Cardiovascular Magnetic Resonance Determines Coronary Bypass Graft Patency

In coronary artery bypass graft (CABG) patients with recurrent angina, cardiovascular magnetic resonance (CMR) can determine whether a vein graft has significant stenosis or not, Dutch researchers report.

“We have made the first steps to a noninvasive approach for detecting graft disease in patients,” Dr. Willemijn L. F. Bedaux from the VU University Medical Center, Amsterdam, told Reuters Health. “Up till now x-ray coronary angiography has been the clinical standard,” he added.

Dr. Bedaux and colleagues used three-dimensional contrast-enhanced CMR to evaluate 21 randomly selected patients who were scheduled to undergo X-ray angiography due to recurrent chest complaints after CABG. CMR was followed by flow measurements in patent grafts at rest and during hyperemia, the Dutch team notes.

CMR found occlusion in three grafts, the researchers report, as did X-ray angiography. Basal blood flow in nine of the 37 patent grafts was less than 20 mL/minute. All these grafts showed significant stenosis on X-ray angiography, they add.

CMR showed that in grafts with resting flow greater than 20 mL/minute there was a significant difference in flow reserve between grafts with stenosis or diseased run-off and grafts without stenosis, Dr. Bedaux’s team found.

An algorithm for identifying grafts with significant stenosis or diseased run-off, which combines basal volume flow greater than 20 mL/minute and graft flow reserve of less than 2, had a sensitivity of 78% and a specificity of 80%, according to the report in the November 20th issue of the Journal of the American College of Cardiology.

Dr. Bedaux added, “At the moment, CMR flow measurements cannot replace coronary angiography, but with more advanced CMR machines, like most centers have nowadays, it could be.”

J Am Coll Cardiol 2002;40:1848-1855.