Improved Survival After Acute Myocardial Infarction Complicated by Cardiogenic Shock With Circulatory Support and Transplantation: Comparing Aggressive Intervention With Conservative Treatment

Dynamic Modulation of Device-Arterial Coupling to Determine Cardiac Output and Vascular Resistance

Clinical adoption of mechanical circulatory support for shock is rapidly expanding. Achieving optimal therapeutic benefit requires metrics of state to guide titration and weaning of support. Using the transvalvular positioning of a percutaneous ventricular assist device (pVAD), device:heart interactions are leveraged to determine cardiac output (CO) and systemic vascular resistance (SVR) near-continuously without disrupting therapeutic function. An automated algorithm rapidly alternates between device support levels to dynamically modulate physiological response. Employing a two-element lumped parameter model of the vasculature, SVR and CO are quantified directly from measurements obtained by the pVAD without external calibration or invasive catheters. The approach was validated in an acute porcine model across a range of cardiac (CO = 3-10.6 L/min) and vascular (SVR = 501-1897 dyn s/cm⁵) states. Cardiac output calculations closely correlated (r = 0.82) to measurements obtained by the pulmonary artery catheter-based thermodilution method with a mean bias of 0.109 L/min and limits of agreement from - 1.67 to 1.89 L/min. SVR was also closely correlated (r = 0.86) to traditional catheter-based measurements with a mean bias of 62.1 dyn s/cm⁵ and limits of agreement from - 260 to 384 dyn s/cm⁵. Use of diagnostics integrated into therapeutic device function enables the potential for optimizing support to improve outcomes for cardiogenic shock.

Stem cell therapy of myocardial infarction: a promising opportunity in bioengineering

Myocardial infarction (MI) is a life-threatening disease resulting from irreversible death of cardiomyocytes (CMs) and weakening of the heart blood-pumping function. Stem cell-based therapies have been studied for MI treatment over the last two decades with promising outcome. In this review, we critically summarize the past work in this field to elucidate the advantages and disadvantages of treating MI using pluripotent stem cells (PSCs) including both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), adult stem cells, and cardiac progenitor cells. The main advantage of the latter is their cytokine production capability to modulate immune responses and control the progression of healing. However, human adult stem cells have very limited (if not 'no') capacity to differentiate into functional CMs in vitro or in vivo. In contrast, PSCs can be differentiated into functional CMs although the protocols for the cardiac differentiation of PSCs are mainly for adherent cells under 2D culture. Derivation of PSC-CMs in 3D, allowing for large-scale production of CMs via modulation of the Wnt/β-catenin signal pathway with defined chemicals and medium, may be desired for clinical translation. Furthermore, the technology of purification and maturation of the PSC-CMs may need further improvements to eliminate teratoma formation after in vivo implantation of the PSC-CMs for treating MI. In addition, in vitro derived PSC-CMs may have mechanical and electrical mismatch with the patient's cardiac tissue, which causes arrhythmia. This supports the use of PSC-derived cells committed to cardiac lineage without beating for implantation to treat MI. In this case, the PSC derived cells may utilize the mechanical, electrical, and chemical cues in the heart to further differentiate into mature/functional CMs in situ. Another major challenge facing stem cell therapy of MI is the low retention/survival of stem cells or their derivatives (e.g., PSC-CMs) in the heart for MI treatment after injection in vivo. This may be resolved by using biomaterials to engineer stem cells for reduced immunogenicity, immobilization of the cells in the heart, and increased integration with the host cardiac tissue. Biomaterials have also been applied in the derivation of CMs in vitro to increase the efficiency and maturation of differentiation. Collectively, a lot has been learned from the past failure of simply injecting intact stem cells or their derivatives in vivo for treating MI, and bioengineering stem cells with biomaterials is expected to be a valuable strategy for advancing stem cell therapy towards its widespread application for treating MI in the clinic.

Leveraging Device-Arterial Coupling to Determine Cardiac and Vascular State

OBJECTIVE

Limitations in available diagnostic metrics restrict the efficacy of managing therapies for cardiogenic shock. In current clinical practice, cardiovascular state is inferred through measurement of pulmonary capillary wedge pressure and reliance on linear approximations between pressure and flow to estimate peripheral vascular resistance. Mechanical circulatory support devices residing within the left ventricle and aorta provide an opportunity for both determining cardiac and vascular state and offering therapeutic benefit. We leverage the controllable mode of operation and transvalvular position of an indwelling percutaneous ventricular assist device to assess vascular and, in turn, cardiac state through the effects of device-arterial coupling across different levels of device support.

