Intraaortic balloon counterpulsation with and without reperfusion for myocardial infarction shock

Still a place for aortic counterpulsation in cardiac surgery and patients with cardiogenic shock?

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2021. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2021 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901 .

IABP: history-evolution-pathophysiology-indications: what we need to know

Treatment with the intraaortic balloon pump (IABP) is the most common form of mechanical support for the failing heart. Augmentation of diastolic pressure during balloon inflation contributes to the coronary circulation and the presystolic deflation of the balloon reduces the resistance to systolic output. Consequently, the myocardial work is reduced. The overall effect of the IABP therapy is an increase in the myocardial oxygen supply/demand ratio and thus in endocardial viability.

This is an overall synopsis of what we need to know regarding IABP. Furthermore, this review article attempts to systematically delineate the pathophysiology linked with the hemodynamic consequences of IABP therapy. The authors also look at the future of the use of the balloon pump and conclude that the positive multi-systemic hemodynamic regulation during IABP treatment should further justify its use.

Hemodynamic Support Devices for Complex Percutaneous Coronary Intervention

High-risk percutaneous coronary intervention (PCI) encompasses a growing portion of total PCIs performed and typically includes patients with high-risk clinical and anatomic characteristics. Such patients may represent not only a high-risk group for complications but also a group who may derive the most benefit from complete revascularization. Several hemodynamic support devices are available. Trial data, consensus documents, and guidelines currently recommend high-risk PCI aided by hemodynamic support devices, and this article discusses the patient populations who would benefit from such an approach, the available devices and strategies, and expected outcomes.

Counterpulsation: a concept with a remarkable past, an established present and a challenging future

The intra-aortic balloon pump (IABP), which is the main representative of the counterpulsation technique, has been an invaluable tool in cardiologists' and cardiac surgeons' armamentarium for approximately half a century. The IABP confers a wide variety of vaguely understood effects on cardiac physiology and mechano-energetics. Although, the recommendations for its use are multiple, most are not substantially evidence-based. Indicatively, the results of recently performed prospective studies have put IABP's utility in the setting of post-infarction cardiogenic shock into question. However, the particular issue remains open to further research. IABP support in high-risk patients undergoing PCI is associated with favorable long-term clinical outcome. In cardiac surgery, the use of IABP in cases of peri-operative low-output syndrome, refractory angina or ischemia-related mechanical complications is a usual, but poorly justified strategy. Anecdotal cases of treatment of incessant ventricular arrhythmias, reversal of right ventricular dysfunction and partial myocardial recovery have also been reported with its use. Converging data demonstrate the potential of safe long-term IABP support as a bridge to decision making or a bridge to transplantation modality in patients with heart failure. The feasibility of IABP insertion via other than the femoral artery sites enhances this potential. Despite the fact that several other counterpulsation devices have been developed and tested overtime none has managed to substitute the IABP, which continues to be most frequently used mechanical assist device.

Intra-aortic balloon pump (ΙΑΒΡ): from the old trends and studies to the current "extended" indications of its use

This report outlines the well defined indications of using IABP and also favours extending the indications of IABP use, to include not only “therapeutically” the aging unstable patients but also “prophylactically” patients with low EF or high Euroscore.

Cardiogenic shock: a historical perspective

Significant progress has been made over the past 60 years in defining and recognizing cardiogenic shock (CS), and there have been tremendous advances in the care of patients who have this illness. Although there are many causes of this condition, acute myocardial infarction with loss of a large amount of functioning myocardium is the most frequent cause. It was recognized early in the study of CS that prompt diagnosis and rapid initiation of therapy could improve the prognosis, and this remains true today. Although the mortality from CS remains high, especially in elderly populations, modern therapies improve the chance of survival from this critical illness.

Efficacy of balloon valvuloplasty in patients with critical aortic stenosis and cardiogenic shock--the role of shock duration

BACKGROUND

Because of limited long-term success, aortic balloon valvuloplasty is considered to be a palliative procedure, including patients at excessive risk for standard therapy-aortic valve replacement-that is, those in cardiogenic shock.

HYPOTHESIS

The study was undertaken to evaluate the outcome of balloon valvuloplasty for critical aortic stenosis complicated by cardiogenic shock.

METHODS

Over a 10-year-period, we followed 14 patients (age 74+/-11 years, range 50-91) presenting in cardiogenic shock and critical aortic stenosis, who underwent valvuloplasty, together with 19 patients with critical aortic stenosis requiring urgent major noncardiac surgery.

RESULTS

In patients in shock, calculated aortic valve area could be increased successfully by at least 0.3 cm2, from 0.38+/-0.09 to 0.81+/-0.12 cm2, with an insignificant increase in cardiac index from 1.89+/-0.33 to 2.01+/-0.41 l/min * m2. In-hospital mortality was 71% (10 patients). Two patients underwent valve replacement within 16 days and survived after 1 year, as did two patients refusing surgery. By multivariate logistic regression analysis, only an interval between onset of shock symptoms and valvuloplasty of > 48 h was significantly associated with fatal outcome (p < 0.01). In those patients requiring noncardiac surgery, this was possible after valvuloplasty in 95% who survived 1 year after hospital discharge. One patient in this group died of pulmonary embolism the day after the procedure.

