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Additional content is available online at Elsevier eBooks for Practicing Clinicians The care of patients with ST-elevation myocardial infarction (STEMI) has transformed in conjunction with the shift in approach to reperfusion therapy from primarily pharmacologic to catheter-based strategies. 123 Wi...

Additional content is available online at Elsevier eBooks for Practicing Clinicians The care of patients with ST-elevation myocardial infarction (STEMI) has transformed in conjunction with the shift in approach to reperfusion therapy from primarily pharmacologic to catheter-based strategies. 123 With simultaneous advances in medical therapy, the case-fatality rate for patients with STEMI has continued to decline ( Fig. 38.1 ). 4 , 5 Nevertheless, optimal management of patients at high risk for or with established major complications of STEMI remains critical to the care of this condition. A discussion of the management of STEMI can follow the clinical course of the patient. Chapter 25, Chapter 40 address primary and secondary prevention of coronary artery disease (CAD). Chapter 35 reviews the emergency evaluation of patients with chest pain. This chapter addresses treatment at the time of onset of STEMI (prehospital care, initial recognition and management in the emergency department (ED), and reperfusion), hospital management (medications, complications, and preparation for discharge), and early secondary prevention after STEMI. Chapter 41 discusses percutaneous coronary intervention (PCI) in patients with STEMI. Chapter 69 describes the use of implantable defibrillators for prevention of sudden cardiac death after myocardial infarction (MI). Chapter 40 discusses the long-term management of the patient with established stable ischemic heart disease, including patients with prior acute MI. FIGURE 38.1 Early mortality rates have declined in major randomized trials of STEMI patients from 1986 to 2018 with the introduction and improvement in pharmacologic and/or mechanical reperfusion therapy. Prim PCI , Primary percutaneous coronary intervention; SK , streptokinase; tPA , tissue plasminogen activator. From Van de Werf F. The history of coronary reperfusion. Eur Heart J. 2014;35;2510–2515; Le May et al. JAMA Cardiol. 2020;5:126–134. Prehospital Management Given the progressive loss of functioning myocytes with persistent occlusion of the infarct-related artery in STEMI (see Chapter 37 ), initial management aims to restore blood flow to the infarct zone as rapidly as possible. Primary PCI is generally the preferred option, provided that an experienced operator and team can perform it in a timely fashion. 123 , 6 Missed opportunities for improvement in the care of STEMI include failure to deliver any form of reperfusion therapy in approximately 15% of patients and failure to minimize delays in reperfusion because of inefficient systems of care. 7 , 8 The “chain of survival” for STEMI involves a highly integrated strategy beginning with patient education about the symptoms of MI and early contact with the medical system, coordination of destination protocols in emergency medical service (EMS) systems, efficient practices in EDs to shorten door-to-reperfusion time, and expeditious implementation of the reperfusion strategy by a trained team. 8 , 9 The American Heart Association (AHA) has maintained a national initiative engineering improved health care delivery for STEMI, including implementation of systems that shorten total ischemic time while emphasizing overall quality of care for STEMI ( Tables 38.1 and 38.2 ). 9 TABLE 38.1 Criteria for a System of Care for ST-Elevation Myocardial Infarction (STEMI) 1. The system should be registered with Mission: Lifeline. 2. Ongoing multidisciplinary team meetings should occur, including EMS, non-PCI hospitals/STEMI referral centers, and PCI hospitals/STEMI receiving centers, to evaluate outcomes and quality improvement data. Operational issues should be reviewed, problems identified, and solutions implemented. 3. Each STEMI system should include a process for prehospital identification and activation, destination protocols to STEMI receiving centers, and transfer for patients who arrive at STEMI referral centers and are primary PCI candidates, are ineligible for fibrinolytic therapy, and/or are in cardiogenic shock. 4. Each system should have a recognized system coordinator, physician champion, and EMS medical director. 5. Each system component (EMS, STEMI referral centers, and STEMI receiving centers) should meet the appropriate criteria. EMS, Emergency medical services; PCI, percutaneous coronary intervention. TABLE 38.2 Interventions to Improve Door-to-Device Times From O’Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013;61:e78. 1. A prehospital ECG for diagnosing STEMI is used to activate the PCI team while the patient is en route to the hospital. 2. Emergency physicians activate the PCI team. 3. A single call to a central page operator activates the PCI team. 4. A goal is set for the PCI team to arrive at the catheterization laboratory within 20 min after being paged.  