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Alexandre FR Stewart and Robert Roberts
American Heart Hospital Journal Volume 9 No.1

More than one million percutaneous coronary interventions are carried out each year in the US, 70% resulting in the placement of a coronary stent.¹ As more stents are placed, greater need arises for post-procedure evaluation of stent patency and progression of native coronary disease in patients with recurrent symptoms. This follow-up becomes even more imperative when it is considered that in-stent restenosis occurs in nearly 7% of patients, even in the age of drug-eluting devices. The incidence of restenosis is even higher in cases of ostial stenting, stent overlap, and diabetes.¹ Follow-up exercise stress testing with radionuclide imaging is not recommended in asymptomatic patients within two years of an intervention.² Limited experience exists in using coronary computed tomographic angiography (CTA) to assess coronary stent patency. The authors present a case using cardiac CTA for the evaluation of a coronary stent in a clinical scenario that has not yet been addressed by appropriate, formal coronary CTA utilization criteria.

Case Presentation
A 77-year-old female with a history of hypertension and hyperlipidemia presented with exertional angina and shortness of breath. She underwent exercise stress testing with nuclear imaging, reproducing her symptoms but failing to demonstrate electrocardiographic abnormalities or single photon emission computed tomography myocardial perfusion defects. Left ventricular function was normal at rest, with no segmental wall-motion abnormalities and an ejection fraction of 60%. Due to continued symptoms highly suggestive of myocardial ischemia, the stress test was thought to be a false-negative.

The patient underwent coronary angiography, which revealed multiple non-critical lesions throughout the left coronary artery system. The left main coronary artery had a distal 20% lesion. The left anterior descending artery was normal, but the first diagonal branch had a 40—50% stenosis. A 30–40% proximal stenosis was noted in the left circumflex artery. Angiography of the right coronary artery (RCA) revealed complex 99% ostial and proximal stenosis associated with marked calcified plaque, see Figures 1A and 1B. Percutaneous coronary intervention was performed on the right coronary lesion. Guide catheter seating at the right coronary ostium was difficult. Rotablation was performed due to the calcified plaque (two passes with a 1.5burr for 20 seconds at 170,000rpm). The lesion was then dilated with a 2.5x6mm cutting balloon, see Figure 1C. A 4x23mm drug-eluting stent was then deployed, with residual stenosis probably due to incomplete expansion of the calcified plaque, see Figure 1D. Post-stent dilatation was therefore performed with a 4.5x8mm high-pressure balloon, producing an improved but still suboptimal angiographic result, see Figure 1E. The patient was followed periodically by her cardiologist. She denied any chest pain or shortness of breath, but was relatively inactive. She was compliant with all her medications. Given her sedentary lifestyle, the ostial location of the lesion, the fact that previous non-invasive diagnostic testing failed to reveal a defect and the sub-optimal stent deployment due to calcified plaque, a decision was made to reassess the RCA anatomically. Coronary CTA was chosen rather than intra arterial coronary angiography, in light of the technical difficulties previously encountered engaging the RCA and the risk of damaging the ostial stent.

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• Correspondence: Robert Roberts, MD, FRCP(C), MACC, President and CEO, University of Ottawa Heart Institute, Professor of Medicine and Director, Ruddy Canadian Cardiovascular Genetics Centre, 40 Ruskin Street, Ottawa, Ontario, K1Y 4W7, Canada. E: rroberts@ottawaheart.ca