High-risk cardiac surgery: Time to explore a new paradigm

A profile of the impella 5.5 for the clinical management of cardiogenic shock and a review of the current indications for use and future directions

INTRODUCTION

The Impella 5.5 device is a surgically inserted, trans-valvular, microaxial flow device capable of providing 5.5 L/min of continuous, antegrade flow from the left ventricle (LV) to the aorta. The ability of the Impella 5.5 to fully pressure and volume unload the dysfunctional LV while allowing for mobilization and rehabilitation has rapidly expanded its use. Clinical use scenarios include escalation of support for acute myocardial infarction cardiogenic shock (AMICS), transition from extracorporeal membrane oxygenation to mobile support, bridge to transplantation or durable MCS in acute decompensated heart failure, or perioperative use in post-cardiotomy cardiogenic shock (PCCS).

AREAS COVERED

This review provides a profile of the Impella 5.5 device, summarizes the current literature surrounding clinical applications, reviews active and upcoming clinical trials, and projects future applications for the device through an expert review.

EXPERT OPINION

The development of the Impella 5.5 has allowed for monitoring of left-heart recovery, optimizing right ventricular function, and rehabilitating patients to meet bridging endpoints. The 2018 heart transplant allocation system modifications have expanded the use of temporary mechanical circulatory support (tMCS) on the transplant waitlist, increasing the number of patients transplanted on support. With increased safety and durability, an expanding frontier is used in perioperative support for PCCS in high-risk cardiac surgery.

Machine learning-derived multivariable predictors of postcardiotomy cardiogenic shock in high-risk cardiac surgery patients

Objective

To develop a model for preoperatively predicting postcardiotomy cardiogenic shock (PCCS) in patients with poor left ventricular (LV) function undergoing cardiac surgery.

Methods

From the Society of Thoracic Surgeons Adult Cardiac Database, 11,493 patients with LV ejection fraction ≤35% underwent isolated on-pump surgery from 2018 through 2019, of whom 3428 experienced PCCS. In total, 68 preoperative clinical variables were considered in machine-learning algorithms trained and optimized using scikit-learn software.

Results

Compared with patients with ideal recovery, those that did were younger (65 vs 67 years), more likely female, Black, with low LV ejection fraction (26.5 vs 28.9%), previous myocardial infarction, chronic lung disease, diabetes, reoperation, or advanced heart failure. Among those with PCCS versus ideal recovery, operative mortality was 27% (925/3428) versus 0.1% (5/8065). PCCS occurred more often after coronary artery bypass grafting with concomitant mitral valve repair or after longer perfusion and clamp times. Reliable preoperative PCCS predictors were more advanced cardiac, liver, and renal failure; frailty; and greater white cell count. Out of sample test set receiver operating curve achieved an area under the curve of 0.74 with acceptable calibration Hosmer-Lemeshow statistic χ2 = 1.33, P = .25.

Conclusions

In patients with severe LV dysfunction undergoing cardiac surgery, risk of PCCS is elevated by preoperative failure of other organ systems and complexity of the planned operation that prolongs myocardial ischemia and cardiopulmonary bypass. This risk calculator could serve as an important tool to preoperatively identify patients in need of advanced levels of support.

The use of perioperative Impella 5.5 support in high-risk cardiac surgery: a retrospective cohort study

Background

Although the Impella device has an established role in high-risk percutaneous intervention and cardiogenic shock, its role in open cardiac surgery remains unclear. We undertook this study to better understand the role of Impella support in cardiac surgical intervention.

Methods

This is a retrospective cohort study of consecutive patients who underwent cardiac surgery with surgically placed Impella 5.5 device support from October 2020 through June 2023. Patient charts were identified and systematically reviewed for relevant information. The primary outcome for this study was patient survival to discharge. Secondary outcomes included intraoperative survival, 30-day survival and 1-year survival.

Results

From 2020-2023, ten patients underwent open cardiac surgery with Impella 5.5 support. Five patients were male and the median age was 56.5 years [interquartile range (IQR), 52-63.8 years]. Three patients (30%) presented for isolated revascularization, 3 patients (30%) presented for single valve surgical intervention, 3 patients (30%) presented for revascularization and valve intervention, and 1 patient (10%) presented for multivalve intervention. The median ejection fraction (EF) of patients was 25% (IQR, 21.25-32.5%), the median Society of Thoracic Surgeons risk score was 4.32% (IQR, 1.73-11.06%). Of the patients, 40% underwent axillary cannulation while 60% had central cannulation. Intraoperative survival was 100%, survival to discharge was 90% and 30-day survival was 80%.

