Primary left ventricular unloading with delayed reperfusion in patients with anterior ST-elevation myocardial infarction: Rationale and design of the STEMI-DTU randomized pivotal trial

Tailored Therapy in Cardiogenic Shock: Case-Based Management Choices

Cardiogenic shock (CS) is a complex, multisystem disorder precipitated by hypoperfusion from cardiac dysfunction. Our current approach to defining and treating CS encompasses all patients under 1 umbrella regardless of phenotype. This has created challenges for clinical trials and patient care owing to the heterogeneity of the patient population with CS. The Society of Coronary Angiography and Interventions shock classification has created a universal language for CS that has been rapidly adopted by researchers and clinicians. Its latest iteration established the 3-axis model incorporating shock severity, risk modifiers, and phenotypes. Phenotypes of CS have unique hemodynamic profiles that require nuanced adjustment approaches. In this study, we discuss representative cases including acute myocardial infarction, acute-on-chronic heart failure, fulminant myocarditis, and right ventricular failure. For each phenotype, specific hemodynamic parameters may help confirm appropriate diagnosis and direct to therapeutic targets signaling stability and recovery. The underlying pathophysiology of each phenotype can also help predict the extent of stabilization with pharmacologic interventions or the need to escalate to mechanical circulatory support. In conclusion, this tailored approach to CS, rather than a 1-size-fits-all approach, could help improve outcomes.

ECLS-SHOCK and DanGer Shock: Implications for optimal temporary mechanical circulatory support use for cardiogenic shock due to acute myocardial infarction

Despite concerted efforts to rapidly identify patients with cardiogenic shock complicating acute myocardial infarction (AMI-CS) and provide timely revascularization, early mortality remains stubbornly high. While artificially augmenting systemic flow through the use of temporary mechanical circulatory support (tMCS) devices would be expected to reduce the rate of progression to multi-organ dysfunction and thereby enhance survival, reliable evidence for benefit has remained elusive with lingering questions regarding the appropriate selection of both patients and devices, as well as the timing of device implantation relative to other critical interventions. Further complicating matters are the resource-intensive multidisciplinary systems of care that must be brought to bear in this complex patient population. Until recently, studies of tMCS were extremely heterogenous in design, populations treated, and the timing of device implantation with regards to shock onset and revascularization. Attempts at summarizing the available data had resulted in a lack of clear benefit for any type of tMCS modality. On this background, two landmark trials of tMCS in the setting of AMI-CS - ECLS-SHOCK and DanGer Shock - have recently been published with divergent results that deserve detailed consideration. Herein, we therefore provide a detailed narrative review of the current state of knowledge regarding tMCS for AMI-CS. The most common types of tMCS and related evidence are presented, as well as evidence for organizational considerations, such as the Shock Team. We also provide some insight into how this new evidence might be incorporated in to practice today and influence future research.

Safety and utility of mechanical circulatory support in patients with acute myocardial infarction complicated by cardiogenic shock: A systematic review and meta-analysis

BACKGROUND

Acute myocardial infarction complicated by cardiogenic shock (AMI-CS) is a major cause of morbidity and mortality. Although mechanical circulatory support (MCS) is an increasingly utilized therapeutic option in AMI-CS, studies evaluating the efficacy and safety of different forms of MCS have yielded conflicting results. This systematic review and meta-analysis aims to evaluate the safety and efficacy of different forms of MCS.

METHODS

A database search was performed for studies reporting on the association of different forms of MCS with clinical outcomes in patients with AMI-CS. The primary efficacy endpoints were short term (≤30 days) and long term (>30 days) all-cause mortality. Secondary efficacy endpoints included recurrent AMI, cardiovascular (CV) mortality, device-related limb complications, moderate to severe bleeding events, and cerebrovascular accidents (CVA).

