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Myocardial blood flow response to revascularization therapies in patients with diabetes mellitus
R De Kemp1
1University of Ottawa Heart Institute - Ottawa - Canada
Topic(s): Positron Emission Tomography (PET)
Introduction: In patients with diabetes mellitus (DM) and coronary artery disease (CAD), revascularization with coronary artery bypass grafting (CABG) has been shown to decrease the number of adverse events compared to percutaneous coronary intervention (PCI) and optimal medical therapy (OMT) alone. Myocardial Flow Reserve (MFR) measured by Positron Emission Tomography (PET) is a robust tool that can provide diagnostic and prognostic information, and may aid in the selection of therapy for CAD patients.
Purpose: To investigate the MFR response to therapy in patients following CABG, PCI or OMT.
Methods: We screened 15,023 Rb-82 PET perfusion studies performed between 1 March 2008 and 30 June 2018. 4,064 studies were identified in which patients underwent serial (2 or more) PET scans. Serial scans were paired, then grouped based on diabetic status (DM/NDM) and intervening treatment (OMT/PCI/CABG). We analyzed data from rest/stress perfusion studies for 1,151 OMT, 223 PCI, and 28 CABG scan pairs. Improvements in MFR were compared between treatment groups, globally (per patient) and regionally (per vessel) according to the territory supplied by each coronary artery. Multi-factor ANOVA was used to analyze the data.
Results: Global MFR changes were greatest with CABG, followed by PCI, then OMT (0.66 ± 0.73 vs 0.097 ± 0.90 vs -0.069 ± 0.73, ANOVA P < 0.01 – Figure 1A). Patients receiving CABG had the lowest baseline flow, followed by PCI then OMT (1.6 ± 0.53 vs 2.1 ± 0.86 vs 2.4 ± 0.81, ANOVA P < 0.01), however, there were no significant differences between the groups post-treatment. MFR was lower in DM vs NDM groups at both baseline and post-treatment (baseline: 2.5 ± 0.84 vs 2.1 ± 0.75, ANOVA P < 0.01). As expected, target vessel revascularization by PCI or CABG achieved a greater improvement in regional MFR compared to non-target vessels (PCI: 0.064 ± 0.19 vs 0.0 ± 0.16, CABG: 0.16 ± 0.17 vs 0.090 ± 0.18, ANOVA P < 0.01 – Figure 1B). When stratifying for treated vessel, regional MFR improvements were significantly greater in NDM patients treated for LAD disease vs NDM patients treated for LCX disease, and in DM patients treated for LAD or LCX disease (P < 0.05 – Figure 1C).
Conclusions: Patients with DM had similar improvements in local and regional MFR compared to NDM patients, across all treatment groups. While CABG provided greater improvement than PCI and OMT, it achieved similar post-treatment MFR due to lower perfusion at baseline in patients selected for CABG. This suggests that baseline MFR may be a helpful tool in directing choice of revascularization therapy. DM patients had lower baseline perfusion than NDM (possibly due to more microvascular and diffuse disease) and this difference remained post-treatment. These results demonstrate the importance of baseline MFR in predicting post-treatment flow, and suggest possible applications of PET imaging for flow quantification to assist in management decisions for revascularization.