CONCLUSION

These data support the concept of causal treatment in patients with cardiogenic shock, as well as in the setting of cardiogenic shock and critical aortic stenosis, at the earliest possible convenience.

Cardiogenic shock: therapy and prevention

Cardiogenic shock is defined as profound circulatory failure resulting in insufficient tissue perfusion to meet resting metabolic demands. It occurs in approximately 7.5% of patients with acute myocardial infarction. Treatment strategies include inotropic agents, use of intra-aortic balloon counterpulsation, and revascularization. Current evidence supports the use of primary angioplasty. Surgery should be considered in patients with triple-vessel disease. If early catheterization is not available, thrombolytic therapy should be given to eligible patients and transfer to an interventional facility should be considered. Effective therapy for shock must also include a prevention strategy. This requires identification of patients at high risk for shock development and selection of patients who are candidates for aggressive intervention.

[Left ventricular assist devices in the catheterisation laboratory]

Mechanical cardiac support represents a large spectrum of devices. The duration of assistance may vary from a few hours in the cath lab to several weeks. The goals for a temporary support by percutaneus assistance are: improve end-organ perfusion; decrease pulmonary capillary wedge pressure; decrease myocardial oxygen consumption. The potential indications are: acute left ventricular dysfunction; "bridge to recovery": acute myocarditis, acute myocardial infarction, valve disease bridge to surgery; "bridge to implantable LVAD"; "bridge to transplant"; high risk PCI and surgery.

Surgery for myocardial salvage in acute myocardial infarction and acute coronary syndromes

This article addresses the pathophysiology, the treatment options, and their rationale in the setting of life-threatening acute myocardial infarction and acute on chronic ischemia. Although biases may exist between cardiologists and surgeons, with this review, we hope to provide the reader with information that will shed light on the options that best suit the individual patient in a given set of circumstances.

Mechanical Circulatory Support for Cardiogenic Shock Complicating Acute Myocardial Infarction: An Experimental and Clinical Review

Cardiogenic shock (CS) occurs in 7% to 10% of cases after acute myocardial infarction and remains the most common cause of death in these patients. Despite aggressive treatment regimens such as fibrinolysis and percutaneous transluminal coronary angioplasty, mortality rates from CS remain extremely high. It has been shown that intra-aortic balloon pumping can result in initial hemodynamic stabilization. However, in the majority of studies, death was merely delayed. In recent years, efforts have been made to develop ventricular devices (LVAD) capable of providing complete short-term hemodynamic support. Seventeen major studies of LVAD support for CS complicating acute myocardial infarction are reported in the literature, with a mean weaning and survival rate of 58.5% and 40%, respectively. Patients considered in these studies are difficult to compare in terms of demographic and anatomic data, but taking these considerations into account, LVAD support seems to give no survival improvement in these patients compared with early reperfusion alone or associated with intra-aortic balloon pumping. Data emerging from experimental studies of acute myocardial infarction supported with LVAD are intriguing. In this review, we report the LVAD experience in the CS setting, starting from percutaneous extracorporeal support up to bridge therapy with implantable devices.

A Novel Mechanical Circulatory Approach for Patients with Cardiogenic Shock in the Intensive Care Unit

BACKGROUND

The capacity of the heart to maintain cardiac output can be acutely impaired as a result of myocardial infarction, graft failure after transplantation, or other cardiac events. Medical therapy or the use of an intra-aortic balloon pump may be insufficient to help the patient overcome acute cardiogenic shock. The set-up of mechanical assist devices such as extracorporeal membrane oxygenation or patient relocation into the operating room requires valuable time that is often not available. The aim of our study was to test whether a novel left ventricular assist device can be percutaneously implanted without fluoroscopy under echocardiographic navigation in a preclinical model.

METHODS

Pigs were subjected to percutaneous implantation of a novel left ventricular assist device under navigation of transesophageal echocardiography (TEE) without fluoroscopic support. Percutaneous puncture of the interatrial septum using a Brockenbrough needle and insertion of the afferent cannula into the femoral vein and its advance to the right atrium and through the interatrial septum into the left atrium was performed under echocardiographic control. The efferent cannula was inserted into the contralateral femoral artery using the Seldinger technique.

RESULTS

In all animals, the percutaneous implantation of a left ventricular assist device was successful under only TEE navigation.

CONCLUSIONS

The ability to abstain from fluoroscopy and the feasibility of inserting the afferent cannula across the interatrial septum guided by TEE allows for application of this system in intensive care units, saving precious time as well as financial and human resources.

Percutaneous Left Ventricular Support Devices

Patients undergoing percutaneous coronary intervention (PCI) who have severely compromised left ventricular systolic function and complex coronary lesions including multivessel disease, left main disease, or bypass graft disease are at higher risk of adverse outcomes from hemodynamic collapse. The TandemHeart percutaneous left ventricular assist device and the Impella Recover LP 2.5 System may provide rapid circulatory support in high-risk PCI patients and in those who have cardiogenic shock. Identification of patients who are at high risk for severe hemodynamic compromise and most likely to benefit from mechanical circulatory support is crucial to derive the most benefit from this therapy. Multicenter randomized clinical trials are needed to clearly define the role of these two devices in providing circulatory support in a variety of clinical settings.