RESULTS

2752 patients with AMI-CS met inclusion criteria. Results were available comparing ECMO to other MCS or medical therapy alone, comparing IABP to medical therapy alone, and comparing pLVAD to IABP. Use of ECMO was not associated with lower risk of 30-day or long-term mortality compared to pVAD or standard medical therapy with or without IABP placement but was associated with higher risk of device-related limb complications and moderate to severe bleeding compared to pVAD. IABP use was not associated with a lower risk of 30 day or long-term mortality but was associated with higher risk of recurrent AMI and moderate to severe bleeding compared to medical therapy. Compared to IABP, pVAD use was associated with lower risk of CV mortality but not recurrent AMI. pVAD was associated with a higher risk of device-related limb complications and moderate to severe bleeding compared to IABP use.

CONCLUSION

Use of ECMO or IABP in patients with AMI-CS is not associated with significant improvement in mortality. pVAD is associated with a lower risk of CV mortality. All MCS types are associated with increased risk of complications. Additional high-quality studies are needed to determine the optimal MCS therapy for patients with AMI-CS.

A Systematic Review and Meta-Analysis of the Efficacy and Safety of Combined Mechanical Circulatory Support in Acute Myocardial Infraction Related Cardiogenic Shock

BACKGROUND

Acute myocardial infarction-related cardiogenic shock (AMICS) is a severe complication associated with exceedingly high mortality rates. While mechanical circulatory support (MCS) has emerged as a potential intervention, the evidence base for independent MCS use remains weak. In contrast, systematic reviews of observational studies have revealed significant mortality reduction when a combination of MCS was used: VA-ECMO in conjunction with a left ventricular (LV) unloading device (Impella or IABP). The ongoing dilemma concerning the selection between two LV unloading devices (VA-ECMO + Impella vs. VA-ECMO + IABP) warrants further investigation and clarification.

AIM

This is the first systematic review and meta-analysis assessing the short-term efficacy and safety of VA-ECMO + Impella versus VA-ECMO + IABP in treatment of AMICS.

METHODS

A systematic search was performed on the EMBASE, MEDLINE, and Cochrane databases. Studies reporting the short-term (30-day/inpatient) mortality and complications of adult patients with AMICS treated with VA-ECMO + Impella and VA-ECMO + IABP were included. Subgroup analysis was performed including studies with ACS predominant CS (CS etiology 100% by AMI).

RESULTS

Four observational studies with 14,247 patients were included. There was no significant difference in mortality between VA-ECMO + Impella and VA-ECMO + IABP (56.5% vs. 66.5%; OR, 0.90; 95% CI, 0.79-1.02; p = 0.09). However, VA-ECMO + Impella was associated with significantly lower mortality in patients with ACS predominant CS (53.2% vs. 67.7%; OR, 0.72; 95% CI, 0.62-0.85; p < 0.0001). VA-ECMO + Impella was concomitantly associated with a significantly higher risk of complications.

CONCLUSIONS

When comparing LV unloading devices in patients with AMICS requiring a combination of MCS, VA-ECMO + Impella was superior in mortality reduction only in the cohort where 100% of CS was caused by AMI.

Impact of ECPELLA support on 1-year outcomes and myocardial damage in patients with acute myocardial infarction and refractory cardiogenic shock: A single-center retrospective observational study

BACKGROUND

Venoarterial-extracorporeal membrane oxygenation (VA-ECMO) is a vital mechanical circulatory support for treating patients with refractory cardiogenic shock (CS). VA-ECMO can improve end-organ perfusion; however, it increases left ventricular (LV) afterload, resulting in further myocardial damage. ECPELLA, a combination of VA-ECMO and Impella (Abiomed Inc., Danvers, MA, USA) treatments, is an emerging modality to optimize end-organ perfusion and LV unloading. The impact of ECPELLA in refractory CS has not been established. We aimed to investigate the effects of ECPELLA on acute-phase LV damage and outcomes in patients with acute myocardial infarction (AMI) and refractory CS and compare them with those of VA-ECMO with an intra-aortic balloon pump (IABP).

METHODS

This single-center retrospective observational study included 90 consecutive patients with AMI and refractory CS who received VA-ECMO between January 2012 and December 2022. Of these, 44 and 46 received ECPELLA and VA-ECMO with IABP, respectively. We assessed the serum creatine kinase myocardial band (CK-MB) levels and 1-year mortality.

