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20 R. M. Cole et al.
a
b
Fig. 2.3 composite end point and overall survival
in a study of 5-year outcomes in patients with fully
magnetically levitated versus axial-flow left ventricular assist devices. Reproduced with permission from [JAMA. 2022. 328 (13): 1233–1242. doi:
and pump thrombosis, were found to occur less
frequently in the centrifugal flow (HeartMate
3) LVAD group (Fig. 2.3) [17]. At the time of
this writing, the HeartMate 3 LVAD system is
indicated as a bridge to transplantation or myocardial recovery or as destination (long-term)
therapy.
Total Articial Heart (TAH)
As an emerging alternative to VADs in patients
with biventricular failure or anatomy unsuitable
for univentricular support, TAHs will be discussed in Chap. 28
Trends in Ventricular Assist Device Use: Strategies and Outcomes
Ventricular assist devices are typically intended
for use as either short or long-term therapy.
Short-term therapy refers to utilization as a
bridge-to-transplant or stabilization of the
patient with an anticipated possibility of future
listing for transplant, known as bridge-to-candidacy. It can also refer to utilization as a possible
bridge to cardiac recovery. Long-term therapy is
also known as destination therapy and refers to
https://doi.org/10.1001/jama.2022.16197]. Copyright
© (2022) American Medical Association. All rights
reserved, including those for text and data mining, AI
training, and similar technologies
patients in whom a HTx is not intended in the
future; thus, the VAD is the terminal treatment.
It is important to note that patients who receive
VAD therapy may subsequently shift between
short and long-term therapy categorizations
depending on clinical outcomes and transplant
candidacy, which may alter future intentions,
particularly as survival in destination therapy
has improved (Fig. 2.4) [18, 19].
In rare cases (<5% of implants), LVADs
have acted as a bridge to myocardial recovery,
the theory being that unloading of the ventricle
leads to reverse ventricular remodeling and subsequent functional improvement [20], in combination with time and administration of optimal
guideline-directed medical therapies. While this
appears more likely to occur in myocarditis and
other recoverable etiologies of HF, there are
currently no reliable parameters with which to
predict those patients who will demonstrate substantial myocardial recovery.
The Interagency Registry for Mechanically
Assisted Circulatory Support (INTERMACS)
represents the largest registry of MCS device
utilization in the world, with more than 150 participating hospitals across the US and Canada.
Its purpose is to collect MCS-related data and
assess trends in survival, device strategy, and
risk factors for poor outcomes. The most recent
a
2 Mechanical and Surgical Options for Patients with End-Stage Heart Failure
21
b
Fig. 2.4 Kaplan–Meier survival analysis for all patients
and by continuous flow left ventricular assist device (CF
LVAD) era. a Kaplan–Meier estimated survival after CF
LVAD implantation for the past decade. Hazard rates are
depicted by dashed red line. b The estimated survival is
compared between the previous era (2012–2016) and
the current era (2017–2021). Intermacs, Interagency
Registry for Mechanically Assisted Circulatory Support.
Reprinted from The Annals of Thoracic Surgery, 115
(2), Melana Yuzefpolskaya, Sarah E. Schroeder, Brian
A. Houston, Monique R. Robinson, Igor Gosev, Alex
Reyentovich, Devin Koehl, Ryan Cantor, Ulrich P.
Jorde, J ames K. Kirklin, Francis D. Pagani, David
A. D’Alessandro, The Society of Thoracic Surgeons
Intermacs 2022 Annual Report: Focus on the 2018 Heart
Transplant Allocation System, 311–327., Copyright
(2023), with permission from Elsevier
22 R. M. Cole et al.
INTERMACS 2022 annual report highlights
MCS data from 2012 to 2022, including outcomes data for 27,314 patients who have undergone continuous flow LVAD therapy [18]. Of
note, the 1-year and 5-year survival of patients
who underwent LVAD implantation between
2017 and 2021 was 83.0 and 51.9%, respectively. This improvement from the prior decade is likely multifactorial and likely reflects
improvement in device technology, patient
selection, and patient management [18]. In
recent years, with the growing development and
improvement of temporary MCS devices as a
bridge to transplant in combination with changes
in the US HTx allocation system in 2018, there
has been an overall decline in utilization of
short-term (bridge-to-transplant) LVADs, with
destination-therapy devices being the predominantly intended implant strategy, representing
81.1% of implants in 2021 compared to 56.5%
in 2018 [18].