Racial and ethnic differences in the treatment and outcome of cardiogenic shock following acute myocardial infarction

We investigated the association between race/ethnicity on the use of cardiac resources in patients who have acute myocardial infarction that is complicated by cardiogenic shock. The Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock (SHOCK) trial examined the effect of reperfusion and revascularization treatment strategies on mortality. Patients screened but not enrolled in the SHOCK Trial (n = 1,189) were entered into the SHOCK registry. Of the patients in the United States registry (n = 538) who had shock due to predominant left ventricular failure, 440 were characterized as white (82%), 42 as Hispanic (8%), 34 as African-American (6%), and 22 as Asian/other (4%). The use of invasive procedures differed significantly by race/ethnicity. Hispanic patients underwent coronary angiography significantly less often than did white patients (38 vs 66%, p = 0.002). Among those patients who underwent coronary angiography, there were no race/ethnicity differences in the proportion of patients who underwent revascularization (p = 0.353). Overall in-hospital mortality (57%) differed significantly by race/ethnicity (p = 0.05), with the highest mortality rate in Hispanic patients (74% vs 65% for African-Americans, 56% for whites, and 41% for Asian/other). After adjustment for patient characteristics and use of revascularization, there were no mortality differences by race/ethnicity (p = 0.262), with all race/ethnicity subgroups benefiting equally by revascularization. In conclusion, the SHOCK registry showed significant differences in the treatment and in-hospital mortality of Hispanic patients who had cardiogenic shock, with these patients being less likely to undergo percutaneous coronary intervention. Therefore, early revascularization should be strongly considered for all patients, independent of race/ethnicity, who develop cardiogenic shock after acute myocardial infarction.

Randomized comparison of intra-aortic balloon support with a percutaneous left ventricular assist device in patients with revascularized acute myocardial infarction complicated by cardiogenic shock

AIMS

Mortality in cardiogenic shock (CS) following acute myocardial infarction (AMI) remains unacceptably high despite percutaneous coronary intervention (PCI) of the infarcted artery and use of intra-aortic balloon pump (IABP) counterpulsation. A newly developed percutaneous left ventricular assist device (VAD) (Tandem Heart, Cardiac Assist, Pittsburgh, PA, USA) with active circulatory support might have positive haemodynamic effects and decrease mortality.

METHODS AND RESULTS

Patients in CS after AMI, with intended PCI of the infarcted artery, were randomized to either IABP (n=20) or percutaneous VAD support (n=21). The primary outcome measure cardiac power index, as well as other haemodynamic and metabolic variables, could be improved more effectively by VAD support from 0.22 [interquartile range (IQR) 0.19-0.30] to 0.37 W/m2 (IQR 0.30-0.47, P<0.001) when compared with IABP from 0.22 (IQR 0.18-0.30) to 0.28 W/m2 (IQR 0.24-0.36, P=0.02; P=0.004 for intergroup comparison). However, complications like severe bleeding (n=19 vs. n=8, P=0.002) or limb ischaemia (n=7 vs. n=0, P=0.009) were encountered more frequently after VAD support, whereas 30 day mortality was similar (IABP 45% vs. VAD 43%, log-rank, P=0.86).

CONCLUSION

Haemodynamic and metabolic parameters can be reversed more effectively by VAD than by standard treatment with IABP. However, more complications were encountered by the highly invasive procedure and by the extracorporeal support.

Percutaneous left ventricular assist device: “TandemHeart” for high-risk coronary intervention

Patients undergoing percutaneous coronary intervention (PCI) with severely compromised left ventricular systolic function and complex coronary lesions, including multivessel disease, left main disease, or bypass graft disease, are at higher risk of adverse outcomes from hemodynamic collapse. The TandemHeart percutaneous ventricular assist device may provide circulatory support during high-risk PCI. We implanted the TandemHeart device in eight patients who underwent high-risk PCI. The patients were considered to be at exceptionally high risk for decompensation due to procedural complexity combined with underlying LV dysfunction. The mean ejection fraction was 30% +/- 9% and five patients were turned down for surgical revascularization. Seven patients underwent multivessel PCI, including three patients who underwent unprotected left main coronary artery PCI. There was 100% procedural success. The TandemHeart was removed immediately post-PCI with no groin complications. Six patients are event- and symptom-free at 189 +/- 130 days; one patient died 10 days post-PCI after lower extremity bypass surgery and another developed acute renal failure postprocedure, requiring hemodialysis. Our initial clinical experience with the TandemHeart ventricular assist device demonstrates that hemodynamic support can be rapidly achieved percutaneously during high-risk PCI, with excellent procedural success in highly complex and critically ill patients.

Survival of patients treated with intra-aortic balloon counterpulsation for cardiogenic shock in a tertiary centre: variables correlated with death

OBJECTIVE

To describe the characteristics and mortality rates of 132 cardiogenic shock patients treated with intra-aortic balloon counterpulsation at a university hospital.

INTERVENTIONS

All patients underwent intra-aortic balloon counterpulsation. A total of 99 out of 132 patients were revascularized with angioplasty, surgery or were transplanted (intervention group), 33 out of 132 had no further intervention (no-intervention group).

