Author Archives: Paul Older

Exercise Intolerance in HFpEF: Diagnosing and Ranking its Causes Using Personalized O2 Pathway Analysis.

Houstis NE, Eisman AS, Pappagianopoulos PP, Wooster L, Bailey CS,
Wagner PD, Lewis GD

Circulation. 2017 Oct 9. pii:

Background -Heart failure with preserved ejection fraction (HFpEF) is a common
syndrome with a pressing shortage of therapies. Exercise intolerance is a
cardinal symptom of HFpEF, yet its pathophysiology remains uncertain.

Methods -We investigated the mechanism of exercise intolerance in each of 134 patients
referred for cardiopulmonary exercise testing (CPET): 79 with HFpEF and 55
controls. We performed CPET with invasive monitoring to measure hemodynamics,
blood gases, and gas exchange during exercise. We used these measurements to
quantify 6 steps of oxygen transport and utilization (the “O2 pathway”) in each
HFpEF patient, identifying the defective steps that impair each one’s exercise
capacity (peak VO2). We then quantified the functional significance of each O2
pathway defect by calculating the improvement in exercise capacity a patient
could expect from correcting the defect.

Results -Peak VO2 was reduced by 34%±2% (mean±SEM, P<0.001) in HFpEF
compared with controls of comparable age, gender,
and body mass index. The vast majority (97%) of HFpEF patients harbored defects
at multiple steps of the O2 pathway, the identity and magnitude of which varied
widely. Two of these steps, cardiac output and skeletal muscle O2 diffusion, were
impaired relative to controls by an average of 27±3% and 36±2%, respectively
(P<0.001 for both). Due to interactions between a given patient’s defects, the
predicted benefit of correcting any single one was often minor; on average,
correcting a patient’s cardiac output led to a 7±0.5% predicted improvement in
exercise intolerance, while correcting a patient’s muscle diffusion capacity led
to a 27±1% improvement. At the individual level, the impact of any given O2
pathway defect on a patient’s exercise capacity was strongly influenced by
comorbid defects.

Conclusions -Systematic analysis of the O2 pathway in HFpEF
showed that exercise capacity was undermined by multiple defects, including
reductions in cardiac output and skeletal muscle diffusion capacity. An important
source of disease heterogeneity stemmed from variation in each patient’s personal
profile of defects. Personalized O2 pathway analysis could identify patients most
likely to benefit from treating a specific defect; however, the system properties
of O2 transport favor treating multiple defects at once, as with exercise
training.

Quality of life measures predict cardiovascular health and physical performance in chronic renal failure patients.

Rogan A; McCarthy K; McGregor G; Hamborg T; Evans G; Hewins S; Aldridge N;
Fletcher S; Krishnan N; Higgins R; Zehnder D; Ting SM,

Plos One [PLoS One], ISSN: 1932-6203, 2017 Sep 14; Vol. 12 (9), pp. e0183926

Background:
Patients with advanced chronic kidney disease (CKD) experience complex
functional and structural changes of the cardiopulmonary and
musculoskeletal system. This results in reduced exercise tolerance,
quality of life and ultimately premature death. We investigated the
relationship between subjective measures of health related quality of
life and objective, standardised functional measures for cardiovascular
and pulmonary health.

Methods: Between April 2010 and January 2013, 143
CKD stage-5 or CKD5d patients (age 46.0±1.1y, 62.2% male), were
recruited prospectively. A control group of 83 healthy individuals
treated for essential hypertension (HTN; age 53.2±0.9y, 48.22% male)
were recruited at random. All patients completed the SF-36 health
survey questionnaire, echocardiography, vascular tonometry and
cardiopulmonary exercise testing.

