Coronary artery bypass graft surgery in patients with acute ST-elevation myocardial infarction

INTRODUCTION — In patients with acute ST-elevation myocardial infarction (STEMI), prompt restoration of myocardial blood flow is essential to optimize myocardial salvage and decrease mortality. This is particularly important in the first few hours after symptom onset, when the amount of myocardium salvageable by reperfusion is greatest. Coronary artery reperfusion, if performed in a timely manner, improves clinical outcomes compared to no reperfusion in nearly all groups of patients with an acute STEMI. (See "Primary percutaneous coronary intervention in acute ST elevation myocardial infarction: Determinants of outcome", section on 'Time from hospital arrival (door-to-balloon time)' and "Acute ST-elevation myocardial infarction: The use of fibrinolytic therapy", section on 'Timing'.)

Both primary percutaneous coronary intervention and fibrinolysis can restore blood flow in an acutely occluded coronary artery in a much shorter time in most hospital settings than can coronary artery bypass graft surgery (CABG) and these procedures are preferred to CABG in most cases. (See "Acute ST-elevation myocardial infarction: Selecting a reperfusion strategy".)

This topic will address the indications, optimal timing, technical considerations, and outcomes of urgent or emergent CABG in patients with acute STEMI. The role of CABG in patients with non-ST elevation MI or unstable angina is discussed separately. (See "Non-ST-elevation acute coronary syndromes: Selecting an approach to revascularization".)

INDICATIONS — In all studies of percutaneous coronary intervention (PCI) or fibrinolysis, outcomes improve as the time from symptom onset to reperfusion decreases. (See "Primary percutaneous coronary intervention in acute ST elevation myocardial infarction: Determinants of outcome", section on 'Time from hospital arrival (door-to-balloon time)' and "Acute ST-elevation myocardial infarction: The use of fibrinolytic therapy", section on 'Timing'.)

In most cases, PCI or fibrinolysis can usually restore flow to the ischemic myocardium more quickly than coronary artery bypass graft surgery (CABG), largely attributable to delays in getting the patient to the operating room and the time it takes to complete the bypass surgical procedure. Thus, CABG is uncommonly used as the reperfusion strategy of choice in ST elevation myocardial infarction (STEMI); it is estimated that CABG is performed in 5 percent or less of cases [1-3]. In one study of 3,347,470 patients hospitalized for STEMI between 2002 and 2016, 7.7 percent underwent isolated CABG. The incidence of CABG after STEMI decreased over the study period from 9.2 percent in 2002 to 5.5 percent in 2016 [4].

CABG may be considered for the several subgroups of patients with STEMI detailed below.

After unsuccessful or complicated percutaneous coronary intervention — In most acute STEMI cases, the site of occlusion responsible for the MI can be identified and successfully opened with PCI and stenting. When successful, this leads to an improvement in clinical and electrocardiographic signs of ischemia. In a minority of cases, either the culprit lesion cannot be identified or reperfusion cannot be reestablished. In patients with STEMI and multivessel coronary artery disease, ongoing ischemia may be an indication for urgent/emergent CABG in an effort to minimize myocardial damage and decrease in-hospital morbidity and mortality.

Increased interventional experience and advances in technology have led to a decline in the incidence of acute complications of PCI in the setting of STEMI to about 1 percent [5]. Examples of complications for which urgent CABG might be indicated include failed stent deployment, extensive coronary artery dissection, perforation of a coronary artery leading to pericardial tamponade, or recurrent acute closure. (See "Periprocedural complications of percutaneous coronary intervention", section on 'Emergency CABG for failed PCI'.)

