Long-term follow-up of thoratec ventricular assist device bridge-to-recovery patients successfully removed from support after recovery of ventricular function

doi:10.1016/S1053-2498(01)00408-9

The Journal of Heart and Lung Transplantation

Volume 21, Issue 5, May 2002, Pages 516-521

https://doi.org/10.1016/S1053-2498(01)00408-9 Get rights and content

Abstract

Background:

In certain forms of severe heart failure there is sufficient improvement in cardiac function during ventricular assist device (VAD) support to allow removal of the device. However, it is critical to know whether there is sustained recovery of the heart and long-term patient survival if VAD bridging to recovery is to be considered over the option of transplantation.

Methods:

To determine long-term outcome of survivors of VAD bridge-to-recovery procedures, we retrospectively evaluated 22 patients with non-ischemic heart failure successfully weaned from the Thoratec left ventricular assist device (LVAD) or biventricular assist device (BVAD) after recovery of ventricular function at 14 medical centers. All patients were in imminent risk of dying and were selected for VAD support using standard bridge-to-transplant requirements. There were 12 females and 10 males with an average age of 32 (range, 12–49). The etiologies were 12 with myocarditis, 7 with cardiomyopathies (4 post-partum [PPCM], 1 viral [VCM], and 2 idiopathic [IDCM]), and 3 with a combination of myocarditis and cardiomyopathy. BVADs were used in 13 patients and isolated LVADs in 9 patients, for an average duration of 57 days (range, 11–190 days), before return of ventricular function and successful weaning from the device. Post-VAD survival was compared with 43 VAD bridge-to-transplant patients with the same etiologies who underwent cardiac transplantation instead of device weaning.

Results:

Nineteen of the 22 patients are currently alive. Three patients required heart transplantation, 1 within 1 day, 2 at 12 and 13 months post-weaning, and 2 died at 2.5 and 6 months. The remaining 17 patients are alive with their native hearts after an average of 3.2 years (range, 1.2–10 years). The actuarial survival of native hearts (transplant-free survival) post-VAD support is 86% at 1 year and 77% at 5 years, which was not significantly different (p = 0.94) from that of post-VAD transplanted patients, also at 86% and 77%, respectively.

Conclusion:

Long-term survival for bridge-to-recovery with VADs for acute cardiomyopathies and myocarditis is equivalent to that for cardiac transplantation. Recovery of the native heart, which can take weeks to months of VAD support, is the most desirable clinical outcome and should be actively sought, with transplantation used only after recovery of ventricular function has been ruled out.

Section snippets

Methods

The Thoratec VAD voluntary registry database was reviewed for the 10-year period 1990 to 1999. This study included patients who were supported with VADs for severe intractable cardiac failure and who were later weaned from VAD support following recovery of ventricular function. Patients with post-cardiotomy cardiac dysfunction were excluded. Patients with ischemic heart failure were also excluded.

Results

The average VAD support period before the devices could be removed following recovery of ventricular function was 57 days (median, 50 days), with 80% of patients supported for less than 90 days and the shortest and longest duration being 11 and 190 days. All LVADs were removed due to an impression of recovered myocardial function. One right VAD was removed early because of thrombus, but there were no premature removals due to infection. Two VADs were replaced due to mechanical malfunction. The

Discussion

The results of this report show encouraging long-term survival for patients supported with VADs for severe heart failure and then weaned from the device after recovery of ventricular function. The 5-year native heart transplant-free survival of 77% for recovery patients was identical to patient survival 5 years after bridge to cardiac transplantation. Recovery of the natural heart is the preferred clinical outcome, especially for those young patients who otherwise require long-term

Conclusion

These results provide evidence that long-term survival after VAD use as a bridge-to-recovery for acute cardiomyopathies and myocarditis is equivalent to survival for bridging-to-transplantation. Recovery of ventricular function is the most desirable outcome and should be actively sought, especially in patients with short histories of heart failure. Heart transplantation should be used only if sufficient recovery does not occur.

