Transient ischemic dilatation with 13N-ammonia PET myocardial perfusion imaging: prognostic significance in patients with non-obstructive coronary artery disease

Introduction: Transient ischemic dilation (TID) on myocardial perfusion imaging (MPI) has been validated to provide incremental diagnostic and prognostic value in patients with obstructive coronary artery disease (CAD). The prognostic value of TID with ¹³N-ammonia PET MPI in individuals with non-obstructive CAD has not been studied yet. Transient ischemic dilation (TID) on myocardial perfusion imaging (MPI) has been validated to provide incremental diagnostic and prognostic value in patients with obstructive coronary artery disease (CAD). The prognostic value of TID with ¹³N-ammonia PET MPI in individuals with non-obstructive CAD has not been studied yet.

Methods: We retrospectively recruited consecutive patients with non-obstructive CAD who underwent one-day rest-stress ¹³N-ammonia PET MPI. TID was measured using an automated software program. The receiver operative characteristic curve was used to determine the optimal threshold of TID. The follow-up outcome was major adverse cardiac events (MACE), a composite of cardiac death, non-fatal myocardial infarction, late vascularization and readmission due to any cardiac reasons. Cardiac event-free survivals for normal and abnormal TID were compared using Kaplan–Meier plots and log-rank test.

Results: The study population consisted of 151 patients (53 + 9 years, 56% male, 23% diabetes, left ventricular ejection fraction--LVEF 55 + 6%). An abnormal TID (≥ 1.04) was present in 63 (42%) patients. During a median follow-up of 38.5 + 18.9 months (range 6 - 68 months), MACE occurred in 23 (15%) patients. Baseline clinical characteristics were not different based on the occurrence of MACE. TID was associated with increased risk of MACE (log-rank P = 0.016). In the subgroup of patients with normal coronary flow reserve (CFR≥ 2), event-free survival also displayed significant difference for TID (log-rank P = 0.028).

Conclusions: TID on ¹³N-ammonia MPI carries important prognostic information in individuals with non-obstructive CAD, and may have incremental value over CFR.

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