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Case Report
Percutaneous Treatment of a Large Coronary Aneurysm with a Ball Thrombus: An Interventional Challenge
December 2006
A coronary artery aneurysm is defined as a coronary artery dilatation greater than 1.5 times the diameter of either the normal adjacent segments or the diameter of the patient’s largest coronary vessel.1,2 The prevalence varies from 0.3% to 4.9% among patients undergoing coronary angiography with a male preponderance.1 The true prevalence may be lower, as only one-third of angiographically diagnosed aneurysms have the intravascular ultrasound (IVUS) appearance of a true or false aneurysm.3 The most common site for a coronary aneurysm is the right coronary artery (41%).4 A coronary aneurysm may be congenital or acquired, with atherosclerosis accounting for 50% of them in adults.1
Reported complications include thrombosis and distal embolization, rupture, vasospasm and myocardial infarction. The turbulent flow within the aneurysm, combined with areas of decreased flow, may lead to intravascular thrombus formation with distal embolization or acute vessel closure and myocardial infarction.2,5 We report a case of a large right coronary artery (RCA) aneurysm with an associated ball thrombus.
Case Report. A 72-year-old female was admitted to a local hospital with an inferior ST-elevation myocardial infarction (STEMI). She was successfully reperfused with streptokinase. A week later, she represented with reinfarction in the same territory and was transferred for further treatment.
Selective coronary angiography using a 6 Fr JL4 diagnostic catheter from the femoral approach showed a normal left main stem. The left anterior descending and the left circumflex arteries had only minor disease. A 6 Fr JR4 diagnostic catheter showed an occluded RCA.
Following heparinization using a 7 Fr AR1 side-hole guide catheter (Medtronic Inc., Minneapolis, Minnesota), a Traverse wire (Guidant Corp., Indianapolis, Indiana) was passed down the RCA. The occluded lesion was ballooned with a 2.5 mm x 12 mm Sprinter balloon (Medtronic), which opened the artery. There was a very large aneurysmal segment (11 mm in length, 10 mm in diameter) just distal to the initial occlusion which contained a large ball thrombus (Figure 1). Unfortunately, the ball thrombus immediately flopped down into the vessel (Figure 2). An intravenous bolus of glycoprotein IIb/IIIa inhibitor was administered.
An Export catheter (Medtronic) was used twice in an attempt to aspirate the thrombus with no effect. A Choice® Plus floppy exchange wire (Boston Scientific Corp., Natick, Massachusetts) was used to allow the passage of a 1.5 mm X-Sizer® catheter (ev3, Inc., Plymouth, Minnesota), but this would not pass around the proximal bend of the RCA, even after full dilatation of this area with the 2.5 mm x 12 mm Sprinter balloon (Medtronic). The thrombus continued to embolize downstream (Figure 3). After a further attempt with the X-Sizer device, we used a Diver® CE aspiration catheter (Invatec, Roncadelle, Italy), but again no real impact was made. We subsequently elected to proceed with balloon dilatation and stenting. Following further dilatation of the vessel with a 2.5 mm x 20 mm Maverick® balloon (Boston Scientific), the aneurysmal segment was stented with a 3 mm x 16 mm GraftMaster coronary stent (Abbott Vascular, Rongendingen, Germany) and was inflated at 12 atmospheres (atm) for 30 seconds. The stent was further dilated with a 3.5 x 10 mm Tracker balloon (Cordis, LJ Roden, The Netherlands), which was inflated twice at 16 atm for 20 seconds.
Final angiography, showed good flow distally to the posterior descending artery branch, but there was an embolic occlusion of the distal part of the postero-lateral branch (Figure 4). Intravenous glycoprotein IIb/IIIa inhibitor was continued 12 hours postprocedure. Interestingly, there were no ECG changes. The peak creatine kinase (measured at 6 and 18 hours postprocedure) was 319 U/L (upper limit 150), and the peak CK-MB was 46 IU/L (upper limit 24). The patient’s subsequent clinical course was uncomplicated. She was discharged and advised to take dual antiplatelet therapy (aspirin and clopidogrel) for a year and then to continue with aspirin alone.
Discussion. A coronary aneurysm may predispose patients to acute thrombosis, embolization and myocardial infarction, but the exact incidence of this complication is unknown.2 It is also not clear whether thrombosis and embolism occur only in certain types of aneurysms.6 The presence of thrombus inside a coronary aneurysm has been reported in several case reports. Daoud et al7 found thrombus inside coronary aneurysms in 7 out of 10 patients at autopsy. Anabtawi et al8 and Ebert et al9 have reported thrombus inside an aneurysm during coronary bypass graft surgery (CABG). Myler et al10 reported a case of coronary aneurysm with extensive thrombus during coronary angiography. Swanton et al11 reported reduced coronary sinus blood flow in ectatic compared with nonectatic coronary arteries. Abnormal flow patterns within the coronary aneurysm may lead to thrombus formation and thromboembolization. A few case series and case studies have reported wall motion abnormalities in patients with coronary aneurysm without significant obstruction.12,13 These case reports suggest predisposition to thrombus formation inside the aneurysm with possible distal embolization of the thrombus causing regional left ventricular dysfunction or thrombotic occlusion within the aneurysm without embolization.
The most common cause of death in patients with a coronary artery aneurysm is thrombosis causing myocardial infarction. As the incidence of this complication is unknown, the selection of the most appropriate treatment option, surgical or interventional, is still controversial. The natural history and prognosis are still obscure, and may depend on the extent of associated coronary artery disease, which will also influence choice of therapy. Surgical techniques like excision and ligation of the aneurysmal segment with concomitant coronary bypass grafting can be used for progressively enlarging aneurysms with significant coronary artery disease.14 In the absence of significant coronary artery disease requiring CABG, percutaneous techniques are an alternative. Most experience has been with polytetrafluoethylene (PTFE)-covered stents,15 although there are no randomized trial data. A sequential technique with 2 PTFE-covered stents from proximal to distal segments to seal a long, giant aneurysm has been reported recently.16 Athough covered stents are inferior to conventional stents in the treatment of saphenous vein graft disease,17 the use of a covered stents in cases such as the one we describe, may still be warranted to exclude the aneurysmal segment and prevent further enlargement.
One of the major concerns with the use of PTFE stents is the high incidence (> 5%) of subacute stent thrombosis postprocedure, probably due to delayed complete endothelialization of the luminal surface of the stent.18 With mortality rates of 20–30% in non-PTFE stent thrombosis, this is clearly a concern. Therefore, prolonged use of dual antiplatelet therapy is recommended,19 with our current practice prescribing dual therapy for 1 year.
In the current report, we describe a patient who presented with reinfarction. Initial ballooning of the vessel revealed a large aneurysm containing a ball thrombus. Unfortunately, the restoration of flow encouraged the ball thrombus to dislodge downstream from the aneurysm. Once distal embolization had occurred, our attempts to extract the thrombus with 3 different extraction devices were unsuccessful. This was partly because of the size of the thrombus and also because of the technical difficulties in delivering a 1.5 mm X-Sizer device.
In summary, coronary aneurysms may predispose patients to acute thrombosis leading to myocardial infarction. Treatment strategies vary depending on the presentation of the patient, the size of the aneurysm, the presence of thrombus and the extent of associated coronary disease. Unless there is an important adjacent side branch, the use of a well-deployed covered stent during percutaneous intervention remains a compelling choice, but a prolonged course of antiplatelet therapy is recommended to reduce the incidence of subacute stent thrombosis.
References
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