Screening scale predicts patients successfully receiving long-term implantable left ventricular assist devices

Evaluation of Extracorporeal Membrane Oxygenation Therapy as a Bridging Method

BACKGROUND

With the implementation of the new heart allocation system, heart transplantation teams are prompted to reevaluate management of patients requiring mechanical circulatory support. The purpose of our study is to compare the outcomes of patients supported with extracorporeal membrane oxygenation (ECMO) before transplantation.

METHODS

The United Network for Organ Sharing database was queried for all adult patients (aged 18 years or more) who required support with ECMO before heart transplantation from 2001 to 2018. Patients were stratified into patients who did not require ECMO before transplantation, who were weaned off ECMO before transplantation, who were bridged immediately to transplantation from ECMO, and who were bridged to a left ventricular assist device (LVAD) before transplantation. Demographics and outcomes including 1-year survival, postoperative stroke, postoperative renal failure requiring dialysis, episodes of rejection, and graft failure were compared.

RESULTS

Overall, 29,370 patients did not require ECMO before transplantation, 101 patients were weaned off ECMO before transplantation, 118 were bridged from ECMO directly to transplantation, and 55 patients were successfully bridged from ECMO to LVAD before transplantation. Kaplan-Meier survival estimates found a statistically significant decrease in 1-year survival for patients who were bridged from ECMO to transplantation compared with patients who were bridged to LVAD before subsequent transplantation (P < .001).

CONCLUSIONS

Our study suggests bridging ECMO patients to an LVAD before transplantation will result in improved 1-year survival compared with patients bridged to immediate transplantation. With the new heart allocation system, continued evaluation of outcomes is required to inform management strategies.

Evolution of association between renal and liver functions while awaiting heart transplant: An application using a bivariate multiphase nonlinear mixed effects model

In many longitudinal follow-up studies, we observe more than one longitudinal outcome. Impaired renal and liver functions are indicators of poor clinical outcomes for patients who are on mechanical circulatory support and awaiting heart transplant. Hence, monitoring organ functions while waiting for heart transplant is an integral part of patient management. Longitudinal measurements of bilirubin can be used as a marker for liver function and glomerular filtration rate for renal function. We derive an approximation to evolution of association between these two organ functions using a bivariate nonlinear mixed effects model for continuous longitudinal measurements, where the two submodels are linked by a common distribution of time-dependent latent variables and a common distribution of measurement errors.

Accuracy of Seattle Heart Failure Model and HeartMate II Risk Score in Non-Inotrope-Dependent Advanced Heart Failure Patients: Insights From the ROADMAP Study (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management in Ambulatory Heart Failure Patients)

BACKGROUND

Timing of left ventricular assist device (LVAD) implantation in advanced heart failure patients not on inotropes is unclear. Relevant prediction models exist (SHFM [Seattle Heart Failure Model] and HMRS [HeartMate II Risk Score]), but use in this group is not established.

METHODS AND RESULTS

ROADMAP (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management in Ambulatory Heart Failure Patients) is a prospective, multicenter, nonrandomized study of 200 advanced heart failure patients not on inotropes who met indications for LVAD implantation, comparing the effectiveness of HeartMate II support versus optimal medical management. We compared SHFM-predicted versus observed survival (overall survival and LVAD-free survival) in the optimal medical management arm (n=103) and HMRS-predicted versus observed survival in all LVAD patients (n=111) using Cox modeling, receiver-operator characteristic (ROC) curves, and calibration plots. In the optimal medical management cohort, the SHFM was a significant predictor of survival (hazard ratio=2.98; P<0.001; ROC area under the curve=0.71; P<0.001) but not LVAD-free survival (hazard ratio=1.41; P=0.097; ROC area under the curve=0.56; P=0.314). SHFM showed adequate calibration for survival but overestimated LVAD-free survival. In the LVAD cohort, the HMRS had marginal discrimination at 3 (Cox P=0.23; ROC area under the curve=0.71; P=0.026) and 12 months (Cox P=0.036; ROC area under the curve=0.62; P=0.122), but calibration was poor, underestimating survival across time and risk subgroups.

CONCLUSIONS

In non-inotrope-dependent advanced heart failure patients receiving optimal medical management, the SHFM was predictive of overall survival but underestimated the risk of clinical worsening and LVAD implantation. Among LVAD patients, the HMRS had marginal discrimination and underestimated survival post-LVAD implantation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01452802.