Conclusions

Our study suggests the use of surgical Impella in high-risk cardiac surgical patients is associated with acceptable survival regardless of site or timing of cannulation. However, Impella usage is associated with significant morbidity. Further investigation is warranted to better understand which patients benefit perioperative Impella support.

The intra-aortic balloon pump as a rescue device: Do we need to shift our strategy for cardiogenic shock rescue after cardiac surgery?

OBJECTIVE

The intra-aortic balloon pump (IABP) is widely used to rescue patients from complications following cardiac surgery. Given improvements in rescue strategies over the past decade, the appropriateness of IABP must be reexamined. This study assessed the risk factors, outcomes, and predictors of survival of rescue IABP placement.

METHODS

Patients receiving an isolated rescue IABP during or after cardiac surgery from 2012 to 2020 were studied. All adult patients undergoing cardiac surgery except transplantation and primary mechanical circulatory support (MCS) procedures were included.

RESULTS

Of 10,591 patients, 397 (3.7%) received a perioperative IABP, including 182 (45.8%) with rescue IABP placement. The indications for rescue IABP were postcardiotomy shock (n = 66; 36.3%), failure to wean off cardiopulmonary bypass (n = 58; 31.9%), myocardial ischemia (n = 30; 16.5%), cardiac arrest (n = 25; 13.7%), and ventricular arrhythmia (n = 3; 1.6%). The in-hospital failure to rescue rate was 17.6% (n = 32 of 182) with a 90-day survival of 80.8% and 1-year survival of 76.9%. The most common etiology of mortality was ongoing cardiogenic shock (61.9%; n = 26 of 42). IABP use for >4 days and cardiac arrest as an indication for IABP were risk factors for 1-year mortality (adjusted hazard ratio, 2.68 [95% confidence interval (CI), 1.31-5.50] and 2.69 [95% CI, 1.11-6.54], respectively).

CONCLUSIONS

Rescue IABP following cardiac surgery is associated with increased early and 1-year mortality. Prolonged IABP use beyond 4 days or cardiac arrest as an indication portended a significantly worse prognosis. Rescue IABP may not be the optimal first-line temporary MCS for all patients, as the level of support provided might not match the severity of cardiogenic shock. Alternative MCS strategies should be considered early.

Advanced statistical methods for hazard modeling in cardiothoracic surgery: a comprehensive review of techniques and approaches

Hazard modeling in cardiothoracic surgery, crucial for understanding patient outcomes, utilizes survival analysis like the Cox proportional hazards model. Kaplan-Meier curves are employed in survival analysis to represent the probability of survival over time. While Cox assumes proportional hazards, the Fine-Gray model deals with competing risks. Parametric models (e.g., Weibull) specify survival distributions, unlike Cox. Bayesian analysis integrates prior knowledge with data. Machine learning, including decision trees and support vector machines, enhances risk prediction by analyzing extensive datasets. However, it is important to note that whatever new approaches one may adopt will enhance the quality of risk assessment and not the risk assessment as such. Preprocessing is vital for data quality in complex cardiovascular datasets, alongside robust validation methods like cross-validation for model reliability across patient cohorts.

Management of Post-cardiotomy Shock

Patients undergoing cardiac surgery experience significant physiologic derangements that place them at risk for multiple shock phenotypes. Any combination of cardiogenic, obstructive, hemorrhagic, or vasoplegic shock occurs commonly in post-cardiotomy patients. The approach to the diagnosis and management of these shock states has many facets that are distinct compared to non-surgical cardiac intensive care unit patients. Additionally, the approach to and associated outcomes of cardiac arrest in the post-cardiotomy population are uniquely characterized by emergent bedside resternotomy if the circulation is not immediately restored. This review focuses on the unique aspects of the diagnosis and management of post-cardiotomy shock.

