Open AccessReview Mechanical Support in Myocardial Infarction Complicated by Cardiogenic Shock: What Have We Learned from Trials? by Cristina Aurigemma Cristina Aurigemma SciProfiles Scilit Preprints.org Google Scholar 1,*, Norman Mangner Norman Mangner SciProfiles Scilit Preprints.org Google Scholar 2, Vasileios Panoulas Vasileios Panoulas SciProfiles Scilit Preprints.org Google Scholar 3 and Jacob Eifer Møller Jacob Eifer Møller SciProfiles Scilit Preprints.org Google Scholar 4 1 Department of Cardiovascular Sciences, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy 2 Department of Internal Medicine and Cardiology, Herzzentrum Dresden, Faculty of Medicine, University Hospital Carl Gustav Carus, TUD Dresden University of Technology, 01307 Dresden, Germany 3 Department of Cardiology, Harefield Hospital, Royal Brompton and Harefield Hospitals, Guy’s and St Thomas’ NHS Foundation Trust, London UB9 6JH, UK 4 Department of Cardiology, Copenhagen University Hospital, 2100 Copenhagen, Denmark * Author to whom correspondence should be addressed. J. Clin. Med. 2026, 15(12), 4453; https://doi.org/10.3390/jcm15124453 (registering DOI) Submission received: 9 May 2026 / Revised: 31 May 2026 / Accepted: 3 June 2026 / Published: 9 June 2026 Abstract Cardiogenic shock (CS) is the most lethal complication of acute myocardial infarction (AMI), with a 30-day mortality of approximately 40–50% despite early revascularization. Temporary mechanical circulatory support (tMCS) devices, including the intra-aortic balloon pump (IABP), microaxial flow pumps (MAFP) and veno-arterial extracorporeal membrane oxygenation (VA-ECMO), are used as adjunctive therapy in refractory shock, but evidence of a survival benefit is limited and often conflicting. The IABP-SHOCK II trial found no 30-day mortality reduction with IABP, supporting a Class III (no benefit) recommendation, whereas the DanGer Shock trial reported a 12.7% absolute mortality reduction at 180 days with the MAFP Impella CP in highly selected patients. In contrast, the ECLS-SHOCK and ECMO-CS trials showed no improvement in survival with early VA-ECMO and noted high complication rates. Real-world data reveal significant disparities between trial populations and clinical practice, highlighting limitations of current evidence, since many AMI-CS patients are older, in more advanced shock or have multiple comorbidities and would not meet typical randomized controlled trial (RCT) inclusion criteria. In clinical practice, in-hospital mortality with IABP or VA-ECMO often exceeds 50–60%. Given the heterogeneity of AMI-CS, rapid identification of appropriate tMCS candidates and personalized therapy are essential. Management guided by individual patient profile, hemodynamic stage and neurological status, supported by multidisciplinary shock teams, may improve timely triage, device selection and outcomes. This review emphasizes the need for individualized, protocol-driven care within structured shock systems to optimize tMCS use in AMI-CS. Keywords: cardiogenic shock; myocardial infarction; Impella; intra-aortic balloon pump; VA-ECMO; microaxial flow pump 1. Introduction Early revascularization of the infarct-related artery remains the cornerstone of therapy and improves survival in AMI-CS [ 6]. Accordingly, current guidelines give a Class I B recommendation for immediate culprit-lesion revascularization in AMI-CS [ 7]. For non-culprit lesions, European and American guidance advise that routine immediate multivessel percutaneous coronary intervention (PCI) is not recommended in cardiogenic shock, given the potential for procedural complications, longer ischemic times and contrast overload [ 7, 8]. However, even with prompt revascularization, many patients continue to experience profound hemodynamic instability and require additional supportive therapies. Pharmacologic support with vasopressors and inotropes is often necessary to maintain systemic perfusion. Norepinephrine is generally preferred as the first-line vasopressor because of lower arrhythmia risk compared with dopamine, and inotropic agents such as dobutamine, milrinone or adrenaline are commonly used to augment cardiac output [ 9]. In addition to pharmacotherapy, temporary mechanical circulatory support (tMCS) devices are increasingly used in refractory cardiogenic shock