Patients with either unsuccessful or complicated PCI who have ongoing ischemia and anatomy suitable for CABG should be referred for consideration of CABG as opposed to a strategy of medical therapy only. The rationale includes older studies demonstrating acceptable surgical mortality after CABG in patients with failed balloon angioplasty [6-9]. Moreover, in patients with STEMI complicated by cardiogenic shock, an early revascularization strategy is associated with a significant survival benefit [10]. Evidence from all studies of patients who are reperfused with either fibrinolytic therapy or primary PCI shows outcomes are uniformly better than with medical therapy alone. (See "Primary percutaneous coronary intervention in acute ST elevation myocardial infarction: Determinants of outcome", section on 'Time from hospital arrival (door-to-balloon time)' and "Acute ST-elevation myocardial infarction: The use of fibrinolytic therapy", section on 'Timing'.)

The risks and benefits should be discussed among members of the heart team, including the patient and family. Factors favoring emergent CABG include a large amount of ischemic myocardium, good general health, bypassable vessels, and the ability to perform surgery within six hours of the PCI. The presence of life-threatening ventricular arrhythmia should also drive the decision for emergent CABG. Factors against performing emergent CABG include absence of ischemia, presence of a small area of myocardium at risk, poor surgical target(s), and a no-reflow state. (See 'Life-threatening ventricular arrhythmias' below.)

Mechanical complications of acute MI — Mechanical complications of acute MI include rupture of the left ventricular free wall or interventricular septum and acute mitral regurgitation. Medical treatment alone results in close to 100 percent mortality in these patients [11]. Most of these patients will require emergency cardiac surgical repair of the mechanical defect; CABG will be performed at that time. The approach to these patients is discussed separately. (See "Acute myocardial infarction: Mechanical complications".)

We prefer immediate CABG as opposed to PCI of the infarct related artery followed by CABG and repair of the mechanical defect since termination of the ischemia often does not lessen the adverse hemodynamic impact of the mechanical defect, which may cause death. However, in some patients, it may be appropriate to initially perform PCI and then have the patient undergo cardiac surgery. For example, a patient with an acutely occluded (culprit) lesion in the circumflex coronary artery, significant mitral regurgitation, and severe disease in the left anterior descending and right coronary arteries (LAD and RCA) might benefit from acute PCI of the circumflex and then CABG to the LAD and RCA with repair of the mitral valve. In this scenario, however, initial stent placement introduces the dilemma of performing CABG in a patient treated with dual antiplatelet therapy or delaying definitive surgery.

In all cases in which a mechanical defect has been identified, we recommend immediate consultation between the interventional cardiologist, the cardiothoracic surgeon, and other members of the multidisciplinary heart team.

As the primary reperfusion strategy — Most patients with acute STEMI should receive either PCI or fibrinolysis as the primary reperfusion strategy. (See 'Indications' above.) Studies of patients treated with either fibrinolysis or PCI have demonstrated that outcomes improve as the time to reperfusion decreases.

Approximately 50 percent of patients with STEMI have multivessel disease [12]. In stable patients with left main or severe three vessel coronary artery disease, CABG is often preferred to PCI (table 1). (See "Revascularization in patients with stable coronary artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention", section on 'Summary and recommendations' and "Left main coronary artery disease", section on 'Summary and recommendations'.)

There are no randomized trials or large, well-conducted observational studies that have compared PCI to CABG in patients with left main or severe multivessel disease in the setting of an acute MI. Our experience is that PCI can be performed successfully and without major complication in the majority of cases. The decision of whether to perform PCI or CABG as the primary reperfusion strategy in patients with left main coronary artery disease or severe multivessel disease who are unstable or who have ongoing ischemia is complex and should be individualized. Management should involve cardiothoracic surgeons and interventional cardiologists on the multidisciplinary heart team. The discussion should include deciding on the primary reperfusion strategy and subsequent steps after "culprit lesion" intervention if PCI is performed, as well as what will be done if initial catheter based therapy fails. The role of non-culprit PCI in STEMI patients is discussed separately. (See "Acute coronary syndromes: Approach to nonculprit lesions", section on 'STEMI'.)