MEASUREMENTS AND RESULTS

Overall mortality was 54.5% (72/132). In the intervention group mortality was 50.5% (50/99), in the no-intervention group mortality was 66.6% (22/33). The odds ratio for death comparing the intervention group with the no-intervention group was 0.533 (95% confidence interval 0.238-1.189, P = 0.122). By univariate analysis, diabetes and a left ventricular ejection fraction of less than 0.35 represented an increased odds ratio of death of 4.25 (1.813-9.965, P = 0.001) and 3.03 (1.22-7.54, P = 0.015), respectively. A lactate level greater than 2.5 mg/dl at baseline resulted in an increased odds ratio of death of 5.185 (1.988-13.525, P = 0.0001). Using a multivariate logistic regression analysis, a left ventricular ejection fraction less than 0.35 and diabetes remained significantly correlated with death.

CONCLUSION

Mortality rates remain high in cardiogenic shock patients in need of intra-aortic balloon counterpulsation. The odds ratio for death tended to be lower in the intervention group compared with the no-intervention group, although the absolute difference in mortality as a result of an intervention was only 15.2%, and did not reach statistical significance probably because of the small sample size. Diabetes and an ejection fraction lower than 35% are significant predictors for a worse prognosis.

Appropriate timing of surgical intervention after transmural acute myocardial infarction

OBJECTIVE

Recommended timing of coronary revascularization after transmural acute myocardial infarction ranges from immediate surgical intervention to repair 4 weeks after infarction. Such wide variation has created a dilemma in the management of these patients. The objective of this study was to delineate the optimal timing of revascularization after transmural acute myocardial infarction in a large and contemporary patient population.

METHODS

We performed a retrospective multicenter analysis of 32,099 patients who underwent coronary artery bypass grafting as the sole procedure after transmural myocardial infarction between 1991 and 1996 by 179 surgeons at 33 hospitals in New York State.

RESULTS

Overall hospital mortality for all patients who underwent coronary revascularization with a history of transmural myocardial infarction was 3.3%. Hospital mortality decreased with increasing time interval between revascularization and transmural acute myocardial infarction: 14.2%, 13.8%, 7.9%, 3.8%, 2.9%, and 2.7% for less than 6 hours, 6 hours to 1 day, 1 to 3 days, 4 to 7 days, 7 to 14 days, and greater than 15 days, respectively. Multivariate analyses of 43 potential risk factors suggests that revascularization within 3 days of transmural acute myocardial infarction is independently associated with mortality.

CONCLUSIONS

Coronary revascularization within 3 days of a transmural acute myocardial infarction might be an added risk for mortality. In the absence of absolute indications for emergency surgical intervention, such as structural complications and ongoing ischemia, a 3-day waiting period before surgical revascularization should be considered.

[Elective primary angioplasty in cardiogenic shock: results from a single center]

INTRODUCTION

Cardiogenic shock is the leading cause of death among patients hospitalized for acute myocardial infarction. Conventional treatment for acute myocardial infarction does not achieve a better outcome in these patients, but prior studies with emergency revascularization by coronary angioplasty seem to provide encouraging results.

PATIENTS AND METHOD

A retrospective study of the clinical and angiographic results of elective primary angioplasty in 48 patients with cardiogenic shock complicating acute myocardial infarction of less than 12 hours is described. Intraaortic balloon counterpulsation was used in 79% of the patients. Patients with cardiogenic shock secondary to mechanical complications were excluded.

RESULTS

Angiographic success, defined as a residual stenosis < 50% and final TIMI flow >/= 2, was achieved in 85% of the culprit lesions, and stents were implanted in 76%. Multivessel angioplasty was performed in 25% of the patients, and abciximab was used in 35% of the cases. Mean time from the onset of symptoms to angioplasty was 7.4 +/- 3.1 hours. In-hospital survival was 58%, and was 54% at six months follow-up.

CONCLUSIONS

Emergency coronary revascularization with primary angioplasty and intracoronary stenting is effective in patients with acute myocardial infarction and cardiogenic shock. TIMI flow >/= 2 is achieved in most patients, and mortality is reduced when compared with conservative treatment in historical series.

Cardiogenic shock

Mortality rates in patients with cardiogenic shock remain frustratingly high. Its pathophysiology involves a downward spiral in which ischemia causes myocardial dysfunction, which in turn worsens ischemia. Areas of viable but nonfunctional myocardium can contribute to the development of cardiogenic shock. Rapid diagnosis and prompt initiation of supportive therapy to maintain blood pressure and cardiac output, followed by expeditious coronary revascularization, are crucial. The SHOCK multicenter randomized trial has provided important new data that support a strategy of emergent cardiac catheterization and revascularization with angioplasty or coronary surgery when feasible. This strategy can improve survival and represents standard therapy at this time. In hospitals without direct angioplasty capability, stabilization with IABP and thrombolysis followed by transfer to a tertiary care facility may be the best option.

Recent magnitude of and temporal trends (1994-1997) in the incidence and hospital death rates of cardiogenic shock complicating acute myocardial infarction: the second national registry of myocardial infarction

BACKGROUND

Limited recent data are available to describe the magnitude of, and temporal trends in, the incidence and case-fatality rates associated with cardiogenic shock complicating acute myocardial infarction. The purpose of this study was to examine recent (1994-1997) trends in the incidence of, and hospital death rates from, cardiogenic shock complicating acute myocardial infarction from a large, multihospital national perspective.

METHODS

An observational study was performed of 426,253 patients hospitalized with acute myocardial infarction in 1662 hospitals throughout the United States between 1994 and 1997.

