Page 75 - ARNM-2-3

Advances in Radiotherapy
& Nuclear Medicine Association between PET-derived flows and angiography

perfusion data could be a strong tool to reduce potentially which could, therefore be used to guide revascularization
unnecessary downstream invasive testing. Conversely, decision-making. Our study suggests that at different
regional MFR had a low positive predictive value to detect cutoff MFR values per coronary territory, for example,
true obstructive disease per vessel, likely secondary to the ≤1.7 in the LAD, Rb PET regional MFR has a specificity
82
vascular and anatomic considerations described earlier. of 65% and negative predictive value of 89% to predict
This may be overcome with the use of hybrid imaging, as ≥50% stenosis across all vessels. Although there is
described by Javadi et al. 25 heterogeneity in the association between regional
coronary territory MFR and the degree of stenosis,
It is known that globally reduced MFR is a relevant
marker for predicting short-term cardiovascular events. our data suggest that regional MFR performs best in
26
predicting normal tests and decreasing downstream
Our study expands this concept by showing that regional invasive testing. Larger studies with an increased
coronary territory MFR at or below the cutoffs described number of events (stenosis ≥50%) and incorporation of
were associated with increased all-cause mortality individual coronary anatomy are crucial in elucidating
compared to those without impaired regional MFR, this relationship.
even after adjusting for known risk factors, including
revascularization. The integration of this important finding Acknowledgments
into anatomical and perfusion data could be used to guide
treatment, including the decision for medical management None.
versus revascularization, as well as preventive measures. Funding
Our study has several potential methodological None.
limitations that might have influenced our results.
Although this is the largest study to date reporting on the Conflict of interest
applicability of regional coronary territory MBF indices on
the prediction of significant coronary stenosis, this was a Kim G. Smolderen is a consultant for Happify, Hook, and
single-center, retrospective, non-randomized study, which UnitedHealthcare. Carlos Mena Hurtado is a consultant
carries inherent limitations to this design, including referral for Cook and Abbott. Edward J. Miller is a consultant for
bias. Another limitation is that the study is underpowered to Alnylam, Pfizer, GE, and CSL Behring. The other authors
detect “true negatives” and specificity since the angiographic have no conflicts of interest to declare.
referral was clinically decided. In addition, despite the large Author contributions
amount of data collected over 2 years, the number of events
(stenoses ≥50%) was low, limiting the power. The inclusion Conceptualization: Cesia Gallegos, Edward J. Miller, Albert
of patients with prior myocardial infarction also confounds J. Sinusas
the relationship between flow and stenosis, as it may reduce Formal analysis: Jiun-Ruey Hu, Edith L. Posadas
stress flow and regional MFR depending on the degree Investigation: Cesia Gallegos, Camila Trejo Paredes,
of injury and total LV mass affected. Though this was Edward J. Miller, Albert J. Sinusas, Carlos Mena-
accounted for in the subgroup analysis, it further decreased Hurtado, Alexandra Lansky, Yuichi Saito
the number of events per group (prior infarction versus no Methodology: Cesia Gallegos, Camila Trejo Paredes,
prior infarction). Important angiographic characteristics, Edward J. Miller, Kim G. Smolderen, Samit Shah
such as shape, serial stenosis, and vessel morphology that Writing – original draft: Cesia Gallegos, Camila Trejo
may significantly affect resistance, were not evaluated. Paredes, Jiun-Ruey Hu
Finally, a good proportion of patients had decreased MFR Writing – review & editing: All authors
without significant lesions, which raises the question of Ethics approval and consent to participate
the presence of isolated microvascular dysfunction in
this population. Studies have reported that these patients This study was approved by the Yale Institutional Review
constitute ≤20% of patients with angina and no obstructive Board (IRB) (Approval ID: 2000021621).
disease. Hence, the presence of microvascular disease in
27
our cohort is likely a significant contributor to decreased Consent for publication
regional blood follow, which is currently being investigated. Not applicable.
5. Conclusion Availability of data

Data are lacking regarding the correlation of regional The data underlying this article will be shared on reasonable
MBF and MFR with angiographically defined CAD, request to the corresponding author.

Volume 2 Issue 3 (2024) 7 doi: 10.36922/arnm.3786