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Residual Ischemia After Revascularization in Multivessel Coronary Artery Disease: Insights From Measurement of Absolute Myocardial Blood Flow Using Magnetic Resonance Imaging Compared With Angiographic Assessment
Study Questions:
What is the completeness of revascularization for percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), as assessed by coronary angiography and by quantitative serial perfusion imaging using cardiovascular magnetic resonance (CMR)?
Methods:
Patients with multivessel coronary disease were recruited into a randomized trial of treatment with either CABG or PCI. Angiographic disease burden was determined by the Bypass Angioplasty Revascularization Investigation (BARI) myocardial jeopardy index. CMR first-pass perfusion imaging was performed before and 5-6 months after revascularization. Using model-independent deconvolution, hyperemic myocardial blood flow was evaluated, and ischemic burden was quantified.
Results:
Sixty-seven patients completed follow-up (33 CABG and 34 PCI). The myocardial jeopardy index was 80.7 ± 15.2% at baseline and 6.9 ± 11.3% after revascularization (p < 0.0001), with revascularization deemed complete in 62.7% of patients. Relative to CMR, angiographic assessment overestimated disease burden at baseline (80.7 ± 15.2% vs. 49.9 ± 29.2%; p < 0.0001), but underestimated it post-procedure (6.9 ± 11.3% vs. 28.1 ± 33.4%; p < 0.0001). Fewer patients achieved complete revascularization based on functional criteria than on angiographic assessment (38.8% vs. 62.7%; p = 0.015). After revascularization, hyperemic myocardial blood flow was significantly higher in segments supplied by arterial bypass grafts than those supplied by venous grafts (2.04 ± 0.82 ml/min/g vs. 1.89 ± 0.81 ml/min/g, respectively; p = 0.04).
Conclusions:
The authors concluded that angiographic assessment may overestimate disease burden before revascularization, and underestimate residual ischemia after revascularization.
Perspective:
This study reported that relative to functional assessment, angiographic scoring systems overestimate the degree of disease burden before revascularization and systematically underestimate the degree of residual ischemia after revascularization. These data would appear to support the potential complementary role of CMR-based functional assessment both before and possibly after revascularization, in patients with complex coronary disease. If validated in additional larger prospective studies, the use of functional techniques such as CMR may help facilitate clinical decision making regarding the choice of optimal revascularization strategy for the individual patient.
Keywords: Coronary Artery Disease, Follow-Up Studies, Coronary Angiography, Ischemia, Myocardial Revascularization, Coronary Artery Bypass, Angioplasty, Magnetic Resonance Spectroscopy, Magnetic Resonance Imaging, Perfusion Imaging, Percutaneous Coronary Intervention
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