to improve hemodynamics. Options include the intra-aortic balloon pump (IABP), percutaneous ventricular assist devices such as the microaxial flow pump (MAFP, Impella ପ୍ପ) and veno-arterial extracorporeal membrane oxygenation (VA-ECMO). In theory, these devices can unload failing ventricles or provide supplemental circulatory flow, serving as bridges to myocardial recovery or to more definitive interventions. However, evidence that tMCS improves survival outcomes remains mixed and often limited ( Figure 1). The present review provides a critical analysis of the available evidence and current perspectives on the use of tMCS in AMI-related cardiogenic shock. 2. Intra-Aortic Balloon Pump in Cardiogenic Shock 2.1. Mechanism of Action 2.2. Clinical Evidence Despite long-standing use in AMI-CS, randomized trials have not demonstrated a survival benefit. The IABP-SHOCK II trial ( n = 600) randomized patients with AMI-CS undergoing early PCI to IABP therapy or standard medical management [ 11]. It found no reduction in 30-day mortality (39.7% vs. 41.3%, p = 0.69) and no benefit in secondary outcomes such as hemodynamic stabilization, lactate clearance or intensive care unit (ICU) length of stay [ 11] ( Table 2). Crossover occurred in approximately 10% of patients, reflecting rescue IABP use in deteriorating controls; a total of 7.4% in the IABP arm and 5.1% in the standard-care arm required escalation to more advanced support. Excluding crossovers yielded the same neutral result. Long-term follow-up at six years confirmed no mortality benefit [ 12]. Safety outcomes were broadly comparable: major peripheral ischemia requiring intervention occurred in 4.3% versus 3.4% ( p = 0.53) and life-threatening or severe bleeding in 3.3% versus 4.4% ( p = 0.51). Overall, routine IABP did not improve clinical outcomes ( Table 1). 2.3. Guideline Recommendations and Clinical Practice 4. Veno-Arterial Extracorporeal Membrane Oxygenation in Cardiogenic Shock 4.1. Mechanism of Action VA-ECMO provides temporary full cardiopulmonary support by draining venous blood, passing it through an oxygenator and returning it to the arterial system. This enables high-flow support (typically 3–5 L/min) and gas exchange, supporting patients with biventricular failure, severe hypoxemia or during cardiac arrest. A key limitation is that retrograde arterial flow can increase LV afterload, raising wall stress, oxygen demand and pulmonary congestion unless active LV unloading is used (e.g., Impella, surgical vent or atrial septostomy). Without unloading, LV distension may contribute to thrombus formation, pulmonary edema and further myocardial injury [ 25] ( Table 1). 4.3. Guideline Recommendations and Clinical Practice 5. Limitations of the Evidence tMCS trials have enrolled markedly different populations. IABP-SHOCK II included mostly Stage C patients (median lactate ~4 mmol/L; ~45% post-arrest) [ 12]. IMPRESS randomized a profoundly compromised cohort (~94% out-of-hospital cardiac arrest, lactate > 8 mmol/L, ROSC 22 min), implying high risk of hypoxic brain injury [ 17]. ECLS-SHOCK similarly enrolled 78% post-arrest patients [ 14]. Such differences likely influenced neutral outcomes and limit the generalizability of any single trial beyond its enrolled phenotype. Conversely, DanGer Shock focused on a selected STEMI-CS population and excluded patients at high risk of irreversible neurological injury. Only ~20% had any cardiac arrest (during transport or after arrival), and comatose out-of-hospital arrest patients were excluded. Impella was implanted very early and according to standardized protocols at experienced centers; however, complication rates remained substantial, emphasizing the need for expertise and optimal timing of early intervention. Real-world registries reinforce concerns about external validity ( Table 3). Schrage et al. reported that only a minority of contemporary shock patients would qualify for major trials: 24.4% for DanGer Shock and 55.3% for IABP-SHOCK II [ 41]. Similarly, in the Dresden Impella Registry, 28.4% of STEMI-CS patients fulfilled DanGer Shock eligibility criteria [ 24]. These findings highlight that RCTs often exclude older patients, those with prolonged arrests and those with major comorbidities. Notably, in the Dresden registry, 30-day mortality remained high in