Subacute stent thrombosis (SAT), though less common in the era of dual antiplatelet therapy, continues to produce serious clinical consequences including major myocardial infarction and death.1 The treatment modalities described in the literature include pharmacological agents, repeat angioplasty, stent implantation and in failed cases, emergency coronary artery bypass graft surgery. Pharmacological agents commonly employed are heparin, thrombolytic agents and glycoprotein (GP) IIb/IIIa inhibitors.2 There are no reports of local administration of thrombolytics and GP IIb/IIIa inhibitors in addition to angioplasty to improve procedural and clinical outcomes. There are few reports of intracoronary administration of abciximab associated with reduced major adverse cardiac events (MACE).3 Commonly employed techniques for delivering drugs locally include the use of a larger-sized guiding catheter through which an infusion catheter is passed over an exchange-length intracoronary guidewire. We report on a patient with subacute stent thrombosis who was treated by intracoronary abciximab delivered locally by a novel method using a monorail balloon with an indigenous modification to act as an infusion catheter. Case Report. A 52-year-old male chronic smoker with hypertension of 2 years’ duration presented with class III angina (Canadian Cardiological Society) of 3 weeks’ duration. The patient experienced no angina at rest. Electrocardiography (ECG) revealed ST-segment depression of 1 mm in leads V1– V5, and with a CPK-MB of 150 IU (lab cutoff up to 40 IU). A loading dose of 600 mg clopidogrel with 350 mg of chewable aspirin was given. Coronary angiography revealed a total occlusion of the mid left anterior descending artery (LAD) with Grade II collaterals (Rentrop and Cohen) from the right coronary system.4 The patient underwent successful stenting of the LAD with 3 x 28 mm BX Velocity stent (Cordis Europa, The Netherlands) delivered at 15 atm pressure. Subsequently, 150 mg of clopidogrel and aspirin were continued on a daily basis. Seventy-two hours after the procedure, he developed SAT (rest angina along with ST-segment elevation in leads V1–V5).The angiogram revealed complete occlusion of the LAD at the inlet of the stent, suggestive of thrombus occluding the stent (Figure 1). After a bolus of 10,000 units of intravenous heparin, the left coronary artery was intubated with a 7 Fr JL 3.5 (Judkins left) guide catheter (Boston Scientific, Natick, Massachusetts). A Balanced Middle Weight (BMW), Universal™ guidewire (Guidant Corp., Indianapolis, Indiana) was steered through the thrombus-laden stent and followed by balloon dilatation with 1.5 x 20 and 2.5 x 20 mm balloons (Amadeus, EuroCor, Bonn, Germany) (Figure 2). However, there was no antegrade flow (Figure 3). Repeated balloon dilatation failed to establish antegrade flow. At this time, we decided to administer abciximab as an intracoronary bolus. In the absence of an exchange-length intracoronary guidewire and an infusion catheter, we decided to shave off the balloon component of the monorail coronary balloon catheter to deliver the abciximab. The balloon material was shaved off the shaft of the monorail balloon catheter (Apollo/Jupiter, stent balloon, InTek Technology SA, Switzerland) (Figure 4). This monorail balloon catheter (with the balloon shaved off) was then advanced over the BMW wire and positioned within the stent. The position of the balloon within the thrombus was confirmed by observing the staining of the thrombus by the contrast injected into the balloon catheter (Figure 5). A bolus of abciximab (0.25 mg/kg) was slowly injected into the monorail balloon catheter positioned at the site of the thrombus. Ten minutes later, balloon angioplasty was repeated with 1.5 x 20 mm and 2.5 xx 20 mm balloons (Amadeus, EuroCor, Bonn, Germany) within the stent. Intracoronary nitroglycerine (200 µg) was also given in a similar fashion. Following this, TIMI 2 antegrade flow was established and a few minutes later, the patient’s chest pain began to lessen (Figure 6). ST-segment changes in ECG settled with appearance of T-wave inversion in V1–V5. Maintenance dose of abciximab (0.125 µg/kg/minute) was given through a femoral venous sheath for the next 12 hours. Antiplatelet agents, clopidogrel (150 mg/day) and aspirin (150 mg/day) were continued. Repeat angiography a week later showed normal in-stent segment with TIMI 3 antegrade flow. Discussion. Despite various advances in the technique of coronary stenting and with the advent of potent antiplatelet agents, SAT continues to be a significant problem. Randomized trials have reported the incidence of SAT ranging from 