The North American perspective on short-term mechanical circulatory support for cardiogenic shock: could differences in policy be driving differences in temporary mechanical circulatory support use?

Cardiogenic shock (CS) is a high-acuity and time-sensitive condition associated with a reported 24–52% risk of short-term mortality.1–3 To date, the only randomized controlled trial intervention that has been definitively shown to improve survival is an early invasive approach in patients with ST-segment elevation myocardial infarction (STEMI)–associated CS.4 In recent years, there has been substantial growth in the use of advanced temporary mechanical circulatory support (tMCS) deployment, which have been shown to improve cardiac output and potentially restore end-organ hypoperfusion.5–7 Although it remains unclear if tMCS devices improve mortality in CS, efforts to generate high-quality data on device efficacy, safety, configurations, and timing are ongoing.8–12 Given the rapid expansion of tMCS device utilization, which now commonly extends beyond select tertiary CS hub centres13 together with the lack of high-quality evidence, there is a clear need for expert panels to summarize contemporary best practices. In this multi-societal consensus statement endorsed by Acute CardioVascular Care (ACVC), the European Society of Intensive Care Medicine (ESCIM), European Extracorporeal Life Support Organization (EuroELSO), and the European Association for Cardio-Thoracic Surgery (EACTS), Dr Møller et al.14 provide practical critical care unit management suggestions based on a mix of available evidence and expert consensus. It outlines tMCS indications, monitoring, pharmacologic therapies, critical care management (including sedation and mechanical ventilation), approach to anti-coagulation, escalation and de-escalation strategies, and an approach to prevention and management of common complications. The strengths of this consensus statement are that it is extremely practical and easy to read whilst retaining an evidence-based foundation. The presentation of common management issues stratified by early (<24 h), intermediate, (24–72 h), and late (>72 h) after device implantation highlights the common-sense clinician’s approach and will likely make this document a valued resource for key stakeholders, including non-experts and trainees. It was careful to avoid definitive statements about best practices given the evolving evidence reflects both the clinical and guideline development expertise within the writing group. The document’s suggestions to adopt shock team-based tMCS cannulation and management decisions, along with Society for Cardiovascular Angiography & Interventions (SCAI) shock risk stratification, as important points of emphasis that have not yet been universally adopted are viewed as strengths, though we acknowledge these are based solely on observational evidence.1,15,16 We would like to highlight a few relatively minor differences in opinion we have with the writing group regarding (i) staging, (ii) pharmacologic management, and (iii) device selection or deployment timing, which may exist. First, it is worth noting that Figure 1 in the document has adopted a modified SCAI shock definition. In the recently revised classification, SCAI Stage C is not exclusively defined by mean arterial pressures (MAP) threshold and there is a growing recognition of normotensive patients with CS, whilst SCAI D is more broadly defined by clinical deterioration despite pharmacologic or tMCS support.17–19 There is also a growing recognition that haemodynamic congestive profiles [left ventricular (LV), right ventricular (RV), or biventricular failure], aetiology (STEMI and non-STEMI, acute-on-chronic vs. de novo heart failure, valvular) and/or mixed shock state (infectious or vasodilator shock) may confer important risk and clinical management differences.20–23 We acknowledge, however, that some of this level of detail may be beyond the scope of a practical document. At a minimum, we believe there may be an important role for pulmonary arterial catheterization prior to tMCS deployment to help define uni- or biventricular congestion profiles to facilitate optimal device selection and configuration. From a pharmacologic perspective, we would propose an amendment to Figure 2 in their document, which pertains to patients supported with an Impella™ with RV failure and ongoing hypoperfusion. First, prior to escalation to BiPella or ECMELLA configuration, we would suggest RV pharmacologic support, which may include inotropes, inhaled pulmonary artery vasodilator, vasopressin, and/or fluid preload.8,24–26 Second, the assertion that norepinephrine be utilized as a first line agent in all patients is not only subject to important limitations of the underlying trials discussed elsewhere8,25–27 but also fails to recognize the aforementioned haemodynamic diversity of CS. Right ventricular dominant shock, hypertrophic cardiomyopathy with dynamic outflow tract gradients, and severe stenotic valvular diseases are three examples wherein norepinephrine may be harmful as a first line agent.8 Whilst norepinephrine has the strongest current evidence base,25,26 we would advocate that there may be logical role for aetiology-, phenotype-, and haemodynamic-based pharmacologic tailoring. The most controversial tMCS decision, which is not unique to this ACVC statement, is how we should match the right therapy to the right patient at the right time. The recent negative extracorporeal membrane oxygenation (ECMO)-CS and underpowered EURO-Shock trials evaluating the impact of ECMO on mortality in patients with CS underscore the importance of the ongoing DANGER, ECLS-Shock, ANCHOR, and RECOVER-IV trials to demonstrate the efficacy and safety of tMCS support across the spectrum of CS.10–12 Given that a majority of patients with CS survive with medical therapy alone (i.e. without tMCS), it is plausible that we have not yet identified the cohort (or SCAI class of patients) who are most likely to benefit from