Introduction
As of August 3rd 2020, the coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus type 2), responsible for the disease COVID-19 (coronavirus disease 2019), had infected more than 18 million people worldwide and caused nearly 700,000 deaths.¹ After an initial wave that predominantly affected the northeastern United States, there has recently been a resurgence in cases across many states. The clinical spectrum of COVID-19 is wide, ranging from asymptomatic infection and mild upper respiratory tract illness to acute respiratory distress syndrome (ARDS), shock, and death. Critically ill patients frequently have extra-pulmonary manifestations, including myocardial injury, with elevated biomarkers,² electrocardiographic changes,³ or echocardiographic abnormalities.⁴ Herein, we outline the central role for critical care cardiologists during this pandemic, changes to pre-pandemic practices in the cardiac intensive care unit (CICU), and the need for change at an institutional, regional, and national level in response to a surge in CICU COVID-19 patients.

The Genesis of the Cardiac Intensive Care Unit
The inception of the first coronary care unit (CCU) in 1962 by the late Professor Desmond Julian transformed the care of critically ill cardiac patients.⁵ Prompt care, close monitoring, and meticulous follow-up improved cardiovascular outcomes in critically ill patients, and led to the rapid development of CCUs across the world. Importantly, the demographics of CCU patients have changed markedly over the decades; CCU patients are now older, with more co-morbidities such as renal dysfunction or obstructive lung disease.⁶ As a result, the importance of general critical care medicine has been amplified in the CCU to optimally manage a medically-complex patient population with advanced cardiac pathology. It is against this background that CICUs have formed and cardiac critical care has developed as an essential subspecialty with a focus on good critical care practices in addition to cardiovascular care.

Hospital Level Re-organization to Accommodate Surge in CICU Patients
With progression of the COVID-19 pandemic and a dramatic increase in the demand for critical care delivery, hospitals have made several changes to maximize CICU resources. These have included the cancellation of elective cardiac procedures, particularly those requiring recovery in the CICU, as well as new guidelines for patient triage to maximize the benefit of critical care delivery in the CICU and other ICUs. These changes not only act to maximize CICU bed availability but also CICU personnel including cardiac critical care physicians, nurses, trainees, and allied health professionals. Katz et al. provide a useful illustration to guide hospital-level CICU restructuring during different stages of the pandemic.⁷ According to their report, as hospitals reach >100% capacity, additional intermediate care and recovery units may be converted to ICUs and the nurse to patient ratios may reach 1:6 or higher. While it may be necessary to implement such nurse to patient ratios, other strategies to address this imbalance may be considered, including rapid training of floor level nurses practicing under the close supervision of more experienced ICU staff. In addition, rapid testing in the emergency department has been instrumental in the early identification of COVID-19 patients, many of whom have similar symptoms to those with acute cardiovascular disease. This has led to improved CICU workflows and a reduction in the number of cases requiring isolation in COVID-19 ICUs due to an undetermined infective status.

Adaptations to Cardiovascular Care Delivery
In order to expand the ability of healthcare systems to provide cardiovascular care during the pandemic, and particularly to COVID-19 patients, Katz et al. highlight important changes to the pre-pandemic norms of cardiovascular medicine. For example, they highlight the use of point-of-care ultrasound as an initial means to evaluate COVID-19 patients with suspected cardiac pathology. This serves to provide both rapid diagnostic information to more patients and, to the extent that it reduces other imaging needs, may reduce the exposure of other healthcare providers to infection. Another important adaptation that will allow improved access to cardiovascular care is the expansion of cardiovascular consultation via inpatient telemedicine. Critical care cardiologists can provide virtual consultative care to other ICU patients, and access virtual consultative services from other services. Technology can also be leveraged to provide real-time multi-disciplinary collaboration without additional exposure risk to patient populations treated in the CICU (e.g. cardiogenic shock patients evaluated for mechanical circulatory support [MCS] by the "Shock team") or to providers.

Inter-institution Collaboration
Patients with acute severe cardiac disease including complex STEMI, cardiogenic shock, acute aortopathies, and massive pulmonary embolism are typically managed at tertiary or quaternary centers. While the 'hub-and-spoke' model has efficiently streamlined critical care resources and healthcare delivery, the pandemic has put 'hub' hospitals at risk, as they are increasingly overwhelmed with critically ill patients. As a result, when 'hub' hospitals operate at >100% capacity, it may become difficult to proceed with inter-hospital transfers. Critical care cardiologists serve an important role in triaging patients for transfer, prioritizing those most likely to benefit from tertiary or quaternary center care, as well as providing remote guidance to physicians caring for patients in community hospitals. In order to continue the 'hub-and-spoke' model and help maximize CICU capacity, hospital networks will need to make a concerted effort to repatriate convalescing patients back into community hospitals to make CICU beds at the tertiary and quaternary centers available for other patients.

