In many ways, the cardiac care unit (CCU) will be a center of convergence for the population and economic trends relating to health care in our society. Our longevity continues to improve steadily and dramatically, but this effect is modest compared with the increase in our functionality. Thus, we have a population that is healthier until the time of acute vascular events, which constitute the leading cause of death and disability by a growing margin. At the same time, societal investment has resulted in an ever-enlarging arsenal of expensive biotechnology: the drug-coated stent, the implantable defibrillator, , and the left-ventricular assist device are now well entrenched in the clinical arena, and the advent of cell replacement therapy will greatly affect the cost of care and patients’ expectations. With more and more recently functional elderly patients making up the bulk of the CCU population and with rapidly advancing technologic capacity, the issue of effectiveness relative to cost and, perhaps more than in younger populations, patient preferences will become dominant in coming years. Clearly, we will not be able to afford to do everything that could prolong life in every patient, nor may that always be an appropriate or even desired goal. Therefore, it will become paramount to develop more systematic approaches to delivering the most effective therapy to patients who will benefit most from it.
The massive increase in heart failure is straining the capacity of CCUs and stimulating discussions of specialized heart-failure units to add to the prevalent chest-pain centers. As left-ventricular assist devices become more widely available, the CCU is likely to become the focus of decision-making for an increasing number of people who are ineligible for cardiac transplantation but who still need to make decisions about treatment that will require enormous expenditures but may significantly lengthen life.
The trends in out-of-hospital outcomes are more difficult to gauge than inpatient trends. We know that out-of-hospital cardiac arrest remains the leading cause of death by far, and we know that extending technology formerly available only in the hospital can significantly reduce mortality and morbidity in communities. Automated external defibrillators, community cardiopulmonary resuscitation (CPR), the performance of electrocardiograms (ECGs) at the scene to identify ST-segment elevation myocardial infarction (STEMI) or high-risk non–ST-segment elevation (NSTE) acute coronary syndromes (ACSs), and techniques for initiating cooling post-cardiac arrest are initial examples of the extension of the CCU into the community. Inadequate effort has been expended to organize these technologies into a comprehensive, evidence-based approach to the application of these emerging therapies. Such an effort will be essential in the next few years.
From Coronary Care Unit to Contemporary Cardiac Care Unit
Care of the patient with acute myocardial infarction (MI) has changed significantly in the past 50 years. The CCU has been cited as the one of the most important advances in the treatment of acute myocardial infarction, rendering perhaps the largest and longest-lasting impact. The CCU has become such a cornerstone in MI care that it is hard to imagine a time when we did not rely on these specialized intensive care units to care for such highly vulnerable patients. Prior to the development of the CCU in the late 1960s there were few specific interventions available for the care of patients with MI, except for the use of morphine analgesia. The treatment of acute MI was based upon bed rest and “benign neglect.” Physicians were powerless in the face of thrombotic, mechanical, and electrical complications for which there were no effective interventions. The development of open-chest and subsequently closed-chest defibrillation, as well as closed-chest massage, provided physicians with the ability to abort life-threatening arrhythmias and circumvent terminal arrest.
During a presentation to the British Thoracic Society in 1961, Julian was the first to formally propose the idea of an organized coronary care unit. He proposed that patients with MI should have continuous electrocardiographic monitoring with an alarm system and that medical staff caring for these patients should be trained in resuscitative efforts. He called for the admission of MI patients to a single location where there were trained nurses who could respond to emergent life-threatening problems without a physician present. In the years to follow, several centers reported their experiences implementing such coronary care units. Killip and Kimball described the care of 250 acute MI patients in a four-bed unit at New York Hospital/Cornell Medical Center. While their work is most often cited for their landmark classification of MI severity, their results suggested that implementation of CCU care reduced in-hospital MI mortality from 27% to 6%. Additionally, their results argued that all patients who experienced cardiac arrest had much higher survival when cared for in the CCU. Similarly, Lown and others at the Peter Bent Brigham Hospital showed that aggressive MI care in the CCU, with an emphasis on arrhythmia suppression, reduced mortality in both the intensive care unit (11.5%) and in-hospital periods (16.9%). The early successes documented with CCUs largely hinged on the central availability of defibrillation and cardiopulmonary resuscitation. The development of mobile resuscitation tools (e.g., crash carts) was an extension of these early efforts to rescue those with cyanotic cardiac arrest. Day was the first to coin the term “code blue” in his description of acute resuscitative care, and he was the first physician to use the term “coronary care unit,” in his description of an 11-bed MI unit at Bethany Hospital in Missouri ( Fig. 35-1 ).