tMCS and are not too sick from their underlying or comorbid illnesses.28 Thus, early or stable SCAI stage C CS may be too early (which are ostensibly considered a potential tMCS indication in the consensus document) and we may need to enrol more advanced CS stages such as SCAI stage D, E, or persistent C. This begs the question: is there an international consensus about the optimal timing and device selection, or could national/regional differences in policies, tMCS funding, and reimbursement that are summarized in Table 1 be driving utilization patterns? Herein, we provide the North American perspective on tMCS utilization in three countries (Canada, the USA, and Mexico) with different health care coverage models, tMCS funding, access to health care, and social determinants of health. North American structural and policy factors potentially driving temporary mechanical circulatory support and perceived challenges Single payer system Only 9 CS hub centres tMCS funding challenges in 48% of centres Lack tMCS evidence Lack of tMCS access in 41% of centres Lack of CS teams and protocols in ∼25% Low CS volumes, low PAC use Multiple payer system with differential access to care in poor and rural areas Lack of standardized CS networks and centres of excellence, particularly among uninsured and underinsured patients Delayed recognition of CS Lack of standardized CS teams and protocols at most hospitals Lack of or delayed use of PAC in patients to guide tMCS selection Significant intra- and inter-hospital variation in tMCS device capabilities Lack of suitable exit strategies (bridge to LVAD, transplant, or recovery) Lack of CS policies Multiple payer system—fragmented health system No CS networks Lack of CS teams and protocols Underutilization of PAC in cardiac care centres Lack of access to advance care in non-metropolitan areas Lack of tMCS access Single payer system Only 9 CS hub centres tMCS funding challenges in 48% of centres Lack tMCS evidence Lack of tMCS access in 41% of centres Lack of CS teams and protocols in ∼25% Low CS volumes, low PAC use Multiple payer system with differential access to care in poor and rural areas Lack of standardized CS networks and centres of excellence, particularly among uninsured and underinsured patients Delayed recognition of CS Lack of standardized CS teams and protocols at most hospitals Lack of or delayed use of PAC in patients to guide tMCS selection Significant intra- and inter-hospital variation in tMCS device capabilities Lack of suitable exit strategies (bridge to LVAD, transplant, or recovery) Lack of CS policies Multiple payer system—fragmented health system No CS networks Lack of CS teams and protocols Underutilization of PAC in cardiac care centres Lack of access to advance care in non-metropolitan areas Lack of tMCS access Abbreviations: CS, cardiogenic shock; LVAD, left ventricular assist device; PAC, pulmonary arterial catheter; tMCS, temporary mechanical circulatory support. North American structural and policy factors potentially driving temporary mechanical circulatory support and perceived challenges Single payer system Only 9 CS hub centres tMCS funding challenges in 48% of centres Lack tMCS evidence Lack of tMCS access in 41% of centres Lack of CS teams and protocols in ∼25% Low CS volumes, low PAC use Multiple payer system with differential access to care in poor and rural areas Lack of standardized CS networks and centres of excellence, particularly among uninsured and underinsured patients Delayed recognition of CS Lack of standardized CS teams and protocols at most hospitals Lack of or delayed use of PAC in patients to guide tMCS selection Significant intra- and inter-hospital variation in tMCS device capabilities Lack of suitable exit strategies (bridge to LVAD, transplant, or recovery) Lack of CS policies Multiple payer system—fragmented health system No CS networks Lack of CS teams and protocols Underutilization of PAC in cardiac care centres Lack of access to advance care in non-metropolitan areas Lack of tMCS access Single payer system Only 9 CS hub centres tMCS funding challenges in 48% of centres Lack tMCS evidence Lack of tMCS access in 41% of centres Lack of CS teams and protocols in ∼25% Low CS volumes, low PAC use Multiple payer system with differential access to care in poor and rural areas Lack of standardized CS networks and centres of excellence, particularly among uninsured and underinsured patients Delayed recognition of CS Lack of standardized CS teams and protocols at most hospitals Lack of or delayed use of PAC in patients to guide tMCS selection Significant intra- and inter-hospital variation in tMCS device capabilities Lack of suitable exit strategies (bridge to LVAD, transplant, or recovery) Lack of CS policies Multiple payer system—fragmented health system No CS networks Lack of CS teams and protocols Underutilization of PAC in cardiac care centres Lack of access to advance care in non-metropolitan areas Lack of tMCS access Abbreviations: CS, cardiogenic shock; LVAD, left ventricular assist device; PAC, pulmonary arterial catheter; tMCS, temporary mechanical circulatory support. As a nation with universal single-payer health care coverage, there are no significant physician or hospital reimbursements for tMCS utilization. Moreover, given the cost constraints of our health system, CS hub centres more frequently use less costly tMCS, including ECMO and temporary surgical support devices, and significantly fewer Impella™ or TandemHeart™ devices compared with our American colleagues. Moreover, several Canadian provinces do not have dedicated funding envelopes for some tMCS devices and current practices are frequently funded through a mix of budgetary re-allocation and philanthropy. A 2022 survey of all 46 percutaneous coronary intervention (PCI) centres found only nine were Level 1 CS centres.13 The existing regionalized systems of cardiovascular care with relatively little economic competition between centres for this patient population represents a strength and potential opportunity