RESULTS

The incidence rates of cardiogenic shock averaged 6.2%. There was evidence for a slight decline in these rates between 1994 (6.6%) and 1997 (6.0%). Results of a multivariable regression analysis controlling for factors that might affect the risk of development of cardiogenic shock indicated that patients hospitalized in more recent years were at significantly lower risk for shock. Patients with shock had a markedly increased risk for dying during hospitalization compared with patients not having shock (74% vs 10%). Significant, albeit small, absolute differences were observed in the risk of dying after cardiogenic shock over time (76% dying in 1997, 72% dying in 1994). These improving trends were magnified, however, after potentially confounding prognostic factors were controlled: patients having shock in 1997 were at approximately one fifth lower risk of dying (odds ratio 0.79, 95% confidence interval 0.71-0.87) than those hospitalized in 1994.

CONCLUSIONS

Our findings indicate a slight decline in the incidence rates of cardiogenic shock and improving trends in the hospital survival of patients with shock. Despite these trends, it remains of considerable importance to prevent this clinical syndrome, given its high lethality.

Cardiogenic shock complicating acute coronary syndromes

Cardiogenic shock remains the major cause of death among patients with all types of acute coronary syndromes. Thus, there is a growing interest in the identification of patients who are at risk for developing cardiogenic shock, in the exploration of different therapeutic approaches to preventing its development, and in the improvement of outcome when it occurs. This article reviews the aetiology and pathophysiology of cardiogenic shock, its epidemiology, its treatment (including pharmaceutical agents, counterpulsation, and revascularisation), and its outcome. Algorithms are presented that predict its occurrence in both ST-segment-elevation myocardial infarction and unstable angina or non-ST-elevation myocardial infarction, and that predict its mortality in patients with ST-segment-elevation acute myocardial infarction. Such new areas as metabolic therapy and glycoprotein IIb/IIIa inhibitors are discussed, as are the economic implications of shock.

Effect of early revascularization on mortality from cardiogenic shock complicating acute myocardial infarction in California

Recent retrospective analyses of treatment of cardiogenic shock suggest that early revascularization reduces mortality. All nonfederal hospital admissions in California for 1994 with a diagnosis of acute myocardial infarction (AMI) were identified. From that cohort, patients who developed cardiogenic shock were selected to determine demographic features, procedure utilization, and outcomes of their admission compared with patients with AMI without cardiogenic shock. Multivariate logistic regression analysis was performed to assess the effect of early revascularization on survival of patients in cardiogenic shock. Cardiogenic shock was identified in 1,122 patients. Mean age was 70.4 years, 45% of patients were women, and 28% had diabetes mellitus. Shock patients were more likely to be older, diabetic, women, and having an anterior Q-wave AMI. Overall in-hospital mortality for patients with shock was 56%. Patients referred for early revascularization had more favorable risk profiles, but after multivariate analysis early revascularization remained a powerful, independent predictor of improved survival, reducing the odds of death by 80%. This population-based study suggests that early revascularization may improve in-hospital survival of patients with cardiogenic shock complicating AMI, even after adjustment for baseline differences between patients who underwent early revascularization and those who did not.

Emergency myocardial revascularization for acute myocardial infarction: survival benefits of avoiding cardiopulmonary bypass

OBJECTIVE

Emergency coronary artery bypass grafting (CABG) for acute myocardial infarction (AMI) is associated with increased operative mortality. It has been suggested that this mortality might be reduced by performing the operation without cardiopulmonary bypass (CPB).

METHODS

Between January 1992 and April 1998, 77 patients underwent emergency CABG within 48 h of AMI. Thirty seven were operated on with CPB, and 40 without CPB. The two groups were similar regarding age, gender, left-ventricular ejection fraction (EF) and preoperative use of intra-aortic balloon pump (IABP; 50%). The mean number of grafts/patient was 3 in the CPB group, and 1.9 in the No-CPB group (P<0.0001).

RESULTS

Operative mortality in the CPB group was 24% (nine of 37) compared to 5% (two of 40) without CPB (P=0.015). Follow-up ranged between 6 and 66 months. There were no late deaths in the CPB group compared to nine (22%) in the No-CPB group (P<0.0066). Patients operated on with CPB had lower rates of recurrent angina (0 versus 15%; P=0.04) and re-interventions (0 versus 15%; P=0.04).

CONCLUSIONS

Our experience suggests that CABG without CPB is the preferred method of myocardial revascularization, due to the fact that it carries lower mortality than CABG with CPB. The trade-off includes increased rates of recurrent angina, re-interventions and late mortality.

Cardiogenic Shock

In the setting of acute myocardial infarction, the timely recognition and treatment of cardiogenic shock are essential in reducing the incidence of death. Patients with cardiogenic shock should be treated aggressively with a combination of pharmacologic agents and mechanical support devices to achieve stabilization. Once stabilization has been achieved, the ultimate goal should be the restoration of flow in the infarct-related artery. This is best achieved with angioplasty or bypass surgery. In those centers not equipped for these procedures, thrombolysis should be performed, and the patient should then be transferred to a higher-level facility.