The advent of additional technologies that could alter the natural history of acute MI quickly accelerated the evolution of the CCU. The intra-aortic balloon pump, pulmonary artery catheter, and fibrinolytic therapy provided new options for treating and stabilizing ACS patients, but they also simultaneously increased the complexity of the clinical care and the technical services provided by the CCU.
As these emerging therapies enabled cardiologists to treat ongoing ischemia and pump failure, they also contributed to the escalating costs associated with improvements in outcomes. The emergence of CCUs across the United States is thought to have been responsible for a 13.5% decline in cardiovascular death between 1968 and 1976. , However, the high resource use and economic burden characteristic of CCUs has subjected the modern CCU to increasing scrutiny. The financial burdens extend not only to patients and health care systems, but also to payers and society in general. To further illustrate this point, intensive care unit costs increased by more than 200% between 1985 and 2000.
As the CCU has evolved to assume a prominent role in contemporary cardiovascular care, the characteristics of CCU patients also have changed considerably. The prevalence of nonischemic cardiac disorders, and noncardiovascular critical illnesses have increased. CCU patients in today’s units are more likely to have multiple comorbid illnesses, which themselves may require intensive care. The reasons behind this escalating comorbidity are many, but certainly include the burgeoning epidemics of obesity, diabetes, heart failure, chronic kidney disease, complications of implantable cardiac devices, and the aging population. Additionally, the expansion of noncardiovascular critical care therapies, including continuous veno-venous hemodialysis, noninvasive ventilation, and therapeutic hypothermia have made the CCU environment all the more complex. The culmination of all of these changes is that the modern CCU is more similar to the medical intensive care unit (ICU) than ever before.
Prehospital Care
The extension of the CCU into the prehospital phase involves a shift in thinking from the CCU as a fortress, inside which excellent clinical care can be divorced from the chaos of the external world. Instead, we now know that applying the same principles of evidence, using outcomes studies and clinical trials, can improve the fate of patients in the highest-risk situation—before reaching the hospital—and that we can have a major effect in the period of highest risk in the hospital, the emergency department (ED).
Acute cardiac care begins with the basic principle of encouraging those with symptoms to enter the care system as quickly and efficiently as possible. Most people with symptoms of myocardial ischemia do not seek help quickly, and when they do, most do not call 911 or other emergency medical services (EMS); rather, they arrange nonmedical transport to an emergency facility. , Though these statements simply present the facts, they belie the underlying complexity of this principle. First, it is based on the assumption that the public understands or can recognize the symptoms of ischemia and the implications of delay. Without those two concepts, people at risk will not enter the system quickly or efficiently. Although the implications of delay may be relatively simple to teach, accurate symptom recognition is difficult even for medically trained personnel, and this has fueled the widespread use of chest pain units. Further, we have limited understanding of what influences even knowledgeable people in the decisions they make when confronted with potential ischemic symptoms. Coupled with wide variability in EMS systems and in patient perceptions of them, fulfilling the basic principle of patients’ quick entry into the care system is a great challenge to successful prehospital cardiac care.
The National Heart, Lung, and Blood Institute-sponsored Rapid Early Action for Coronary Treatment (REACT) trial randomized communities to a massive public-relations effort or conventional approaches to attempting to improve responses to symptoms of possible ischemia. The trial showed no effect on time to treatment, appropriate diagnoses, or improved outcomes, but it did show an improvement in the use of EMS as the mode of transport. These results and those of previous studies suggest a need for more-targeted education and refocus of these efforts. Patient delay (prehospital delay) is the major factor in treatment delay, and it has not changed substantially in the reperfusion era. , Efforts to understand the factors predisposing to delay and to define and target educational efforts to high-risk, high-yield populations may ultimately be a better approach than massive public-education efforts.