Left Ventricular Assist Device in Older Adults

Left ventricular assist devices (LVADs) are an effective therapy for a growing and aging population in the background of limited donor supply. Selecting the proper patient involves assessment of indications, risk factors, scores for overall outcomes, assessment for right ventricular failure, and optimal timing of implantation. LVAD complications have a 5% to 10% perioperative mortality and complications of bleeding, thrombosis, stroke, infection, right ventricular failure, and device failure. As LVAD engineering technology evolves, so will the risk-prediction scores. Hence, more large-scale prospective data from multicenters will continually be required to aid in patient selection, reduce complications, and improve long-term outcomes.

A dynamic Bayesian network approach for time-specific survival probability prediction in patients after ventricular assist device implantation

In this work we present a decision support tool for the calculation of time-dependent survival probability for patients after ventricular assist device implantation. Two different models have been developed, a short term one which predicts survival for the first three months and a long term one that predicts survival for one year after implantation. In order to model the time dependencies between the different time slices of the problem, a dynamic Bayesian network (DBN) approach has been employed. DBNs order to capture the temporal events of the patient disease and the temporal data availability. High accuracy results have been reported for both models. The short and long term DBNs reached an accuracy of 96.97% and 93.55% respectively.

Biomarkers in mechanical circulatory support

Heart failure is a complex multifaceted syndrome occurring as a result of impaired cardiac function. Understanding the neurohormonal, inflammatory and molecular pathways involved in the pathophysiology of this syndrome has led to the development of effective and widely used pharmacological treatments. Despite this, mortality and hospitalization rates associated with this condition remain high. The natural course of this illness is usually progressive, often leading inexorably to end stage heart failure, for which orthotopic heart transplant is a treatment option but one with limited resource. In the past decade, mechanical circulatory support has emerged as a potential therapy for certain patients with advanced heart failure. This article reviews the published data regarding biomarkers in the setting of mechanical circulatory support, and highlights areas of ongoing work and potential future areas of interest.

Mitral valve repair at the time of continuous-flow left ventricular assist device implantation confers meaningful decrement in pulmonary vascular resistance

We hypothesized that the addition of mitral valve replacement or repair (MVR) to implantation of continuous-flow left ventricular assist device (cf-LVAD) may further decrease pulmonary vascular resistance (PVR) over Heartmate II (HMII) implantation alone. Patients undergoing MVR with concomitant HMII implantation were compared with those undergoing HMII implantation alone. Of the 57 patients undergoing cf-LVAD implantation, 21 (36.8%) underwent concomitant MVR and 36 (63.2%) underwent cf-LVAD implantation alone. Patients receiving MVR had greater decrement in PVR (59.4% vs. 35.2%, p = 0.01). Decrease in end-diastolic diameter was greater for patients receiving MVR but did not reach statistical significance (18.2 vs. 13.5 mm, p = 0.33). Duration of mechanical ventilation (121.6 vs. 181.4 hours, p = 0.45) and inotropic support (162.4 vs. 153.2 hours, p = 0.86), change in creatinine (0.19 vs. -0.26 mg/dl, p = 0.34), increase in bilirubin (2.54 vs. 1.55 mg/dl, p = 0.63), intensive care unit stay (168.0 vs. 231.5 hours, p = 0.38), and overall length of stay (32.0 vs. 42.5 days, p = 0.75) were similar. There was no difference in survival at 3 months (89.7% vs. 83.3%) and 1 year (83.7 vs. 67.3%, p = 0.34). Addition of MVR may result in greater decrement of PVR than HMII implantation alone. This may permit certain patients thought to be ineligible for transplantation to become candidates.

Ventricular assist devices: is destination therapy a viable alternative in the non-transplant candidate?

The topic of this article, stated a more familiar way, is whether left ventricular assist devices (LVADs) are ready for 'Primetime' as a therapeutic option in and of themselves. In order to provide an update and insight on this question, we briefly review from where the field has come, and in more detail describe its current state and where we are heading. We believe the short answer to this question is 'Yes', but like many things, a short answer is not adequate. Here we attempt to deliver a more comprehensive answer, providing some historical context, outlining the great achievements that have been made, as well as the many challenges that still remain before LVADs become a truly mainstream therapy.

Predicting survival in patients receiving continuous flow left ventricular assist devices: the HeartMate II risk score

OBJECTIVES

The aim of this study was to derive and validate a model to predict survival in candidates for HeartMate II (HMII) (Thoratec, Pleasanton, California) left ventricular assist device (LVAD) support.

BACKGROUND

LVAD mortality risk prediction is important for candidate selection and communicating expectations to patients and clinicians. With the evolution of LVAD support, prior risk prediction models have become less valid.