both trial-eligible and trial-ineligible patients, suggesting that current criteria may not fully identify those most likely to benefit from tMCS. In routine practice, patients are often older, more metabolically compromised and present later in the shock course. Observational data show that real-world mortality with IABP often exceeds 50%, higher than the 39.7% in IABP-SHOCK II [ 12, 13, 14, 42]. ECMO-related mortality in registries can exceed 60%, above RCT rates. For Impella, reported mortality in practice (often 45–60%) is closer to trial data, possibly reflecting selective use in specialized centers ( Table 4). Recent analyses have attempted to refine selection by identifying “DanGer-like” profiles, i.e., patients with less advanced shock and intact neurological function. Some meta-analyses and registry evaluations suggest that when ECMO is applied in DanGer-like patients, outcomes are better than in non-DanGer-like patients treated with ECMO, underscoring the importance of neurological status and early selection [ 24, 34, 41, 42, 43, 44, 45]. Overall, these data emphasize that one-size-fits-all interpretations of RCTs may not apply across the spectrum of AMI-CS and support individualized decisions integrating trial and real-world evidence. 6. Discussion Cardiogenic shock remains highly lethal after AMI, with 30-day mortality around 40–50% and ~50% at one year despite advances in reperfusion and critical care. A major challenge is the heterogeneity of presentation and trajectory. The SCAI framework stratifies severity from Stage A to Stage E and, together with modifiers such as lactate and cardiac arrest, can support prognostication and management decisions. This heterogeneity is reflected in key tMCS trials. IABP-SHOCK II predominantly enrolled moderately severe shock (median lactate ~4 mmol/L; 8 mmol/L [ 17]; ECLS-SHOCK: 78% post-arrest [ 14]). These baseline differences likely contributed to neutral outcomes and limit generalizability beyond the enrolled phenotypes. VA-ECMO offers full cardiopulmonary support but introduces unique physiological challenges. Retrograde arterial flow increases afterload and can worsen LV distension and ischemia unless unloading is implemented. Trials reported limited and inconsistent venting, potentially contributing to a lack of mortality benefit. Additionally, ECMO complication rates, particularly bleeding and vascular injury, are high and may offset hemodynamic gains in broad shock populations [ 25, 32]. Guidelines reflect this mixed evidence ( Table 1). The 2023 ESC guidelines provided a cautious Class IIb recommendation for Impella in refractory shock at experienced centers and advised against routine IABP or VA-ECMO (Class III) in AMI-CS [ 7]. These recommendations were formulated before the DanGer Shock and ECLS-SHOCK results, relying on earlier evidence [ 25, 30]. In 2025, the ACC/AHA upgraded Impella to Class IIa for STEMI with severe or refractory shock while continuing to discourage routine VA-ECMO (Class III) [ 8]. Notably, no tMCS device has a Class I endorsement, underscoring continued uncertainty regarding optimal selection, timing and risk–benefit balance. Device-related bleeding and vascular risks, particularly outside expert centers or without established protocols, further justify caution. In summary, early recognition of cardiogenic shock and timely hemodynamic support are crucial to improve prognosis by enabling intervention before irreversible metabolic or multiorgan injury. For patients with severe but potentially survivable shock (e.g., SCAI Stage C or D with ongoing hypoperfusion but intact neurological status), judicious early tMCS may stabilize perfusion and bridge to recovery or definitive therapy. Device choice should be tailored: IABP may be sufficient for LV venting or mechanical complications; Impella can support isolated LV failure; and VA-ECMO is appropriate for patients in extremis or with severe biventricular/respiratory failure, ideally combined with unloading when needed ( Figure 2). Registry data also highlight that expertise matters: higher-volume CS/MCS centers have lower in-hospital mortality, with hazard ratios of approximately 0.80 for MCS-treated patients in centers performing ≥25 cases/year [ 37]. Improving survival in AMI-CS will likely require advances in devices and