METHODS

Vascular state is determined by measuring changes in the pressure waveforms induced through intentional variation in the device generated blood flow. We evaluate this impact by applying a lumped parameter model to quantify state-specific vascular resistance and compliance and calculate beat-to-beat stroke volume and cardiac output in both animal models and retrospective patient data without external calibration.

RESULTS

Vascular state was accurately predicted in patients and animals in both baseline and experimental conditions. In the animal, stroke volume was predicted within a total root mean square error of 3.71 mL (n = 482).

CONCLUSION

We demonstrate that device-arterial coupling is a powerful tool for evaluating patient and state specific parameters of cardiovascular function.

SIGNIFICANCE

These insights may yield improved clinical care and support the development of next generation mechanical circulatory support devices that determine and operate in tandem with the supported organ.

Mechanical circulatory support device-heart hysteretic interaction can predict left ventricular end diastolic pressure

The full potential of mechanical circulatory systems in the treatment of cardiogenic shock is impeded by the lack of accurate measures of cardiac function to guide clinicians in determining when to initiate and how to optimally titrate support. The left ventricular end diastolic pressure (LVEDP) is an established metric of cardiac function that refers to the pressure in the left ventricle at the end of ventricular filling and immediately before ventricular contraction. In clinical practice, LVEDP is typically only inferred from, and poorly correlates with, the pulmonary capillary wedge pressure (PCWP). We leveraged the position of an indwelling percutaneous ventricular assist device and advanced data analysis methods to obtain LVEDP from the hysteretic operating metrics of the device. We validated our hysteresis-derived LVEDP measurement using mock flow loops, an animal model of cardiac dysfunction, and data from a patient in cardiogenic shock to show greater measurement precision and correlation with actual pressures than traditional inferences via PCWP. Delineation of the nonlinear relationship between device and heart adds insight into the interaction between ventricular support devices and the native heart, paving the way for continuous assessment of underlying cardiac state, metrics of cardiac function, potential closed-loop automated control, and rational design of future innovations in mechanical circulatory support systems.

Predictors of Outcomes in Myocardial Infarction and Cardiogenic Shock

Myocardial infarction (MI) complicated by cardiogenic shock (MI-CS) is a major cause of cardiovascular morbidity and mortality. Predictors of outcomes in MI-CS include clinical, laboratory, radiologic variables, and management strategies. This article reviews the existing literature on short- and long-term predictors and risk stratification in MI complicated by CS.

Initial Experience of Transaortic Catheter Venting in Patients with Venoarterial Extracorporeal Membrane Oxygenation for Cardiogenic Shock

Extracorporeal membrane oxygenation (ECMO) has become one of the often applied mechanical support for acute cardiogenic shock. During venoarterial (VA) ECMO support, left heart decompression should be considered when left ventricular (LV) distension develops with pulmonary edema and LV dysfunction. The aim of this study was to report the results of transaortic catheter venting (TACV), as an alternative venting method, performed during VA-ECMO in patients with acute cardiogenic shock. We retrospectively reviewed the records of seven patients who underwent both ECMO and TACV between February 2013 and February 2014. Extracorporeal membrane oxygenation was performed uneventfully, and TACV was introduced under transthoracic echocardiographic guidance in all cases. Hemodynamic parameters, LV ejection fraction, and LV end-diastolic dimension (LVEDD) were measured 24 hours after initiating TACV in survivors. There were no procedure-related complications. Four of the seven patients (58%) survived. Transaortic catheter venting led to an increase in mean blood pressure in all patients (p = 0.050). There was a significant difference between pre- and post-TACV-LVEDD (59 ± 14 vs. 50 ± 12 mm, p = 0.044), with a 10-23% reduction in LVEDD in survivors. Transaortic catheter venting might be an acceptable alternative to venting procedures and useful for LV recovery during VA-ECMO in patients with severe LV dysfunction.