We believe it is reasonable to perform PCI of a culprit unprotected left main coronary artery if distal flow is abnormal and PCI can be performed more rapidly and safely than CABG. This recommendation is consistent with that made in the 2021 American College of Cardiology Foundation/American Heart Association/Society of Cardiovascular angiography and Intervention (ACC/AHA/SCAI) revascularization guideline [13-15] and the 2018 European Society of Cardiology/European Association of Cardiothoracic Surgery Guidelines on Myocardial Revascularization [16].

Patients who might benefit from CABG as the primary reperfusion strategy include those who are no longer showing signs of acute ischemia (patients who have stabilized) and have coronary anatomy at the time of coronary angiography that suggests a benefit from CABG as opposed to PCI. Patients with left main or severe multivessel coronary disease, particularly with depressed left ventricular systolic function or those with diabetes are examples. If the patient is stable without signs or symptoms of ongoing ischemia either clinically or by electrocardiogram, CABG should be strongly considered as the primary reperfusion strategy in these patients. (See "Revascularization in patients with stable coronary artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention", section on 'Summary and recommendations'.)

Late presentation or recurrent ischemia — Some patients with STEMI present late (after 12 hours) and have no evidence of ongoing ischemia at the time of presentation; thus, urgent intervention is not necessary. Subsequently, some of these individuals develop recurrent or inducible angina or have reinfarction and require revascularization with either PCI or CABG. We suggest using recommendations made for patients with stable coronary artery disease as a guide for who should be referred for CABG and who for PCI. (See "Revascularization in patients with stable coronary artery disease: Coronary artery bypass graft surgery versus percutaneous coronary intervention", section on 'Summary and recommendations'.)

A few patients with STEMI who have received successful primary PCI develop recurrent angina due to ischemia in a territory not reperfused at the time of PCI. Many of these patients should be referred for repeat revascularization with either PCI or CABG. For patients with multivessel disease who fall into this category within the first 48 hours after STEMI, we agree with the 2021 ACC/AHA/SCAI coronary revascularization guideline and the 2018 European Society of Cardiology/European Association of Cardiothoracic Surgery Guidelines on Myocardial Revascularization [15,16] that state that complete revascularization by either multivessel PCI or urgent CABG is reasonable and in selected patients might be the preferred approach compared with a delayed revascularization strategy [17].

Cardiogenic shock — Cardiogenic shock occurs in 6 to 7 percent of patients with acute MI (excluding patients with mechanical complications). This complication signifies loss of at least 40 percent of the left ventricular contractile mass. Mortality with medical treatment of cardiogenic shock in acute MI approaches 80 percent. (See "Clinical manifestations and diagnosis of cardiogenic shock in acute myocardial infarction".)

Cardiogenic shock occurs most often in patients with left main or severe three vessel coronary artery disease, but can occur in patients with one- or two-vessel disease. Although the limited evidence suggests similar outcomes, we prefer PCI to CABG, irrespective of the extent of disease, if it can be performed in a timely manner by a skilled team and if a mechanical complication of STEMI is not present. In the SHOCK trial, patients with STEMI and cardiogenic shock were randomized to either initial medical stabilization or to early revascularization. In the group assigned revascularization, 37.5 percent underwent CABG [1]. The secondary outcome of survival at six months was significantly higher in the group of patients randomized to early revascularization and treated with either PCI or CABG [10]. The full discussion of the use of CABG in such patients is presented separately. (See "Prognosis and treatment of cardiogenic shock complicating acute myocardial infarction".)

After failed fibrinolysis — CABG is employed infrequently for revascularization after failed fibrinolysis. PCI is preferred in this setting because of increased risks of perioperative mortality and major hemorrhage with CABG, especially if the interval between administration of the fibrinolytic agent and surgery is short. In an analysis from the TIMI II study, 390 patients underwent CABG after fibrinolytic treatment [18]. Patients undergoing surgery within 24 hours of study, compared to those undergoing later surgery, had higher rates of perioperative mortality (17 versus 4 percent) and major hemorrhage (74 versus 51 percent). (See "Diagnosis and management of failed fibrinolysis or threatened reocclusion in acute ST-elevation myocardial infarction".)

