Changes in Use of Left Ventricular Assist Devices as Bridge to Transplantation With New Heart Allocation Policy

Clancy W. Mullan, MD; Fouad Chouairi, BS; Sounok Sen, MD; Makoto Mori, MD; Katherine A.A. Clark, MD, MBA; Samuel W. Reinhardt, MD; P. Elliott Miller, MD; Michael A. Fuery, MD; Daniel Jacoby, MD; Christopher Maulion, MD; Muhammad Anwer, MBBS; Arnar Geirsson, MD; David Mulligan, MD; Richard Formica, MD; Joseph G. Rogers, MD; Nihar R. Desai, MD, MPH; Tariq Ahmad, MD, MPH

Disclosures

JACC Heart Fail. 2021;9(6):420-429.

Abstract and Introduction

Abstract

Objectives: The goal of this study was to describe outcomes of patients with bridge to heart transplantation (BTT) after changes were made to the donor heart allocation system.

Background: Left ventricular assist devices (LVADs) have been used as a BTT. On October 18, 2018, the donor heart allocation system in the United States was updated.

Methods: This study identified adults in the United Network for Organ Sharing database with durable, continuous-flow LVAD at listing or implanted while listed between April 2017 and April 2020. Baseline recipient and donor characteristics, waitlist survival, and post-transplantation outcomes were compared pre- and post-allocation system change.

Results: A total of 1,794 patients met inclusion criteria: 983 in the pre-change period and 814 afterward. The number of patients listed with LVAD decreased nationally over time from 102 in April 2017 to 12 in April 2020 (p < 0.001). The proportion of patients with LVAD at time of transplant decreased from 47% to 14%. Before the change, the majority were Status 1A (75.8%) at transplantation; afterward, most were Status 2/3 (67.8%). Transplantation rates were not different (85.4% vs. 83.6%; p = 0.225), but waitlist time decreased in the post period (82 vs. 65 days; p = 0.004). Donors were more likely to be high risk (39.0% vs. 32.2%; p = 0.005), and both ischemic times and distance traveled increased (3.4 h vs. 3.1 h; p < 0.001; 199 miles vs. 82 miles; p < 0.001). Waitlist survival did not change, but post-transplantation survival was worse in patients with BTT post-change (p < 0.001).

Conclusions: The number of patients with BTT on the transplant list decreased steadily and dramatically after the allocation system change. Although time to transplant decreased, there was an increase in post-transplant mortality. These data suggest that the risks and benefits of LVAD implantation as a BTT have changed under the new allocation system and that the appropriate indication for this treatment strategy warrants a re-evaluation.

Introduction

For several decades, heart transplantation was the only life-prolonging treatment option for patients with end-stage heart failure. Imbalances between a relatively static donor supply and increasing number of patients in need for transplantation led to increases in waitlist mortality.^[1] Furthermore, many patients deteriorated clinically to the point of not being suitable recipients.^[2] With improvements in durable left ventricular assist device (LVAD) technology, many of these patients were able to be stabilized en route to eventual cardiac transplantation, resulting in nearly one-half of donor hearts being transplanted into patients on LVAD support in 2018.^[1,3] This pattern challenged the donor allocation system and raised questions regarding equity of a system that did not necessarily prioritize or adequately stratify the clinical instability of patients on LVAD support.^[4]

In 2018, the Organ Procurement and Transplantation Network (OPTN) allocation system modified adult heart allocation by changing from a 3-tiered system to a 6-tiered system.^[5] The intentions were to increase organ availability for patients believed to be the most medically urgent, improve discrimination among listed patients with distinct levels of urgency, reduce waitlist mortality and waitlist time, and address disproportionate organ availability due to the prior geographic sharing.^[6] Under the prior system, patients with LVAD were eligible to be listed as Status 1A (the most urgent status) for 30 days or if they were experiencing a life-threatening device complication; otherwise, they were listed Status 1B. The 2018 heart allocation system revision acknowledged the low mortality risk for clinically stable patients with LVAD and developed uniform definitions for LVAD complications to stratify risk more robustly. Under this scheme, stable patients with LVAD are listed as Status 4, with increased urgency afforded to those with life-threatening ventricular arrhythmias (Status 1), nondischargeable patients or those with device failure (Status 2), or those with other device-related complications such as device infection, hemolysis, pump thrombosis, aortic insufficiency, and right heart failure (Status 3). Patients still have access to a 30-day discretionary period at a higher priority (Status 3).^[7] Status 1 or 2 patients are, additionally, given preference for organ offers from a wider geographic area (up to 500 miles from the donor location).