RESULTS

No significant differences were observed in the baseline characteristics and time from onset to reperfusion between the two groups. Compared with VA-ECMO with IABP, ECPELLA produced lower peak CK-MB levels (265 IU/L vs. 500 IU/L, p = 0.016) and a smaller area under the curve of the time course in the first 3 days (274 IU/L vs. 534 IU/L × d, p = 0.025). ECPELLA was associated with significantly lower 1-year mortality (64 % vs 91 %; p = 0.001). Cox proportional hazards analysis revealed that ECPELLA was inversely and independently associated with 1-year mortality (hazard ratio: 0.38, 95 % confidence interval: 0.23-0.64; p < 0.001).

CONCLUSIONS

Our findings suggest that ECPELLA may offer myocardial protection and be associated with improved 1-year mortality in patients with AMI and refractory CS. Further prospective studies are needed to confirm these observations and better understand the potential benefits of ECPELLA in this population.

MI2AMI-CS: A meta-analysis comparing Impella and IABP outcomes in Acute Myocardial Infarction-related Cardiogenic Shock

BACKGROUND

Cardiogenic Shock (CS) complicating acute myocardial infarction (AMI) poses a significant mortality risk, suggesting the opportunity to implement effective mechanical circulatory support strategies. The comparative efficacy of Intra-Aortic Balloon Pump (IABP) and Impella in managing CS-AMI remains a subject of investigation.

OBJECTIVE

This meta-analysis aims to evaluate the comparative effectiveness of Impella and IABP in managing CS-AMI, exploring mortality and adverse events.

METHODS

A systematic search of major databases from inception to November 2023 identified eight studies, comprising 10,628 patients, comparing Impella and IABP in CS-AMI. Retrospective studies (preferably Propensity-matched) and Randomized Clinical Trials (RCTs) were included.

RESULTS

Impella use exhibited significantly higher mortality (57% vs. 46%; OR: 1.44, 95% CI: 1.29-1.60; p < 0.001) and major bleeding (30% vs 15%; OR: 2.93, 95% CI: 1.67-5.13; p < 0.001).

CONCLUSIONS

In unselected CS-AMI patients, Impella usage is associated with significantly higher mortality and major bleeding.

SCAI Expert Consensus Statement on the Management of Patients With STEMI Referred for Primary PCI

ST-elevation myocardial infarction (STEMI) remains a leading cause of morbidity and mortality in the United States. Timely reperfusion with primary percutaneous coronary intervention is associated with improved outcomes. The Society for Cardiovascular Angiography & Interventions puts forth this expert consensus document regarding best practices for cardiac catheterization laboratory team readiness, arterial access with an algorithm to help determine proper arterial access in STEMI, and diagnostic angiography. This consensus statement highlights the strengths and limitations of various diagnostic and therapeutic interventions to access and treat a patient with STEMI in the catheterization laboratory, reviews different options to manage large thrombus burden during STEMI, and reviews the management of STEMI across the spectrum of various anatomical and clinical circumstances.

Pharmacological and Device-Based Intervention for Preventing Heart Failure After Acute Myocardial Infarction - A Clinical Review

In patients with acute myocardial infarction (MI), heart failure (HF) is one of the most common complications that is associated with a significant burden of mortality and healthcare resources. The clinical benefits of key HF drugs, the so-called "4 pillars" or "fantastic 4", namely β-blockers, mineralocorticoid receptor antagonists, angiotensin receptor-neprilysin inhibitor, and sodium-glucose cotransporter 2 inhibitors, have been established in patients with HF with reduced ejection fraction, whereas the effects of these drugs are not comprehensively appreciated in patients with acute MI. This review summarizes current evidence on pharmacological and device-based interventions for preventing HF after acute MI.

CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute coronary syndromes (ACS) in 2024

Primary Percutaneous Coronary Intervention (PCI) has significantly contributed to reducing the mortality of patients with ST-segment elevation myocardial infarction (STEMI) even in cardiogenic shock and is now the standard of care in most of Japanese institutions. The Task Force on Primary PCI of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) proposed an expert consensus document for the management of acute myocardial infarction (AMI) focusing on procedural aspects of primary PCI in 2018 and updated in 2022. Recently, the European Society of Cardiology (ESC) published the guidelines for the management of acute coronary syndrome in 2023. Major new updates in the 2023 ESC guideline include: (1) intravascular imaging should be considered to guide PCI (Class IIa); (2) timing of complete revascularization; (3) antiplatelet therapy in patient with high-bleeding risk. Reflecting rapid advances in the field, the Task Force on Primary PCI of the CVIT group has now proposed an updated expert consensus document for the management of ACS focusing on procedural aspects of primary PCI in 2024 version.

Mechanical Circulatory Support with Impella: Principles, Evidence, and Daily Practice

The Impella (Abiomed, Danvers, MA, USA) microaxial pump is a percutaneous mechanical circulatory support (MCS) that has been shown to increase coronary perfusion, reduce myocardial oxygen demand, and improve peripheral organ perfusion. Therefore, indications for the Impella device include emergency use for cardiogenic shock (CS) and pre-emptive implantation during high-risk percutaneous coronary intervention (HR-PCI). However, despite their exponential use in cardiovascular practice over the past decade, there is limited randomized evidence to support the benefits of this therapy and growing concern regarding complication rates. In this review, we summarize the principles, evidence, and practical considerations of the most widely used Impella CP percutaneous left ventricular support in both CS and HR-PCI settings, moving from the historical background to current issues and future expectations for this device.

Safety and efficacy of low-dose intracoronary thrombolysis during primary percutaneous coronary intervention in patients with ST elevation myocardial infarction: A meta-analysis of randomized trials

BACKGROUND

In patients with ST elevation myocardial infarction (STEMI), intracoronary thrombolysis (ICT) may reduce thrombotic burden and microvascular obstruction in the infarct-related artery. We performed a meta-analysis to evaluate the role of adjunctive low-dose ICT during primary percutaneous coronary intervention (PPCI) in improving clinical outcomes and indices of microvascular function.

METHODS

We searched electronic databases (Cochrane, EMBASE, Medline; inception to October 2023) for randomized controlled trials (RCTs) evaluating the effects of adjunctive ICT in STEMI patients undergoing PPCI, compared with placebo or usual care. Study-level data on efficacy and safety outcomes were pooled using a fixed-effect model. The primary outcome was major adverse cardiovascular events (MACE).

RESULTS

A total of 8 RCTs were included, comprising a total of 1,208 patients. Compared with placebo or usual care, ICT was associated with a trend towards lower MACE (11.3% vs. 15.1%; odds ratio [OR] 0.73, 95% confidence interval [CI] 0.51 to 1.04). Infarct size (mean difference [MD] -1.98, 95% CI -3.68 to -0.27; p=0.02), ST-segment resolution (MD: 6.06, 95% CI: 0.69 to 11.43; p=0.03) and corrected TIMI frame count (MD: -2.26, 95% CI: -4.03 to -0.48; p=0.01; I2=78%). The odds for major (0.7% vs. 0.7%; OR 0.94, 95% CI 0.24 to 3.7; p=0.93) and minor bleeding (7.7% vs. 4.3%; OR 1.81, 95% CI 0.87 to 3.76; p=0.11) were similar between the two groups.

CONCLUSION

Adjunctive low-dose ICT during PPCI is safe, associated with a trend towards lower MACE, and may improve surrogate markers of microvascular function. These hypothesis-generating findings warrant validation in larger, adequately powered randomized trials.

Reperfusion Injury in Patients With Acute Myocardial Infarction: JACC Scientific Statement

Despite impressive improvements in the care of patients with ST-segment elevation myocardial infarction, mortality remains high. Reperfusion is necessary for myocardial salvage, but the abrupt return of flow sets off a cascade of injurious processes that can lead to further necrosis. This has been termed myocardial ischemia-reperfusion injury and is the subject of this review. The pathologic and molecular bases for myocardial ischemia-reperfusion injury are increasingly understood and include injury from reactive oxygen species, inflammation, calcium overload, endothelial dysfunction, and impaired microvascular flow. A variety of pharmacologic strategies have been developed that have worked well in preclinical models and some have shown promise in the clinical setting. In addition, there are newer mechanical approaches including mechanical unloading of the heart prior to reperfusion that are in current clinical trials.

