Impact of Rubidium Imaging Availability on Management of Patients with Acute Chest Pain

Introduction: Chest pain (CP) and related symptoms are among the most frequent complaints of patients presenting to emergency departments (ED). Despite the central role of myocardial perfusion imaging (MPI) in the evaluation of patients with CP, very few studies investigated the role of positron emission tomography (PET) MPI in the ED setting. The purpose of this study is to evaluate the impact of the availability of PET MPI with Rubidium-82 Chloride on patient management presenting at the ED with CP.

Methods: This is a single-center retrospective study of clinical databases. Patients presenting with CP with a non-definitive suspicion of acute coronary syndrome (ACS) at the ED between April 2016 and February 2020 were included and divided into 2 groups based on PET availability: PET Not Available from Apr 2016 to Dec 2016 and from Nov 2018 to Feb 2019, and PET Available from Jan 2017 to Oct 2018 and from Mar 2019 to Feb 2020 (Figure A). The proportion of coronary angiography without significant epicardial stenosis and ED length-of-stay (LoS) were compared between groups. Additionally, requirements for additional downstream testing were evaluated.

Results: There were 21,242 ED visits for CP with a non-definitive suspicion of ACS, with 5,492 in the PET Not Available group and 15,750 in the PET Available group. When PET is available, the proportion of patients who underwent a MPI study was greater (20.7% vs 17.6%, p<0.0001) and the proportion of coronary angiography without significant coronary artery disease (CAD) was similar (18.5% vs 21.4%, p=0.24), compared to when PET is not available. Among patients who underwent risk stratification testing, MPI was chosen 65.9% of the time when PET was available compared to 59.5% when PET was not available (p<0.0001, Figure B). Median LoS in the ED of patients who underwent MPI risk stratification prior to discharge was shorter when PET was available 16.6 (IQR: 6.7-25.2) hours compared to 18.1 (IQR: 6.5-27.8) hours when PET was not available (p=0.03). Regardless of the period, patients who underwent single photon emission computed tomography (SPECT) MPI had significantly more downstream testing (8.9% vs 6.4%, p=0.003) and tended to have a higher rate of coronary angiogram without significant CAD (21.2% vs 14.2% p=0.09) compared to those who underwent PET MPI.

Conclusions: Availability of PET MPI is associated with an increased number of MPI referral from the ED for the evaluation of patients with CP. In our cohort, PET availability was not associated with a statistically significant lower rate of coronary angiography without significant epicardial stenoses. Among patients undergoing non-invasive testing for evaluation of CP, MPI is the modality most frequently chosen by the referring physician when PET is available. In addition, PET MPI availability is also associated with a decreased ED LoS for patients imaged prior to discharge. Finally, patients undergoing PET MPI have significantly fewer downstream testing compared to those undergoing SPECT MPI.

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