Acknowledgements

The authors thank Gerald Champsaur, MD, from Hôpital Louis Pradel, Lyon, France, Donald Esmore from Alfred Hospital, Melbourne, Australia, J. Donald Hill, MD, from California Pacific Medical Center, San Francisco, James A. Narrod, MD, from Columbia Presbyterian/St. Luke’s Medical Center, Denver, and Mark W. Turrentine, MD, from Riley Hospital for Children, Indianapolis, IN, and also from the surgeons and support staffs at 13 additional medical centers for their help with the transplant group.

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Left ventricular (LV) assist devices (LVADs) are known to elicit reverse remodeling by mechanically unloading the left ventricle. Current guidelines target a reduction in LV end-diastolic diameter (LVEDD) of 15% compared with pre-LVAD dimensions; however, there is significant heterogeneity in the degree of unloading achieved. We sought to investigate factors associated with mechanical unloading at 6 months of LVAD support.
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At 6 months, optimally unloaded patients (group A) demonstrated higher fractional shortening (15% ± 10% vs 10% ± 7%, P = .007), lower rates of moderate or severe mitral regurgitation (10% vs 33%, P = .02), and lower pulmonary capillary wedge pressure (9 ± 4 vs 16 ± 7 mm Hg, P = .02). Right ventricular dysfunction was more prevalent at 6 months in poorly unloaded (group B) patients (73% vs 43%, P = .008). Between hospital discharge and 6 months, the percentage increase in pump speed (Δ revolutions per minute) was higher in group A patients (4.4% ± 3.7% vs 0.1% ± 2.6%, P < .001). In a multivariate analysis, Δ revolutions per minute and tricuspid annular systolic velocity (S') at 6 months were independently associated with 6-month ΔLVEDD.
Recipients of LVADs who undergo progressive pump speed up-titration during outpatient follow-up are more likely to sustain optimal LV unloading. Progressive LVAD-related right ventricular failure is prevalent in suboptimally unloaded patients.
Trends in the Incidence of In-Hospital Mortality, Cardiogenic Shock, and Utilization of Mechanical Circulatory Support Devices in Myocarditis (Analysis of National Inpatient Sample Data, 2005–2014)
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Myocarditis may be associated with hemodynamic instability and portends a poor prognosis when associated with cardiogenic shock (CS). There are limited data available on the incidence of in-hospital mortality, CS, and utilization of mechanical circulatory support (MCS) devices in these patients.
We queried the 2005–2014 National Inpatient Sample databases to identify all patients aged >18 years with myocarditis in the United States.
The number of reported cases of myocarditis per 1 million gradually increased from 95 in 2005 to 144 in 2014 (Pfor trend <.01). The trend and incidence of endomyocardial biopsy remained the same despite the increase in clinical diagnosis. Overall, in-hospital mortality was 4.43% of total admissions without a change in overall trend over the study period. We also observed a significant increase in the incidence of CS from 6.94% in 2005 to 11.99% in 2014 (Pfor trend <.01). There was a parallel increase in the utilization of advanced MCS devices during the same time period such as extracorporeal membrane oxygenation or percutaneous cardiopulmonary support (0.32% in 2005 to 2.1% in 2014; P< .01) and percutaneous ventricular assist devices such as Impella/tandem heart (0.176% in 2005 to 1.75% in 2014; P< .01).
Although the incidence of myocarditis has increased in the last decade, the in-hospital mortality has remained the same despite increases in the incidence of CS, possibly reflecting the benefits of increased usage of advanced MCS devices. We noted that increasing age, presence of multiple comorbidities and CS were associated with an increase in in-patient mortality.