Contraindications to LVAD Insertion
Relative, but not absolute contraindications to
LVAD insertion include acute cardiogenic shock
with uncertain neurological status, active severe
bleeding (as patients on VAD require anticoagulation), active uncontrolled systemic infection, severe right ventricular dysfunction, severe
uncorrected aortic insufficiency or mechanical aortic valve that will not be converted to a
bioprosthesis [12]. Furthermore, patients who
would be unable to physically operate their
pump and would not respond to device alarms
may also be considered unsuitable candidates
[21]. Irreversible end-organ damage other than
cardiac also poses a potential contraindication to
VAD therapy. An inability to take anticoagulant
therapy is an absolute contraindication to LVAD
support. Management guidelines for LVAD
patients are continually being updated and
assessed, with increasing numbers of centers
reporting their data [15, 21]; as such, it is anticipated that these contraindications will change
with improvements in LVAD technology, surgical methods, and postoperative management.
INTERMACS Prole and Risk Factors
for Mortality Post-Implant
The INTERMACS profile [22] assigns patients
with advanced HF into seven different classifications according to clinical status, hemodynamic profile, and level of end-organ
damage (Table 2.2). The lower the number,
the more gravely ill the patient; for example,
an INTERMACS 1 patient will demonstrate
hemodynamic instability and cardiogenic shock
despite increased inotropic doses and/or MCS;
in contrast, an INTERMACS 7 patient is a functional, ambulatory NYHA class IIIa patient with
no fluid overload. Such a scale was designed
for the purposes of perioperative risk prediction and stratification for future outcomes postimplant, including mortality and complications.
The major risk factors for mortality following
continuous-flow device implantation include
patients on hemodialysis, patients who represent INTERMACS 1 and 2 levels at the time of
LVAD implant, advanced age, history of stroke,
previous ICD placement, increased bilirubin
and requirement for RVAD implant in the same
operation [18].
Potential Adverse Events with Left Ventricular Assist Devices
The most common adverse events after LVAD
therapy include stroke, bleeding, infection,
device malfunction, arrhythmia, and renal dysfunction. In the contemporary era of LVAD
therapy, major adverse events typically occur
most frequently in the first 90 days from LVAD
implantation, except for MCS-related infection,
which typically occurs after the first 90 days.
Fortunately, the most recent era of LVAD
support (2017–2021) has shown significant
improvement in rates of adverse events when
compared to the prior era. More specifically,
1-year freedom from gastrointestinal bleeding
improved from 74.9 to 82.1%, and 1-year freedom from device malfunction/pump thrombosis
improved from 80.7 to 92.9%. 1-year freedom
from a first stroke has improved to 88.7% [18].