Use of adenosine diphosphate receptor inhibitor prior to left ventricular assist device implantation is not associated with increased bleeding

Current guidelines recommend adenosine diphosphate receptor inhibitors (ADPRi) be discontinued 5-7 days prior to cardiac surgery due to increased bleeding events, rates of re-exploration, and transfusions. However, the risks of left ventricular assist device (LVAD) implantation in patients taking an ADPRi have not previously been studied. We retrospectively identified 134 eligible patients with ischemic cardiomyopathy that underwent LVAD implantation between July 2009 and August 2013. The cohorts received an ADPRi ≤5 days of surgery (n = 25) versus >5 days prior or not at all (n = 109). Subgroup analyses adjusted for differences in frequency of redo sternotomy between cohorts, excluded patients that received an ADPRi >1 year prior to surgery, and excluded patients with a redo sternotomy. The ADPRi and control groups did not have significant differences in the primary outcomes, intraoperative PRBC units transfused (3.0 vs. 4.0, p = 0.12) or chest tube output within 24 h of surgery (1.66 L vs. 1.80 L, p = 0.61). After adjusting for differences in frequency of redo sternotomy (ADPRi vs. control, 12 vs. 52%, p ≤ 0.001), no significant difference in PRBC units transfused (3.1 vs. 3.5, p = 0.59) or chest tube output (2.04 L vs. 2.04 L, p = 0.98) was seen. No significant difference in 30-day mortality (8.0 vs. 11.0%, p = 0.63), 90-day mortality (16.4 vs. 23.3%, p = 0.42), or length of stay (29.0 vs. 28.0, p = 0.61) was seen. In this single-center experience, use of an ADPRi ≤5 days prior to LVAD implantation was not associated with increased bleeding, length of stay, or mortality.

Moving Beyond SHOCK: New Paradigms in the Management of Acute Myocardial Infarction Complicated by Cardiogenic Shock

The current management of patients with acute myocardial infarction complicated by cardiogenic shock (AMI-CS) is associated with a high rate of mortality, despite widespread regional implementation of rapid transfer to percutaneous coronary intervention-capable centres for prompt infarct-related artery reperfusion. The limited clinical effectiveness of early revascularization in patients with AMI-CS might be secondary to the extent of coronary artery disease in these patients and the risk of incomplete revascularization, as well as the lower probability of achieving successful reperfusion compared with acute myocardial infarction without hemodynamic instability. Also, the severity of end-organ injury is a critical determinant of outcome. We review adjunctive therapies to early revascularization in AMI-CS, specifically with a focus on the role of short-term mechanical circulatory support. In selected patients with AMI-CS, there might be a benefit associated with early institution of mechanical circulatory support before revascularization.

Cardiogenic Shock: Failure of Oxygen Delivery and Oxygen Utilization

Cardiogenic shock remains a highly lethal condition. Conventional therapy including revascularization and mechanical circulatory support aims to improve cardiac output and oxygen delivery, but increasing basic and clinical observations indicate wider circulatory and cellular abnormalities, particularly at the advanced stages of shock. Progressive cardiogenic shock is associated with microcirculatory and cellular abnormalities. Cardiogenic shock is initially characterized by a failure to maintain global oxygen delivery; however, progressive cardiogenic shock is associated with the release of pro-inflammatory cytokines, derangement of the regulation of regional blood flow, microcirculatory abnormalities, and cellular dysoxia. These abnormalities are analogous to septic shock and may not be reversed by increase in oxygen delivery, even to supranormal levels. Earlier mechanical circulatory support in cardiogenic shock may limit the development of microcirculatory and cellular abnormalities.

Central extracorporeal life support with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure

BACKGROUND

The purpose of this prospective study was to evaluate the effects and functional outcome of central extracorporeal life support (ECLS) with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure.

METHODS

Between August 2010 and August 2013, 12 consecutive patients (2 female) with a mean age of 31.6 ± 15.1 years received central ECLS with left ventricular decompression for the treatment of refractory cardiogenic shock and lung failure. Underlying disease was acute cardiac decompensation due to dilated cardiomyopathy (n = 3, 25%), coronary artery disease with acute myocardial infarction (AMI) (n = 3, 25%), and acute myocarditis (n = 6, 50%). We routinely implemented ECLS by cannulating the ascending aorta, right atrium and inserting a left ventricular decompression cannula vent via the right superior pulmonary vein.

RESULTS

All patients were successfully bridged to either recovery (n = 3, 25%), long-term biventricular support (n = 6, 50%) or cardiac transplantation (n = 3, 25%). Seven patients (58.3%) were discharged after a mean hospital stay of 42 ± 11.9 days. The overall survival from ECLS implantation to the end of the study was 58.3%. The cumulative ICU stay was 23.1 ± 9.6 days. The length of support was 8.0 ± 4.3 days (range 3-17 days).