METHODS

Patients enrolled into the HMII bridge to transplantation and destination therapy trials (N = 1,122) were randomly divided into derivation (DC) (n = 583) and validation cohorts (VC) (n = 539). Pre-operative candidate predictors of 90-day mortality were examined in the DC with logistic regression, from which the HMII Risk Score (HMRS) was derived. The HMRS was then applied to the VC.

RESULTS

There were 149 (13%) deaths within 90 days. In the DC, mortality (n = 80) was higher in older patients (odds ratio [OR]: 1.3, 95% confidence interval [CI]: 1.1 to 1.7 per 10 years), those with greater hypoalbuminemia (OR: 0.49, 95% CI: 0.31 to 0.76 per mg/dl of albumin), renal dysfunction (OR: 2.1, 95% CI: 1.4 to 3.2 per mg/dl creatinine), coagulopathy (OR: 3.1, 95% CI: 1.7 to 5.8 per international normalized ratio unit), and in those receiving LVAD support at less experienced centers (OR: 2.2, 95% CI: 1.2 to 4.4 for <15 trial patients). Mortality in the DC low, medium, and high HMRS groups was 4%, 16%, and 29%, respectively (p < 0.001). In the VC, corresponding mortality was 8%, 11%, and 25%, respectively (p < 0.001). HMRS discrimination was good (area under the receiver-operating characteristic curve: 0.71, 95% CI: 0.66 to 0.75).

CONCLUSIONS

The HMRS might be useful for mortality risk stratification in HMII candidates and may serve as an additional tool in the patient selection process.

Is resternotomy a risk for continuous-flow left ventricular assist device outcomes?

BACKGROUND

The number of patients undergoing resternotomy continues to rise. Although catastrophic hemorrhage remains a dreaded complication, most published data suggest that sternal reentrance is safe, with negligible postoperative morbidity and mortality. A significant proportion of left ventricular assist device (LVAD) implantations are reoperative cardiac procedures. The aim of our study was to compare outcomes between first time sternotomy and resternotomy patients receiving continuous-flow LVADs, as a bridge to transplantation or destination therapy.

METHODS AND MATERIALS

From March 2006 through February 2012, 100 patients underwent implantation of a HeartMate II or HeartWare LVAD at our institution. Patients were stratified into two groups, primary sternotomy and resternotomy. Variables were compared using two-sided t-tests, chi-square tests, Cox proportional hazards models, and log-rank tests to determine whether there was a difference between the two groups and if resternotomy was a significant independent predictor of outcome.

RESULTS

We identified 29 patients (29%) who had resternotomy and 71 patients (71%) who had first time sternotomy. The resternotomy group was significantly older (56 years vs. 51 years, p = 0.05), was more likely to have ischemic cardiomyopathy (ICM) (69% vs. 30%, p < 0.001), chronic obstructive pulmonary disease (COPD) (31% vs. 14%, p = 0.05) and had longer cardiopulmonary bypass times (135 min vs. 100 min, p = 0.011). Survival rates at 30 days (93.1% vs. 95.8%, p = 0.564), 180 days (82.8% vs. 93%, p = 0.131), and 360 days (82.8% vs. 88.7%, p = 0.398) were similar for the resternotomy and primary sternotomy groups, respectively. Postoperative complications were also comparable, except for re-exploration for bleeding which was higher for the resternotomy group (17.2% vs. 4.2%, p = 0.029), although blood transfusion requirements were not significantly different (1.4 units vs. 1.2 units, p = 0.815). Left and right heart catheterization measurements and echocardiographic (ECHO) findings after 1 and 6 months of LVAD therapy were similar between the two groups.

CONCLUSIONS

Survival at 30, 180, and 360 days after LVAD implantation is similar between the resternotomy and primary sternotomy group. No major differences in complications or hemodynamic measurements were observed. Although a limited observational study, our findings agree with previously published resternotomy outcomes.

[Improvements in implantable mechanical circulatory support systems : literature overview and update]

In recent years, ventricular assist devices (VAD) supporting the left (LVAD), the right (RVAD) or both ventricles (BVAD) have rapidly emerged as the standard of care for advanced heart failure patients. Both the numbers and ages of patients in which they are used are rising worldwide, especially when used as a permanent support (bridge to destination, BTD). Due to the continuing lack of donor organs, these devices now represent a viable alternative to bridge patients to transplantation (BTT), with a 1-year survival rate of 86%. BTD, especially in long-term support, might be a valid, and the sole, option for those patients in whom heart transplantation is contraindicated. Patient selection, pre- and intra-operative preparation, as well as the timing of VAD implantation are important factors critical to successful circulatory support. While BTT remains the goal in the majority of patients, the number of permanent VADs (i. e. BTD) is rising significantly. Although explantation of a VAD system as a bridge to recovery (BTR) can be considered in only a small number of patients, it represents a very special part of this therapy modality.