to better integrate and standardize best-care practices in a hub-and-spoke model. Level 1 and Level 2 centres reported the availability of both ECMO and Impella™ as 78% and 41%, respectfully. Funding (48%), access to tMCS (41%), and lack of evidence were identified as the leading challenges in caring for CS, which may help explain current Canadian practices. The USA currently maintains a multiple payer system for health insurance coverage, which has differential effects on health care access and equity. There is significant variation in tMCS device selection and use across US hospitals, with intra-aortic balloon pump (IABP) still the most common device employed in both acute myocardial infarction CS (AMI-CS) and heart failure CS (HF-CS).29 Whilst the 2017 European Society of Cardiology guidelines advise against the routine use of IABP in patients with AMI-CS (Class III, level of Evidence B), the American Heart Association (AHA)/American College of Cardiology (ACC) guidelines offer a Class IIa recommendation for IABP use in AMI-CS. Furthermore, for HF-CS patients eligible and listed for heart transplantation, the use of tMCS has significantly increased since the United Network for Organ Sharing (UNOS) allocation system was revised in October 2018.5,30 Patients receiving venoarterial ECMO or non-dischargeable, biventricular tMCS devices are designated UNOS Status 1, whereas patients supported with IABP or percutaneous ventricular assist devices (Impella™ or TandemHeart™ devices) are designated Status 2. Perhaps, not surprisingly, there have been significant shifts in tMCS utilization and heart transplantation practices and clinical outcomes following the allocation change. The allocation change has had several unintended consequences as well.31 In the year following implementation of this UNOS allocation system change, tMCS use increased in patients admitted with HF-CS increased in US transplant centres but not in other cardiac intensive care units and not for other forms of CS.5 The use of IABP has risen >20% and is largely responsible for the dramatic rise in the use of tMCS as compared with the prior allocation system.32 Furthermore, whilst tMCS use increased for both sexes, there was significantly greater use in men under the new policy,33 highlighting sex-based disparities that merit further investigation. Patients are also now maintained on support for weeks to months longer than originally intended, albeit in many instances via ambulatory configurations (i.e. axillary as opposed to femoral access). For patients with HF-CS, the current UNOS allocation system limits opportunities for using tMCS as bridge to myocardial recovery, given the shorter waiting times for urgent transplantation for candidates receiving tMCS devices.34 These expanded indications for tMCS use have led to the advent and implementation of interdisciplinary CS teams, which have been associated with improved survival in several single centre and multicentre reports and are now endorsed by the 2022 AHA/ACC/Heart Failure Society of America (HFSA) guidelines for heart failure with a Class IIa recommendation.1,15,35 Given the paucity of randomized data, clinicians have developed their own institutional algorithms or adopted suggestions from a recent AHA Scientific Statement of Escalating and De-Escalating tMCS in CS.36 The changes in national tMCS use in the absence of new randomized evidence suggests the need for ongoing prospective and randomized studies to guide clinicians in timely and appropriate device selection for tMCS in CS in the USA. In Mexico, the most frequent cause of CS is acute myocardial infarction is associated with a reported 70% in-hospital mortality rate.37 The poor outcomes may be, in part, due to STEMI care delays, low rates of revascularization, and lower use of tMCS. Unfavourable social circumstances, along with inadequate and inefficient public spending on health care, are barriers to improve outcomes in patients with CS. The most frequently used tMCS device in Mexican hospitals is the IABP, although recently, some tertiary centres have gained access to IMPELLA CP and ECMO. Regionalizing networks that mirror STEMI programs, dedicated to CS in Mexico, have begun with collaborative programmes between non-PCI capable centres and specialized tertiary hospitals with CS teams using a ‘hub-and-spoke’ model that coordinates the most appropriate and time-effective therapeutic strategy. Additionally, reimbursement policies and coverage by public and private health insurance systems need to be expanded to include tMCS therapies to ensure that patients have access to these potentially life-saving interventions without facing significant financial burdens. Collaboration between the government, health care institutions, and medical device manufacturers is essential in negotiating more accessible price agreements and facilitating tMCS availability in Mexico. Continuous monitoring and evaluation of tMCS outcomes need to be incorporated into national health care systems to enable data-driven decision-making and quality improvement initiatives. The authors should be congratulated for a well-conceived and thoughtful tMCS document that provides practical management recommendations to a broad array of health care professionals caring for this critically ill population. The consensus statement will likely serve as a valuable international resource for years to come. In our opinion, a leading challenge in tMCS care for patients with CS is a lack of adequately powered randomized controlled trials that clearly inform efficacy, safety, and patient selection. We surmise that the international and North American disparities and potential determinants of tMCS practice discussed herein could be partially minimized if future science—as opposed to policy funding and access—drove patient selection and clinical decision-making for tMCS. We would like to gratefully acknowledge Ms L. Soulard for copy editing the manuscript. None declared.

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