CONCLUSIONS

We strongly recommend left ventricular decompression in refractory cardiogenic shock and lung failure to avoid pulmonary edema, left heart distension and facilitate myocardial recovery.

Outcomes among patients requiring unplanned intra-aortic balloon pump reinsertion in cardiogenic shock

INTRODUCTION

The intra-aortic balloon pump (IABP) is the most frequently utilized form of temporary mechanical circulatory support (MCS) in cardiogenic shock (CS). Withdrawal of IABP support may precipitate hemodynamic compromise such that IABP reinsertion is required. Data are scarce regarding the incidence and outcomes of patients undergoing IABP reinsertion in this setting.

METHODS

In this single-center retrospective study, we identified consecutive patients with CS in whom IABP reinsertion was required for hemodynamic decompensation. These patients were compared to matched controls in whom IABP withdrawal was successful. The primary outcome measure was in-hospital mortality, while the secondary outcome measure was a composite of in-hospital death, need for advanced MCS or heart transplantation, or discharge to hospice.

RESULTS

Among 222 patients requiring IABP for CS, we identified 20 case patients (incidence=9.0%) and 38 matched controls. Baseline characteristics were similar for the two groups. In-hospital mortality was 70% in the reinsertion group and 31% in the controls (Odds ratio (OR) 5.2, 95% CI 1.4-18.9, P=0.005). The composite secondary endpoint was also significantly more common in the reinsertion group than the controls (85% vs. 42%; OR 7.3, 95% CI 1.6-33.1, P=0.002). On multivariate analysis, the need for IABP reinsertion was independently associated with in-hospital mortality (OR 7.7, 95% CI 1.6-36.2, P=0.01).

CONCLUSION

Among patients with CS undergoing IABP removal, hemodynamic deterioration requiring IABP reinsertion is associated with extremely poor outcomes and, in appropriate patients, should prompt consideration of more advanced cardiac support.

Mechanical circulatory support in cardiogenic shock

Despite advances in coronary revascularization and widespread use of primary percutaneous interventions, cardiogenic shock complicating an acute ST-elevation myocardial infarction (CSMI) remains a clinical challenge with high mortality rates. Conservative management with catecholamines is associated with serious limitations, including arrhythmias, increased myocardial oxygen consumption, and inadequate circulatory support. Clinicians have therefore turned to mechanical means of circulatory support. Circulatory assist systems for CSMI can be distinguished by the method of placement (i.e. percutaneous vs. surgical), the type of circulatory support (i.e. left ventricular, right ventricular, or biventricular pressure and/or volume unloading), and whether they are combined with extracorporal membrane oxygenation (ECMO). The percutaneous assist systems most commonly used in CSMI are the intra-aortic balloon pump (IABP), venoarterial ECMO, the Impella pump, and the TandemHeart. Decades of clinical studies and experience demonstrated haemodynamic improvement, including elevation of diastolic perfusion pressure and cardiac output. Recently, the large randomized IABP-Shock II Trial did not show a significant reduction in 30-day mortality in CSMI with IABP insertion. There are no randomized study data available for ECMO use in CSMI. Both the Impella pump and the TandemHeart did not reduce 30-day mortality when compared with IABP in small randomized controlled trials (RCTs). In conclusion, despite the need for effective mechanical circulatory support in CSMI, current devices, as tested, have not been demonstrated to improve short- or long-term survival rates. RCTs testing the optimal timing of device therapy and optimal device design are needed to improve outcomes in CSMI.

Cardiogenic Shock: Background, Shock Trial/Registry, Evolving Data, Changing Survival, Best Medical Therapy

Cardiogenic shock remains associated with unacceptably high mortality, but recent improvements with early revascularization, continued support with pharmacologic agents, and use of an intra-aortic balloon pump have led to improvements in the rate of mortality. Timely intervention with cardiac surgery in patients with mechanical complications, 3-vessel disease, and left main disease is beneficial. Continued research and ever-improving understanding of this once deadly condition have helped further in improving prognosis. Cutting-edge technologies, such as myocyte cell implantation and the use of a cooling system, will help in pushing the boundaries farther.