Current trends in implantable left ventricular assist devices

The shortage of appropriate donor organs and the expanding pool of patients waiting for heart transplantation have led to growing interest in alternative strategies, particularly in mechanical circulatory support. Improved results and the increased applicability and durability with left ventricular assist devices (LVADs) have enhanced this treatment option available for end-stage heart failure patients. Moreover, outcome with newer pumps have evolved to destination therapy for such patients. Currently, results using nonpulsatile continuous flow pumps document the evolution in outcomes following destination therapy achieved subsequent to the landmark Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure Trial (REMATCH), as well as the outcome of pulsatile designed second-generation LVADs. This review describes the currently available types of LVADs, their clinical use and outcomes, and focuses on the patient selection process.

Clinical management of continuous-flow left ventricular assist devices in advanced heart failure

Continuous-flow left ventricular assist devices (LVAD) have emerged as the standard of care for advanced heart failure patients requiring long-term mechanical circulatory support. Evidence-based clinical management of LVAD-supported patients is becoming increasingly important for optimizing outcomes. In this state-of-art review, we propose key elements in managing patients supported with the new continuous-flow LVADs. Although most of the presented information is largely based on investigator experience during the 1,300-patient HeartMate II clinical trial, many of the discussed principles can be applied to other emerging devices as well. Patient selection, pre-operative preparation, and the timing of LVAD implant are some of the most important elements critical to successful circulatory support and are principles universal to all devices. In addition, proper nutrition management and avoidance of infectious complications can significantly affect morbidity and mortality during LVAD support. Optimizing intraoperative and peri-operative care, and the monitoring and treatment of other organ system dysfunction as it relates to LVAD support, are discussed. A multidisciplinary heart failure team must be organized and charged with providing comprehensive care from initial referral until support is terminated. Preparing for hospital discharge requires detailed education for the patient and family or friends, with provisions for emergencies and routine care. Implantation techniques, troubleshooting device problems, and algorithms for outpatient management, including the diagnosis and treatment of related problems associated with the HeartMate II, are discussed as an example of a specific continuous-flow LVAD. Ongoing trials with other continuous-flow devices may produce additional information in the future for improving clinical management of patients with these devices.

Results following implantation of mechanical circulatory support systems: the Montreal Heart Institute experience

BACKGROUND

Mechanical circulatory support systems (MCSS) have been available in Canada since 1986. Accepted indications include bridging to transplantation or recovery. The present study reviewed the results following MCSS implantation at the Montreal Heart Institute (Montreal, Quebec).

METHODS

From September 1987 to September 2006, 43 MCSS were implanted (32 Thoratec [Thoratec Corporation, USA], nine CardioWest TAH [SynCardia Systems Inc, USA], two Novacor [WorldHeart Corporation, Canada]) in 43 patients (mean [+/- SD] age 44+/-13 years; range 19 to 64 years). Indications for implantation included cardiogenic shock due to ischemic (n=19), viral (n=10) or other types of cardiomyopathies (n=14).

RESULTS

The mean ejection fraction before implantation was 17.6+/-6.5% (range 10% to 45%). Before MCSS implantation, most patients showed signs of end-organ failure, including mechanical ventilation (77%), central venous pressure higher than 16 mmHg (44%), oliguria (35%) and hepatic dysfunction (19%). The mean duration of MCSS support was 22.8+/-32.8 days (range one to 158 days). Survival to transplantation or recovery was 74%. Only one patient was successfully bridged to recovery. Complications were common during MCSS support. They included reexploration for bleeding (47%), respiratory failure (44%), renal failure requiring temporary dialysis (40%), infection (33%) and neurological events (16%). Only one patient had device failure. In patients successfully bridged to transplantation, early actuarial survival (one month) following transplantation averaged 71+/-8% and was 57+/-9% at one year.

CONCLUSION

MCSS support with a left ventricular assist device or a total artificial heart provides an effective means of bridging terminally ill patients to transplantation or recovery. Early survival after transplantation shows satisfactory results. However, these results come at the expense of frequent device-related complications, and device failure remains a constant threat.