Results: Patients with CKD had significantly lower SF-36 scores than the HTN group; for physical
component score (PCS; 45.0 vs 53.9, p<0.001) and mental component score
(MCS; 46.9 vs. 54.9, p<0.001). CKD subjects had significantly poorer
exercise tolerance and cardiorespiratory performance compared with HTN
(maximal oxygen uptake; VO2peak 19.9 vs 25.0ml/kg/min, p<0.001).
VO2peak was a significant independent predictor of PCS in both groups
(CKD: b = 0.35, p = 0.02 vs HTN: b = 0.27, p = 0.001). No associations
were noted between PCS scores and echocardiographic characteristics,
vascular elasticity and cardiac biomarkers in either group. No
associations were noted between MCS and any variable. The interaction
effect of study group with VO2peak on PCS was not significant (ΔB =
0.08; 95%CI -0.28-0.45, p = 0.7). However, overall for a given VO2peak,
the measured PCS was much lower for patients with CKD than for HTN
cohort, a likely consequence of systemic uremia effects.

Conclusion: In CKD and HTN, objective physical performance has a significant effect on
quality of life; particularly self-reported physical health and
functioning. Therefore, these quality of life measures are indeed a
good reflection of physical health correlating highly with objective
physical performance measures.

Predictors of serious arrhythmic events in patients with nonischemic heart failure.

Pimentel M, Zimerman A, Chemello D, Giaretta V, Andrades
M, Silvello D, Zimerman L, Rohde LE

J Interv Card Electrophysiol. 2017 Mar;48(2):131-139.

PURPOSE: Risk stratification of serious arrhythmic events in patients with
nonischemic heart failure (HF), beyond estimates of left ventricular ejection
fraction (LVEF), remains an important clinical challenge. This study aims to
determine the clinical value of different noninvasive and invasive tests as
predictors of serious arrhythmic events in patients with nonischemic HF.

METHODS: A prospective observational study was conducted including 106
nonischemic HF patients who underwent a comprehensive clinical and laboratory
evaluation including two-dimensional echocardiography, 24-h Holter monitoring,
cardiopulmonary exercise testing (CPX), and an invasive electrophysiological
study. The study’s primary end-point was either syncope, appropriate therapy by
implantable cardioverter-defibrillators, or sudden cardiac death.

RESULTS: During a mean follow-up of 704 ± 320 days, the primary end-point
occurred in 15 patients (14.2%). In multivariable analysis, LV end-diastolic
diameter >73 mm (hazard ratio [HR] 3.7; p = 0.016), exercise periodic breathing
(EPB) on CPX (HR 2.88; p = 0.045), and non-sustained ventricular tachycardia
(NSVT) ≥10 beats (HR 8.2; p < 0.01) remained independently associated with
serious arrhythmic events. The positive predictive value of the presence of two
of these predictors ranged from 44 to 100%. The absence of all three factors
(n = 65, 61% of the sample) identified a subset of patients with low risk of
future arrhythmic events, with a negative predictive value of 96.9%.

CONCLUSIONS: In this cohort study of nonischemic HF patients, LV dimension, EPB,
and NSVT ≥10 beats were independent predictors of serious arrhythmic events. The
presence or absence of these characteristics identified sub-groups of high and
low risk of serious arrhythmic events, respectively.

Exercise Intolerance in HFpEF: Diagnosing and Ranking its Causes Using Personalized O2 Pathway Analysis

Houstis NE, Eisman AS, Pappagianopoulos PP, Wooster L, Bailey CS,
Wagner PD, Lewis GD
Mass. General, Boston

Circulation. 2017 Oct 9. pii

Background -Heart failure with preserved ejection fraction (HFpEF) is a common
syndrome with a pressing shortage of therapies. Exercise intolerance is a
cardinal symptom of HFpEF, yet its pathophysiology remains uncertain. Methods -We
investigated the mechanism of exercise intolerance in each of 134 patients
referred for cardiopulmonary exercise testing (CPET): 79 with HFpEF and 55
controls. We performed CPET with invasive monitoring to measure hemodynamics,
blood gases, and gas exchange during exercise. We used these measurements to
quantify 6 steps of oxygen transport and utilization (the “O2 pathway”) in each
HFpEF patient, identifying the defective steps that impair each one’s exercise
capacity (peak VO2). We then quantified the functional significance of each O2
pathway defect by calculating the improvement in exercise capacity a patient
could expect from correcting the defect.