5. Timely data feedback and analysis are provided to members of the STEMI care team. ECG, Electrocardiogram; PCI, percutaneous coronary intervention, STEMI , ST-elevation myocardial infarction. Prehospital Care The prehospital care of patients suspected of having STEMI bears directly on the likelihood of survival. Most deaths associated with STEMI occur within the first hour of its onset and usually result from ventricular fibrillation (VF) (see Chapter 70 ). Therefore, immediate implementation of resuscitative efforts and rapid transportation of the patient to a hospital have prime importance. Major components of the time from the onset of ischemic symptoms to reperfusion include (1) the time for the patient to recognize the problem and seek medical attention; (2) prehospital evaluation, treatment, and transportation; (3) the time for diagnostic measures and initiation of treatment in the hospital (e.g., “door-to- device” time for patients undergoing a catheter-based reperfusion strategy and “door-to-needle” time for patients receiving a fibrinolytic agent); and (4) the time from initiation of treatment to restoration of flow. Patient-related factors that correlate with a longer delay until deciding to seek medical attention include older age; female sex; black race; low socioeconomic or uninsured status; history of angina, diabetes, or both; consulting a spouse or other relative; and consulting a physician. 1 , 8 Health care professionals should heighten the level of awareness of patients at risk for STEMI (e.g., those with hypertension, diabetes, history of angina pectoris). They should use elective patient encounters to review and reinforce with patients and their families the need to seek urgent medical attention for a pattern of symptoms that includes chest discomfort, or dyspnea. Patients should also be instructed in the proper use of sublingual nitroglycerin and to call emergency services if the ischemic-type discomfort persists for more than 5 minutes. 1 Emergency Medical Service Systems EMS systems have three major components: emergency medical dispatch, first response, and the EMS ambulance response (see Chapter 35 ). The expanded capability to record a prehospital 12-lead electrocardiogram (ECG) represents a major advance in EMS systems (see Table 38.2 ). 8 , 10 , 11 The ability to transmit such ECGs and to activate the STEMI care team before arrival at the hospital places EMS efforts at the center of the early response to STEMI. 8 Efforts to shorten the time until treatment of patients with STEMI include improvement in the medical dispatch component by expanding 911 coverage, providing automated external defibrillators to first responders, placing automated external defibrillators in critical public locations, and greater coordination of the EMS ambulance response. Well-equipped ambulances and helicopters staffed by personnel trained in the acute care of patients with STEMI allow definitive therapy to begin during transport to the hospital. Electronic transmission of the ECG to a medical control officer facilitates the triage of patients with STEMI ( Fig. 38.2 ). FIGURE 38.2 System goals and initial reperfusion treatment of patients with STEMI. Reperfusion in STEMI patients can be accomplished by pharmacologic (fibrinolysis) or catheter-based (primary PCI) approaches and may involve transfer from a non-PCI-capable to a primary PCI-capable center. A, Patient transported by the emergency medical services (EMS). The STEMI systems goal is to maintain a network of transportation and destination hospitals so that the total ischemic time is kept to less than 120 minutes. In addition to this overall goal, three additional time objectives exist. (1) If the EMS has fibrinolytic capability and the patient qualifies for therapy, prehospital fibrinolysis may be considered and, if used, should be started within 30 minutes of arrival of the EMS on scene. (2) For patients transported to a non-PCI-capable hospital where a fibrinolytic is to be administered, the hospital door-to-needle time should be 30 minutes or less. (3) If the patient is transported to a PCI-capable hospital, the time from first medical contact (FMC) to deployment of the first PCI device (FMC-to-device time) should be 90 minutes or less. Patient self-transportation is discouraged. If the patient arrives at a non-PCI-capable hospital and a fibrinolytic is to be administered, the door-to-needle time should be 30 minutes or less. If the patient arrives at a PCI-capable hospital, the door-to-balloon time should be 90 minutes or less. The treatment options and time recommendations after arrival at the hospital are the same. Consideration of emergency interhospital transfer of the patient to a PCI-capable hospital for mechanical revascularization is also appropriate if the use of a fibrinolytic is contraindicated or PCI can be initiated promptly (anticipated FMC-to-device time ≤120 minutes) or if fibrinolysis is unsuccessful (i.e., “rescue PCI”). Secondary nonemergency interhospital transfer can be considered for recurrent ischemia or routine invasive evaluation 3 to 24 hours after fibrinolysis. B, Reperfusion strategies for patients with STEMI, regardless of whether they go to a PCI-capable or to a non–PCI-capable hospital. The optimal strategy depends on the timing of the onset of symptoms, the patient’s eligibility for fibrinolysis, and the options for timely transfer to a PCI-capable hospital. The denoted class I and class II recommendations are from the ACCF/AHA guidelines for the management of STEMI. For patients who receive fibrinolysis, noninvasive risk stratification is recommended to guide decisions regarding delayed coronary revascularization. CABG , Coronary artery bypass grafting. Modified from Armstrong PW, Collen D, Antman E. Fibrinolysis for acute myocardial infarction: the future is here and now. Circulation. 2003;107:2533; and O’Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013;61:e78. In addition to prompt defibrillation, the efficacy of prehospital care appears to depend on several factors, including early relief of pain with its deleterious physiologic sequelae, reduction of excessive activity of the autonomic nervous system, and treatment of arrhythmias such as ventricular tachycardia (VT)—but these efforts must not delay rapid transfer to the hospital (see Fig. 38.2 ). Prehospital Fibrinolysis Multiple observational studies and several randomized trials have evaluated the potential benefits of prehospital versus in-hospital fibrinolysis. 