in coronary artery disease

Abstract

Aim In this retrospective study, fractional flow reserve was compared to stress myocardial blood flow derived by 13 N-ammonia (13 N-NH3) myocardial perfusion PET/CT. Methods From a large cohort of patients referred for 13 N-NH3 PET/CT, patients who also had fractional flow reserve-measurements within 6 months of the PET study were selected. These fractional flow reserve measurements were compared to PET/CT derived stress myocardial blood flow of the corresponding coronary territory. Results were categorized as concordant or discordant. Patients with discordant results were subdivided into a group with reduced fractional flow reserve but normal stress myocardial blood flow (group A) or into a group with normal fractional flow reserve but reduced stress myocardial blood flow (group B). Results From September 2013 through July 2016, 46 patients examined with 13 N-NH3 PET/CT also had fractional flow reserve-measurements within 6 months. A total of 66 measurements were used for comparison. Discordance was found in 32% of the measurements. Group B showed a significant reduction in stress myocardial blood flow of all coronary territories compared to group A (P = 0.000). During follow-up (median 3.96 years), group B showed more visits to the emergency department and newly developed heart failure. Conclusion Discordance with stress myocardial blood flow in the corresponding flow territory was found in 32% of the fractional flow reserve-measurements. Patients with reduced stress myocardial blood flow but normal fractional flow reserve showed significantly reduced stress myocardial blood flow in all coronaries and a trend towards more cardiac adverse events.