Peripheral extracorporeal membrane oxygenation system as salvage treatment of patients with refractory cardiogenic shock: preliminary outcome evaluation

The novel Permanent Life Support (PLS; Maquet, Jostra Medizintechnik AG, Hirrlingen, Germany) as peripheral veno-arterial extracorporeal membrane oxygenation (ECMO) support system has been investigated as treatment for patients with refractory cardiogenic shock (CS). Between January 2007 and July 2011, 73 consecutive adult patients were supported on peripheral PLS ECMO system at our institution (55 men; age 60.3 ± 11.6 years, range: 23-84 years). Indications for support were failure to wean from cardiopulmonary bypass in the setting of postcardiotomy (n = 50) and primary donor graft failure (n = 8), post-acute myocardial infarction CS (n = 12), and CS on chronic heart failure (n = 3). Mean support time was 10.9 ± 7.6 days (range: 2-34 days). Overall, 26 (35.6%) patients died on ECMO. Among survivors on ECMO, 44 (60.2%) patients were successfully weaned from support, and three (4.1%) were switched to a mid-long-term ventricular assist device. Thirty-three (45.2%) were successfully discharged. The following variables were significantly different if survivors and nonsurvivors on ECMO were compared: age (P = 0.04), female gender (P < 0.01), cardiopulmonary resuscitation before ECMO (P < 0.01), lactate level before ECMO (P = 0.01), number of platelets, fresh frozen plasma units, and packed red blood cells (PRBCs) transfused during ECMO support (P = 0.03, P = 0.02, and P < 0.01), blood lactate level (P = 0.01), and creatine kinase isoenzyme MB (CK-MB) relative index 72 h after ECMO initiation (P < 0.001), and multiple organ failure on ECMO (P < 0.01). Stepwise logistic regression identified blood lactate level and CK-MB relative index at 72 h after ECMO initiation, and number of PRBCs transfused on ECMO as significant predictors of mortality on ECMO (P = 0.011, odds ratio [OR] = 2.48; 95% confidence interval [CI] = 1.11-3.12; P = 0.012, OR = 2.81, 95% CI = 1.026-2.531; and P = 0.012, OR = 1.94, 95% CI = 1.02-5.21; respectively). Patients with an initial poor hemodynamic status could benefit by rapid peripheral installation of PLS ECMO. The blood lactate level, CK-MB relative index, and PRBCs transfused should be strictly monitored during ECMO support.

Percutaneous ventricular assist devices: new deus ex machina?

The development of ventricular assist devices has broadened the means with which one can treat acute heart failure. Percutaneous ventricular assist devices (pVAD) have risen from recent technological advances. They are smaller, easier, and faster to implant, all important qualities in the setting of acute heart failure. The present paper briefly describes the functioning and assets of the most common devices used today. It gives an overview of the current evidence and indications for left ventricular assist device use in cardiogenic shock and high-risk percutaneous coronary intervention. Finally, extracorporeal life support devices are dealt with in the setting of hemodynamic support.

Portable mechanical circulatory support: human experience with the LIFEBRIDGE system

PURPOSE

This study was designed to demonstrate the safety and functional performance of the LIFEBRIDGE B2T system (Medizintechnik GmbH, Ampfing, Germany), a novel portable life support system, during human applications under controlled conditions.

DESCRIPTION

The LIFEBRIDGE system was used as a modular closed-circuit miniaturized cardiopulmonary bypass system for total support of circulation and gas exchange in a series of 8 elective coronary artery bypass grafting procedures using normothermic cardioplegic arrest.

EVALUATION

Mean blood flow rates provided by the LIFEBRIDGE system were 4.82±0.47 L/min throughout the procedures (ie, 100% of calculated normal blood flow). Adequate gas exchange and arterial oxygenation were provided at all times. All patients survived the operations with no neurologic sequelae.

CONCLUSIONS

The LIFEBRIDGE system provides sufficient circulatory support and gas exchange during cardiac arrest and apnea, which are the maximum stress conditions for a life support system. It is anticipated that the system will be widely used as a circulatory support system in future applications that require portability and rapid delivery of short-term mechanical circulatory support, such as with cardiogenic shock.