Treatment and Care of Patients with ST-Segment Elevation Myocardial Infarction-What Challenges Remain after Three Decades of Primary Percutaneous Coronary Intervention?

Primary percutaneous coronary intervention (pPCI) has revolutionized the prognosis of ST-segment elevation myocardial infarction (STEMI) and is the gold standard treatment. As a result of its success, the number of pPCI centres has expanded worldwide. Despite decades of advancements, clinical outcomes in STEMI patients have plateaued. Out-of-hospital cardiac arrest and cardiogenic shock remain a major cause of high in-hospital mortality, whilst the growing burden of heart failure in long-term STEMI survivors presents a growing problem. Many elements aiming to optimize STEMI treatment are still subject to debate or lack sufficient evidence. This review provides an overview of the most contentious current issues in pPCI in STEMI patients, with an emphasis on unresolved questions and persistent challenges.

Coronary microvascular obstruction and dysfunction in patients with acute myocardial infarction

Despite prompt epicardial recanalization in patients presenting with ST-segment elevation myocardial infarction (STEMI), coronary microvascular obstruction and dysfunction (CMVO) is still fairly common and is associated with poor prognosis. Various pharmacological and mechanical strategies to treat CMVO have been proposed, but the positive results reported in preclinical and small proof-of-concept studies have not translated into benefits in large clinical trials conducted in the modern treatment setting of patients with STEMI. Therefore, the optimal management of these patients remains a topic of debate. In this Review, we appraise the pathophysiological mechanisms of CMVO, explore the evidence and provide future perspectives on strategies to be implemented to reduce the incidence of CMVO and improve prognosis in patients with STEMI.

Novel Role for Cardiolipin as a Target of Therapy to Mitigate Myocardial Injury Caused by Venoarterial Extracorporeal Membrane Oxygenation

BACKGROUND

Cardiolipin is a mitochondrial-specific phospholipid that maintains integrity of the electron transport chain (ETC) and plays a central role in myocardial ischemia/reperfusion injury. Tafazzin is an enzyme that is required for cardiolipin maturation. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) use to provide hemodynamic support for acute myocardial infarction has grown exponentially, is associated with poor outcomes, and is under active clinical investigation, yet the mechanistic effect of VA-ECMO on myocardial damage in acute myocardial infarction remains poorly understood. We hypothesized that VA-ECMO acutely depletes myocardial cardiolipin and exacerbates myocardial injury in acute myocardial infarction.

METHODS

We examined cardiolipin and tafazzin levels in human subjects with heart failure and healthy swine exposed to VA-ECMO and used a swine model of closed-chest myocardial ischemia/reperfusion injury to evaluate the effect of VA-ECMO on cardiolipin expression, myocardial injury, and mitochondrial function.

RESULTS

Cardiolipin and tafazzin levels are significantly reduced in the left ventricles of individuals requiring VA-ECMO compared with individuals without VA-ECMO before heart transplantation. Six hours of exposure to VA-ECMO also decreased left ventricular levels of cardiolipin and tafazzin in healthy swine compared with sham controls. To explore whether cardiolipin depletion by VA-ECMO increases infarct size, we performed left anterior descending artery occlusion for a total of 120 minutes followed by 180 minutes of reperfusion in adult swine in the presence and absence of MTP-131, an amphipathic molecule that interacts with cardiolipin to stabilize the inner mitochondrial membrane. Compared with reperfusion alone, VA-ECMO activation beginning after 90 minutes of left anterior descending artery occlusion increased infarct size (36±8% versus 48±7%; P<0.001). VA-ECMO also decreased cardiolipin and tafazzin levels, disrupted mitochondrial integrity, reduced electron transport chain function, and promoted oxidative stress. Compared with reperfusion alone or VA-ECMO before reperfusion, delivery of MTP-131 before VA-ECMO activation reduced infarct size (22±8%; P=0.03 versus reperfusion alone and P<0.001 versus VA-ECMO alone). MTP-131 restored cardiolipin and tafazzin levels, stabilized mitochondrial function, and reduced oxidative stress in the left ventricle.