Temporary mechanical circulatory support & enhancing recovery after cardiac surgery

PURPOSE OF REVIEW

This review highlights the integration of enhanced recovery principles with temporary mechanical circulatory support associated with adult cardiac surgery.

RECENT FINDINGS

Enhanced recovery elements and efforts have been associated with improvements in quality and value. Temporary mechanical circulatory support technologies have been successfully employed, improved, and the value of their proactive use to maintain hemodynamic goals and preserve long-term myocardial function is accruing.

SUMMARY

Temporary mechanical circulatory support devices promise to enhance recovery by mitigating the risk of complications, such as postcardiotomy cardiogenic shock, organ dysfunction, and death, associated with adult cardiac surgery.

Programmatic approach to patients with advanced ischemic cardiomyopathy: Integrating microaxial support into strategies for the modern era

Patients with advanced ischemic cardiomyopathy manifesting as left ventricular dysfunction exist along a spectrum of severity and risk, and thus decision-making surrounding optimal management is challenging. Treatment pathways can include medical therapy as well as revascularization through percutaneous coronary intervention or coronary artery bypass grafting. Additionally, temporary and durable mechanical circulatory support, as well as heart transplantation, may be optimal for select patients. Given this spectrum of risk and the complexity of treatment pathways, patients may not receive appropriate therapy given their perceived risk, which can lead to sub-satisfactory outcomes. In this review, we discuss the identification of high-risk ischemic cardiomyopathy patients, along with our programmatic approach to patient evaluation and perioperative optimization. We also discuss our strategies for therapeutic decision-making designed to optimize both short- and long-term patient outcomes.

Coronary artery bypass grafting in left ventricular dysfunction: when and how

PURPOSE OF REVIEW

The surgical management of patients undergoing coronary artery bypass grafting (CABG) with low ejection fraction presents unique challenges that require meticulous attention to details and good surgical technique and judgement. This review details the latest evidence and best practices in the care of such patients.

RECENT FINDINGS

CABG in patients with low ejection fraction carries a significant risk of perioperative mortality and morbidity related to the development of postcardiotomy shock. Preoperative optimization with pharmacological or mechanical support is required, especially in patients with cardiogenic shock. Rapid and complete revascularization is what CABG surgeons aim to achieve. Multiple arterial revascularization should be reserved to selected patients. Off-pump CABG, on-pump breathing heart CABG, and new cardioplegic solutions remain of uncertain benefit compared with traditional CABG.

SUMMARY

Tremendous advancements in CABG allowed surgeons to offer revascularization to patients with severe left ventricular dysfunction and multivessel disease with acceptable risk. Despite that, there is a lack of comprehensive and robust studies particularly on long-term outcomes. Individualized patient assessment and a heart team approach should be used to determine the optimal surgical strategy for each patient.

The Use of Cardioprotective Devices and Strategies in Patients Undergoing Percutaneous Procedures and Cardiac Surgery

In the United States, about one million people are seen to visit the operating theater for cardiac surgery annually. However, nearly half of these visits result in complications such as renal, neurological, and cardiac injury of varying degrees. Historically, many mechanisms and approaches have been explored in attempts to reduce injuries associated with cardiac surgery and percutaneous procedures. Devices such as cardioplegia, mechanical circulatory support, and other methods have shown promising results in managing and preventing life-threatening cardiac-surgery-related outcomes such as heart failure and cardiogenic shock. Comparably, cardioprotective devices such as TandemHeart, Impella family devices, and venoarterial extracorporeal membrane oxygenation (VA-ECMO) have also been proven to show significant cardioprotection through mechanical support. However, their use as interventional agents in the prevention of hemodynamic changes due to cardiac surgery or percutaneous interventions has been correlated with adverse effects. This can lead to a rebound increased risk of mortality in high-risk patients who undergo cardiac surgery. Further research is necessary to delineate and stratify patients into appropriate cardioprotective device groups. Furthermore, the use of one device over another in terms of efficacy remains controversial and further research is necessary to assess device potential in different settings. Clinical research is also needed regarding novel strategies and targets, such as transcutaneous vagus stimulation and supersaturated oxygen therapy, aimed at reducing mortality among high-risk cardiac surgery patients. This review explores the recent advances regarding the use of cardioprotective devices in patients undergoing percutaneous procedures and cardiac surgery.