Download Cardiac Resynchronization Therapy in the Autumn of Life∗

JACC: HEART FAILURE
VOL. 3, NO. 6, 2015
ª 2015 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION
ISSN 2213-1779/$36.00
PUBLISHED BY ELSEVIER INC.
http://dx.doi.org/10.1016/j.jchf.2015.04.002
EDITORIAL COMMENT
Cardiac Resynchronization Therapy
in the Autumn of Life*
Sana M. Al-Khatib, MD, MHS
T
o implant or not to implant a primary preven-
those trials can be extrapolated to older patients.
tion
defibrillator
Although several investigations suggested an associ-
(ICD) in older patients is a question that has
ation between CRT and improved echocardiographic
challenged clinicians for years. On the one hand, the
and/or clinical outcomes in older patients (9–13), most
ICD is a highly effective therapy for the prevention of
results were limited by the relatively small sample of
sudden cardiac death. On the other hand, there are
older patients (9–12), and some results were limited by
no definitive data regarding the benefit of the ICD in
the retrospective analysis (10–12). Those studies were
older patients. Indeed, in the pivotal randomized clin-
not a priori designed to examine survival or heart
ical trials that demonstrated the efficacy of the ICD, the
failure hospitalization in older patients nor were they
mean or median age of enrolled patients was well
statistically powered to do so (9–13). Therefore, in
below 75 years of age (1–4). There are reasons why older
those studies, the similar survival observed between
patients may not derive survival benefit from the ICD.
older patients and that of their younger counterparts is
Such patients typically have heart failure along with
possibly due to the lack of adequate statistical power
other comorbidities that may attenuate the efficacy
and should not be interpreted as a proof of survival
of the ICD. Older patients may also be frail, and this,
benefit of CRT in the elderly. Although some of these
along with the coexisting diseases, may make the de-
studies examined New York Heart Association (NYHA)
vice implantation risky and negatively impact their
functional class before and after CRT (10–13), only a
quality of life, raising concerns about therapies, like
minority used robust and validated tools to assess
the ICD, that prolong life but do not necessarily
quality of life (13).
implantable-cardioverter
improve its quality. However, when the ICD is coupled
Several of the knowledge gaps regarding the out-
with cardiac resynchronization therapy (CRT), there is
comes of CRT in older patients were highlighted in a
potential for improved quality of life and reduced heart
2014 report to the Agency for Healthcare Research
failure hospitalizations, 2 important goals in the care of
and Quality (14). Relevant questions included: what
heart failure patients.
are the clinical predictors of response in Medicare-
In the main randomized clinical trials of CRT-
eligible patients who are deemed appropriate candi-
defibrillator (CRT-D) or CRT-pacemaker (CRT-P), the
dates for CRT-D devices? What are the adverse effects
relatively young age of enrolled patients is noticeable,
or complications associated with CRT-D implantation
with a mean age ranging from 64 to 68 years (5–8).
in the Medicare population? What are the clinical
As expected, their level of comorbidity was lower
predictors of response in Medicare-eligible patients
than that seen in the average older patient. As such,
who are deemed appropriate candidates for CRT-P
it is reasonable to wonder whether the results of
devices? What are the adverse effects or complications associated with CRT-P implantation in the
Medicare population? What is the effectiveness of
CRT-D versus that of CRT-P in reducing heart failure
*Editorials published in JACC: Heart Failure reflect the views of the
authors and do not necessarily represent the views of JACC or the
American College of Cardiology.
From the Duke Clinical Research Institute and Duke University Medical
symptoms, improving myocardial function, reducing
hospitalization, and/or improving survival in patients
with a left ventricular ejection fraction (LVEF)
Center, Durham, North Carolina. Dr. Al-Khatib has reported that she has
of #35% and a QRS duration of $120 ms? What are the
no relationships relevant to the contents of this paper to disclose.
adverse effects or complications associated with
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Al-Khatib
JACC: HEART FAILURE VOL. 3, NO. 6, 2015
JUNE 2015:505–7
Cardiac Resynchronization Therapy
CRT-D versus that of CRT-P implantation (14) in the
may be far more important than its duration. What is
Medicare population? This national recognition of the
the impact of frailty and the burden and severity of
importance of addressing these knowledge gaps in
comorbidities on various outcomes? A robust 80-
older patients is encouraging!
year-old patient with 1 to 2 comorbidities may fare
much better than a frail 60-year-old patient with
SEE PAGE 497
multiple comorbidities. Although the authors’ state-
In this issue of JACC: Heart Failure, Heidenreich
ment that “[a]dditional studies are needed to deter-
et al. (15) report the results of a study that examined
mine the age threshold at which the life years gained
the association between CRT-D and survival in older
from CRT become too small to justify the use of the
patients enrolled in the National Cardiovascular Dis-
device” is correct, this statement should be revised
ease Registry ICD registry from 2006 to 2009 and
to also incorporate thresholds for frailty and burden
were eligible for a CRT device based on the following
of comorbidities. Finally, what were the effects of
criteria: LVEF of #35%, a QRS interval of $120 ms,
confounding and selection bias on the results of
and NYHA functional class III or IV. Importantly,
this study? Using even the most robust statistical
22,686 of their patients were 75 to 84 years of age, and
methods, residual confounding cannot be totally
4,613 patients were $85 years of age, making this
avoided in observational studies. Therefore, a ran-
study the largest study ever of CRT-D in older pa-
domized clinical trial is the best study design to
tients. Compared with ICD only, CRT-D was associ-
examine the effect of CRT-D versus that of CRT-P
ated with better survival at 1 and 4 years of follow-up
on different patient outcomes while accounting for
across all age groups (15).
frailty and comorbidities and examining complex
Despite the important clinical data that Heidenreich et al. (15) provide, their study leaves sev-
interactions between different factors like race, sex,
age, CRT, and outcomes.
eral questions unanswered. What would the results
An important goal of any related future initiative
look like if the authors used the updated criteria
should be to enhance the knowledge of CRT-D and
for CRT implantation that are largely based on QRS
CRT-P outcomes in older patients and, as a result,
duration and morphology and include patients
improve the effectiveness of clinical decision making.
with NYHA functional class II symptoms (16)? Such
The ultimate vision is to be able to provide patients
results would be more relevant to today’s clinical
with all the information they need to make the best
practice. What about other important endpoints
decision for themselves based on what is most
like short- and long-term complications, appropriate
important to them.
and inappropriate ICD shocks; and most important,
patient-centered outcomes like functional status
REPRINT REQUESTS AND CORRESPONDENCE: Dr.
and quality of life? What about outcomes of CRT-P?
Sana M. Al-Khatib, Duke Clinical Research Institute,
Outcomes associated with CRT-P are especially
PO Box 17969, Durham, North Carolina 27715. E-mail:
intriguing in older patients for whom quality of life
[email protected].
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JUNE 2015:505–7
14. Agency for Healthcare Research and Quality.
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Cardiac Resynchronization Therapy
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KEY WORDS cardiac resynchronization
therapy, elderly, implantable cardioverterdefibrillator
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