Emergency cardiac surgery in patients with acute coronary syndromes: a review of the evidence and perioperative implications of medical and mechanical therapeutics

Patients with acute coronary syndromes who require emergency cardiac surgery present complex management challenges. The early administration of antiplatelet and antithrombotic drugs has improved overall survival for patients with acute myocardial infarction, but to achieve maximal benefit, these drugs are given before coronary anatomy is known and before the decision to perform percutaneous coronary interventions or surgical revascularization has been made. A major bleeding event secondary to these drugs is associated with a high rate of death in medically treated patients with acute coronary syndrome possibly because of subsequent withholding of antiplatelet and antithrombotic therapies that otherwise reduce the rate of death, stroke, or recurrent myocardial infarction. Whether the added risk of bleeding and blood transfusion in cardiac surgical patients receiving such potent antiplatelet or antithrombotic therapy before surgery specifically for acute coronary syndromes affects long-term mortality has not been clearly established. For patients who do proceed to surgery, strategies to minimize bleeding include stopping the anticoagulation therapy and considering platelet and/or coagulation factor transfusion and possibly recombinant-activated factor VIIa administration for refractory bleeding. Mechanical hemodynamic support has emerged as an important option for patients with acute coronary syndromes in cardiogenic shock. For these patients, perioperative considerations include maintaining appropriate anticoagulation, ensuring suitable device flow, and periodically verifying correct device placement. Data supporting the use of these devices are derived from small trials that did not address long-term postoperative outcomes. Future directions of research will seek to optimize the balance between reducing myocardial ischemic risk with antiplatelet and antithrombotics versus the higher rate perioperative bleeding by better risk stratifying surgical candidates and by assessing the effectiveness of newer reversible drugs. The effects of mechanical hemodynamic support on long-term patient outcomes need more stringent analysis.

Percutaneous left ventricular assist devices during cardiogenic shock and high-risk percutaneous coronary interventions

Left ventricular assist devices were developed to support the function of a failing left ventricle. Owing to recent technological improvements, ventricular assist devices can be placed by percutaneous implantation techniques, which offer the advantage of fast implantation in the setting of acute left ventricular failure. This article reviews the growing evidence supporting the clinical use of left ventricular assist devices. Specifically, we discuss the use of left ventricular assist devices in patients with cardiogenic shock, in patients with acute ST-elevation myocardial infarction without shock, and during high-risk percutaneous coronary interventions.

Early risk stratification of patients with cardiogenic shock complicating acute myocardial infarction who undergo percutaneous coronary intervention

The mortality rate of patients with cardiogenic shock complicating acute myocardial infarction remains exceedingly high despite early mechanical revascularization. Early risk stratification is of great importance to identify patients who could benefit from ventricular assist devices and urgent heart transplantation (UHT). All consecutive patients with cardiogenic shock complicating acute myocardial infarction admitted from June 2001 to December 2007 were prospectively included. Clinical, hemodynamic, and echocardiographic variables were registered on admission and patients were followed for a median of 297 days. A total of 74 patients were included. One-year mortality was 55% and 7 patients (9%) underwent UHT. One-year mortality or need for UHT for patients with postprocedural Thrombolysis In Myocardial Infarction (TIMI) grade 3, 2, and 0 or 1 flows were 38%, 92%, and 90%, respectively (p <0.001). After adjustment by multivariate analysis, the most important predictors of mortality or need for UHT were age >75 years (hazard ratio [HR] 3.56, 95% confidence interval [CI] 1.07 to 11.80), left main coronary artery occlusion (HR 3.75, 95% CI 1.09 to 12.84), left ventricular ejection fraction <25% (HR 2.70, 95% CI 1.17 to 6.22), and postprocedural TIMI grade <3 flow (HR 3.37, 95% CI 1.48 to 7.72). A simple risk score constructed with these 4 variables effectively predicted 1-year survival without the need for UHT (83% for score 0, 19% for score 1, and 6% for score 2, p <0.001). In conclusion, age >75 years, left main coronary artery occlusion, left ventricular ejection fraction <25%, and postprocedural TIMI grade <3 flow were significantly associated with worse prognosis. A simple risk score rapidly available in the catheterization laboratory can efficiently estimate prognosis.

Surgical therapies for post-myocardial infarction patients

Occasionally, high-risk patients in the post-myocardial infarction (MI) period require surgical intervention for stabilization and/or revascularization. In a meta-analysis involving 3,088 patients with ischemic heart disease, revascularization was associated with nearly an 80% reduction in the risk of death. Coronary artery bypass graft (CABG) surgery is commonly performed in post-MI patients and is associated with more favorable outcomes than medical therapy. However, several factors have to be considered in proper patient selection for CABG, such as the left ventricular ejection fraction (LVEF), severity of heart failure (HF), and myocardial viability. The ongoing Surgical Treatment for Ischemic Heart Failure (STICH) trial will assess the benefits of CABG in patients with both a low LVEF and HF. Unstable post-MI patients who fail revascularization can be managed via mechanical circulatory support devices or pumps. These options significantly improve hemodynamic parameters. In addition, other surgical techniques, such as mitral valve repair, ventricular reconstruction surgery, and atrial fibrillation ablation, are being evaluated in patients with ischemic heart disease.