Equitable Resource Allocation
In the early phases of the pandemic there were serious concerns regarding the availability of life-saving ventilators in hard-hit areas such as New York City. During this period, critical care physicians faced serious ethical dilemmas relating to the allocation of life-saving resources. Katz et al. highlighted the need to apply standardized protocols when considering resource-intensive but potentially lifesaving procedures, such as mechanical ventilation.⁷ This framework may be based on illness acuity, likelihood of survival to discharge and possibility of long-term survival. In addition to ventilator allocation, critical care cardiologists will likely encounter discussions regarding candidacy for MCS. Venoarterial (VA) or venovenous (VV) extra-corporeal membrane oxygenation (ECMO) in particular may be useful to treat critically ill COVID-19 patients with severe cardiopulmonary deterioration. However, questions often arise as to whether withholding or withdrawing these potentially life-sustaining treatments is appropriate.

These therapies are perhaps the most resource intensive of those considered for COVID-19 patients and should not be used in futile circumstances to simply prolong the dying process. They require carefully delineated institutional guidelines for candidacy, prioritizing those with a high likelihood of survival. Medical ethicists, palliative care specialists, as well as critical care cardiologists should all engage in shared decision making with the patient or the patient's caregivers. This multi-disciplinary care team provides important and additional support to the critical care cardiologist when considering transition from aggressive care to comfort-focused measures for critically ill patients. In addition to embracing other specialties to help guide optimal resource allocation, collaboration between centers capable of providing these technologies and services within a defined geographic area will be important for the triage of patients outside of hospital networks above their capacity to maximize the benefit to the population as a whole.

Conclusion
As cases of COVID-19 continue to rise in parts of the US, CICU beds in these highly prevalent regions will be filled with severely ill patients. Several changes to pre-pandemic practices in the CICU are required to accommodate this surge in patient volume. The expertise of critical care cardiologists is vital in not only managing acutely ill patients at their local institution, but in aiding hospital and government leaders reorganize healthcare delivery. In addition, their knowledge and expertise are essential in assisting community physicians to manage cardiovascular sequelae of COVID-19 and leading decisions determining the utility of resource-intensive therapies. Finally, while the pandemic has paused trials and halted research efforts in non-COVID-19 related fields, an entirely new COVID-19 research enterprise has been established in the last few months. It is in this capacity that critical care cardiologists may adopt a central role in leading pivotal research studies to determine optimal therapies for patients with severe COVID-19 related disease.

Figure 1: The Role of the Critical Care Cardiologist During COVID-19

References

1. Dong E, Du H, Gardner L. An interactive web-based dashboard to track COVID-19 in real time. Lancet Infect Dis 2020;20:533-4.
2. Guo T, Fan Y, Chen M, et al. Cardiovascular implications of fatal outcomes of patients with coronavirus disease 2019 (COVID-19). JAMA Cardiol 2020;5:1-8.
3. Kochav SM, Coromilas E, Nalbandian A, et al. Cardiac arrhythmias in COVID-19 infection. Circ Arrhythm Electrophysiol 2020;13:e008719.
4. Churchill TW, Bertrand PB, Bernard S, et al. Echocardiographic features of COVID-19 illness and association with cardiac biomarkers. J Am Soc Echocardiogr 2020;33:1053-4.
5. Julian DG. Treatment of cardiac arrest in acute myocardial ischaemia and infarction. Lancet 1961;2:840–4.
6. Quinn T, Weston C, Birkhead J, Walker L, Norris R. Redefining the coronary care unit: an observational study of patients admitted to hospital in England and Wales in 2003. QJM 2005;98:797–802.
7. Katz JN, Sinha SS, Alviar CL, et al. COVID-19 and disruptive modifications to cardiac critical care delivery: JACC Review Topic of the Week. J Am Coll Cardiol 2020;76:72–84.

Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, COVID-19 Hub, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure

Keywords: Heart Failure, Arrhythmias, Cardiac, Cardiac Imaging Techniques, Diagnostic Imaging, COVID-19, Pandemics, Coronavirus, Coronavirus Infections, severe acute respiratory syndrome coronavirus 2, Coronary Care Units, Critical Illness, Respiratory Distress Syndrome, Palliative Care, Triage, Patient Discharge, Point-of-Care Systems, Shock, Cardiogenic, Caregivers, Hospitals, Community

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