Results -Peak VO2 was reduced by 34%±2% (mean±SEM, P<0.001) in HFpEF
compared with controls of comparable age, gender,
and body mass index. The vast majority (97%) of HFpEF patients harbored defects
at multiple steps of the O2 pathway, the identity and magnitude of which varied
widely. Two of these steps, cardiac output and skeletal muscle O2 diffusion, were
impaired relative to controls by an average of 27±3% and 36±2%, respectively
(P<0.001 for both). Due to interactions between a given patient’s defects, the
predicted benefit of correcting any single one was often minor; on average,
correcting a patient’s cardiac output led to a 7±0.5% predicted improvement in
exercise intolerance, while correcting a patient’s muscle diffusion capacity led
to a 27±1% improvement. At the individual level, the impact of any given O2
pathway defect on a patient’s exercise capacity was strongly influenced by
comorbid defects.

Conclusions -Systematic analysis of the O2 pathway in HFpEF
showed that exercise capacity was undermined by multiple defects, including
reductions in cardiac output and skeletal muscle diffusion capacity. An important
source of disease heterogeneity stemmed from variation in each patient’s personal
profile of defects. Personalized O2 pathway analysis could identify patients most
likely to benefit from treating a specific defect; however, the system properties
of O2 transport favor treating multiple defects at once, as with exercise
training.

Cardiopulmonary Exercise Testing: What Is its Value?

Guazzi M; Bandera F; Ozemek C; Systrom D; Arena R

Journal Of The American College Of Cardiology [J Am Coll Cardiol], ISSN: 1558-3597, 2017 Sep 26; Vol. 70 (13), pp. 1618-1636;

Compared with traditional exercise tests, cardiopulmonary exercise testing (CPET) provides a thorough assessment of exercise integrative physiology involving the pulmonary, cardiovascular, muscular, and cellular oxidative systems. Due to the prognostic ability of key variables, CPET applications in cardiology have grown impressively to include all forms of exercise intolerance, with a predominant focus on heart failure with reduced or with preserved ejection fraction. As impaired cardiac output and peripheral oxygen diffusion are the main determinants of the abnormal functional response in cardiac patients, invasive CPET has gained new popularity, especially for diagnosing early heart failure with preserved ejection fraction and exercise-induced pulmonary hypertension. The most impactful advance has recently come from the introduction of CPET combined with echocardiography or CPET imaging, which provides basic information regarding cardiac and valve morphology and function. This review highlights modern CPET use as a single or combined test that allows the pathophysiological bases of exercise limitation to be translated, quite easily, into clinical practice.

 

The Role of Cardiopulmonary Exercise Testing for Decision Making in Patients with Repaired Tetralogy of Fallot

Dallaire F; Wald RM; Marelli A,

Pediatric Cardiology [Pediatr Cardiol], ISSN:
1432-1971, 2017 Aug; Vol. 38 (6), pp. 1097-1105;

Tetralogy of Fallot is the most common form of
cyanotic congenital heart disease. As a result of the surgical
strategies employed at the time of initial repair, chronic pulmonary
regurgitation (PR) is prevalent in this population. Despite sustained
research efforts, patient selection and timing of pulmonary valve
replacement (PVR) to address PR in young asymptomatic patients with
repaired tetralogy of Fallot (rToF) remain a fundamental but as yet
unanswered question in the field of congenital heart disease. The
ability of the heart to compensate for the chronic volume overload
imposed by PR is critical in the evaluation of the risks and benefits
of PVR. The difficulty in clarifying the functional impact of PR on the
cardiovascular capacity may be in part responsible for the uncertainty
surrounding the timing of PVR. Cardiopulmonary exercise testing (CPET)
may be used to assess abnormal cardiovascular response to increased
physiologic demands. However, its use as a tool for risk stratification
in asymptomatic adolescents and young adults with rToF is still
ill-defined. In this paper, we review the role of CPET as a potentially
valuable adjunct to current risk stratification strategies with a focus
on asymptomatic rToF adolescents and young adults being considered for
PVR. The role of maximal and submaximal exercise measurements to
identify young patients with a decreased or borderline low peak VO2
resulting from impaired ventricular function is explored. Current
knowledge gaps and research perspectives are highlighted.

