Contributed by David Laxson, MD
Coronary artery bypass grafting is often performed to alleviate the symptoms of coronary artery disease. Medication-resistant angina, however, can emerge after coronary artery bypass grafting as a result of chronic total occlusion (CTO).1
A patient in his 50s presented to his community hospital with acute coronary syndrome. He was found to have left main coronary artery disease and a CTO in his right coronary artery. Cardiac surgeons performed coronary artery bypass grafting, placing an internal mammary artery graft to the left anterior descending artery and a vein graft to the right coronary artery. Years after the procedure, a coronary angiogram revealed that the vein graft to the right coronary artery had failed and the graft to the left anterior descending artery was supplying collateral blood flow to the right coronary artery via the left anterior descending artery (LAD). He was referred to the University of Minnesota Health Heart Care angioplasty clinic for evaluation of his right coronary artery occlusion.
Medical therapy rendered the patient stable for 1 year, after which he began experiencing angina upon exertion. He was frustrated that he was no longer able to take his dog for a walk. A subsequent combination of beta blockers, calcium channel blockers, and long-acting nitrates failed to relieve his worsening chest pain.
An angiogram revealed progression of left main coronary artery disease to a complete occlusion and continued right coronary artery CTO, which reduced collateral blood flow to the right coronary artery (Figs. 1 and 2). At this point, the internal mammary artery graft was supplying blood flow to his whole heart. The disease progression left the patient a poor candidate for coronary bypass surgery. However, nuclear stress testing indicated that the heart wall affected by the right coronary artery CTO was still viable, making him an appropriate candidate for consideration of CTO angioplasty. The patient agreed to the procedure.
Using dual angiography of the CTO vessel, the cardiologist was able to visualize the totally occluded artery both before and beyond the occluded segment. (The simultaneous coronary angiograms were of the occluded artery and of the bypass graft to the LAD, which supplied collateral blood flow to the branches of the right coronary artery beyond the occlusion.) The cardiologist performed a CTO angioplasty employing an antegrade reentry technique and using a special catheter and guide wire technology to traverse the occluded segment and reenter the true lumen. The channel resulting from this approach allowed the passage of dilating balloon catheters and then coronary stents. The procedure successfully addressed the 2 cm occlusion in the patient’s right coronary artery (Fig. 3).
Eight years after a first diagnosis of total right coronary artery occlusion, the patient, now in his 60s, has experienced complete relief from angina and is regularly walking his dog again.
Although coronary artery bypass grafting is a common and effective procedure for treating coronary artery disease, there is some debate about its risk/benefit ratio and efficacy in patients with chronic total occlusion. Angioplasty can be a successful treatment option for these patients provided interventional cardiologists carefully consider the unique characteristics of the occlusion, the presence of coronary disease, and the dimension of the artery under consideration before undertaking CTO angioplasty.2 In this patient, angioplasty provided a successful outcome.
A difficult-to-treat condition often traditionally addressed through coronary artery bypass grafting finds new treatment options as new technology and surgical approaches are improving patient outcomes.Continue reading