Risk score derived from pre-operative data analysis predicts the need for biventricular mechanical circulatory support

BACKGROUND

Right ventricular (RV) failure after left ventricular assist device (LVAD) placement is a serious complication and is difficult to predict. In the era of destination therapy and the total artificial heart, predicting post-LVAD RV failure requiring mechanical support is extremely important.

METHODS

We reviewed patient characteristics, laboratory values and hemodynamic data from 266 patients who underwent LVAD placement at the University of Pennsylvania from April 1995 to June 2007.

RESULTS

Of 266 LVAD recipients, 99 required RV assist device (BiVAD) placement (37%). We compared 36 parameters between LVAD (n = 167) and BiVAD patients (n = 99) to determine pre-operative risk factors for RV assist device (RVAD) need. By univariate analysis, 23 variables showed statistically significant differences between the two groups (p < or = 0.05). By multivariate logistic regression, cardiac index < or =2.2 liters/min/m(2) (odds ratio [OR] 5.7), RV stroke work index < or =0.25 mm Hg . liter/m(2) (OR 5.1), severe pre-operative RV dysfunction (OR 5.0), pre-operative creatinine > or =1.9 mg/dl (OR 4.8), previous cardiac surgery (OR 4.5) and systolic blood pressure < or =96 mm Hg (OR 2.9) were the best predictors of RVAD need.

CONCLUSIONS

The most significant predictors for RVAD need were cardiac index, RV stroke work index, severe pre-operative RV dysfunction, creatinine, previous cardiac surgery and systolic blood pressure. Using these data, we constructed an algorithm that can predict which LVAD patients will require RVAD with >80% sensitivity and specificity.

Assisting the failing heart

Anesthesiologists increasingly encounter patients who have a spectrum of heart failure ranging from stable chronic heart failure to acute heart failure to cardiogenic shock. Improved medical therapy has increased the survival of patients who have chronic heart failure but not of patients who have acute heart failure. New surgical techniques and mechanical devices may offer alternatives to certain patients who have refractory heart failure This article provides an overview of established and newer pharmacologic and nonpharmacologic therapies and surgical interventions to manage patients who have heart failure, including the perioperative management of heart transplantation and ventricular assist devices.

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.

Destination therapy: does progress depend on left ventricular assist device development?

The role of therapy using mechanical circulatory support devices has evolved rapidly over the last two decades. New developments in the field achieved smaller adverse events, but, currently, only minor improvements in survival were observed in published observational data. The authors discuss the development of mechanical circulatory support devices as a "destination therapy" option for patients who have end-stage heart failure and are ineligible for heart transplantation as it relates to left ventricular assist device development.

Experience with the Levitronix CentriMag circulatory support system as a bridge to decision in patients with refractory acute cardiogenic shock and multisystem organ failure

OBJECTIVE

Patients with refractory acute cardiogenic shock and multisystem organ failure have a poor outcome with implantation of permanent ventricular assist devices. We review our experience with the use of the CentriMag (Levitronix LLC, Waltham, Mass) circulatory support system in such patients whose neurologic status was uncertain.

METHODS

From January 2004 to June 2006, 30 patients underwent CentriMag circulatory support system placement at the University of Minnesota. Of these patients, 12 were transferred from an outside hospital with refractory acute cardiogenic shock requiring biventricular support; they are the focus of this study.

RESULTS

Of our 12 study patients, 8 underwent successful bridging to the HeartMate XVE (Thoratec Corp, Pleasanton, Calif) ventricular assist device after biventricular support (mean support time of 9.4 days, range: 5-22 days). Another 2 patients underwent successful explantation (after 8 and 9 days); the remaining 2 patients died (after 4 days). Thus, the survival on CentriMag support, to either bridge or recovery, was 83% (10/12). Of the 8 patients who subsequently underwent HeartMate implantation, 5 also underwent a heart transplant within 6.9 months (range, 4.5-10 months), another 2 are still awaiting a transplant, and 1 died of sepsis and right ventricular failure 3 days after HeartMate implantation. Thus, for our 12 study patients, long-term survival was 75% at 1 month and 62.5% at 1 year.

CONCLUSIONS

Our aggressive strategy in this group of patients involved early operative intervention and implantation of biventricular support. By using this strategy, we avoided the urgent placement of expensive long-term ventricular assist devices in hemodynamically unstable patients with multisystem organ failure whose neurologic status was uncertain until end-organ recovery and excellent hemodynamic stability were achieved with the relatively inexpensive short-term CentriMag circulatory support system. The excellent midterm outcomes in this group of patients whose original prognosis was poor justify this therapeutic strategy.