2 Mechanical and Surgical Options for Patients with End-Stage Heart Failure
Table 2.2 INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) scale for classifying
patients with advanced heart failure
Profiles Definition Description
INTERMACS 1 Crash and burn Hemodynamic instability in spite of increasing doses of
catecholamines and/or mechanical circulatory support
with critical hypoperfusion of target organs (severe
cardiogenic shock)
INTERMACS 2 Sliding on inotropes Intravenous inotropic support with acceptable blood
pressure but rapid deterioration of kidney function,
nutritional state, or signs of congestion
INTERMACS 3 Dependent stability Hemodynamic stability with low or intermediate, but
necessary due to hypotension, doses of inotropics, worsening of symptoms, or progressive kidney failure
INTERMACS 4 Frequent flyer Temporary cessation of inotropic treatment is possible,
but the patient presents frequent symptom recurrences
and typically with fluid overload
INTERMACS 5 Housebound Complete cessation of physical activity, stable at rest,
but frequently with moderate water retention and some
level of kidney dysfunction
INTERMACS 6 Walking wounded Minor limitation on physical activity and absence of
congestion while at rest. Easily fatigued by light activity
INTERMACS 7 Placeholder Patient in NYHA functional class II or III with no cur-
rent or recent unstable water balance
Reprinted from The Journal of Heart and Lung Transplantation, 28 (6), Lynne Warner Stevenson, Francis D. Pagani, James B. Young, Mariell Jessup, Leslie Miller, Robert L. Kormos, David C. Naftel, Karen Ulisney, Patrice Desvigne-Nickens, James K. Kirklin, INTERMACS Profiles of Advanced Heart Failure: The Current Picture, 535–541,
Copyright (2009), with permission from Elsevier
23
Despite the improved morbidity and adverse
event profile in the modern era of third generation LVADs, rehospitalization rates still remain
high, with one study demonstrating an average of 1.64 ± 1.97 admissions per patient-year
follow-up [23]. The most common reasons for
readmission are infection and gastrointestinal
bleeding resulting from anticoagulation.
Left Ventricular Assist Device Selection
Ventricular assist device selection is generally
tailored according to the patient’s expectations
and clinical status, using a multidisciplinary
approach. Hemodynamically stable patients
who are typically classified as INTERMACS
1–3 may be considered for bridge-to-transplant
or destination therapy using a durable, longterm continuous flow device such as those
already mentioned. However, in the hemodynamically unstable or deteriorating patient (i.e.,
INTERMACS 1 or 2), short-term MCS therapy
should be immediately considered (see next
section). Such a measure provides the patient
with essential circulation and allows the medical team more time to optimize clinical status,
perform neurologic assessment, and decide on
further management (LVAD, transplant, etc.).
Pertinently, in regard to the timing of assist
device therapy, reports have shown that the survival of patients undergoing bridge‐to‐transplan-
tation therapy is improved when assist devices
are implanted electively, as compared to implantations for urgent or emergency indications [16].
Of note, there may be a further benefit from the
implantation of LVAD therapy in patients who
are INTERMACS profile 4 when compared to
the continuation of optimal medical therapy, as
seen in the 2-year follow-up to the ROADMAP
trial [24].
24 R. M. Cole et al.
Short-Term Options for Mechanical Circulatory Support
Intra-Aortic Balloon Pump
The intra-aortic balloon pump is a mechanical device that increases myocardial oxygen
perfusion while simultaneously increasing cardiac output and decreasing afterload. Typically
inserted via the femoral artery, it consists of a
cylindrical polyethylene balloon that sits in the
aorta, approximately 2 cm (0.79 in) from the
left subclavian artery and counter pulsates. This
method is often used as the first mechanical support treatment in efforts to improve coronary
perfusion in the setting of refractory cardiogenic shock. Absolute contraindications include
severe aortic valve insufficiency and severe aortic pathology, including dissection, while relative contraindications include aortic aneurysm
and the presence of any aortic vascular grafts.
Possible complications include ischemic leg,
cerebral embolism, aortic dissection, and mediastinal bleeding.
