Assessment of coronary artery bypass graft disease using cardiovascular magnetic resonance determination of flow reserve
Willemijn L. F. Bedaux, MD*||,*,
Mark B. M. Hofman, PhD ,
Stefan L. A. Vyt, MD ,
Jean G. F. Bronzwaer, MD*,
Cees A. Visser, MD, PhD* and
Albert C. van Rossum, MD, PhD*||
* Department of Cardiology, Amsterdam, The Netherlands
Department of Clinical Physics and Informatics, Amsterdam, The Netherlands
Department of Radiology, VU University Medical Center, Amsterdam, The Netherlands
Institute for Cardiovascular Research ICaR-VU, Amsterdam, The Netherlands
|| Interuniversity Cardiology Institute Netherlands, Utrecht, The Netherlands
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Figure 1 X-ray coronary bypass angiogram (A), and 3D contrast-enhanced cardiovascular magnetic resonance angiogram obtained through post-processing using a maximum intensity projection (B) of a patient with a sequential graft with anastomoses to the posterolateral branch of the circumflex and the posterior descending branch of the right coronary artery. The open arrow points to a stenosis with 59% luminal narrowing, the white arrow to a stenosis with 73% luminal narrowing. Luminal stenosis was determined by quantitative coronary angiography on two orthogonal projections. Ao = aorta.
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Figure 2 Images obtained simultaneously in an orientation perpendicular to grafts inserted to the obtuse marginal branch of the circumflex artery (white arrow) and the diagonal branch of the left anterior descending artery (open arrow). (A) The anatomic image. (B) The corresponding velocity map in diastole. Ao = aorta.
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Figure 3 Plot of mean basal volume flow measurements as a function of stenosis severity in all patent grafts. In nine grafts a basal volume flow of <20 ml/min was measured. X-ray angiography demonstrated a significant stenosis in each graft.
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Figure 4 Plot of graft flow reserves in three different groups: grafts with stenosis <50% (n = 10), grafts with diseased graft run-off (n = 8), and grafts with stenosis >50% (n = 10). Flow reserves in these groups were 2.5 ± 0.7, 2.0 ± 1.0, and 1.6 ± 0.8, respectively (*p = 0.02).
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Figure 5 Plot of graft flow reserves in two different groups: grafts with stenosis <50% and grafts with significant stenosis or diseased run-off. Flow reserve in the non-significantly diseased grafts with a normal run-off (n = 10) and in the group of grafts with a significant stenosis or with a diseased run-off (n = 18) was 2.5 ± 0.7 versus 1.8 ± 0.9, respectively (*p = 0.04). An algorithm combining an absolute basal volume flow <20 ml/min or graft flow reserve <2 had a sensitivity of 78% and a specificity of 80%.
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