In a substudy, the REACT investigators showed that the decision to use EMS depended on the person’s thinking about the symptoms: those who lived alone, those who thought that their symptoms were serious enough to take nitroglycerin, and those who were prompted to “go quickly” by others used EMS. Those who called their doctors were less likely to use EMS. Further, communities that had an EMS prepayment plan tended to have greater EMS use than communities in which individuals paid out of pocket (as fee for service) for EMS.
Despite these difficulties, given that the risk of life-threatening arrhythmias and death is greatest in the first few hours after MI, earlier access to life-saving technology is a crucial part of any community cardiac care program. This technology includes the following four main elements: (1) extensions of interventions available in the hospital, for example, the defibrillator; (2) the 12-lead ECG; (3) acute reperfusion therapy; and (4) other drugs.
Time to defibrillation is a critical variable in determining the likelihood of surviving a cardiac arrest. The ultimate approach to this problem is implantation of an automated internal cardioverter/defibrillator (ICD). Even with the expanded Multicenter Automatic Defibrillator Implantation Trial (MADIT)-2 criteria, , this approach is unlikely to meet the need for primary prophylaxis against sudden death because a patient must have already experienced major dysrhythmia or MI to meet these criteria. Another approach is wider distribution of automated external cardioverter defibrillators (AECDs). A recent pilot study from Germany reported a threefold improvement in meaningful recovery from cardiac arrest in the community when AECDs were introduced, and the positive results of deploying AECDs in casinos in Las Vegas have been much discussed.
The standard 12-lead ECG completes the loop for modern acute care of people with thrombosis-induced MI, given that both pathophysiology and definitive therapies have been established for this condition. The standard 12-lead ECG that provides key diagnostic information in patients with ACS symptoms is commonly performed by EMS personnel before hospital arrival. More modern technology can provide wireless ECG transmission from the scene to a handheld liquid crystal display (LCD) to support the on-call cardiologist making triage decisions. A recent study showed that 50% of patients with ECG interpretation of “acute MI” by trained emergency medical technologists and 85% with cardiologist concurrence of “acute MI” will have an acute thrombotic occlusion confirmed during attempted primary percutaneous coronary intervention (PCI). Further, the ability of practicing cardiologists to make both the same ECG diagnosis and the same reperfusion triage decision on paper and on the LCD of a handheld device has been reported. , Trials have shown that prehospital transmission of ECGs to cardiologists is associated with a 50-minute reduction in door-to-balloon times. , Recently, a large registry-based observational study of more than 12,000 patients confirmed that prehospital ECG acquisition is associated with a greater use of reperfusion therapy and improved reperfusion times.
The ST segment has been the portion of the ECG typically used to provide both diagnostic and prognostic information. Ischemia-induced terminal distortion of the QRS complex, however, has been shown to be superior to ST-segment measurements in predicting final acute MI size and assessing the possible effects of fibrinolytic therapy. Also, comparative quantitative changes in T waves and infarction-induced initial distortion of the QRS complex have been shown to add to historical timing in the prediction of limiting MI size through reperfusion therapy.
When the prehospital ECG is perceived to indicate acute coronary thrombosis and the clinical situation is appropriate, early reperfusion therapy can be started intravenously by emergency medical technicians, by rapid administration in the ED, or by PCI in the catheterization laboratory. Electronic transmission of 12-lead ECGs to the hospital ED has been shown to reduce the time to reperfusion via primary PCI by 50 minutes. The administration of fibrinolytic therapy in the field, also predicated on the availability of 12-lead ECGs at the scene, now has been tested in multiple clinical trials. A systematic overview showed reduced mortality with prehospital versus hospital administration of fibrinolytic therapy, and a pilot trial of field fibrinolysis suggested outcomes comparable with direct PCI. For the most part, field administration of fibrinolytic therapy in the United States has been limited by concerns about liability and the absence of physicians in ambulances. In countries such as France, the system supports the effort, but it is unclear in the United States whether appropriately trained nonphysician personnel can safely give prehospital fibrinolytic or other medical therapy unless there is direct exchange of clinical and ECG information with an on-call physician. When they become available, the results of the ASsessment of the Safety and Efficacy of a New Thrombolytic Agent (ASSENT)-III Plus study, in which patients from around the world were treated with fibrinolytic therapy in the field by personnel with various clinical backgrounds, should help to address these concerns.