Extracorporeal Membrane Oxygenation
Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a rapid mode of emergency biventricular support typically used as
a last resort salvage therapy in the setting of
cardiogenic shock, where implanting durable mechanical device is not possible/feasible
(Fig. 2.5). Acting essentially as a form of cardiopulmonary bypass, VA-ECMO provides excellent hemodynamic support via a non-pulsatile
(often centrifugal) pump connected in-line to a
membrane oxygenator that receives blood via
inflow venous cannulas, commonly inserted into
the femoral vein, and which returns oxygenated blood via an outflow arterial cannula, commonly inserted into the femoral artery. Survival
rates in refractory cardiogenic shock patients
with ECMO vary by clinical indication, with
survival to discharge varying from 39 to 80%
[25, 26]. The main disadvantages of ECMO are
the relative lack of durability (mean of 4 days),
the inability to unload the left ventricle, and the
potential hemocompatibility issues, including
Fig. 2.5 Functional diagram of femoral venoarterial ECMO in a patient. Reprinted from Journal of the
American College of Cardiology, 63/25, Darryl Abrams,
Alain Combes, Daniel Brodie, Extracorporeal Membrane
Oxygenation in Cardiopulmonary Disease in Adults,
2769–2778, Copyright (2014), with permission from
Elsevier
252 Mechanical and Surgical Options for Patients with End-Stage Heart Failure
bleeding related to vascular access [25, 26].
Patients who survive are typically subsequently
transitioned to a VAD, TAH, or, less commonly,
to a transplant.
Percutaneous Mechanical Circulatory Support
Continued advances in temporary MCS technology have resulted in new devices such as
the Impella (Abiomed, Danvers, MA, USA)
(Fig. 2.1); the Impella is a micro axial catheterbased percutaneous ventricular assist device,
which can be inserted in either venous or arterial access configurations to support the right
and left ventricle, respectively. In the left-sided
support configuration, the catheter is inserted
via the femoral or axillary/subclavian artery
and directed retrograde across the aortic valve
to provide adequate perfusion in hemodynamically unstable patients. Impella catheters can
be considered for support during high-risk percutaneous coronary interventions, cardiogenic
shock, and as a bridge to myocardial recovery or
transplant/LVAD, amongst other indications. As
of the time of writing, the surgically implanted
Impella 5.5 offers the most significant left ventricular support, up to 6 L per minute of flow.
Impella devices are more frequently utilized as a
bridge to HTx and are currently prioritized over
durable LVADs under the current US heart allocation policy. In a study of the UNOS database
from 2010 to 2021, waitlist and post-transplant
outcomes were assessed for patients bridged to
HTx with Impella 5.0 and 5.5 devices. It showed
that bridging with these devices was safe, with
low overall rates of waitlist mortality or clinical deterioration. These patients also had excellent 1-year post-transplant outcomes [27]. The
TandemHeart
Pennsylvania, USA) is another percutaneous
LVAD that requires a trans-septal puncture [28].
In a contemporary cohort of 50 patients presenting with cardiogenic shock enrolled in the
THEME registry (a multicenter, prospective,
observational study), the use of TandemHeart®
®
(Cardiac Assist, Inc., Pittsburgh,
was associated with a 74% 30-day survival and a
66% 180-day survival [29].
Heart Transplantation
HTx remains the gold-standard surgical option
for refractory end-stage HF. Chaps. 3 and 4
will detail indications and evaluation criteria.
In summary, despite improved outcomes of
the novel HF therapeutics, morbidity and mortality rates remain excessively high for patients
with advanced HF. In these cases, MCS, including temporary and durable devices, are imperative in their management. Once the patient is
deemed to have advanced HF and likely to
benefit from advanced therapies, the optimal
strategy for implantation should include selecting the most appropriate MCS device with the
best durability and lowest incidence of adverse
events and which provides adequate cardiac output for either one or both failing ventricles.
References
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13. Lok SI, Martina JR, Hesselink T, Rodermans BFM,
Hulstein N, Winkens B, et al. Single-centre experience of 85 patients with a continuous-flow left ventricular assist device: clinical practice and outcome
after extended support. Eur J Cardiothorac Surg.
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14. Park SJ, Milano CA, Tatooles AJ, Rogers JG,
Adamson RM, Steidley DE, et al. Outcomes in
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Fail. 2012;5(2):241–8.
15. Kirklin JK, Naftel DC, Kormos RL, Stevenson LW,
Pagani FD, Miller MA, et al. Fifth INTERMACS
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Heart Lung Transplant. 2013;32(2):141–56.
