Images in Cardiovascular Medicine Unexpected Cause for Chest Pain Compression of the Right Coronary Artery Caused by a Protruding Sternal Wire

A 71-year-old man was admitted to our hospital with new onset of typical symptoms of angina on exertion corresponding to a Canadian Cardiovascular Society functional class III. The patient had undergone mitral valve replacement with a mechanical bileaflet valve (ATS medical prosthesis, ATS Medical Inc., Minneapolis, Minn.) in December 1997 and transvenous pacemaker implantation for intermittent high-degree atrioventricular node block (Biotronik Philos II DR, ventricular demand inhibited pacemaker mode VVIR0, Biotronik SE & Co. KG, Berlin, Germany) in 2006. Medical history revealed chronic kidney disease and diabetes mellitus. He had chronic atrial fibrillation and was taking oral anticoagulants. The ECG showed discrete ST depression in leads I, II, III, and aVF (Figure 1). Cardiac troponin T on admission was slightly elevated (0.046 ng/mL; reference value at our institution is 0.0014 ng/mL), and his creatine kinase-MB was negative. Anterior-posterior and lateral chest x-ray showed a fracture of the sixth sternal wire with the lateral view showing a protrusion of the cerclage loop into the anterior mediastinum (Figure 2). Transthoracic echocardiography revealed moderately reduced left ventricular function with mediobasal septal akinesia and good right ventricular function; the mechanical mitral valve was functioning well. No right ventricular regional wall movement abnormalities suggestive of wire protrusion were detectable on echocardiography. The patient underwent cardiac catheterization. Left ventriculography revealed moderately reduced systolic function. Coronary angiography showed no signs of left coronary artery stenosis. However, a significant proximal stenosis of the right coronary artery was detected by virtue of extrinsic compression caused by the protruding fractured sternal wire (Figure 3). Primary percutaneous coronary intervention with stent implantation resulted in a gradual improvement of coronary blood flow and symptom relief. For planning of surgical wire removal, a contrast-enhanced computed tomography (Siemens Somatom Definition Flash 2 64, Siemens