CONCLUSIONS

We identified a novel mechanism by which VA-ECMO promotes myocardial injury and further identify cardiolipin as an important target of therapy to reduce infarct size and to preserve mitochondrial function in the setting of VA-ECMO for acute myocardial infarction.

Microaxial Flow Pump or Standard Care in Infarct-Related Cardiogenic Shock

BACKGROUND

The effects of temporary mechanical circulatory support with a microaxial flow pump on mortality among patients with ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock remains unclear.

METHODS

In an international, multicenter, randomized trial, we assigned patients with STEMI and cardiogenic shock to receive a microaxial flow pump (Impella CP) plus standard care or standard care alone. The primary end point was death from any cause at 180 days. A composite safety end point was severe bleeding, limb ischemia, hemolysis, device failure, or worsening aortic regurgitation.

RESULTS

A total of 360 patients underwent randomization, of whom 355 were included in the final analysis (179 in the microaxial-flow-pump group and 176 in the standard-care group). The median age of the patients was 67 years, and 79.2% were men. Death from any cause occurred in 82 of 179 patients (45.8%) in the microaxial-flow-pump group and in 103 of 176 patients (58.5%) in the standard-care group (hazard ratio, 0.74; 95% confidence interval [CI], 0.55 to 0.99; P = 0.04). A composite safety end-point event occurred in 43 patients (24.0%) in the microaxial-flow-pump group and in 11 (6.2%) in the standard-care group (relative risk, 4.74; 95% CI, 2.36 to 9.55). Renal-replacement therapy was administered to 75 patients (41.9%) in the microaxial-flow-pump group and to 47 patients (26.7%) in the standard-care group (relative risk, 1.98; 95% CI, 1.27 to 3.09).

CONCLUSIONS

The routine use of a microaxial flow pump with standard care in the treatment of patients with STEMI-related cardiogenic shock led to a lower risk of death from any cause at 180 days than standard care alone. The incidence of a composite of adverse events was higher with the use of the microaxial flow pump. (Funded by the Danish Heart Foundation and Abiomed; DanGer Shock ClinicalTrials.gov number, NCT01633502.).

Reduction of left ventricular diastolic pressure as a key regulator of infarct coronary flow under mechanical left ventricular support

Restoring ischaemic myocardial tissue perfusion is crucial for minimizing infarct size. Acute mechanical left ventricular (LV) support has been suggested to improve infarct tissue perfusion. However, its regulatory mechanism remains unclear. We investigated the physiological mechanisms in six Yorkshire pigs, which were subjected to 90-min balloon occlusion of the left anterior descending artery. During the acute reperfusion phase, LV support using an Impella heart pump was initiated. LV pressure, coronary flow and pressure of the infarct artery were simultaneously recorded to evaluate the impact of LV support on coronary physiology. Coronary wave intensity was calculated to understand the forces regulating coronary flow. Significant increases in coronary flow velocity and its area under the curve were found after mechanical LV support. Among the coronary flow-regulating factors, coronary pressure was increased mainly during the late diastolic phase with less pulsatility. Meanwhile, LV pressure was reduced throughout diastole resulting in significant and consistent elevation of coronary driving pressure. Interestingly, the duration of diastole was prolonged with LV support. In the wave intensity analysis, the duration between backward suction and pushing waves was extended, indicating that earlier myocardial relaxation and delayed contraction contributed to the extension of diastole. In conclusion, mechanical LV support increases infarct coronary flow by extending diastole and augmenting coronary driving pressure. These changes were mainly driven by reduced LV diastolic pressure, indicating that the key regulator of coronary flow under mechanical LV support is downstream of the coronary artery, rather than upstream. Our study highlights the importance of LV diastolic pressure in infarct coronary flow regulation. KEY POINTS: Restoring ischaemic myocardial tissue perfusion is crucial for minimizing infarct size. Although mechanical left ventricular (LV) support has been suggested to improve infarct coronary flow, its specific mechanism remains to be clarified. LV support reduced LV pressure, and elevated coronary pressure during the late diastolic phase, resulting in high coronary driving pressure. This study demonstrated for the first time that mechanical LV support extends diastolic phase, leading to increased infarct coronary flow. Future studies should evaluate the correlation between improved infarct coronary flow and resulting infarct size.

