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

A LCX MFR (Figure 4C). Individuals with global MFR <1.7
had overall poorer survival (P log-rank = 0.002) compared to
those without impaired global MFR (Figure 4D). Note that
59/189 (31%) patients had impairment in all four MFR
parameters (LAD, RCA, LCX, and global) (Figure S4).

3.5. Unadjusted all-cause mortality associated with
perfusion defects in ≥10% of territory

To ascertain the role of epicardial versus microvascular
disease, we examined the survival of patients with and
B without baseline perfusion defects spanning ≥10% and
<10% of LV segments. There was no significant difference
(P log-rank = 0.56) in all-cause mortality of patients whose
perfusion defects were ≥10% and <10% of the LV (Figure 5).
There was no significant difference in LAD territory MFR,
RCA territory MFR, LCX territory MFR, or global MFR
between patients whose perfusion defects were ≥10% and
<10% of the LV (Table S3).

3.6. Adjusted all-cause mortality associated with
impaired MFR
We adjusted for age at the time of PET MPI, sex, BMI,
C presence of Type 2 diabetes, CAD, HF, smoking history, and
need for subsequent revascularization to further account
for the possibility of confounders in patient survival. 3%
(6/189) of patients underwent subsequent CABG, and
6% (11/189) of patients underwent subsequent PCI. After
adjustment for covariates, all parameters (regional and
global MFR <1.7) were associated with higher mortality:
LAD territory MFR (adjusted hazard ratio [aHR] = 2.1,
95% confidence interval [CI] = 1.048 – 4.3, P Cox = 0.037);
RCA territory MFR (aHR = 3.4, 95% CI = 1.6 – 7.1, P Cox =
0.001); LCX territory (aHR = 2.8, 95% CI = 1.4 – 5.9, P Cox
= 0.006); global MFR <1.7 (aHR = 2.7, 95% CI = 1.3 – 5.7,
Figure 3. Correlation between global myocardial flow reserve and
per-vessel angiographic percent stenosis as continuous variables in the P Cox = 0.007).
(A) LAD, (B) RCA, and (C) LCX
Abbreviations: LAD: Left descending artery; LCX: Left circumflex artery; 4. Discussion
RCA: Right coronary artery.
To the best of our knowledge, this is the first large study
to examine the relationship between regional coronary
3.4. Unadjusted all-cause mortality associated with territory MBF and MFR and coronary artery stenosis
impaired regional MFR through QCA, and its relationship to all-cause mortality.

We then sought to ascertain if impairment in regional Furthermore, we assessed whether there is an optimal
coronary territory MFR had any prognostic implication threshold of hyperemic MBF or MFR that can be used
despite its weak correlation with angiographic percent routinely to predict stenosis severity. Current data support
stenosis. Median survival in our cohort was 4.1 years that a global hyperemic MBF of >2 mL/min/g and MFR of
(IQR: 3.7, 4.5). A total of 38/189 (20%) individuals died. more than >2 reliably excludes the presence of high-risk
Individuals with LAD MFR <1.7 had poorer survival angiographic CAD. 9,11,16 Multiple studies also support that
(P log-rank = 0.007) compared to those without impaired LAD global MFR <1.5 is suggestive of higher-risk CAD. 8,12,13
MFR (Figure 4A). This was also true for individuals with Our research yielded several important findings.
RCA MFR <1.7 (P log-rank <0.001) compared to those without First, it found that while a regional LAD territory MFR
impaired RCA MFR (Figure 4B) and those with LCX MFR of <1.7 is suggestive of obstructive disease in the LAD,
<1.7 (P log-rank = 0.002) compared to those without impaired there was significant heterogeneity in this association,

Volume 2 Issue 3 (2024) 5 doi: 10.36922/arnm.3786