Value of Strain Imaging and Maximal Oxygen Consumption in Patients With Hypertrophic Cardiomyopathy

Moneghetti KJ; Stolfo D; Christle JW; Kobayashi Y; Finocchiaro G; Sinagra G; Myers J; Ashley
EA; Haddad F; Wheeler MT,

The American Journal Of Cardiology [Am JCardiol], ISSN: 1879-1913, 2017 Oct 01; Vol. 120 (7), pp. 1203-1208;

Longitudinal strain (LS) has been shown to be predictive of outcome in hypertrophic
cardiomyopathy (HC). Percent predicted peak oxygen uptake (ppVO2),
among other cardiopulmonary exercise testing (CPX) metrics, is a strong
predictor of prognosis in HC. However, there has been limited
investigation into the combination of LS and CPX metrics. This study
sought to determine how LS and parameters of exercise performance
contribute to prognosis in HC. One hundred and thirty-one consecutive
patients with HC who underwent CPX and stress echocardiography were
included. Global, septal, and lateral LS were assessed at rest and
stress. Eighty matched individuals were used as controls. Patients were
followed for the composite end point of death and worsening heart
failure. All absolute LS components were lower in patients with HC than
in controls (global 14.3 ± 4.0% vs 18.8 ± 2.2%, p <0.001; septal
11.9 ± 4.9% vs 17.9 ± 2.7%, p <0.001; lateral 16.0 ± 4.7% vs
19.4 ± 3.1%, p = 0.001). Global strain reserve was also reduced in
patients with HC (13 ± 5% vs 19 ± 8%, p = 0.002). Over a median
follow-up of 56 months (interquartile range 14 to 69), the composite
end point occurred in 53 patients. Global LS was predictive of outcome
on univariate analysis (0.55 [0.41 to 0.74], p <0.001). When combined
with CPX metrics, lateral LS was the only strain variable predictive of
outcome along with indexed left atrial volume (LAVI) and ppVO2. The
worst outcomes were observed for patients with lateral LS <16.1%, LAVI
>52 ml/m2, and ppVO2 <80%. The combination of lateral LS, LAVI, and
ppVO2 presents a simple model for outcome prediction.

Statins are related to impaired exercise capacity in males but not females.

PLoS One. 2017 Jun 15;12(6):e0179534

Bahls M, Groß S, Ittermann T, Busch R, Gläser S, Ewert
R, Völzke H, Felix SB, Dörr M

BACKGROUND: Exercise and statins reduce cardiovascular disease (CVD). Exercise
capacity may be assessed using cardiopulmonary exercise testing (CPET). Whether
statin medication is associated with CPET parameters is unclear. We investigated
if statins are related with exercise capacity during CPET in the general
population.
METHODS: Cross-sectional data of two independent cohorts of the Study of Health
in Pomerania (SHIP) were merged (n = 3,500; 50% males). Oxygen consumption (VO2)
at peak exercise (VO2peak) and anaerobic threshold (VO2@AT) was assessed during
symptom-limited CPET. Two linear regression models related VO2peak with statin
usage were calculated. Model 1 adjusted for age, sex, previous myocardial
infarction, and physical inactivity and model 2 additionally for body mass index,
smoking, hypertension, diabetes and estimated glomerular filtration rate.
Propensity score matching was used for validation.
RESULTS: Statin usage was associated with lower VO2peak (no statin: 2336;
95%-confidence interval [CI]: 2287-2,385 vs. statin 2090; 95%-CI: 2,031-2149
ml/min; P < .0001) and VO2@AT (no statin: 1,172; 95%-CI: 1,142-1,202 vs. statin:
1,111; 95%-CI: 1,075-1,147 ml/min; P = .0061) in males but not females (VO2peak:
no statin: 1,467; 95%-CI: 1,417-1,517 vs. statin: 1,503; 95%-CI: 1,426-1,579
ml/min; P = 1.00 and VO2@AT: no statin: 854; 95%-CI: 824-885 vs. statin 864;
95%-CI: 817-911 ml/min; P = 1.00). Model 2 revealed similar results. Propensity
scores analysis confirmed the results.
CONCLUSION: In the general population present statin medication was related with
impaired exercise capacity in males but not females. Sex specific effects of
statins on cardiopulmonary exercise capacity deserve further research

The Role of Cardiopulmonary Exercise Testing for Decision Making in Patients with Repaired Tetralogy of Fallot.