techniques, refined selection and timing, reduction in complications and shock-team pathways that deliver the right therapy to the right patient at the right time. 7. Conclusions AMI complicated by cardiogenic shock remains associated with unacceptably high mortality despite modern early revascularization and advanced critical care. tMCS devices such as IABP, Impella and VA-ECMO can provide important hemodynamic support, but robust evidence for improved survival is limited and sometimes conflicting. Current data support the selective use of Impella in carefully chosen patients, whereas routine use of IABP or VA-ECMO in unselected AMI-CS is not supported. The DanGer Shock trial offers encouraging evidence that early LV unloading can improve outcomes in selected STEMI-CS patients, but the associated complication burden and narrow eligibility criteria limit broad applicability. Implementation of multidisciplinary cardiogenic shock teams has been linked to better outcomes, with systematic reviews reporting that shock-team care is associated with higher 30-day and in-hospital survival and reduced ICU mortality compared with usual care [ 47]. These findings support the use of coordinated team-based protocols in managing AMI-related shock. A multidisciplinary shock-team approach, guided by SCAI staging and early identification of patients most likely to benefit, appears central to improving care. Ongoing and future research should focus on refining the timing of MCS initiation, sharpening patient selection criteria and developing strategies to minimize complications, so that mechanical support can be better tailored to the needs of this diverse, high-risk population. Author Contributions Conceptualization, C.A. and J.E.M.; methodology, C.A., N.M., V.P. and J.E.M.; investigation, C.A., N.M., V.P. and J.E.M.; writing—original draft preparation, C.A.; writing—review and editing, C.A., N.M., V.P. and J.E.M.; visualization, C.A. and N.M.; supervision, J.E.M. All authors have read and agreed to the published version of the manuscript. Funding This research received no external funding. Institutional Review Board Statement Not applicable. Informed Consent Statement Not applicable. Data Availability Statement No new data were created or analyzed in this study. Conflicts of Interest C.A. has received speaker’s fees from Abbott, Abiomed, Medtronic, Edwards Lifesciences, Terumo, Johnson & Johnson and Daiichi Sankyo. N.M. has received a research grant to his institution from Abiomed, outside the submitted work, and payment or honoraria for speaker fees from Abbott, Abiomed, Amgen, AstraZeneca, B.Braun, Biotronik, Boston Scientific, Cordis, Edwards Lifesciences, Inari, Medtronic and Shockwave, outside the submitted work. J.E.M. has received institutional research grants from Abiomed and the Novo Nordisk Foundation, and serves as an advisor for Abiomed, Magenta and Boston Scientific. V.P. declares no conflicts of interest related to this work. Abbreviations The following abbreviations are used in this manuscript: AMI Acute Myocardial Infarction AMI-CS Acute Myocardial Infarction-related Cardiogenic Shock CS Cardiogenic Shock tMCS Temporary Mechanical Circulatory Support MCS Mechanical Circulatory Support IABP Intra-Aortic Balloon Pump IABP-SHOCK II Intra-Aortic Balloon Pump in Cardiogenic Shock II (trial) MAFP Microaxial Flow Pump Impella Microaxial Flow Pump (device brand/system) VA-ECMO Veno-Arterial Extracorporeal Membrane Oxygenation ECMO-CS Extracorporeal Membrane Oxygenation in Cardiogenic Shock (trial) ECLS-SHOCK Extracorporeal Life Support in Cardiogenic Shock (trial) LV Left Ventricle RV Right Ventricle LVEDP Left Ventricular End-Diastolic Pressure PCI Percutaneous Coronary Intervention STEMI ST-Elevation Myocardial Infarction ROSC Return of Spontaneous Circulation RCT Randomized Controlled Trial NNT Number Needed to Treat NNH Number Needed to Harm HR Hazard Ratio RR Risk Ratio OR Odds Ratio ICU Intensive Care Unit BARC Bleeding Academic Research Consortium eCPR Extracorporeal Cardiopulmonary Resuscitation ECMELLA Combined ECMO + Impella strategy References Mebazaa, A.; Combes, A.; van Diepen, S.; Hollinger, A.; Katz, J.N.; Landoni, G.; Hajjar, L.A.; Lassus, J.; Lebreton, G.; Montalescot, G.; et al. 