1 , 4 Although none of the individual trials showed a significant reduction in mortality with prehospital-initiated fibrinolytic therapy, earlier treatment generally provides greater benefit, and a meta-analysis of all the available trials demonstrated a 17% reduction in mortality. 1 , 2 In the STREAM (Strategic Reperfusion Early After Myocardial Infarction) trial, prehospital fibrinolysis offered similar efficacy to primary PCI in 1892 patients with STEMI who presented within 3 hours of symptom onset and who could not undergo primary PCI within 1 hour of first medical contact. The primary endpoint of death, shock, heart failure, or reinfarction at 30 days occurred in 12.4% of the fibrinolysis arm and 14.3% in the primary PCI arm (p = 0.21) ( Fig. 38.3 ). 12 Rescue or urgent PCI was required in 36% of patients initially receiving fibrinolysis, with the remainder undergoing coronary angiography per protocol a median of 17 hours after randomization. The rate of intracranial hemorrhage was higher in the fibrinolysis group (1.0% versus 0.2%, p= 0.04), but non-intracranial bleeding rates were similar between the treatment groups. Prehospital fibrinolysis is reasonable in settings in which substantial time can be saved by prehospital treatment because of long transportation times (60 to 90 minutes or longer), and physicians are present in the ambulance, or there is a well-organized EMS system with full-time paramedics who can obtain and transmit 12-lead ECG recordings from the field to an online medical command able to authorize prehospital fibrinolysis (see Fig. 38.2 ). 123 FIGURE 38.3 The STREAM (Strategic Reperfusion Early After Myocardial Infarction) study found that prehospital fibrinolysis offers similar efficacy to primary PCI in 1892 patients with STEMI who presented within 3 hours of symptom onset and who could not undergo primary PCI within 1 hour of FMC, where the primary endpoint of death, shock, heart failure, or reinfarction at 30 days occurred in 12.4% of the fibrinolysis arm and 14.3% in the primary PCI arm (hazard ratio, 0.86; confidence interval, 0.68 to 1.09; P = 0.21 by log-rank test). Modified from Armstrong PW, Gershlick AH, Goldstein P, et al. Fibrinolysis or primary PCI in ST-segment elevation myocardial infarction. N Engl J Med. 2013;368(15):1379–1387. Management in the Emergency Department When evaluating patients with chest pain in the ED, physicians must confront the difficult tasks of rapidly identifying patients who require urgent reperfusion therapy, triaging lower- risk patients to the appropriate setting within the hospital, and not discharging patients inappropriately while avoiding unnecessary admissions. A history of ischemic-type discomfort and the initial 12-lead ECG are the primary tools for screening patients with possible acute coronary syndrome (ACS) for STEMI (see Chapter 35 ). Because the 12-lead ECG is at the center of the decision pathway for initiation of reperfusion therapy, it should be obtained promptly (≤10 minutes after hospital arrival) in patients with suspected ischemic symptoms. 1 More extensive use of prehospital 12-lead ECGs has also facilitated early triage of patients with STEMI. 8 , 10 , 11 Because lethal arrhythmias can occur suddenly in patients with STEMI, all patients should have bedside monitoring of the ECG and intravenous (IV) access. The presence of ST-segment elevation on the ECG in a patient with ischemic discomfort suggests thrombotic occlusion of an epicardial coronary artery and should trigger a well- rehearsed sequence of rapid assessment of the patient for initiation of a reperfusion strategy ( eFig. 38G.1 ). 1 Critical factors that weigh into selection of a reperfusion strategy include the time elapsed since the onset of symptoms, the risk associated with STEMI, the time required to initiate an invasive strategy, and if that time is expected to be prolonged, the risk related to administering a fibrinolytic (see Fig. 38.2 ). In non-PCI-capable hospitals, the initial assessment should include evaluation of the contraindications to administration of a fibrinolytic ( Table 38.3 ). Patients with an initial ECG that reveals ST-segment depression and/or T wave inversion without ST-segment elevation are not considered candidates for immediate reperfusion therapy unless a posterior (or inferobasal) injury current is suspected (see Chapter 14 ). TABLE 38.3 Contraindications to and Cautions in the Use of Fibrinolytics for Treating ST-Elevation Myocardial Infarction ∗ From O’ Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol. 2013;61:e78. Absolute Contraindications Any previous intracranial hemorrhage Known structural cerebral vascular lesion (e.g., arteriovenous malformation) Known malignant intracranial neoplasm (primary or metastatic) Ischemic stroke within 3 months except acute ischemic stroke within 4.5 hr Suspected aortic dissection Active bleeding or bleeding diathesis (excluding menses) Significant closed-head or facial trauma within 3 months Intracranial or intraspinal surgery within 2 months Severe uncontrolled hypertension (unresponsive to emergency therapy) For streptokinase, previous treatment within the previous 6 months Relative Contraindications History of chronic, severe, poorly controlled hypertension Significant hypertension at initial evaluation (SBP >180 mm Hg or DBP >110 mm Hg) † History of previous ischemic stroke >3 months Dementia Known intracranial pathology not covered in Absolute Contraindications Traumatic or prolonged (>10 min) cardiopulmonary resuscitation Major surgery (