16. Deng MC, Weyand M, Hammel D, Schmid C,
Kerber S, Schmidt C, et al. Selection and management of ventricular assist device patients: the
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17. Mehra MR, Goldstein DJ, Cleveland JC, Cowger
JA, Hall S, Salerno CT, et al. Five-year outcomes in patients with fully magnetically levitated vs axial-flow left ventricular assist devices
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18. Yuzefpolskaya M, Schroeder SE, Houston BA,
Robinson MR, Gosev I, Reyentovich A, et al.
The Society of Thoracic Surgeons Intermacs
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K, Flannery M, DiTullio M, et al. Low incidence
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Lietz K, Moore SA, et al. The 2013 International
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Miller L, Kormos RL, et al. INTERMACS profiles
of advanced heart failure: the current picture. J
Heart Lung Transplant. 2009;28(6):535–41.
23. Hasin T, Marmor Y, Kremers W, Topilsky Y,
Severson CJ, Schirger JA, et al. Readmissions after
implantation of axial flow left ventricular assist
device. J Am Coll Cardiol. 2013;61(2):153–63.
24. Starling RC, Estep JD, Horstmanshof DA, Milano
CA, Stehlik J, Shah KB, et al. Risk assessment and
comparative effectiveness of left ventricular assist
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results. JACC Heart Fail. 2017;5(7):518–27.
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Extracorporeal life support organization registry
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26. Prodhan P, Bhutta AT, Gossett JM, Dodgen AL, Seib
PM, Imamura M, et al. Comparative effects of ventricular assist device and extracorporeal membrane
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27. Hill MA, Kwon JH, Shorbaji K, Kilic A. Waitlist
and transplant outcomes for patients bridged to heart
transplantation with Impella 5.0 and 5.5 devices. J
Card Surg. 2022;37(12):5081–9.
28. Kar B, Adkins LE, Civitello AB, Loyalka P,
Palanichamy N, Gemmato CJ, et al. Clinical experience with the TandemHeart
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29. Megaly M, Gandolfo C, Zakhour S, Jiang M,
Burgess K, Chetcuti S, et al. Utilization of
TandemHeart in cardiogenic shock: insights from
the THEME registry. Catheter Cardiovasc Interv.
2023;101(4):756–63.
Evaluation for Heart Transplant Candidacy
Michele Hamilton and Yosef Manla
Abstract
Evaluation for heart transplant (HTx) candidacy necessitates a multidisciplinary effort to
integrate medical, and psychosocial parameters and work in concert with the patient’s
care goals, considering the full complement
of individually appropriate options. This
chapter summarizes HTx indications and pretransplant evaluation.
Keywords
Heart failure · Heart transplantation ·
Cardiopulmonary exercise testing
Clinical Pearls
• Evaluation for heart transplantation candidacy necessitates a multidisciplinary effort
to integrate medical and psychosocial parameters and work in concert with the patient’s
care goals.
M. Hamilton (*) · Y. Manla
Cedars-Sinai Smidt Heart Institute, Los Angeles,
CA, USA
e-mail: michele.hamilton@cshs.org
Y. Manla
e-mail: Yosef.manla@cshs.org
3
•
General indications for evaluation for trans-
plant listing include cardiogenic shock
requiring continuous intravenous inotropic
support or mechanical support, refractory
NYHA class III-IV/AHA stage D heart failure, recurrent sustained ventricular arrhythmias, severe untreatable angina and end-stage
congenital heart disease.
• Evaluation for heart transplantation
includes assessment of heart failure severity, immuno-compatibility, evaluation of
multi-organ function, infectious serology
and vaccinations, malignancies, as well as a
psychological, social, and financial assessment (including insurance coverage).
• Cardiopulmonary exercise testing (CPET) provides an objective measure of cardiac impairment and prognosis via measurement of oxygen
consumption at peak exercise (peak VO2).