0.4% to 1.3% in cases of elective stenting, and 2.2% in acute coronary syndromes.4 A number of patient- and procedure-related factors have been shown to predict the occurrence of subacute stent thrombosis (SAT) including longer stent length, smoking status, minimal luminal diameter of the vessel, persistent dissection, multivessel intervention and possibly acute coronary syndromes. Our patient was at risk for SAT, with a number of preprocedure variables predisposing him including a long stent to treat his primary disease, current smoking status and unstable angina at presentation. The proposed management strategies of SAT include pharmacological agents, mechanical devices and a combines approach often referred to as “power thrombectomy” aimed at enhancing or synergizing the effect of mechanical forces on activity of a pharmacological drug.5 Pharmacologic agents proposed for management of SAT include administration of intracoronary or systemic thrombolysis and/or GP IIb/IIIa inhibitors.2,6 However, systemic thrombolysis is not effective in patients with stent thrombosis.7 Reports of intracoronary use of GP IIb/IIIa inhibitors like abciximab in humans are limited to a small number of patients with angiographically visible thrombus in coronary arteries and nonoccluded saphenous vein grafts, revealing a rapid reduction of thrombotic mass. Wohrle et al reported a 50% reduction in MACE in patients receiving an intracoronary compared to intravenous bolus of abciximab.3 Kakkar et al reported a higher 6-month composite endpoint of death or MI in patients who received intravenous abciximab (13.9%) compared to those who received intracoronary administration (5.9%; p = 0.04).9 However, treatment of stent thrombosis with current pharmacological management strategy alone remains suboptimal and is presently best given as an adjunct to catheter-based therapy. Various catheters used for local drug delivery include the Dispatch catheter (Boston Scientific), InfusaSleeve (Local Med Inc., Palo Alto, California), and recently through the central lumen of an over the-wire-balloon.10–12 However, these systems have limitations such as the need to upsize the guide catheter, the need for an exchange-length wire, the bulky nature of infusion catheters and obstruction of flow into the side branches (especially with the Dispatch catheter). In such a situation, the use of a monorail thrombectomy catheter for both thrombectomy and local drug delivery is recommended. Presently, there are specially-designed aspiration thrombectomy catheters for use in such cases. There are reports stating successful use of various thrombectomy catheters like the Pronto aspiration thrombectomy device (Vascular Solutions, Inc., Minneapolis, Minnesota),13 the Export aspiration catheter (EAC, the aspiration component of the GuardWire Plus system, PercuSurge, Inc., Sunnyvale, California)14 and the Rinspiration system (Kerberos Proximal Solutions Inc., Sunnyvale, California).15 The Pronto device is a dual-lumen rapid-exchange aspiration thrombectomy catheter with an atraumatic distal tip and sloped extraction lumen designed to protect the vessel wall. Similarly, the EAC is an atraumatic monorail aspiration thrombectomy catheter. Such custom-made catheters offer several advantages, as they are 6 Fr-compatible systems and effectively reduce the thrombus burden. They can also be used for focal infusion of pharmacological agents, thereby facilitating reperfusion. In our patient, however, the essential hardware was not readily available, hence we decided to administer abciximab through the central lumen of the balloon itself after shaving off the balloon component with a surgical blade. The infusion of abciximab was intentionally given through this novel catheter and not the guide catheter so as to have a selective site infusion and optimal effect. The selective site infusion of abciximab complemented POBA in achieving the final result, which could otherwise not be achieved by POBA. However, it is important to understand that such a system carries a risk of coronary dissection, as it lacks the custom design of an aspiration thrombectomy catheter. A thorough Medline search revealed no reports of such a technique. This case report provides evidence that drugs can be delivered locally via the central lumen of a monorail PTCA balloon catheter in an emergency situation as an adjunct to intervention. Dedicated catheters of monorail design, preferably with multiple holes in the shaft and an atraumatic tip with as low a profile as that of of 1.5 mm balloon, can be designed for selective delivery of a drug into the lesion.
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