Transradial Intracoronar Cathete-Aspiration Embolectomy for Acute Coronary Embolism after Mitral Valve Replacement

Abstract

An anticoagulated 51-year-old woman with a mechanical mitral prosthesis, which had been implanted 12 years earlier, sustained an acute anterior wall myocardial infarction caused by an embolus in the mid left anterior descending coronary artery. After treatment with tissue-plasminogen activator failed to lyse the obstruction, we performed intracoronary catheter-aspiration embolectomy via a transradial approach, which yielded a favorable result. (Tex Heart Inst J 2003;30:316–8)

Although most acute myocardial infarctions (AMIs) are associated with athero-sclerosis and its complications, coronary artery embolism should be considered when there is an associated risk factor such as an intracardiac prosthesis, a cardiac tumor, infective endocarditis, or a mural thrombus. There is no consensus regarding the treatment in such a situation.

We present our experience with a patient who had a mechanical mitral prosthesis and sustained an AMI secondary to an embolic occlusion of the left anterior descending coronary artery (LAD). After tissue-plasminogen activator (t-PA) failed to lyse the obstruction, we catheterized the patient and aspirated the intracoronary embolus, which immediately resolved the lesion without balloon dilation or stent placement.

Case Report

In December 2000, a 51-year-old woman presented with sudden onset of severe chest pain. She had a history of rheumatic mitral stenosis and chronic atrial fibrillation and had received a 31-mm St. Jude mechanical mitral valve 12 years earlier. Although she had been fully anticoagulated with warfarin, she had developed a left popliteal artery embolism 5 years earlier, at which time she had been treated with catheter embolectomy via a surgical cutdown.

One hour after the onset of chest pain, the patient was administered t-PA at a local medical center and received a total of 100 mg before thrombolytic therapy was discontinued. Because the pain persisted, she was transferred to our emergency room 2 hours later. Electrocardiography showed atrial fibrillation and ST-T segment ele-vation over the 1st to 3rd left precordial leads, compatible with anterior wall AMI. In the meantime, hematemesis occurred and the thrombolytic therapy was discontinued. An emergent endoscopy failed to reveal the source of the upper gastrointestinal bleeding.

Emergent cardiac catheterization was performed through the left radial artery with a 6F Terumo artery sheath (Terumo Corporation; Tokyo, Japan) and a 6F Kimny Mini-radial Force™ guiding catheter (Boston Scientific SciMed, Inc.; Maple Grove, Minn). The angiogram showed a focal filling defect in the mid-LAD, with Thrombolysis in Myocardial Infarction grade 2 (TIMI-2) flow (Figs. 1A and 1B); otherwise, the coronary arteries were normal. The guiding catheter was selectively advanced to the proximal edge of the lesion, then a 0.014-in Hi-Torque Floppy II™ guidewire (Guidant; Santa Clara, Calif) was advanced distal to the filling defect. Ten hours after the episode, 2 fragments were aspirated from the LAD coronary artery. The larger clot measured 6 × 2 × 2 mm. Histologic examination demonstrated that the clot was largely fibrin, with no evidence of fresh red blood cells or platelets (Fig. 2). These findings are compatible with embolus but not with thrombus. Angiography performed immediately after the procedure showed neither a filling defect nor residual stenosis, and TIMI-3 flow had been restored (Figs. 1C and 1D); hence balloon dilation or stent placement was not considered. The patient was discharged 3 days later, under maintenance anticoagu-lation (international normalized ratio, 2.5 to 3.5) but without the use of antiplatelet agents. Since then, she has been event free; at her 2-year follow-up, serial 2-dimensional echocardiograms revealed that left ventricular function had been preserved.

Fig. 1 Coronary angiograms in right anterior oblique caudal (A) and lateral (B) projections show an embolus in the mid-left anterior descending artery (arrowheads). The same angio-graphic views (C, D) after catheter-aspiration embolectomy show resolution of the embolus.

Fig. 2 Histologic examination of the coronary embolus shows fibrin contents (H&E stain, orig. ×10).

Discussion

Coronary artery embolism is an uncommon cause of AMI. However, it should be considered when there is an associated risk factor—such as an intracardiac prosthesis, valvular heart disease, endocarditis, or cardiac myxoma. ^1–4 Because the proximal LAD artery is straighter than the left circumflex artery, coronary embolisms have been most frequently reported in the LAD territory, especially in the distal epicardial and intramural branches. ⁵ In regard to the methods of diagnosing this condition, as with other forms of embolic disorder, angiography is still considered the gold standard.

There is no consensus on the treatment of coronary embolism. Although there is some evidence that a double regimen (streptokinase plus aspirin, or uro-kinase plus abciximab) is superior to a single regimen (urokinase or alteplase), 2, 6–8 published reports on thrombolysis are few and the results are not definitive. Hernandez and colleagues ⁴ reported 3 interventional cases in which patients with coronary embolism presented with AMI. These patients were treated successfully with percutaneous transluminal coronary angioplasty and stent placement.

In our patient, t-PA failed to lyse the thrombus and was discontinued because of bleeding. Because both the angiographic findings and the clinical history were consistent with mid-LAD embolism, we performed catheter-aspiration embolectomy alone instead of coronary angioplasty or stenting. There is precedent for this technique. To prevent distal embolization, Belli and associates ⁹ used the GuardWire Plus™ System (PercuSurge; Sunnyvale, Calif) to aspirate thrombus from a native coronary artery, with excellent angiographic results. Beran and associates ¹⁰ used the X-SIZER® Catheter System (ev3, Inc.; Ply-mouth, Minn) for fragmentation and removal of a thrombus, to improve epicardial flow. Aggressive advancement of a guidewire in a coronary artery can cause endothelial injury, intimal dissection, and acute or delayed occlusive events. Rinfret and coworkers ¹¹ achieved excellent results in both venous grafts and native coronary arteries through use of the AngioJet Rheolytic Thrombectomy System™ (Possis Medical; Minneapolis, Minn), which has a tapered tip that is less likely to injure the vessel. In our patient, catheter-aspiration embolectomy for the intracoronary embolism was effective, and postprocedural angiography confirmed that the vessel was totally intact. Balloon angioplasty or stenting was thought unnecessary.

Kiemeneij and co-authors ^12,13 reported their experiences with percutaneous transluminal coronary angioplasty and stenting via a transradial approach. In patients undergoing thrombolytic therapy, they demonstrated that the transradial approach was associated with fewer complications at the access site and with a comparable procedural success rate in comparison with the transfemoral and transbrachial approaches. We advocate this approach even for a complex interventional procedure like the intracoronary catheter-aspiration embolectomy that we report here.

In conclusion, the role of catheter aspiration in the treatment of coronary embolism has not been well established, but our limited experience indicates that it can be a valuable alternative when thrombolysis fails. This technique depends greatly on the pliancy of the Kimny Mini-radial Force™ guiding catheter, which permits super-selection of the target lesion. However, the lack of distal protection against embolization is a major concern in performing this procedure. Further instrumental and technical modifications are needed.