•
Heart failure patients on beta-blockers with a
VO2max ≤ 12 ml/kg/min or younger patients
with less than 50% of predicted VO2max,
considered in conjunction with other evidence of functional impairment and clinical
course, may be appropriate for transplant.
• Hemodynamic assessment with right heart
catheterization also is important for assessment of the level of cardiac impairment and
confirm there is no evidence of irreversible
pulmonary hypertension.
• The Heart Failure Survival Score (HFSS)
and Seattle Heart Failure Model (SHFM)
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
J. Kobashigawa (ed.), Clinical Guide to Heart Transplantation, https://doi.org/10.1007/978-3-031-88290-6_3
27
28 M. Hamilton and Y. Manla
are multifactorial scores that may be helpful in guiding decisions on listing for heart
transplantation.
Introduction
As the outcomes for both heart failure (HF)
therapy and heart transplantation (HTx) have
improved, and the field of durable mechanical
circulatory support (MCS) is maturing, the risk/
benefit ratio for medical therapy and HTx has
evolved [1]. It is appropriate to consider HTx
for patients with advanced heart disease and,
despite maximal medical therapy, a poor quality of life related to HF symptoms [New York
Heart Association (NYHA) Class III/IV) or high
risk of sudden death—in the absence of lifelimiting non-cardiac illnesses. Intensive care
unit patients in cardiogenic shock are now the
substantial majority of patients who receive HTx
[2]. Evaluation for HTx candidacy necessitates
a multidisciplinary effort to integrate medical
and psychosocial parameters and work in concert with the patient’s care goals, considering
the full complement of individually appropriate
options [3]. An additional layer of complexity
in determining candidacy for HTx is the scarcity of donor organs, so we need to consider
not only providing the best treatment for each
patient but also responsible allocation of this
scarce resource. Though there has been some
recent increase in HTx, due in part to the use of
donation after circulatory death, there have been
only approximately 4,000 HTx annually in the
US, with many more in need [4].
Indications for Heart Transplantation
The most common indications for transplantation include refractory cardiogenic shock
requiring continuous intravenous inotropic
or temporary MCS, followed by progressive
NYHA class III-IV/AHA stage D HF, refractory ventricular arrhythmias, severe untreatable
angina, and end-stage congenital heart disease
[5]. Also, patients on a durable ventricular assist
device may be eligible for transplant, and HTx
patients who develop significant cardiac allograft vasculopathy, often with restrictive cardiac
physiology, may be considered for redo-transplant (Table 3.1).
For the patient in irreversible cardiogenic
shock, the options include transplantation, durable left ventricular assist devices (LVAD), total
artificial heart, or palliative care. The role of
durable MCS has been discussed in the previous chapter; short-term (1 year) survival with
the HeartMate III device now rivals transplant at 85–90%, but transplant remains the
gold standard for long-term survival and functional capacity [6, 7]. For ambulatory patients
with progressive stage D HF and NYHA Class
IIIb/IV symptoms, a combination of clinical
Table 3.1 General indications for cardiac transplantation
• Refractory cardiogenic shock requiring intra-aortic balloon pump counterpulsation or mechanical circulatory support (i.e., left ventricular assist device (LVAD), total artificial heart)
• Cardiogenic shock requiring continuous intravenous inotropic therapy (i.e., dobutamine, milrinone, etc.)
• Cardiopulmonary exercise testing demonstrating VO2max ≤ 14 mL/kg/min in patients not on beta-blockers, or
VO2max ≤ 12 mL/kg/min in patients on beta-blockers
• Persistant NYHA class of III or IV heart failure symptoms despite maximized medical, surgical and/or resynchronization therapy
• Recurrent life-threatening left ventricular arrhythmias despite an implantable cardiac defibrillator, maximal pharmacological antiarrhythmic therapy, or catheter-based ablation
• End-stage congenital HF with no evidence of pulmonary hypertension
• Refractory angina despite maximal medical therapy and not amenable to percutaneous or surgical revascularization
• Severe hypertrophic or restrictive cardiomyopathy, with NYHA Class IV symptoms
• Transplanted patients who develop significant cardiac allograft vasculopathy with refractory cardiac allograft
dysfunction
NYHA: New York Heart Association
3 Evaluation for Heart Transplant Candidacy
29
parameters, hemodynamics, and functional status are used to determine if patients are likely to
have improved outcomes with transplantation.