Association Between Serial Measures of Systemic Blood Pressure and Early Coronary Arterial Perfusion Status Following Intravenous Thrombolytic Therapy

Background: Systemic hypotension, at times transient while in other instances more prolonged, is common among patients with myocardial infarction (MI). It also is a characteristic feature for patients experiencing either advanced congestive heart failure or cardiogenic shock. In this group of patients, thrombolytic therapy has failed to exert. favorable impact on their high in-hospital mortality. Although it has been postulated that the success of thrombolytic therapy is directly linked to systemic blood pressure' there is little information available in human subjects. Methods and Results: In a University of Massachusetts Thrombolysis Data Bank Study, 127 patients with MI who were given intravenous thrombolytic therapy (tPA or streptokinase) within 6 hours from symptom onset (4.2 +/- 1.5 hours) had serial systemic blood pressure measurements (at the time of hospital arrival, treatment initiation, and every 30 minutes during the thrombolytic infusion) and underwent coronary angiography within 120 minutes of treatment initiation. All patients received intravenous heparin and oral aspirin. By univariate analysis, disastolic blood pressure below 80 mmHg at the time of treatment initiation was associated with a reduced angiographic coronary perfusion grade [Thrombolysis in Myocardial Infarction (TIMI) flow grade; p + 0.02]. A correlation analysis of tPA-treated patients indicated that a greater maximum change in diastolic blood pressure during treatment correlated inversely with coronary perfusion (r +.24, p < 0.05). By multivariate regression analysis, however, only shorter time to treatment (p + 0.001) and thrombolysis with tPA (p + 0.02) were independent predictors of coronary arterial perfusion grade. Conclusion: Systemic blood pressure (and presumably proximal coronary arterial perfusion pressure) in the ranges investigated in this study is not an independent predictor of coronary reperfusion following intravenous thrombolytic therapy with either tPA or streptokinase. It seems likely, therefore, that properties intrinsic to the ruptured plaque and occlusive thrombus, and potentially the local metabolic environment, either alone or acting synergistically with perfusion pressure, are determinants of thrombolytic success. Further investigation of factors influencing the efficacy of thrombolysis should be undertaken.

[The clinical management guidelines of the Sociedad Española de Cardiología in acute myocardial infarct]

In the recent years, new possibilities have emerged in the diagnosis and management of acute myocardial infarction with ST segment elevation and its complications. Moreover, a deep transformation has taken place in the health care system organization, particularly in aspects related to care of patients presenting non-traumatic chest pain, both in pre-hospital and hospital areas. All these issues warrant a consensus document in Spain dealing with the role that these important changes should play in the whole management of myocardial infarction patients. This document revises and updates all the main clinical issues of acute myocardial infarction patients from the moment they contact with the health care system outside the hospital until they return home, after staying at the coronary care unit and the general hospitalization ward. All those aspects are considered not only in the uncomplicated myocardial infarction but also in the complicated one. This review also includes a set of recommendations on structural and organisational aspects, mainly referred to the prehospital and emergency levels.

Early revascularization in acute myocardial infarction complicated by cardiogenic shock. SHOCK Investigators. Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock

BACKGROUND

The leading cause of death in patients hospitalized for acute myocardial infarction is cardiogenic shock. We conducted a randomized trial to evaluate early revascularization in patients with cardiogenic shock.

METHODS

Patients with shock due to left ventricular failure complicating myocardial infarction were randomly assigned to emergency revascularization (152 patients) or initial medical stabilization (150 patients). Revascularization was accomplished by either coronary-artery bypass grafting or angioplasty. Intraaortic balloon counterpulsation was performed in 86 percent of the patients in both groups. The primary end point was mortality from all causes at 30 days. Six-month survival was a secondary end point.

RESULTS

The mean age of the patients was 66+/-10 years, 32 percent were women and 55 percent were transferred from other hospitals. The median time to the onset of shock was 5.6 hours after infarction, and most infarcts were anterior in location. Ninety-seven percent of the patients assigned to revascularization underwent early coronary angiography, and 87 percent underwent revascularization; only 2.7 percent of the patients assigned to medical therapy crossed over to early revascularization without clinical indication. Overall mortality at 30 days did not differ significantly between the revascularization and medical-therapy groups (46.7 percent and 56.0 percent, respectively; difference, -9.3 percent; 95 percent confidence interval for the difference, -20.5 to 1.9 percent; P=0.11). Six-month mortality was lower in the revascularization group than in the medical-therapy group (50.3 percent vs. 63.1 percent, P=0.027).

CONCLUSIONS

In patients with cardiogenic shock, emergency revascularization did not significantly reduce overall mortality at 30 days. However, after six months there was a significant survival benefit. Early revascularization should be strongly considered for patients with acute myocardial infarction complicated by cardiogenic shock.

Coronary artery bypass without cardiopulmonary bypass for patients with acute myocardial infarction

OBJECTIVE

Between January 1992 and December 1994, 57 patients having an acute myocardial infarction with coronary anatomy suitable for coronary artery bypass grafting without cardiopulmonary bypass underwent this procedure within 1 week of the infarction. We describe the surgical results of these high-risk patients.