Until reforms in medical liability can be addressed and the safety of prehospital therapy given by nonphysicians is clearly shown and accepted, the first consideration in the United States should be to ensure that all EMS units can capture and transmit in-field 12-lead ECGs. Prehospital services then can focus on timely transfer of patients with acute MI to regional centers capable of rapid administration of fibrinolytic therapy or performance of PCI. For rural areas with long transit times to the nearest hospital, however, improved technology, including electronic transmission of ECGs from the field to on-call physicians, should drive consideration of in-field treatment if qualified nonphysician personnel are available. Development of hybrid, but perhaps safer, alternative approaches to full-dose fibrinolysis also could be an answer. Regardless, in addition to understanding patient-related factors in responding to symptoms and using EMS, broad standardization of EMS services and their improved coordination with regional acute cardiac care facilities will be necessary to enhance prehospital care.
In patients with ACS who are not candidates for acute reperfusion therapy, the amount of depression in the ST segment of the initial ECG has been shown to have value in early risk stratification. Unlike STEMI, it has been difficult to show a dramatic time-dependency of outcome after giving effective therapies in NSTE ACS. Thus, it is difficult to know whether the expense of supplies and training needed for prehospital administration of pharmacologic therapy, other than aspirin and acute therapies such as oxygen, nitrates, and morphine, is warranted. However, having ECG information available from the field should aid in patient triage on arrival and inform decisions for early invasive management strategies. Such information also could improve the likelihood of evidence-based therapies being started early on arrival as well as help identify patients eligible for clinical trials, particularly if integrated with input from on-call cardiology services at the receiving hospital.
Future prehospital cardiac care of patients with ACS may be enhanced by the availability of both practice guidelines and access to the medical literature via handheld devices. Even a simple innovation—such as a new way to provide quantitative information from the 12-lead ECG to the handheld device of the on-call cardiologist—might be useful. A new display of the ECG with all 24 views around “clock faces” surrounding schematic images of the heart, in both the frontal and transverse planes, has been introduced. This might provide added decision support for the cardiologist’s interpretation of the initial ECG by indicating the spatial location of the acute ST-segment deviation for more precise localization of the culprit lesion within the coronary artery. A substudy of the Global Use of Strategies To Open occluded coronary arteries (GUSTO) I and II trials has suggested the value of this method.
The Emergency Department
Although geographically distinct, the ED, and even EDs at separate referral hospitals, must be effectively integrated with the CCU for patients progressing from the outpatient to the critical-care setting. An example of success in a joint ED-cardiology initiative was the Heart Attack Alert Program, which resulted in a 50% reduction in time from ED arrival until fibrinolysis during the 1990s. Because the immediate needs of EDs and CCUs are different and at times even contradictory, regular communication among the two sets of physician and nurse leaders is essential to provide optimal acute cardiac care. Common standards and algorithms should be established (e.g., for reperfusion therapy for acute STEMI). Regular meetings of staff representatives, in which cases are reviewed to highlight problems and successes in integrating emergency and intensive care, constitute one mechanism for continuous improvement.
Hospital-wide ACS protocols should begin in the ED. These protocols should include clear direction on the preferred initial evaluation, the immediate therapeutic approach, and the clinical trials in which the institution is participating. Examples of the ACS protocols at Duke University Medical Center, Durham, N.C., are shown in Figure 35-2 . Another important issue for facilities without full cardiac services should be development of a standard approach to determining who should be transferred to a higher-intensity facility and when transfer should occur. In an ideal world, this would be done regionally so that the criteria are standard and the roles and responsibilities of participating facilities (and of the transport links between them and the EMS linking them with the public) are clear. The system would allow such decisions to be made as early as possible after patient arrival in the ED, and with central coordination and input from the EMS and 12-lead ECG in the field, these protocols might be applied even earlier, eliminating the need for transfer to another facility after arrival at the first ED.