Life-threatening ventricular arrhythmias — Life-threatening ventricular arrhythmias occurring in the setting of acute MI are triggered by ischemic myocardium or the combination of ischemic myocardium plus scar formed from prior events. They are associated with worse in-hospital mortality. (See "Ventricular arrhythmias during acute myocardial infarction: Incidence, mechanisms, and clinical features".)

There are no randomized trials or important observational studies that evaluated the optimal management strategy in these patients. Small series have included patients with life-threatening ventricular arrhythmia in the setting of acute MI [19,20]. These studies suggest that operative and long-term mortality (approximately 7 and 15 percent, respectively) are reasonable with urgent CABG and that the incidence of sudden death is reduced compared to no CABG.

As life-threatening ventricular arrhythmias often represent ongoing ischemia in the setting of STEMI, our approach to revascularization is similar to the broad population of patients with STEMI for whom we prefer PCI to CABG. We agree with recommendations made in the 2011 American College of Cardiology Foundation/American Heart Association CABG guideline and the 2018 European Society of Cardiology/European Association of Cardiothoracic Surgery Guidelines on Myocardial Revascularization, which state that urgent CABG is a reasonable approach for patients with ongoing ischemia who will not undergo emergent revascularization with PCI and who have left main stenosis greater than or equal to 50 percent and/or three-vessel coronary artery disease [16,17].

TIMING — For those patients in whom coronary artery bypass graft surgery (CABG) will be performed, the optimal timing depends on the indication. Ongoing ischemia, cardiogenic shock, percutaneous coronary intervention failure, and mechanical complications are indications for emergency operation.

The optimal timing in more stable patients with indications for CABG is unclear, with some older studies showing increased mortality when CABG was performed in the first 12 to 24 hours after acute myocardial infarction (MI) [18,21-25] and others not [26-31].

We feel that CABG can be performed safely in patients with post-MI angina based upon the patient's clinical status. In our view, patients presenting within six hours after onset of symptoms should be operated emergently to maximize myocardial salvage. The goal should be to complete bypass within 12 hours of symptom onset.

Patients who present later than six hours after onset of symptoms when myocardial necrosis has reached its peak should probably be delayed for three to four days to decrease mortality and morbidity, including bleeding complications [1,32]. More recent data showed that CABG performed within the first 48 hours after STEMI is associated with increased mortality and morbidity [4]. Thus, for those who lack the indication for emergency operation, CABG should be deferred to day 3 or later after STEMI.

For patients with recurrent or inducible ischemia or reinfarction, particularly those with multivessel disease, CABG within 48 hours is a reasonable strategy compared to more delayed revascularization.

TECHNICAL CONSIDERATIONS — Several technical issues need to be considered in patients undergoing coronary artery bypass graft surgery (CABG) after acute ST elevation myocardial infarction (STEMI).

Minimizing ischemic time — An expeditious operation to shorten the interval during which the patient is actively ischemic or hemodynamically unstable is a critical component of the overall strategy aimed at reducing myocardial injury and systemic organ dysfunction. Thus, patients who are continuously ischemic, hemodynamically unstable, or having recurrent life-threatening arrhythmias should be stabilized and transferred rapidly to the operating room. Resuscitation should continue en-route to surgery, and unnecessary delays should be avoided. Aggressive use of pharmacologic agents and the intraaortic balloon pump (IABP) is essential to achieve stabilization. Percutaneous bypass may be used in some patients as part of resuscitation in the catheterization laboratory. (See "Short-term mechanical circulatory assist devices".)

Intraaortic balloon pump — The IABP can be an extremely important adjunct to surgical treatment in patients with acute MI and mechanical complications. In a propensity-matched study of 400 patients who underwent CABG after acute STEMI or NSTEMI, preoperative insertion of IABP was associated with reduced in-hospital mortality and myocardial injury [33]. For other patients, such as those with cardiogenic shock, the role of a preoperative IABP is less clear. (See "Prognosis and treatment of cardiogenic shock complicating acute myocardial infarction", section on 'Summary and Recommendations' and "Intraaortic balloon pump counterpulsation".)