METHODS

The study population included 43 male patients (75%) and 14 female patients (25%) whose mean age was 58.5 +/- 10.4 years. Thirty-two patients (56%) underwent emergency bypass grafting within 48 hours of an acute myocardial infarction, 4 of them (12.5%) as a bailout procedure after complicated percutaneous transluminal coronary angioplasty. Of these 32 patients, 7 patients (22%) were in cardiogenic shock, and 10 patients (31%) required preoperative intra-aortic balloon pump. Twenty-five patients (44%) underwent coronary bypass grafting 2 to 7 days after an acute myocardial infarction. The mean number of grafts per patient was 1.8 (range, 1-4), and the internal thoracic artery was used in 47 patients (82%). Only 7 patients (12%) received grafts to a circumflex marginal branch.

RESULTS

Operative mortality was 1.7% (1 patient), and the mean postoperative hospital stay was 6.8 +/- 3 days. One- and 5-year actuarial survivals were 94.7% and 82.3%, respectively. Angina returned in 7 patients (12%), 1 of whom underwent reoperation. Multivariate analysis revealed renal failure and preoperative cardiogenic shock to be independent predictors of overall mortality. Old myocardial infarction and operation within the first 48 hours were independent predictors of overall unfavorable outcome events.

CONCLUSIONS

These results suggest that coronary artery bypass grafting without cardiopulmonary bypass is a relatively low-risk procedure for patients having an infarction with coronary anatomy suitable for this technique.

Temporal trends in cardiogenic shock complicating acute myocardial infarction

BACKGROUND

Limited information is available on trends in the incidence of and mortality due to cardiogenic shock complicating acute myocardial infarction. We studied the incidence of cardiogenic shock complicating acute myocardial infarction and in-hospital death rates among patients with this condition in a single community from 1975 through 1997.

METHODS

We conducted an observational study of 9076 residents of metropolitan Worcester, Massachusetts, who were hospitalized with confirmed acute myocardial infarction in all local hospitals during 11 one-year periods between 1975 and 1997. Our study included periods before and after the advent of reperfusion therapy.

RESULTS

The incidence of cardiogenic shock remained relatively stable over time, averaging 7.1 percent among patients with acute myocardial infarction. The results of a multivariable regression analysis indicated that the patients hospitalized during recent study years were not at a substantially lower risk for shock than patients hospitalized in the mid-to-late 1970s. Patients in whom cardiogenic shock developed had a significantly greater risk of dying during hospitalization (71.7 percent) than those who did not have cardiogenic shock (12.0 percent, P<0.001). A significant trend toward an increase in in-hospital survival among patients with cardiogenic shock in the mid-to-late 1990s was found in crude and adjusted analyses.

CONCLUSIONS

Our findings indicate no significant change in the incidence of cardiogenic shock complicating acute myocardial infarction over a 23-year period. However, the short-term survival rate has increased in recent years at the same time as the use of coronary reperfusion strategies has increased.

Efficacy of invasive strategy for the management of acute myocardial infarction complicated by cardiogenic shock

This retrospective study evaluates the influence of an invasive strategy of urgent coronary revascularization on the in-hospital mortality of patients with acute myocardial infarction (AMI) complicated early by cardiogenic shock. Among 1,981 patients with AMI admitted to our institution from 1994 to 1997, 162 patients (8.2%) developed cardiogenic shock unrelated to mechanical complications. The strategy of management was considered invasive if an urgent coronary angiography was indicated within 24 hours of symptom onset. Every other strategy was considered conservative. Fifty-seven patients who developed the shock late or after a revascularization procedure, or who died on admission, were excluded. The strategy was invasive in 73 patients (70%). Five of them died before angiography could be performed and 65 underwent angioplasty (success rate 72%). By univariate analysis the invasive strategy was associated with a lower mortality than conservative strategy (71% vs 91%, p = 0.03), but this association disappeared after adjustment for baseline characteristics. Older age, nonsmoking, and previous ischemic heart disease were independent predictors of mortality. In conclusion, we have failed to demonstrate that a strategy of urgent coronary revascularization within 24 hours of symptom onset for patients with AMI complicated by cardiogenic shock is independently associated with a lower in-hospital mortality. This strategy was limited by the high mortality within 1 hour of admission in patients with cardiogenic shock, the modest success rate of angioplasty in this setting, and the powerful influence of some adverse baseline characteristics on prognosis.

[Prognosis and management in patients with left main shock syndrome--emergency PTCA following CABG]

To clarify the optimal management and delineate the characteristics of patients with severe left main disease and cardiogenic shock as a result of an acute anterolateral myocardial infarction (left main shock syndrome), we analyzed the course of 13 such patients from September 1989 to June 1997. Of the 13 patients, 7 (53.8%) were managed with emergency coronary angioplasty (group A), 3 (23.1%) were treated with emergency coronary angioplsty following coronary bypass graft surgery (group B) and 3 (23.1%) underwent emergency coronary bypass graft surgery alone (group C). The interval from the beginning of myocardial ischemia to revascularization was 266 +/- 303 min. The degree of diameter stenosis found in the left main coronary artery was 98.1 +/- 1.8%. Overall in-hospital mortality for the 13 patient with left main shock syndrome was 76.9% (group A: 7/7; group B: 1/3; group C: 2/3, NS) and operative mortality was 61.5% (group A: 6/7; group B: 0/3; group C: 2/3, p = 0.03). When all 13 patients were examined together, the presence of ventricular tachycardia (VT) x ventricular fibrillation (Vf) was found to be the most powerful univariate predictor of operative death (p = 0.03). This is, 7 (87.5%) of the 8 patients with VT x Vf at presentation died within 30 postoperative days, and only 1 (20%) of the 5 patients without VT x Vf died (p = 0.03). Age, percent stenosis of the left main or right coronary arteries, the interval from the beginning of myocardial ischemia to revascularization, intubation, systolic pressure, fractional shortning, pulmonary artery pressure, pulmonary capillary wedge pressure, coronary risk factors, pulmonary edema, mitral regurgitation and percutaneous cardiopulmonary support failed to attain univariate significance at the P = .1 level. The postoperative peak CPK level was 15665 +/- 6710 IU/1 in operative death compared to 4733 +/- 2749 IU/1 in operative survival (p = 0.01). In conclusion, emergency coronary angioplasty following coronary bypass graft surgery for left main shock syndrome has been a very successful therapeutic option. Finally, for the entire group of 13 patients with left main shock syndrome, VT x Vf significantly decreased short-term survival.

