Brief Report
Reasons for discordance between positron emission tomography (PET) myocardial perfusion imaging (MPI) results and subsequent management

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Abstract

Background

Referral patterns to coronary angiography following positron emission tomography (PET) myocardial perfusion imaging (MPI) and reasons for non-referral following abnormal PET MPI are largely unknown.

Methods

Referral rates to coronary angiography within 90 days post PET MPI were determined. A random subset of 100 patients with severe (≥ 10%) ischemia on MPI between 2014-16 who were not referred for angiography were examined to better understand reasons as to why patients with high-risk MPI findings did not undergo coronary angiography.

Results

Among 19,282 unique patients, overall rate of 90-day coronary angiography was 18.5% (3574/19282). Among patients with severe ischemia, 64.1% (1930/3011) underwent angiography within 90 days; the rate was lower in those with mild-moderate (20.6% [1010/4898]) and no ischemia (5.6% [634/11373]). In the random sample of 100 patients, the most common physician reasons for non-referral were uncertainty regarding whether the test results were responsible for the patient’s presenting symptoms, renal failure, and patient age, frailty, or cognitive status, while patient preference for medical management was by far the most common patient reason.

Conclusion

Referral rates for coronary angiography after PET correlate with severity of ischemia. However, there appear to be opportunities to reconsider testing for instances when results will not change clinical management.

Introduction

With the shift in health care toward rewarding value and improving outcomes, the association of diagnostic testing with subsequent changes in patient management are especially important to most efficiently optimize patients’ long-term outcomes. Myocardial perfusion imaging (MPI) is commonly used for diagnosis and risk stratification in patients with known or suspected coronary artery disease (CAD). A prior study reported a lower rate of referral to coronary angiography or changes in medical management following an abnormal Single Photon Emission Computed Tomography (SPECT) MPI, Positron Emission Tomography, and coronary computed tomography angiography even in patients with moderate to severe abnormal perfusion results.1 We aimed to describe referral patterns following PET MPI in patients with and without known CAD in a large contemporary patient population. We also aimed to study in detail potential reasons for non-referral to coronary angiography after a significantly abnormal PET MPI result.

Section snippets

Study Population

We examined all consecutive patients who had a rest/stress Rb-82 PET MPI within Saint Luke’s Health system between January 2010 and December 2016. Saint Luke’s Health System includes fully functioning nuclear cardiology laboratories with 4 dedicated cardiac PET-CT systems at 4 major hospitals in the Kansas City metropolitan area. There are also 4 smaller hospitals in outlying towns in Missouri and Kansas plus numerous smaller medical offices and other facilities. The patient population is

Results

Of 19,282 patients, ischemia was absent in 59.0% (n=11373), mild to moderate in 25.4% (n=4898), and severe in 15.6% (n=3011). The overall rate of 90-day coronary angiography was 18.5% (3574/19282). Among patients with severe ischemia, 64.1% (1930/3011) underwent angiography within 90 days; the rate was higher in those without known CAD (69.4%; 761/1097) than in those with known CAD (61.2%; 1169/1914; Figure 1). In those with mild ischemia on MPI, 22.9% (427/1861) of patients without, and 19.2%

Discussion

In this large retrospective registry, 18.5% of patients were referred for coronary angiography following PET MPI. Of patients with severe ischemia on PET, 1 in 3 were not referred for invasive angiography. On the other hand, 1 in 5 with mild to moderate ischemia and 1 in 19 without ischemia underwent angiography. Among a random sample of 100 patients with severe ischemia on PET who were not referred for angiography, both physician reasons and patient preferences were noted. The most common

Conclusions

Overall, referral rates for coronary angiography after PET are higher than previously reported for SPECT 1 and correlate with the severity of ischemia. Uncertainty regarding whether the test results were responsible for the patient’s presenting symptoms and preference for medical management were most commonly cited physician and patient reasons, respectively, for non-referral to angiography post significantly abnormal PET MPI findings. There appear to be opportunities to reconsider testing for

New Knowledge Gained

Referral rates to coronary angiography following PET MPI are higher than SPECT and correlate with the severity of ischemia. Among those not referred, our findings suggest that medication intensification is common and that some reasons for non-referral may be known by providers ahead of testing.

Disclosures

Drs. Thomas and Patel are supported by the National Heart, Lung, and Blood Institutes of Health Under Award Number T32HL110837; the content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Dr. Chan is supported by National Heart, Lung, and Blood Institutes of Health Under Award Number 1R01HL123980 and serves as a consultant for Optum Rx and the American Heart Association. Dr. Spertus reports personal fees

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