Complete left coronary system abolition due to thrombotic occlusion of the left main coronary ostium is an unusual presentation of myocardial infarction. Delays in reaching hospital and restoring coronary blood flow are major predictors of survival in cardiogenic shock. This rare case highlights the high mortality rate of cardiogenic shock due to thrombotic occlusion of the left main coronary ostium in spite of all efforts using innovative devices to remove thrombus and achieve adequate coronary and myocardial perfusion.

       Cardiogenic shock complicating acute myocardial infarction is associated with high mortality.^1,2 Early recognition and coronary revascularization are crucial to improve its poor prognosis. Successful early reperfusion of the infarct-related coronary artery, while maintaining integrity of the downstream microvasculature, limits ongoing necrosis, salvages myocardium, and may prevent the development of cardiogenic shock.³
       In this report we present an unusual case of a patient with acute thrombosis of the left main artery who reached the hospital in cardiogenic shock and underwent emergency percutaneous revascularization. The patient was initially treated with inotropic pharmacological support and intra-aortic balloon counterpulsation. Despite using antithrombotic and antiplatelet therapy, including abciximab, and specific devices to remove thrombus, embolization of thrombus occurred distally with the development of the no-reflow phenomenon. The patient died within a few hours. The management of cardiogenic shock complicating myocardial infarction and intracoronary thrombus is discussed, with an emphasis on the utility of thrombectomy devices.

       Case Report. A 45-year-old female, ex-smoker, was referred to our hospital because of anterior myocardial infarction 6 hours after the onset of symptoms. At admission, her systolic arterial pressure was 80 mmHg, her heart rate 140 beats/minute, and her arterial oxygen saturation was 85%. The

Figure 1

(A) Aortography in LAO view showed complete thrombotic occlusion of the left main coronary ostium. (B) Engagement of the left coronary ostium using an Extra Back Up guiding catheter in LAO caudal view.

electrocardiogram showed sinus tachycardia with ST-segment elevation in the anterior and lateral leads. Mechanical ventilation and inotropic pharmacological support were initiated prior to emergency cardiac catheterization. The patient was also treated with aspirin, unfractionated heparin, and abciximab. Emergency echocardiography ruled out mechanical complications and showed severe left ventricular dysfunction with akinesis of anterior, septal, lateral, and apical segments. First, aortography was performed using the right femoral approach because of the difficulty in catheterizing the left coronary ostium, which showed complete thrombotic occlusion of the left main coronary ostium (Figure 1). The right coronary artery was a dominant vessel, with no significant stenoses. An intra-aortic balloon pump was inserted percutaneously through the left femoral artery prior to primary angioplasty. Subsequently, an Extra Back Up, XB 3.5 7 Fr guiding catheter (Cordis Corp., Miami, Florida.) was used to engage the left coronary ostium (Figure 2A). A 182 cm PT Graphix guidewire (Boston Scientific Scimed, Miami, Florida) was used to cross the thrombotic occlusion of the left main coronary ostium. A Diver CE aspiration catheter (Invatec, Brescia, Italy) was slowly advanced over the guidewire into the left main coronary artery and the left anterior descending artery. Blood aspiration was performed while advancing the tip of the catheter toward the lesion containing the thrombus. Multiple passages were performed across the thrombotic lesion as well as distal to the lesion. Post-thrombus aspiration angiography showed TIMI flow grade 1. Afterwards, the guidewire was removed and a new 300 cm PT Graphix guidewire was introduced into left anterior descending artery. Following placement of the guidewire, a 1.5 X-Sizer catheter (EV3, Plymouth, Minnesota) was introduced over the guidewire, and several passages were performed across the thrombus from proximal to distal segments of the left anterior descending artery by slowly advancing the activated catheter (Figure 1B). TIMI flow grade did not improve after thrombectomy with the X-Sizer catheter. Finally, after the administration of intracoronary nitroglycerine and adenosine, several balloon dilatations were performed from the distal-to-proximal left anterior descending artery using a 2 x 20 mm Maverick™ 2 balloon (Boston Scientific Scimed) without stent implantation because

Figure 2

(A) Thrombus extraction with the X-Sizer catheter system in AP view. (B) Final coronary angiography showed TIMI flow grade 1 in AP view.

nonsignificant coronary stenosis was observed. Despite these pharmacological and mechanical approaches to remove the thrombus, the no-reflow phenomenon was evident, and the final coronary angiography showed TIMI flow grade 1 (Figure 2). The patient developed several episodes of ventricular fibrillation and electromechanical dissociation during the procedure, and died a few hours later while awaiting the implantation of a left ventricular device as a bridge to cardiac transplant.

