Peak Exercise Oxygen Pulse and
Prognosis in Chronic Heart Failure
Carl J. Lavie, MD, Richard V. Milani, MD, and Mandeep R. Mehra, MD
Cardiopulmonary variables, particularly peak oxygen
consumption (peak VO
2
) corrected for total and lean
body weight, have been confirmed to predict prognosis
in patients with chronic systolic heart failure (HF). Only
limited data are available on the prognostic ability of
maximal oxygen (O
2
) pulse, an indicator of stroke vol-
ume and arteriovenous O
2
difference, especially when
corrected for lean body mass. Cardiopulmonary exer-
cise tests were performed in 209 consecutive patients
with mild-to-moderate HF (mean ejection fraction 23%),
followed for 19 12 months to determine the impact of
maximal O
2
pulse in relation to other cardiopulmonary
variables on major clinical events (13 cardiovascular
deaths and 15 urgent transplantations). Compared with
patients with clinical events, those without major events
had a higher peak O
2
pulse (11.4 4.1 vs 9.2 2.3
ml/beat, p <0.0001) and body fat-adjusted peak O
2
pulse (15.6 5.6 vs 11.9 3.4 ml/beat, p <0.0001).
In multivariate analysis, a low peak O
2
pulse was the
strongest independent predictor of clinical events (chi-
square 10.5, p <0.01). Although peak O
2
pulse was a
stronger predictor for clinical events than any other
exercise cardiopulmonary variable, including peak
VO
2
, peak VO
2
lean (defined as the VO
2
corrected for
lean body mass), and percentage of predicted peak
VO
2
, this relation was further strengthened by correcting
peak O
2
pulse for percent body fat (chi-square 12.4, p
<0.001). In most subgroups (including women, obese
subjects, those receiving blockers, and those with class
III HF), peak O
2
pulse lean was similar to or superior to
peak VO
2
lean for predicting major clinical events. Es-
pecially in patients who were class III HF and who were
receiving blockers, peak VO
2
(cutoff 14 ml/kg/min)
poorly predicted prognosis; risk stratification was best
with peak O
2
pulse lean (cutoff 14 ml/beat). These data
indicate the potential usefulness of peak O
2
pulse and
lean body mass–adjusted O
2
pulse for predicting prog-
nosis in patients with systolic HF. 2004 by Excerpta
Medica, Inc.
(Am J Cardiol 2004;93:588 –593)
T
he cardiocirculatory response to exercise in pa-
tients with chronic heart failure (HF) has been
established as an important prognostic indicator. Since
Mancini et al
1
first described the value of peak oxygen
consumption (peak VO
2
) in determining optimal tim-
ing for heart transplantation in ambulatory patients
with HF, numerous other investigators have confirmed
this finding. Although peak VO
2
remains 1 of the best
predictors of outcome in many studies,
2–4
it may lose
prognostic value in some groups of patients, including
those with very low or intermediate ranges of peak
VO
2
4–8
and those with increased body fat, including
women and obese subjects,
9 –12
as well as those who
do not achieve maximal VO
2
.
13
Generally, cardiopul-
monary variables are corrected for total weight as
opposed to lean body weight, although, for practical
purposes, body fat does not metabolize O
2
and does
not receive substantial blood flow.
9 –12,14
Furthermore,
the importance of heart rate response in determining
cardiac reserve and prognosis has been ignored by
traditional cardiopulmonary exercise parameters, al-
though relative refinements, such as the use of percent
of predicted peak VO
2
, have been suggested.
15
Max-
imal O
2
pulse, which represents VO
2
corrected for
heart rate, is an indicator of stroke volume and arte-
riovenous O
2
difference. However, only limited data
are available on the prognostic ability of O
2
pulse in
patients with chronic systolic HF, particularly in co-
horts that received aggressive medical therapy.
8,16
METHODS
Patients: We retrospectively studied 209 consecu-
tive ambulatory patients with chronic systolic HF
(New York Heart Association class I to III) who
underwent cardiopulmonary exercise testing between
January 1996 and December 1998. All patients were
diagnosed with HF 6 months before exercise test-
ing and were receiving stable doses of their medi-
cations, with no increase in symptoms or need for
intravenous inotropic support for 6 weeks before
the study entry. The study was approved by the
institutional review board at the Ochsner Clinic
Foundation.
Cardiopulmonary exercise testing: All patients un-
derwent maximal exercise on a treadmill using an
individually tailored ramping protocol designed to
yield a test duration between 8 and 12 minutes.
9
Patients were encouraged to exercise until symptoms
of chest discomfort or dyspnea were intolerable.
Breath-to-breath on-line gas analysis was performed
using a MedGraphics CPXID metabolic card (St. Paul,
Minnesota). Incremental data including minute venti-
lation, VO
2
, and carbon dioxide production were col-
lected every 15 seconds. From the previously men-
tioned data, maximal VO
2
, anaerobic threshold, and
the VO
2
ratio were calculated as previously de-
scribed.
9
Peak VO
2
was determined as the highest O
2
From the Ochsner Clinic Foundation, New Orleans, Louisiana. Manu-
script received October 20, 2003; revised manuscript received and
accepted November 3, 2003.
Address for reprints: Carl J. Lavie, MD, Department of Cardiology,
Ochsner Clinic Foundation, 1514 Jefferson Highway, New Orleans,
Louisiana 70121. E-mail: clavie@ochsner.org.
588 ©2004 by Excerpta Medica, Inc. All rights reserved. 0002-9149/04/$–see front matter
The American Journal of Cardiology Vol. 93 March 1, 2004 doi:10.1016/j.amjcard.2003.11.023