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CS, cardiogenic shock; MAFP, microaxial flow pump; STEMI, ST-elevation myocardial infarction. Figure 1. Summary of major randomized trials in AMI-related cardiogenic shock (IABP-SHOCK II, DanGer Shock, ECLS-SHOCK). The figure illustrates differences in patient features, study design and device strategies that limit the generalizability of results to broader shock populations. CS, cardiogenic shock; MAFP, microaxial flow pump; STEMI, ST-elevation myocardial infarction. Figure 2. Proposed decision-making algorithm for mechanical circulatory support in AMI-related cardiogenic shock. Early recognition with SCAI staging, lactate levels and neurological status guides candidate selection. Device choice should be tailored to clinical profile and institutional expertise: IABP only for mild shock or LV venting when other options are unavailable; Impella for isolated LV failure in experienced centers; and VA-ECMO (with LV unloading when possible) for refractory shock, cardiac arrest or severe biventricular/respiratory failure. AMI-CS, acute myocardial infarction-related cardiogenic shock; IABP, intra-aortic balloon pump; LV, left ventricle; MAFP, microaxial flow pump; SCAI, Society for Cardiovascular Angiography and Interventions; VA-ECMO, veno-arterial extracorporeal membrane oxygenation. Figure 2. Proposed decision-making algorithm for mechanical circulatory support in AMI-related cardiogenic shock. Early recognition with SCAI staging, lactate levels and neurological status guides candidate selection. Device choice should be tailored to clinical profile and institutional expertise: IABP only for mild shock or LV venting when other options are unavailable; Impella for isolated LV failure in experienced centers; and VA-ECMO (with LV unloading when possible) for refractory shock, cardiac arrest or severe biventricular/respiratory failure. AMI-CS, acute myocardial infarction-related cardiogenic shock; IABP, intra-aortic balloon pump; LV, left ventricle; MAFP, microaxial flow pump; SCAI, Society for Cardiovascular Angiography and Interventions; VA-ECMO, veno-arterial extracorporeal membrane oxygenation. Table 1. Percutaneous mechanical circulatory support devices in acute myocardial infarction-related cardiogenic shock. Table 1. Percutaneous mechanical circulatory support devices in acute myocardial infarction-related cardiogenic shock. IABP Impella VA-ECMO Mechanism of Action Diastolic counterpulsation: Balloon inflates in diastole (↑ coronary perfusion), deflates before systole (↓ afterload). Modest ↑ in CO (~0.5–1.0 L/min). Minimal/no direct effect on RV. Catheter-mounted microaxial pump placed across the aortic valve. Draws blood from LV to ascending aorta. Provides 3.5–5.5 L/min flow depending on model (CP, 5.5). Reduces LVEDP and myocardial O 2 demand; maintains systemic perfusion. Indirect benefit on RV via LV unloading and reduced LVEDP. Veno-arterial bypass: Venous drainage, oxygenation, arterial return. High-flow (3–5 L/min). ↑ LV afterload unless vented. Full cardiopulmonary support and full RV support (venous drainage and systemic return). Introducer Size (French) Typically 8 Fr. Typically 14 Fr. Typically 17–21 Fr venous; 15–19 Fr arterial. Key Clinical Trial IABP-SHOCK II ( n = 600): AMI-CS patients post-PCI randomized to IABP vs. standard care. IMPRESS ( n = 48); DanGer Shock ( n = 360). ECLS-SHOCK ( n = 417); ECMO-CS ( n = 117). Primary Outcome IABP 39.7% vs. control 41.3% ( p = 0.69). No mortality benefit. IMPRESS: 30-day mortality 50% vs. 63% ( p = 0.65); high-risk cohort (60% post-arrest, median lactate > 8 mmol/L). DanGer: Mortality 45.8% vs. 58.5% at 6 months; NNT~8; HR at 10 years 0.70 ( p = 0.01). ECLS-SHOCK: 47.8% vs. 49.0%; ECMO-CS: composite endpoint similar. Other Findings 10% crossover from control to IABP. Escalation to advanced MCS: 7.4% (IABP) vs. 5.1% (control). No significant difference in vascular complications. DanGer: 1.7% crossover, 21% protocolized escalation; ↑ complications (bleeding, limb ischemia, infection, RRT); NNH~6. ECLS-SHOCK: ↑ bleeding (23.4% vs. 9.6%) and vascular complications. Venting inconsistently applied. Meta-analyses: possible benefit in arrest/biventricular failure but high complications. Abbreviations: AMI-CS, acute myocardial infarction-related cardiogenic shock; CO, cardiac output; CP, Impella CP; IABP, intra-aortic balloon