Discussion
       Management of cardiogenic shock complicating acute myocardial infarction. The estimated incidence of cardiogenic shock in patients with myocardial infarction is approximately 7–10%, with a mortality rate of almost 50% at 30 days among patients with early coronary revascularization.^1,2 Therefore, despite the use of early reperfusion therapies with thrombolysis or percutaneous coronary intervention, the mortality rate in these patients remains high. Clinical suspicion, together with preventive treatment in high-risk patients presenting with acute myocardial infarction, is the most effective management strategy, except in the case of a minority of patients (10–15%) who reach the hospital in cardiogenic shock.³ Left main artery disease, TIMI grade flow < 3 after percutaneous coronary intervention, advanced age, three-vessel disease, and delay in establishing treatment have been shown to be independent predictors of mortality.⁴ Once cardiogenic shock has developed in a patient with acute myocardial infarction, early invasive therapy should be applied in a tertiary care hospital. Before emergency coronary angiography, patients should be stabilized with intra-aortic balloon counterpulsation and inotropic pharmacological support at the minimum dose required. Impaired left ventricular function, triple-vessel disease and left main disease are common angiographic findings in cardiogenic shock.⁵ Definition of coronary anatomy should be rapidly followed by selecting the modality of revascularization, percutaneous coronary intervention and/or coronary artery bypass surgery. Percutaneous coronary intervention is most often the treatment of choice in cardiogenic shock, and a combination of stenting and glycoprotein IIb/IIIa antagonists is recommended.^3,6–9 Thrombolysis should be initiated in patients with acute myocardial infarction if the delay before angiography is anticipated to be more than 2 hours.³ Coronary surgery should be considered in shock patients with severe mitral insufficiency or multivessel disease, conditions which are not amenable to relatively complete percutaneous revascularization.⁶
In the patient described here, percutaneous coronary intervention was performed instead of coronary surgery because of severe hemodynamic and electrical instability, despite treatment with vasopressor support and intra-aortic balloon counterpulsation. Additionally, there were no cardiac operating rooms available at that moment.
       Management of intracoronary thrombus in the setting of acute myocardial infarction. The management of intracoronary thrombus encompasses standard pharmacological therapy (aspirin, clopidogrel, heparin, and glycoprotein IIb/IIIa receptor antagonists) and mechanical approaches (thrombus aspiration catheters, mechanical thrombectomy, rheolytic systems, and distal protection devices). Thrombotic occlusion of the left main trunk, as described in this patient, is a relatively rare finding. Abciximab was promptly administered to prevent the no-reflow phenomenon and to allow rapid recovery of coronary vascular function in the microcirculation. New mechanical devices to remove thrombus and prevent distal embolization were also used in the thrombotic occlusion of the left main trunk. First, manual thrombus aspiration with the Diver CE was performed, without coronary flow improvement. This is a rapid-exchange 6 Fr compatible thrombus-aspirating catheter. It has a central aspiration lumen and a soft, smooth tip, with multiple side holes communicating with the central lumen. A 20 or 30 ml luer-lock syringe is connected to the proximal hub of the central lumen for clot aspiration. In a prospective, randomized study, this device improved myocardial reperfusion parameters in patients with acute myocardial infarction undergoing primary or rescue angioplasty compared to standard percutaneous coronary intervention.¹⁰ Subsequently, intracoronary thrombectomy using the X-Sizer catheter was performed without success (TIMI flow 1). The X-Sizer catheter is a two-lumen, over-the-wire system (available in 1.5 and 2 mm diameters); the inner lumen contains a hollow torque cable with a helical cutter housed within the distal tip. The cutter is rotated at approximately 2,100 rpm by a motor, which is powered by a hand-held battery. The outer lumen of the catheter is connected to a 250 ml vacuum bottle, and aspirated debris is collected in an in-line filter. Several prospective and randomized trials demonstrated that the X-Sizer improved myocardial reperfusion by reducing the incidence of distal embolization and slow flow/no-reflow.^11,13
       The utilization of thrombectomy devices represents a mechanical attempt at optimizing myocardial reperfusion in patients undergoing percutaneous coronary intervention in the context of acute coronary syndrome. Currently, apart from considerations as to the safety of thrombectomy devices and their effect on myocardial reperfusion, no conclusions can be drawn about long-term myocardial function and the relationship of these devices with long-term clinical follow up.¹³ There is a paucity of information about their utility in the setting of cardiogenic shock complicating acute myocardial infarction with the presence of extensive thrombus burden, which provides an additional complicating factor. A retrospective study using a rheolytic thrombectomy device in acute myocardial infarction complicated with cardiogenic shock demonstrated low in-hospital mortality (26%).¹⁴
       This rare case illustrates the high cardiogenic shock mortality rate due to complete thrombotic occlusion of the left main coronary ostium as a consequence of delay in reaching the hospital and the failure to obtain adequate coronary and myocardial perfusion despite all efforts made using innovative devices to remove thrombus.

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