Micro-axial flow pump (Impella) — It is uncertain if an Impella device is helpful for hemodynamic support during CABG in patients with an acute STEMI. An Impella flow pump is a left ventricular assist device that is inserted through the aortic valve on a pigtail catheter (Impella, Abiomed, Danvers, MA). It has received some attention in the setting of supported PCI [34]. However, there is only anecdotal experience with its use for high-risk CABG [35]. It may worsen right-to-left shunting in the setting of a ventricular septal defect [36].

Extracorporeal membrane oxygenation (ECMO) — Preoperative or postcardiopulmonary-bypass ECMO support should be considered in patients referred for emergency CABG and who remain in deep cardiogenic shock despite intense pharmacologic treatment and insertion of IABP. Optimal timing of initiation of ECMO is key to avoid irreversible shock and reduce mortality [37]. Contemporary United States national data demonstrated that the use of mechanical circulatory support for patients undergoing CABG after STEMI has increased over time [4]. (See "Extracorporeal life support in adults in the intensive care unit: Overview" and "Short-term left ventricular mechanical circulatory support: Use of echocardiography during initiation and management".)

Type of graft — The choice of bypass conduit is dictated by the patient's condition.

●Stable patients – In the stable patient, arterial revascularization (particularly the left internal mammary artery to the left anterior descending coronary artery) should be used because of its superior short- and long-term clinical results. Even in urgent or emergency situations, aggressive use of arterial conduits should be pursued if the patient can be stabilized. (See "Coronary artery bypass graft surgery: Graft choices", section on 'Two arterial grafts'.)

●Unstable patients – In the unstable patient, venous conduits are preferred. This affords a more expeditious revascularization and an opportunity to directly deliver cardioplegia, to control reperfusion to the acutely ischemic area, and to avoid postoperative vasospasm in patients who are usually on varying amounts of vasopressors [38,39].

Minimally invasive CABG — We believe that both on- and off-pump CABG are acceptable techniques for patients with STEMI. For most patients who are referred for CABG, we recommend an on-pump as opposed to off-pump procedure.

An early report of 57 patients with acute MI treated with minimally invasive (off-pump) CABG without cardiopulmonary bypass suggested that this procedure is associated with relatively low risk [40]. In another trial, 128 patients within 48 hours of symptom onset were randomly assigned to either on- or off-pump CABG [41]. In-hospital mortality was significantly better in the off-pump group (1.6 versus 7.7 percent). (See "Off-pump and minimally invasive direct coronary artery bypass graft surgery: Clinical use".)

Hybrid procedure — An alternative approach to CABG in high-risk groups of patients with STEMI is a hybrid operation. A subset of patients with suitable anatomy may benefit from a minimally-invasive off-pump CABG of a left internal mammary to the left anterior descending coronary artery in conjunction with percutaneous coronary intervention to other significantly diseased coronary arteries. In select groups of patients, this can be achieved during the same procedure performed in a hybrid operating room. In other patients, the revascularization procedure can be staged. (See "Minimally invasive coronary artery bypass graft surgery: Definitions and technical issues", section on 'Hybrid CABG-PCI procedures'.)

OUTCOMES AFTER CABG — Numerous observational studies published between the mid-1970s and the mid-1990s reported early and late outcomes after coronary artery bypass graft surgery for ST elevation myocardial infarction. Hospital mortality was less than 10 percent [1,18,23-25,27-32,38,42-68] and long-term freedom from angina and survival were improved compared to medical therapy [18,24,25,27-29,38,44-48,50-58,60,62,65,66]. Contemporary large-scale United States data indicate that despite an increase in patient comorbidities, the crude in-hospital mortality of CABG after STEMI did not significantly change over time (5.5 percent in 2002 versus 4.2 percent in 2016) [4].