Pediatr Cardiol. 2017 Aug;38(6):1097-1105. doi: 10.1007/s00246-017-1656-z. Epub
2017 Jun 16.

Dallaire F, Wald RM, Marelli A.

Tetralogy of Fallot is the most common form of cyanotic congenital heart disease.
As a result of the surgical strategies employed at the time of initial repair,
chronic pulmonary regurgitation (PR) is prevalent in this population. Despite
sustained research efforts, patient selection and timing of pulmonary valve
replacement (PVR) to address PR in young asymptomatic patients with repaired
tetralogy of Fallot (rToF) remain a fundamental but as yet unanswered question in
the field of congenital heart disease. The ability of the heart to compensate for
the chronic volume overload imposed by PR is critical in the evaluation of the
risks and benefits of PVR. The difficulty in clarifying the functional impact of
PR on the cardiovascular capacity may be in part responsible for the uncertainty
surrounding the timing of PVR. Cardiopulmonary exercise testing (CPET) may be
used to assess abnormal cardiovascular response to increased physiologic demands.
However, its use as a tool for risk stratification in asymptomatic adolescents
and young adults with rToF is still ill-defined. In this paper, we review the
role of CPET as a potentially valuable adjunct to current risk stratification
strategies with a focus on asymptomatic rToF adolescents and young adults being
considered for PVR. The role of maximal and submaximal exercise measurements to
identify young patients with a decreased or borderline low peak VO2 resulting
from impaired ventricular function is explored. Current knowledge gaps and
research perspectives are highlighted.

Quality of life measures predict cardiovascular health and physical performance in chronic renal failure patients.

PLoS One. 2017 Sep 14;12(9):e0183926

Rogan A, McCarthy K, McGregor G, Hamborg T, Evans G, Hewins
S, Aldridge N, Fletcher S, Krishnan N, Higgins R, Zehnder D,
Ting SM

BACKGROUND: Patients with advanced chronic kidney disease (CKD) experience
complex functional and structural changes of the cardiopulmonary and
musculoskeletal system. This results in reduced exercise tolerance, quality of
life and ultimately premature death. We investigated the relationship between
subjective measures of health related quality of life and objective, standardised
functional measures for cardiovascular and pulmonary health.
METHODS: Between April 2010 and January 2013, 143 CKD stage-5 or CKD5d patients
(age 46.0±1.1y, 62.2% male), were recruited prospectively. A control group of 83
healthy individuals treated for essential hypertension (HTN; age 53.2±0.9y,
48.22% male) were recruited at random. All patients completed the SF-36 health
survey questionnaire, echocardiography, vascular tonometry and cardiopulmonary
exercise testing.
RESULTS: Patients with CKD had significantly lower SF-36 scores than the HTN
group; for physical component score (PCS; 45.0 vs 53.9, p<0.001) and mental
component score (MCS; 46.9 vs. 54.9, p<0.001). CKD subjects had significantly
poorer exercise tolerance and cardiorespiratory performance compared with HTN
(maximal oxygen uptake; VO2peak 19.9 vs 25.0ml/kg/min, p<0.001). VO2peak was a
significant independent predictor of PCS in both groups (CKD: b = 0.35, p = 0.02
vs HTN: b = 0.27, p = 0.001). No associations were noted between PCS scores and
echocardiographic characteristics, vascular elasticity and cardiac biomarkers in
either group. No associations were noted between MCS and any variable. The
interaction effect of study group with VO2peak on PCS was not significant (ΔB =
0.08; 95%CI -0.28-0.45, p = 0.7). However, overall for a given VO2peak, the
measured PCS was much lower for patients with CKD than for HTN cohort, a likely
consequence of systemic uremia effects.
CONCLUSION: In CKD and HTN, objective physical performance has a significant
effect on quality of life; particularly self-reported physical health and
functioning. Therefore, these quality of life measures are indeed a good
reflection of physical health correlating highly with objective physical
performance measures.