The need for LVAD as either a destination alternative or bridge to transplant is also considered
as part of the evaluation for this population.
The Evaluation
An evaluation usually consists of consultations from a multidisciplinary team, including
HF /transplant cardiology specialist, cardiothoracic surgeon, and other medical specialties as
needed, as well as transplant coordinators, social
workers, pharmacists, and dieticians. Evaluation
for HTx includes assessment of HF severity,
immuno-compatibility, evaluation of multi-organ
function, infectious serology and vaccinations,
malignancies, as well as a psychological, social,
and financial assessment [8] (Table 3.2).
Assessment of Heart Failure Severity
All patients undergo an echocardiogram to identify structural and hemodynamic parameters,
providing prognostic factors and potential alternatives to transplant. A left ventricular ejection
fraction (LVEF) of <25% has been shown to be
associated with increased mortality and morbidity compared to an ejection fraction > 35% [9].
However, low LVEF alone within a cohort of
patients with advanced HF has been shown to
be poorly predictive of short-term or mediumterm mortality. An echocardiogram may identify
valvular abnormalities, such as severe functional
mitral regurgitation or aortic stenosis, with potential for transcatheter devices or severe RV dysfunction, making LVAD unacceptably high risk.
Right heart catheterization (RHC) measurement of hemodynamics is an important test as
part of the initial assessment for HTx candidacy both to assist in the optimization of current therapy and assess prognosis and potential
contraindications to HTx. RHC will also need to
be repeated in some patients periodically while
waiting if there was initially reversible pulmonary hypertension or if there has been subsequent worsening of HF symptoms [10]. Higher
right atrial, pulmonary capillary wedge and pulmonary artery systolic pressures, lower mean
arterial pressure, and lower cardiac index have
all been variably associated with increased mortality, with pulmonary capillary wedge pressure
after maximal hemodynamically guided therapy being the optimal target to predict survival
[10–14].
Cardiopulmonary exercise testing (CPET), a
bicycle or treadmill-based exercise test with gas
exchange measurements via a mouthpiece, is
considered the best means to objectively determine if a patient’s severity of functional impairment merits listing for transplantation [10]. One
of the key measurements in CPET that provides
prognostic information is oxygen consumption
at peak exercise or peak VO2. This measure is
a reflection of the maximal amount of oxygen
the heart can deliver to the peripheral tissues
at a sufficient rate for aerobic respiration. The
ISHLT guidelines state that a cut-off for peak
VO2 of 12–14 ml/kg/min in HF patients should
be used to guide which patients are sufficiently
impaired for transplantation since studies have
demonstrated that patients with preserved exercise capacity (VO2max > 14 mL/kg/min) despite
severe resting hemodynamic impairment,
have survival and functional capacity equal to
those afforded by HTx [3, 15, 16]. In view of
improved survival in patients on beta-blockers,
these patients should be generally considered at
increased risk only at the low end of this peak
VO2 range. Since peak VO2 is also affected
by age and weight, it is helpful to adjust peak
VO2 to lean body weight in obese patients and
to use a percentage of predicted peak VO2 for
each individual patient, with <50% predicted
considered sufficiently impaired for transplantation [17–19]. It must be emphasized that the
decision to list must not be made on peak VO2
measurement on CPET alone; many other factors, including pulmonary, peripheral vascular, pulmonary vascular, or musculoskeletal
disease, may also reduce the peak VO2. These
can often be differentiated by other parameters