Contemporary approach to cardiogenic shock care: a state-of-the-art review

Cardiogenic shock (CS) is a time-sensitive and hemodynamically complex syndrome with a broad spectrum of etiologies and clinical presentations. Despite contemporary therapies, CS continues to maintain high morbidity and mortality ranging from 35 to 50%. More recently, burgeoning observational research in this field aimed at enhancing the early recognition and characterization of the shock state through standardized team-based protocols, comprehensive hemodynamic profiling, and tailored and selective utilization of temporary mechanical circulatory support devices has been associated with improved outcomes. In this narrative review, we discuss the pathophysiology of CS, novel phenotypes, evolving definitions and staging systems, currently available pharmacologic and device-based therapies, standardized, team-based management protocols, and regionalized systems-of-care aimed at improving shock outcomes. We also explore opportunities for fertile investigation through randomized and non-randomized studies to address the prevailing knowledge gaps that will be critical to improving long-term outcomes.

Delaying reperfusion plus left ventricular unloading reduces infarct size: Sub-analysis of DTU-STEMI pilot study

INTRODUCTION

The STEMI-DTU pilot study tested the early safety and practical feasibility of left ventricular (LV) unloading with a trans-valvular pump before reperfusion. In the intent-to-treat cohort, no difference was observed for microvascular obstruction (MVO) or infarct size (IS) normalized to either the area at risk (AAR) at 3-5 days or total LV mass (TLVM) at 3-5 days We now report a per protocol analysis of the STEMI-DTU pilot study.

METHODS

In STEMI-DTU STUDY 50 adult patients (25 in each arm) with anterior STEMI [sum of precordial ST-segment elevation (ΣSTE) ≥4 mm] requiring primary percutaneous coronary intervention (PCI) were enrolled. Only patients who met all inclusion and exclusion criteria were included in this analysis. Cardiac magnetic resonance (CMR) imaging 3-5 days after PCI quantified IS/AAR and IS/TLVM and MVO. Group differences were assessed using Student's t-tests and linear regression (SAS Version-9.4).

RESULTS

Of the 50 patients enrolled, 2 died before CMR imaging. Of the remaining 48 patients those without CMR at 3-5 days (n = 8), without PCI of a culprit left anterior descending artery lesion (n = 2), with OHCA (n = 1) and with ΣSTE < 4 mm (n = 5) were removed from this analysis leaving 32/50 (64 %) patients meeting all inclusion and exclusion criteria (U-IR, n = 15; U-DR, n = 17) as per protocol. Despite longer symptom-to-balloon times in the U-DR arm (228 ± 80 vs 174 ± 59 min, p < 0.01), IS/AAR was significantly lower with 30 min of delay to reperfusion in the presence of active LV unloading (47 ± 16 % vs 60 ± 15 %, p = 0.02) and remained lower irrespective of the magnitude of precordial ΣSTE. MVO was not significantly different between groups (1.5 ± 2.8 % vs 3.5 ± 4.8 %, p = 0.15). Among patients who received LV unloading within 180 min of symptom onset, IS/AAR was significantly lower in the U-DR group.

CONCLUSION

In this per-protocol analysis of the STEMI-DTU pilot study we observed that LV unloading for 30 min before reperfusion significantly reduced IS/AAR compared to LV unloading and immediate reperfusion, whereas in the ITT cohort no difference was observed between groups. This observation supports the design of the STEMI-DTU pivotal trial and suggests that strict adherence to the study protocol can significantly influence the outcome.