Quality measures, as described later, should be viewed jointly by personnel in the ED and the CCU. For example, time to reperfusion therapy could be delayed at multiple points, ranging from obtaining the initial ECG to gaining a consultation for difficult cases. Ultimately, because time from symptom onset to reperfusion is critical to preservation of myocardium and to patient outcome in STEMI, understanding and eliminating delays at all levels in the system are essential. This can be done only with collaborative review and discussion of the results of quality measures.
Primacy of Timely Reperfusion and Quality Improvement
As has been observed in other emergency medical conditions, such as trauma, timely intervention is of paramount importance. In trauma surgery, regional systems of care have been shown to improve response times and outcomes. In the United States, MI deaths outnumber trauma deaths three to one, yet until recently very little attention was paid to systematic, regional approaches to MI care. While CCU care has evolved in the past decade, timely reperfusion in ST-segment elevation ACS remains a prime objective of acute cardiac care. Unfortunately, many patients with acute STEMI do not receive mechanical reperfusion within 90 minutes of their first medical contact. While the reasons for this common failure are multifactorial, they are largely due to system-related barriers. Timely delivery of reperfusion therapy requires collaboration and integration of care beyond the CCU, at outside tertiary care centers, and into the surrounding communities, especially in hospitals without access to primary PCI. In our state, we have successfully implemented a statewide system for reperfusion in STEMI. The Reperfusion of Acute myocardial infarction in North Carolina Emergency departments (RACE) initiative established five regions across the state and involved 65 hospitals and their affiliated EMS (55 non-PCI centers and 10 PCI-capable centers).
The overarching objective of the RACE program was to improve first-medical contact to reperfusion times, via either primary PCI or fibrinolytic therapy. In order to accomplish this goal, the RACE program enacted several key interventions. First, sites were instructed to give authority to the emergency medicine physician on duty to initiate reperfusion, including single-call activation of the cardiac catheterization laboratory. Additional interventions included creation of site-specific reperfusion plans and protocols, local EMS electrocardiogram interpretation training to enable in-the-field diagnosis, and elimination of intravenous drips in order to facilitate rapid interhospital transport. Finally, non-PCI hospitals were encouraged to leave patients on the stretcher, when permissible.
After 19 months, the RACE interventions improved median reperfusion times, including door-to-device from 85 to 74 minutes, P < .001; door-to-needle in non-PCI hospitals from 35 to 29 minutes, P = .0 02; and door-in to door-out from 120 to 71 minutes, P < .001, for those transferred to a PCI-capable center. Nonreperfusion rates fell from 23% to 11% in the PCI-capable centers. In one region in central North Carolina, the Duke CCU served as the communication hub for all reperfusion calls from outlying centers. This vertical organizational approach enabled rapid patient care and transport decisions to be enacted after a single phone call.
The RACE approach, which used region-specific tailored approaches to optimal reperfusion was formally adopted by the American Heart Association (AHA) Mission Lifeline initiative. Statewide programs focused on regional delivery of care should undertake future quality initiatives. The CCU, which often serves as the coordinating center and priority receiving center for these patients, must be integrated in these approaches. The RACE experience has shown that the CCU should be actively involved in the reperfusion process, and in so doing can extend its benefit to patients as soon as they come into contact with EMS. Other regional systems, employing a standardized protocol for interhospital STEMI transfer from community hospitals to PCI centers also have shown significant improvements in reperfusion times. , In addition, the American College of Cardiology (ACC) has launched a quality improvement initiative for reducing door-to-balloon times (D2B: An Alliance for Quality). At the time of this writing, more than 1000 hospitals have joined the D2B effort.
The Contemporary Cardiac Care Unit
The contemporary CCU faces the challenge of providing efficient care for patients with complex cardiac conditions using an extensive and complicated set of medical and device options. To succeed, key elements include effective teamwork and communication, systematic approaches, and the use of computer technology to improve performance.