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By reduction of ventricular wall-tension and improving the blood supply to vital organs, ventricular assist devices (VADs) can eliminate the major pathophysiological stimuli for cardiac remodeling and even induce reverse remodeling occasionally accompanied by clinically relevant reversal of cardiac structural and functional alterations allowing VAD explantation, even if the underlying cause for the heart failure (HF) was dilated cardiomyopathy. Accordingly, a tempting potential indication for VADs in the future might be their elective implantation as a therapeutic strategy to promote cardiac recovery in earlier stages of HF, when the reversibility of morphological and functional alterations is higher. However, the low probability of clinically relevant cardiac improvement after VAD implantation and the lack of criteria which can predict recovery already before VAD implantation do not allow so far VAD implantations primarily designed as a bridge to cardiac recovery. The few investigations regarding myocardial reverse remodeling at cellular and sub-cellular level in recovered patients who underwent VAD explantation, the differences in HF etiology and pre-implant duration of HF in recovered patients and also the differences in medical therapy used by different institutions during VAD support make it currently impossible to understand sufficiently all the biological processes and mechanisms involved in cardiac improvement which allows even VAD explantation in some patients.
This article aims to provide an overview of the existing knowledge about VAD-promoted cardiac improvement focusing on the importance of bench-to-bedside research which is mandatory for attaining the future goal to use long-term VADs also as therapy-devices for reversal of chronic HF.
Left Ventricular Assist Device as a Bridge to Recovery for Patients With Advanced Heart Failure
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Left ventricular assist devices (LVADs) have been used as an effective therapeutic option in patients with advanced heart failure, either as a bridge to transplantation, as destination therapy, or in some patients, as a bridge to recovery.
This study evaluated whether patients undergoing an LVAD bridge-to-recovery protocol can achieve cardiac and physical functional capacities equivalent to those of healthy controls.
Fifty-eight male patients—18 implanted with a continuous-flow LVAD, 16 patients with LVAD explanted (recovered patients), and 24 heart transplant candidates (HTx)—and 97 healthy controls performed a maximal graded cardiopulmonary exercise test with continuous measurements of respiratory gas exchange and noninvasive (rebreathing) hemodynamic data. Cardiac function was represented by peak exercise cardiac power output (mean arterial blood pressure × cardiac output) and functional capacity by peak exercise O₂ consumption.
All patients demonstrated a significant exertional effort as demonstrated with the mean peak exercise respiratory exchange ratio >1.10. Peak exercise cardiac power output was significantly higher in healthy controls and explanted LVAD patients compared with other patients (healthy 5.35 ± 0.95 W; explanted 3.45 ± 0.72 W; LVAD implanted 2.37 ± 0.68 W; and HTx 1.31 ± 0.31 W; p < 0.05), as was peak O₂ consumption (healthy 36.4 ± 10.3 ml/kg/min; explanted 29.8 ± 5.9 ml/kg/min; implanted 20.5 ± 4.3 ml/kg/min; and HTx 12.0 ± 2.2 ml/kg/min; p < 0.05). In the LVAD explanted group, 38% of the patients achieved peak cardiac power output and 69% achieved peak O₂ consumption within the ranges of healthy controls.
The authors have shown that a substantial number of patients who recovered sufficiently to allow explantation of their LVAD can even achieve cardiac and physical functional capacities nearly equivalent to those of healthy controls.
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Small-scale studies focused mainly on nonischemic cardiomyopathy (NICM) have shown that a subset of left ventricular assist device (LVAD) patients can achieve significant improvement of their native heart function, but the impact of ischemic cardiomyopathy (ICM) has not been specifically investigated. Many patients with acute myocardial infarction are discharged from their index hospitalization without heart failure (HF), only to return much later with overt HF syndrome, mainly caused by chronic remodeling of the noninfarcted region of the myocardium.
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Mechanical circulatory supportLong-term follow-up of thoratec ventricular assist device bridge-to-recovery patients successfully removed from support after recovery of ventricular function

Abstract

Background:

Methods:

Results:

Conclusion:

Section snippets

Methods

Results

Discussion

Conclusion

Acknowledgements

J Thorac Cardiovasc Surg

J Heart Lung Transplant

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

J Thorac Cardiovasc Surg

Ann Thorac Surg

J Thorac Cardiovasc Surg

J Thorac Cardiovasc Surg

J Heart Lung Transplant

Mechanical circulatory support
Long-term follow-up of thoratec ventricular assist device bridge-to-recovery patients successfully removed from support after recovery of ventricular function