Emergency cardiac surgery in patients with acute coronary syndromes: a review of the evidence and perioperative implications of medical and mechanical therapeutics

Abstract

Patients with acute coronary syndromes who require emergency cardiac surgery present complex management challenges. The early administration of antiplatelet and antithrombotic drugs has improved overall survival for patients with acute myocardial infarction, but to achieve maximal benefit, these drugs are given before coronary anatomy is known and before the decision to perform percutaneous coronary interventions or surgical revascularization has been made. A major bleeding event secondary to these drugs is associated with a high rate of death in medically treated patients with acute coronary syndrome possibly because of subsequent withholding of antiplatelet and antithrombotic therapies that otherwise reduce the rate of death, stroke, or recurrent myocardial infarction. Whether the added risk of bleeding and blood transfusion in cardiac surgical patients receiving such potent antiplatelet or antithrombotic therapy before surgery specifically for acute coronary syndromes affects long-term mortality has not been clearly established. For patients who do proceed to surgery, strategies to minimize bleeding include stopping the anticoagulation therapy and considering platelet and/or coagulation factor transfusion and possibly recombinant-activated factor VIIa administration for refractory bleeding. Mechanical hemodynamic support has emerged as an important option for patients with acute coronary syndromes in cardiogenic shock. For these patients, perioperative considerations include maintaining appropriate anticoagulation, ensuring suitable device flow, and periodically verifying correct device placement. Data supporting the use of these devices are derived from small trials that did not address long-term postoperative outcomes. Future directions of research will seek to optimize the balance between reducing myocardial ischemic risk with antiplatelet and antithrombotics versus the higher rate perioperative bleeding by better risk stratifying surgical candidates and by assessing the effectiveness of newer reversible drugs. The effects of mechanical hemodynamic support on long-term patient outcomes need more stringent analysis.

Figure 1

Diagram of Tandem Heart device (Cardiac Assist, Inc., Pittsburgh, PA). Pulmonary venous drainage is from the left atrium via a cannula inserted through the right atrium and then advanced across the atrial septum. Arterial outflow is from an external centrifugal pump via the femoral artery. Reprinted with permission from Thiele et al. Circulation 2001;104:2917 to 2922

Figure 2

Picture of Impella LP 2.5 (Abiomed, Danvers, MA) device. The distal end of the catheter is advanced in a retrograde approach from the femoral artery through the aortic valve into the left ventricle. The inflow inlet of the rotary pump is positioned in the left ventricle while the outflow orifice is positioned in the ascending aorta. Bloodflow of 2.5 L/min and 5.0 L/min can be achieved with the LP2.5 and LP 5.0 devices, respectively. Reprinted with permission from Valgimigli et al. Catheter Cardiovasc Interv 2005;65:263 to 267.

Figure 3

Intraoperative transesophageal echocardiographic image of inflow cannula of the TandemHeart positioned across the atrial septum into the left atrium. Reprinted with permission from Pretorius et al. Anesth Analg 2006;103:1412 to 1413.

Figure 4

Transesophageal echocardiography image of Impella percutaneous left ventricular assist device (labeled 1) placed across the aortic valve (arrow) into the left ventricle (LV). LA = left atrium; RV = right ventricle. Reprinted with permission Intensive Care Med 2006;32:329 to 33.