The spectrum of post-myocardial infarction care: From acute ischemia to heart failure

Heart failure (HF) is the leading cause of mortality in patients with acute myocardial infarction (AMI), with incidence ranging from 14% to 36% in patients admitted due to AMI. HF post-MI develops due to complex inter-play between macrovascular obstruction, microvascular dysfunction, myocardial stunning and remodeling, inflammation, and neuro-hormonal activation. Cardiogenic shock is an extreme presentation of HF post-MI and is associated with a high mortality. Early revascularization is the only therapy shown to improve survival in patients with cardiogenic shock. Treatment of HF post-MI requires prompt recognition and timely introduction of guideline-directed therapies to improve mortality and morbidity. This article aims to provide an up-to-date review on the incidence and pathogenesis of HF post-MI, current strategies to prevent and treat onset of HF post-MI, promising therapeutic strategies, and knowledge gaps in the field.

The Index of Microcirculatory Resistance After Primary PCI: A Pooled Analysis of Individual Patient Data

BACKGROUND

Despite treatment with primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI), the risk of heart failure and late death remains high. Microvascular dysfunction, as assessed by the index of microcirculatory resistance (IMR), after primary PCI for STEMI has been associated with worse outcomes. It is unclear whether IMR after primary PCI predicts cardiac death.

OBJECTIVES

The aims of this analysis were: 1) to determine if IMR is an independent predictor of cardiac death; 2) to assess the optimal cutoff value of IMR after STEMI; and 3) to compare IMR with several cardiac magnetic resonance parameters, including infarct size.

METHODS

In a collaborative, pooled analysis of individual patient data from 6 cohorts that measured IMR directly after primary PCI, cardiac mortality up to 5 years was estimated using Kaplan-Meier analyses. The primary endpoint was cardiac death using the predefined IMR cutoff value of 40.

RESULTS

In total, 1,265 patients were included in this study with a median follow-up of 2.8 years (IQR: 1.2-5.0 years). Cardiac death at 5 years occurred in 2.2% and 4.9% of patients (HR: 2.81; 95% CI: 1.34-5.88; P = 0.006) in the IMR ≤40 and IMR >40 groups, respectively. The composite of cardiac death or hospitalization for heart failure occurred in 4.9% and 8.9% (HR: 1.98; 95% CI: 1.20-3.29; P = 0.008) in the IMR ≤40 and IMR >40 groups, respectively. IMR was an independent predictor of cardiac death, whereas coronary flow reserve was not. The optimal cutoff value of IMR for the prediction of cardiac death in this cohort was 70 (HR: 4.73; 95% CI: 2.27-9.83; P < 0.001). Infarct size was 17.6% ± 13.3% and 23.9% ± 14.6% of the left ventricular mass in the IMR ≤40 and IMR >40 groups, respectively (P < 0.001). Microvascular obstruction and intramyocardial hemorrhage occurred more frequently in the IMR >40 group than in the IMR ≤40 group.

CONCLUSIONS

In this large, pooled analysis of individual patient data, IMR measured directly after primary PCI in STEMI was an independent predictor of cardiac death. IMR may be used as a tool to identify patients at the time of primary PCI who are at highest risk for late cardiac mortality and who might benefit most from additional cardioprotective therapies and monitoring.

Contemporary Management of Cardiogenic Shock Complicating Acute Myocardial Infarction

Despite an improvement in pharmacological therapies and mechanical reperfusion, the outcome of patients with acute myocardial infarction (AMI) is still suboptimal, especially in patients with cardiogenic shock (CS). The incidence of CS accounts for 3-15% of AMI cases, with mortality rates of 40% to 50%. In contrast to a large number of trials conducted in patients with AMI without CS, there is limited evidence-based scientific knowledge in the CS setting. Therefore, recommendations and actual treatments are often based on registry data. Similarly, knowledge of the available options in terms of temporary mechanical circulatory support (MCS) devices is not equally widespread, leading to an underutilisation or even overutilisation in different regions/countries of these treatment options and nonuniformity in the management of CS. The aim of this article is to provide a critical overview of the available literature on the management of CS as a complication of AMI, summarising the most recent evidence on revascularisation strategies, pharmacological treatments and MCS use.