pump; LV, left ventricle; LVEDP, left ventricular end-diastolic pressure; MCS, mechanical circulatory support; NNH, number needed to harm; NNT, number needed to treat; PCI, percutaneous coronary intervention; RRT, renal replacement therapy; RV, right ventricle; STEMI, ST-elevation myocardial infarction; VA-ECMO, veno-arterial extracorporeal membrane oxygenation. Symbols: ↑, increase; ↓, decrease. Table 2. Comparison of major trials on mechanical circulatory support in acute myocardial infarction-related cardiogenic shock. Table 2. Comparison of major trials on mechanical circulatory support in acute myocardial infarction-related cardiogenic shock. Trial (Year) Population ( n) Device vs. Control Primary Endpoint Mortality Outcome Major Complications Abbreviations: AMI-CS, acute myocardial infarction-related cardiogenic shock; HR, hazard ratio; IABP, intra-aortic balloon pump; PCI, percutaneous coronary intervention; RR, risk ratio; RRT, renal replacement therapy; STEMI, ST-elevation myocardial infarction; VA-ECMO, veno-arterial extracorporeal membrane oxygenation. Symbols: ↑, increase; ↓, decrease. Table 3. Main clinical features of trials and real-world registries of mechanical circulatory support in acute myocardial infarction-related cardiogenic shock. Table 3. Main clinical features of trials and real-world registries of mechanical circulatory support in acute myocardial infarction-related cardiogenic shock. Characteristic DanGer Shock Other RCTs (ECLS-SHOCK, ECMO-CS) Real-World Registry Patient selection Highly selected Moderately selected Broad, less selected Mean age 67 years Similar ≈66 years STEMI only Yes Mixed STEMI/NSTEMI Mainly STEMI, variable Pre-Impella CPR 20% ≈50% (ECMO-CS) ≈44% LV ejection fraction 24% 30% ≈26.5% Lactate levels 5.7 mmol/L >5 mmol/L common ≈5.7 mmol/L Device used Impella CP ECLS/ECMO Mainly Impella CP, mixed with others Timing of device 57% pre-PCI (early) Variable Often post-PCI Standardization Strict protocol Variable across centers Clinician judgement PCI performed 97.6% 80–95% 88.9% Additional MCS used Yes, protocolized Yes, depending on trial Frequent, often combined Abbreviations: CP, Impella CP; CPR, cardiopulmonary resuscitation; ECMO, extracorporeal membrane oxygenation; LV, left ventricle; MCS, mechanical circulatory support; NSTEMI, non-ST-elevation myocardial infarction; PCI, percutaneous coronary intervention; RCT, randomized controlled trial; STEMI, ST-elevation myocardial infarction. Table 4. Outcomes of trials and real-world registries on mechanical circulatory support in acute myocardial infarction-related cardiogenic shock. Table 4. Outcomes of trials and real-world registries on mechanical circulatory support in acute myocardial infarction-related cardiogenic shock. Parameter Real-World DanGer Shock ECLS-SHOCK IABP-SHOCK II Total patients 528 355 417 600 Mortality with Impella 43% 45% (Impella group) Not applicable Not applicable Mortality with VA-ECMO 63% Not applicable 47.8% (VA-ECMO group) Not applicable Mortality with IABP 55% Not applicable Not applicable 39.7% Revascularization rate 92% >95% ~95% 100% Use of MCS 33% Impella vs. standard care VA-ECMO vs. standard care IABP vs. no IABP Impella use 17% Yes (randomized) No No VA-ECMO use 9% No Yes (randomized) No IABP use 7% No No Yes (randomized) Abbreviations: IABP, intra-aortic balloon pump; MCS, mechanical circulatory support; VA-ECMO, veno-arterial extracorporeal membrane oxygenation. 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Journal of Clinical Medicine. 2026; 15(12):4453. https://doi.org/10.3390/jcm15124453 Chicago/Turabian Style Aurigemma, Cristina, Norman Mangner, Vasileios Panoulas, and Jacob Eifer Møller. 2026. "Mechanical Support in Myocardial Infarction Complicated by Cardiogenic Shock: What Have We Learned from Trials?" Journal of Clinical Medicine 15, no. 12: 4453. https://doi.org/10.3390/jcm15124453 APA Style Aurigemma, C., Mangner, N., Panoulas, V., & Møller, J. E. (2026). Mechanical Support in Myocardial Infarction Complicated by Cardiogenic Shock: What Have We Learned from Trials? Journal of Clinical Medicine, 15(12), 4453. https://doi.org/10.3390/jcm15124453 Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here. Article Metrics Article metric data becomes available approximately 24 hours after publication online.