Cardiopulmonary resuscitation with assisted extracorporeal life-support versus conventional cardiopulmonary resuscitation in adults with in-hospital cardiac arrest: an observational study and propensity analysis

BACKGROUND

Extracorporeal life-support as an adjunct to cardiac resuscitation has shown encouraging outcomes in patients with cardiac arrest. However, there is little evidence about the benefit of the procedure compared with conventional cardiopulmonary resuscitation (CPR), especially when continued for more than 10 min. We aimed to assess whether extracorporeal CPR was better than conventional CPR for patients with in-hospital cardiac arrest of cardiac origin.

METHODS

We did a 3-year prospective observational study on the use of extracorporeal life-support for patients aged 18-75 years with witnessed in-hospital cardiac arrest of cardiac origin undergoing CPR of more than 10 min compared with patients receiving conventional CPR. A matching process based on propensity-score was done to equalise potential prognostic factors in both groups, and to formulate a balanced 1:1 matched cohort study. The primary endpoint was survival to hospital discharge, and analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00173615.

FINDINGS

Of the 975 patients with in-hospital cardiac arrest events who underwent CPR for longer than 10 min, 113 were enrolled in the conventional CPR group and 59 were enrolled in the extracorporeal CPR group. Unmatched patients who underwent extracorporeal CPR had a higher survival rate to discharge (log-rank p<0.0001) and a better 1-year survival than those who received conventional CPR (log rank p=0.007). Between the propensity-score matched groups, there was still a significant difference in survival to discharge (hazard ratio [HR] 0.51, 95% CI 0.35-0.74, p<0.0001), 30-day survival (HR 0.47, 95% CI 0.28-0.77, p=0.003), and 1-year survival (HR 0.53, 95% CI 0.33-0.83, p=0.006) favouring extracorporeal CPR over conventional CPR.

INTERPRETATION

Extracorporeal CPR had a short-term and long-term survival benefit over conventional CPR in patients with in-hospital cardiac arrest of cardiac origin.

Extracorporeal membrane oxygenation with a poly-methylpentene oxygenator (Quadrox D). The experience of a single Italian centre in adult patients with refractory cardiogenic shock

Although microporous polypropylene hollow fiber oxygenators are standard devices used for extracorporeal membrane oxygenation (ECMO), they have limitations such as development of plasma leakage. Poly-methylpentene (PMP) is a new material used for the last generation of oxygenators. We reviewed our experience with a new PMP oxygenator (Quadrox D) and a centrifugal pump (RotaFlow) used to support adult patients with refractory cardiogenic shock. Between January 2000 and April 2007, 25 patients required ECMO for primary or postcardiotomy cardiogenic shock. Eighteen patients were analyzed [mean age 60.2 years; 11 (61%) men; 7 (39%) women]. Nine patients (50%) suffered primary cardiogenic shock. Cardiopulmonary resuscitation was applied in 11 patients (61%) with a mean duration time of 31.5 minutes. Mean ECMO duration time was 7.1 +/- 6.3 days (range, 1-27 days). Intra-aortic balloon pump was used in 13 patients (72.2%) with a mean duration time of 7.7 +/- 5 (range, 2-17 days). Twelve patients (66.7%) survived on ECMO and five patients (27.8%) were discharged. Our results indicate the PMP oxygenator and the centrifugal pump provided acceptable results in terms of surviving on ECMO and discharge. Patients with an initial catastrophic hemodynamic status could benefit by means of a rapid institution of ECMO with PMP oxygenators.

Mechanical cardiac assistance improves outcome after prolonged hemorrhagic shock

To examine the use of mechanical cardiac assist devices in prolonged hemorrhagic shock lasting up to 120 min. We induced hemorrhagic shock in anesthetized calves that were then treated 30 or 120 min later with either conventional fluid and blood resuscitation methods or the implantation of a mechanical assist device in addition to conventional fluid resuscitation. We measured hemodynamic and hematologic variables, inflammatory mediators, end-organ function via biochemical parameters, and survival time. Although cardiac output and blood flow in the left anterior descending artery decreased significantly in all calves at the end of the hemorrhage period, the drop was significantly less severe in calves who received mechanical assistance in addition to fluids. Furthermore, the biochemical profile, indicating liver and kidney function, and survival time were better after hemorrhage in device-treated calves than in conventionally treated calves. Levels of inflammatory mediators, which contribute to cell and organ dysfunction, were increased after hemorrhage, but calves with mechanical devices had less of an increase than did calves treated only with fluids. Our results indicate that the use of a mechanical cardiac assist device in combination with conventional fluid and blood resuscitation methods improves survival and end-organ recovery and decreases the myocardial inflammatory response after prolonged hemorrhagic shock when compared with the sole use of conventional fluid resuscitation techniques.