Although major cardiology society guidelines provide a detailed framework for applying evidence-based treatment in a spectrum of patients and situations, their complexity and length—91 pages for the 2002 AHA/ACC STEMI guidelines —essentially preclude their use by physicians in a busy patient-care environment. Guidelines can, however, direct systematic approaches to patient care that can be customized to a hospital or unit, especially when there are information systems to track how care is being provided. For example, a poster outlining a systematic approach to early antithrombotic and interventional care of the spectrum of patients with ACS can be placed in both the ED and the CCU to establish standard approaches that incorporate guidelines and evidence-based approaches. This could include strategies for reperfusion therapy in patients with STEMI, how to use platelet glycoprotein (GP) IIb/IIIa inhibitors, and how to select among anticoagulant options for patients with NSTE ACS. For institutions participating in clinical trials, such a poster also can highlight which patients are eligible for which ongoing trials. In the near future, the goal should be to have such algorithms available to the care team by means of handheld computers with direct links to the supporting guidelines or literature and to specific dosing guidelines and caveats. Registries such as the Global Registry of Acute Coronary Events (GRACE), and the Acute Coronary Treatment and Intervention Outcomes Network (ACTION) Registry, (which consolidated the efforts of the National Registry of Myocardial Infarction (NRMI), and the Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines? (CRUSADE), as well as internal quality-assurance data collection, are essential tools in establishing whether treatments are being effectively applied in cardiac emergency and critical care.
After decades of generating negative feelings in the medical community, standardized orders have gained acclaim as part of an effective strategy to reduce medical errors. Standard admission orders can help ensure that common evidence-based treatments, such as aspirin for all patients with ACS, are not forgotten. Standard dosing guidelines for unfractionated heparin, which customize the dose of heparin according to patient weight and call for adjustments according to an algorithm, can improve therapeutic heparin use. Algorithm-driven replacement of potassium and magnesium likewise can allow more accurate and efficient normalization of electrolytes. The ACC-sponsored Guidelines Applied in Practice (GAP) project showed that patients whose doctors were exposed to standard order forms were more likely to be sent home with therapies in alignment with the ACC/AHA guidelines.
Case Mix and Complexity in the Cardiac Care Unit
While many are familiar with the landmark study by Killip and Kimball and their classification of hemodynamic severity in acute MI, their seminal observation was the significant survival advantage conferred by CCU care compared with usual medical ward care. Perhaps the single greatest intervention enabled by the CCU was the delivery of timely therapy for life-threatening arrhythmias. Today, these benefits have been extended to the outpatient setting, as multiple clinical trials have demonstrated reductions in arrhythmic and all-cause mortality in patients with significant left ventricular (LV) dysfunction randomized to defibrillator therapy after MI. , Interestingly, the advent of the ICD has initiated a change in the epidemiology of ventricular tachycardia that has come full circle. Patients who might have otherwise suffered sudden cardiac death outside the hospital, now present to the CCU after isolated episodes of ventricular tachycardia or recalcitrant electrical storm. In our own CCU, the emergence of the ICD in primary prevention settings has led to a significant increase in the number of admissions to the CCU for life-threatening arrhythmias ( Fig. 35-3 ). Patients who present with more than two appropriate ICD discharges in a 24-hour period have electrical storm and represent a particular challenge. Such patients have extremely high mortality and often require intense treatment with aggressive beta blockade, sympatholysis, antiarrhythmic drug treatment, and sometimes require intubation and sedation. , The increasing frequency of ICD admissions has created a need for most CCUs to have 24-hour device interrogation capabilities and access to specialists in electrophysiology.
Further technologic advances in interventional cardiology are also contributing to the escalating acuity and complexity of the CCU population. While not yet mainstream, percutaneous valve replacement, which is reserved for patients who are poor operative candidates, and therefore sicker, will introduce another very complex patient to the CCU environment. Similarly, the use of percutaneous assist devices, such as the TandemHeart (Cardiac Assist, Inc) and the Impella (Abiomed), will increase the number of bedside devices and technologies that CCU providers will have to be experienced in using and comfortable managing. These devices not only represent a new educational challenge to the multidisciplinary team, but they also enable some patients with extreme comorbidity (who were previously not felt to be candidates for interventional procedures) to proceed with high-risk, high-reward procedures.
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