However, the applicability of the results of these studies to patients treated since the introduction of percutaneous coronary intervention and the use of aggressive antithrombotic and statin therapy is limited. Observational studies that have evaluated in-hospital or 30-day mortality since 2000 have reported rates ranging between 1.7 and 22 percent [1-3,69,70]. The variation in mortality is likely explained by differences in patient selection and severity of illness. A Canadian national report summarized the outcomes of 341,001 episodes (323,862 patients) of acute MI between 2004 and 2013, of which 129,752 episodes were STEMI. Six thousand and seven hundred patients (5.2 percent) received CABG [3]. Operative mortality and readmission rates after emergency CABG in the setting of STEMI were 3 and 11 percent, respectively. There was a modest improvement in mortality and readmission rates during the early part of the study period, with some increase in the last two years [3].

RECOMMENDATIONS OF OTHERS — Recommendations for the use of coronary artery bypass graft surgery in patients with ST-elevation myocardial infarction are available from the American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions [3,15,17,71,72]. Our recommendations are generally consistent with those made by these organizations.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: ST-elevation myocardial infarction (STEMI)".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, “The Basics” and “Beyond the Basics.” The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on “patient info” and the keyword(s) of interest.)

●Beyond the Basics topic (see "Patient education: Coronary artery bypass graft surgery (Beyond the Basics)")

●Basics topic (see "Patient education: Coronary artery bypass graft surgery (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Background – Long-term outcome after ST-elevation myocardial infarction (STEMI) is largely determined by the speed with which blood flow is restored to the ischemic myocardium. Revascularization with primary percutaneous coronary intervention (PCI) or fibrinolysis and rescue PCI increase this speed more than coronary artery bypass graft surgery (CABG).

●Indications – In patients with coronary anatomy suitable for surgery, the role of CABG after acute MI is limited to selected patients with the following (see 'Indications' above):

•Cardiogenic shock

•Unsuccessful or complicated primary PCI

•Mechanical complications,

•A late presentation (after 12 hours)

•Early recurrent ischemia

•STEMI patients who are not candidates for fibrinolysis or primary PCI

●Timing – The optimal timing depends on the indication. Ongoing ischemia, cardiogenic shock, PCI failure, and mechanical complications are indications for emergency operation. The optimal timing in more stable patients with indications for CABG is unclear; the decision on timing should be made by a multidisciplinary team. (See 'Timing' above.)

●We recommend the following uses for CABG (or PCI) in patients with acute STEMI:

•For most patients, fibrinolysis or PCI is preferred to CABG. This preference for PCI includes patients with one- or two-vessel disease who have cardiogenic shock, but are without mechanical complications, as the restoration of myocardial blood flow with PCI of the infarct related artery may take only minutes after diagnostic coronary angiography has been performed. (See 'Indications' above.)

•For patients with left main (as the culprit lesion) or three vessel coronary artery disease, with or without cardiogenic shock, who do not have mechanical complications (such as acute mitral regurgitation or rupture of either the ventricular septal or free walls), we suggest immediate PCI rather than CABG (Grade 2C). CABG is a reasonable alternative to PCI when it can be performed more rapidly than PCI. (See 'Cardiogenic shock' above and 'As the primary reperfusion strategy' above.)

•For patients with unsuccessful or complicated PCI with evidence of ongoing ischemia and in whom the coronary anatomy is suitable for CABG, we recommend emergency CABG rather than medical therapy (Grade 1B). (See 'Introduction' above and 'After unsuccessful or complicated percutaneous coronary intervention' above.)

•For most patients with hemodynamically significant mechanical complications, we recommended immediate CABG and attempt at repair of the mechanical defect rather than a strategy of PCI followed by cardiac surgery (Grade 1B). (See 'Mechanical complications of acute MI' above.)

For some patients with ischemic mitral regurgitation, primary PCI with hemodynamic support may reasonably preferred to CABG.

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Oz Shapira, MD, who contributed to earlier versions of this topic review.