Clinical Characteristics and In-Hospital Outcomes of Patients With Cardiogenic Shock Undergoing Coronary Artery Bypass Surgery

Background— There exist few studies that characterize contemporary clinical features and outcomes or risk factors for operative mortality in cardiogenic shock (CS) patients undergoing coronary artery bypass grafting (CABG).

Methods and Results— We evaluated data of 708 593 patients with and without CS undergoing CABG enrolled in the Society of Thoracic Surgeons National Cardiac Database (2002–2005). Clinical, angiographic, and operative features and in-hospital outcomes were evaluated in patients with and without CS. Logistic regression was used to identify predictors of operative mortality and to estimate weights for an additive risk score. Patients with preoperative CS constituted 14 956 (2.1%) of patients undergoing CABG yet accounted for 14% of all CABG deaths. Operative mortality in CS patients was high and surgery specific, rising from 20% for isolated CABG to 33% for CABG plus valve surgery and 58% for CABG plus ventricular septal repair. Although mortality for CABG surgery overall declined significantly over time ( P for trend <0.0001), mortality for CS patients undergoing CABG did not change significantly during the 4-year study period ( P =0.07). Factors associated with higher death risk for CS patients undergoing CABG were identified by multivariable analysis and summarized into a simple bedside risk score (c statistic=0.74) that accurately stratified those with low (<10%) to very high (>60%) mortality risk.

Conclusions— Patients with CS represent a minority of those undergoing CABG yet have persistently high operative risks, accounting for 14% of deaths in CABG patients. Estimation of patient-specific risk of mortality is feasible with the simplified additive risk tool developed in our study with the use of routinely available preprocedural data.

Cardiogenic shock

Cardiogenic shock is the most common cause of death in patients hospitalized with acute myocardial infarction and is associated with a poor prognosis. More than 75% of cases are due to extensive left ventricular infarction and ventricular failure. Other causes include right ventricular infarction and papillary muscle rupture with acute severe mitral regurgitation. Activation of neurohormonal systems and the systemic inflammatory response worsens shock. To improve outcomes, cardiogenic shock needs to be recognized early in its course and its cause needs to be diagnosed rapidly. Treatment strategies using intra-aortic balloon counterpulsation and emergency revascularization by percutaneous coronary interventions or coronary bypass surgery have been shown to improve outcomes. To decrease the incidence of cardiogenic shock, public education regarding early presentation to hospital in the course of acute chest pain is important. Emergency medical transport systems may need to take patients with complicated acute myocardial infarction to hospitals with the capability to perform urgent revascularization.

Percutaneous left ventricular assist devices for treatment of patients with cardiogenic shock

PURPOSE OF REVIEW

This review will discuss the rationale and clinical utility of percutaneous left ventricular assist devices in the management of patients with cardiogenic shock.

RECENT FINDINGS

Left ventricular assist devices maintain partial or total circulatory support in case of severe left ventricular failure. Currently, two percutaneous left ventricular assist devices are available for clinical use: the TandemHeart and the Impella Recover LP system. Compared with the intraaortic balloon pump, the TandemHeart has been shown to significantly reduce preload and to augment cardiac output. In a randomized comparison between the TandemHeart and intraaortic balloon pump support in patients with cardiogenic shock, the improved cardiac index afforded by the left ventricular assist device resulted in a more rapid decrease in serum lactate and improved renal function. There were, however, no significant differences with respect to 30-day mortality, and complications including limb ischemia and severe bleeding were more frequent with left ventricular assist devices than intraaortic balloon pump support.

SUMMARY

The advent of percutaneous left ventricular assist devices constitutes an important advance in the management of patients with severe cardiogenic shock and may serve as bridge to recovery or heart transplantation in carefully selected patients. While improvement of hemodynamic parameters appears promising, it remains to be determined whether this benefit translates into improved clinical outcome.