The impact of these changes on the use of LVADs in patients awaiting cardiac transplantation are unknown, as are the waitlist times and post-transplantation outcomes. To address these questions, we analyzed the United Network for Organ Sharing (UNOS) database from before and after the implementation of the new adult heart allocation system.

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Abstract and Introduction
Methods
Results
Discussion
Conclusions
References
Sidebar

Table 1. Baseline Characteristics of Recipients
	April 2017–October 18, 2018 (n = 1,000)	October 18, 2018-May 2020 (n = 833)	p Value
Age, yrs	56 (47–63)	55 (46–63)	0.122
Female	20.9	24.7	0.053
BMI, kg/m²	28.5 (25.2–32.4)	29.2 (25.8–33.3)	0.006
Race/ethnicity			0.705
White	62.7	61.8
Black	25.6	27.8
Hispanic	7.7	7.5
Asian	2.4	1.8
Blood type			0.043
A	39.3	40.9
AB	3.2	5.7
B	16.5	15.2
O	41.1	38.2
Cardiac diagnosis			0.305
Nonischemic cardiomyopathy	64.4	66.7
Ischemic cardiomyopathy	35.6	33.3
Hemodynamics/laboratory studies
eGFR, ml/min/1.73m²	67.0 (52.5–87.0)	68.3 (53.1–86.8)	0.432
Mean PAP, mm Hg	24 (18–32)	23 (17–29)	<0.001
PCWP mm Hg	15 (9–22)	13 (9–20)	<0.001
Cardiac index, l/min/m²	2.2 (1.8–2.6)	2.2 (1.9–2.6)	0.901
Comorbidities
Ventilator support	0.5	0.5	0.959
Diabetes	33.8	32.7	0.624
Dialysis	2.1	2.0	0.800
Tobacco user	52.4	52.3	0.981
Malignancy	9.5	10.4	0.488
Prior CVA	8.2	9.5	0.364
AICD	76.2	72.7	0.093

Values are median (interquartile range) or %.
AICD = automated implantable cardioverter-defibrillator; BMI = body mass index; CVA = cerebrovascular accident; eGFR = estimated glomerular filtration rate; PAP = pulmonary arterial pressure; PCWP = pulmonary capillary wedge pressure.

Table 2. Donor Characteristics
	April 2017–October 18, 2018 (n = 866)	October 18, 2018–May 2020 (n = 654)	p Value
Age (yrs)	31 (24–40)	32 (25–41)	0.051
Female	25.1	27.5	0.284
BMI, kg/m²	26.6 (23.4–30.9)	27.3 (24.2–31.8)	0.012
High-risk donor	32.2	39.0	0.005
Circulatory death	0.0	2.2	<0.001
Donor race/ethnicity			0.784
White	66.1	67.6
Black	16.6	14.9
Hispanic	14.3	14.0
Asian	1.6	1.9
Substance use
Alcohol use history	17.2	19.1	0.340
Tobacco use	10.2	12.1	0.216
Cocaine use	26.4	28.2	0.444
Other drug use	47.1	46.1	0.690
Comorbidities
Hypertension	44.3	46.7	0.358
Malignancy	1.5	1.6	0.888
Diabetes	4.7	5.1	0.768
Infections
Pneumonia	73.3	71.0	0.299
UTI	11.6	12.6	0.536
HCV	3.9	11.0	<0.001
CMV	58.7	58.5	0.957
Distance
Ischemic time (h)	3.1 (2.3–3.7)	3.4 (2.8–4.1)	<0.001
Distance traveled (mile)	82 (13–225)	199 (59–383)	<0.001

Values are median (interquartile range) or %.
BMI = body mass index; CMV = cytomegalovirus positive by nucleic acid amplification testing; HCV = hepatitis C virus positive by nucleic acid amplification testing; UTI = urinary tract infection.