Survival using percutaneous cardiopulmonary support after acute myocardial infarction due to occlusion of the left main coronary artery--a report of two cases

Two cases of acute myocardial infarction due to an occlusion of the left main coronary artery (LMCA) are presented. Their cardiogenic shock was successfully treated with percutaneous cardiopulmonary support (PCPS), in addition to reperfusion therapy and an intraaortic balloon pump. The 2 patients were able to be weaned from PCPS and discharged from hospital. It is suggested that the early use of PCPS may be life-saving in patients with myocardial infarction due to the occlusion of the LMCA who have progressed to cardiogenic shock.

Use of intraaortic balloon counterpulsation in patients presenting with cardiogenic shock: observations from the GUSTO-I Study. Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries

OBJECTIVES

We sought to examine the use, complications and outcomes with early intraaortic balloon counterpulsation (IABP) in patients presenting with cardiogenic shock complicating acute myocardial infarction and treated with thrombolytic therapy.

BACKGROUND

The use of IABP in patients with cardiogenic shock is widely accepted; however, there is a paucity of information on the use of this technique in patients with cardiogenic shock who are treated with thrombolytic therapy.

METHODS

Patients who presented within 6 h of chest pain onset were randomized to one of four thrombolytic regimens. Cardiogenic shock was not an exclusion criterion, and data for these patients were prospectively collected. Patients presenting with shock were classified into early IABP (insertion within one calendar day of enrollment) or no IABP (insertion on or after day 2 or never).

RESULTS

There were 68 (22%) IABP placements in 310 patients presenting with shock. Early IABP use occurred in 62 patients (20%) and none in 248 (80%). Most IABP use occurred in the United States (59 of 68 IABP placements) involving 32% of U.S. patients presenting with shock. Despite more adverse events in the early IABP group and more episodes of moderate bleeding, this cohort showed a trend toward lower 30-day and 1-year mortality rates.

CONCLUSIONS

IABP appears to be underutilized in patients presenting with cardiogenic shock, both within and outside the United States. Early IABP institution is associated with an increased risk of bleeding and adverse events but a trend toward lower 30-day and 1-year all-cause mortality.

Early management of acute myocardial infarction: thrombolysis, angioplasty, and adjunctive therapies

Early identification and treatment, including administration of intravenous thrombolytics, coronary angioplasty, and adjunctive therapies, has been shown to benefit patients who present with acute myocardial infarction. However, only a small percentage of these patients receive such therapies because of late presentation, associated risks, and controversies around certain myocardial infarct subsets. The logistics involved in carrying out these treatments have resulted in unnecessary prehospital and in-hospital delays. These issues make essential the availability of a streamlined protocol that should be updated at regular intervals to ensure that these time-dependent therapies are more routinely and rapidly utilized. This article discusses these topics in conceptual format and provides a ready-to-use protocol.

Cardiogenic shock: thrombolysis or angioplasty?

Cardiogenic shock (CGS) occurs in 3 to 20% of patients presenting with acute myocardial infarction (MI), and it generally involves dysfunction of at least 40% of the total myocardial mass. Prior to the advent of balloon angioplasty and thrombolysis, in-hospital mortality was greater than 75%. This mortality rate has been consistent in reported series despite the advent of cardiac intensive care units, vasopressor, inotropic, and vasodilator therapy. Intra-aortic balloon counterpulsation therapy provides hemodynamic improvement, and it may provide some mortality benefit when used in conjunction with appropriate revascularization. Survival studies have shown that patency of the infarct-related artery is a strong predictor of survival. No randomized trials have been completed to examine which reperfusion therapy best treats this emergent situation. Subgroup analysis of large scale, multicenter trials, although underpowered, has shown no improvement in mortality with use of thrombolytic agents, leading many to advise use of mechanical intervention. In patients who present with acute MI with contraindications to thrombolysis, primary angioplasty is the treatment of choice. At selected centers, primary angioplasty is comparable to or better than thrombolytic therapy for patients presenting with acute MI, with or without CGS. Studies examining angioplasty in patients with CGS have shown high procedural success rates (75%) and reduced in-hospital mortality (44%), particularly in those patients with successful revascularization. Emergency bypass surgery may improve survival, but it is costly, unavailable to many, and often leads to excessive delays in therapy. If available, we believe that primary angioplasty is the treatment of choice for patients with CGS.