Cardiopulmonary exercise testing and prognosis in severe heart failure: 14 mL/kg/min revisited

Ventilatory efficiency slope correlates with functional capacity, outcomes, and disease severity in pediatric patients with pulmonary hypertension

BACKGROUND

Cardiopulmonary exercise testing is widely used in a variety of cardiovascular conditions. Ventilatory efficiency slope can be derived from submaximal exercise testing. The present study sought to evaluate the relationship between ventilatory efficiency slope and functional capacity, outcomes, and disease severity in pediatric patients with pulmonary hypertension.

METHODS

Seventy six children and young adults with a diagnosis of pulmonary hypertension (PH) performed 258 cardiopulmonary exercise tests from 2001 to 2011. Each individual PH test was matched to a control test. Ventilatory efficiency slope was compared to traditional measures of functional capacity and disease severity including WHO functional classification, peak oxygen consumption, and invasive measures of pulmonary arterial pressures and pulmonary vascular resistance.

RESULTS

Ventilatory efficiency slope was significantly higher in patients with pulmonary arterial hypertension, with an estimated increase of 7.2 for each increase in WHO class (p<0.0001), compared with normal control subjects (38.9 vs. 30.9, p<0.001). Ventilatory efficiency slope correlated strongly with invasive measures of disease severity including pulmonary vascular resistance index (r =0.61), pulmonary artery pressure (r =0.58), mean pulmonary artery pressure/mean aortic pressure ratio (r =0.52), and peak VO2 (r=-0.58). Ventilatory efficiency slope in 12 patients with poor outcomes (9 death, 3 lung transplant), was significantly elevated compared to patients who did not (51.1 vs. 37.9, p<0.001).

CONCLUSIONS

Ventilatory efficiency slope correlates well with invasive and noninvasive markers of disease severity including peak VO2, WHO functional class, and catheterization variables in pediatric patients with PH. Ventilatory efficiency slope may be a useful noninvasive marker for disease severity.

Effects of respiratory exchange ratio on the prognostic value of peak oxygen consumption and ventilatory efficiency in patients with systolic heart failure

OBJECTIVES

The purpose of this analysis was to evaluate the prognostic characteristics of peak oxygen consumption (Vo2) and the minute ventilation/carbon dioxide (VE/Vco2) slope of different peak respiratory exchange ratios (RERs) obtained from cardiopulmonary exercise testing in patients with heart failure (HF).

BACKGROUND

For patients with HF, peak Vo2 and the VE/Vco2 slope are used for assessing prognosis. Peak Vo2 is assessed in association with peak RER ≥1.10, indicating maximal effort and prognostic sensitivity. Conversely, the VE/Vco2 slope provides effort-independent prognostic discrimination.

METHODS

Patients with HF scheduled to undergo cardiopulmonary exercise testing were enrolled. Patients were subclassified by peak RER (RER <1.00, RER 1.00 to 1.04, RER 1.05 to 1.09, RER ≥1.10) and followed for up to 3 years for major cardiac-related events (death, left ventricular assist device implantation, or cardiac transplantation).

RESULTS

Included were 1,728 patients with HF (75% males; 40% ischemic etiology; age: 55 ± 14 years; left ventricular ejection fraction: 28 ± 10%). Two hundred seventy major events occurred, with no proportional differences across the RER subgroups. Multivariate Cox regression analysis indicated that the VE/Vco2 slope and peak Vo2 remained prognostic within each subgroup; the VE/Vco2 slope remained the strongest predictor. Receiver-operating characteristic analysis demonstrated equitable prognostic cutoffs for the VE/Vco2 slope (range: 34.9 to 35.7; area under the curve [AUC] range: 0.69 to 0.75) and peak Vo2 (range: 13.8 to 14.0 ml·kg(-1)·min(-1); AUC range: 0.68 to 0.75).

CONCLUSIONS

Peak Vo2 provided a sensitive assessment of prognosis in patients with HF in all RER subgroups. The VE/Vco2 slope provided greater prognostic discrimination in all RER subgroups. Clinical consideration may be warranted for patients with low RER, low peak Vo2, and an elevated VE/Vco2 slope.

A meta-analysis of the prognostic significance of cardiopulmonary exercise testing in patients with heart failure

The objective of the study is to assess the role of cardiopulmonary exercise testing (CPX) variables, including peak oxygen consumption (VO(2)), which is the most recognized CPX variable, the minute ventilation/carbon dioxide production (VE/VCO(2)) slope, the oxygen uptake efficiency slope (OUES), and exercise oscillatory ventilation (EOV) in a current meta-analysis investigating the prognostic value of a broader list of CPX-derived variables for major adverse cardiovascular events in patients with HF. A search for relevant CPX articles was performed using standard meta-analysis methods. Of the initial 890 articles found, 30 met our inclusion criteria and were included in the final analysis. The total subject populations included were as follows: peak VO(2) (7,319), VE/VCO(2) slope (5,044), EOV (1,617), and OUES (584). Peak VO(2), the VE/VCO(2) slope and EOV were all highly significant prognostic markers (diagnostic odds ratios ≥ 4.10). The OUES also demonstrated promise as a prognostic marker (diagnostic odds ratio = 8.08) but only in a limited number of studies (n = 2). No other independent variables (including age, ejection fraction, and beta-blockade) had a significant effect on the meta-analysis results for peak VO(2) and the VE/VCO(2) slope. CPX is an important component in the prognostic assessment of patients with HF. The results of this meta-analysis strongly confirm this and support a multivariate approach to the application of CPX in this patient population.

Value of peak exercise oxygen consumption combined with B-type natriuretic peptide levels for optimal timing of cardiac transplantation

BACKGROUND

Peak exercise oxygen consumption (VO(2)) is widely used to select candidates for heart transplantation (HTx). However, the prognosis of patients with advanced heart failure and peak VO(2) of 10 to 14 mL/min per kg in the era of modern medical therapy for heart failure is not fully elucidated. B-type natriuretic peptide (BNP) is a useful prognostic marker in patients with heart failure.

METHODS AND RESULTS

A total of 424 patients undergoing HTx evaluation were classified according to peak VO(2) during cardiopulmonary exercise testing (>14, 10-14, and <10 mL/min per kg). Survival after cardiopulmonary exercise testing without HTx or ventricular assist device (VAD) support was compared with survival of 743 de novo HTx recipients. Multivariable analysis revealed that high BNP and low peak VO(2) were independently associated with death, HTx, or VAD requirements (hazard ratio, 3.5 and 0.6; 95% CI, 1.24-9.23 and 0.03-0.71; P=0.02 and <0.0001, respectively). VAD-free or HTx-free survival of patients with peak VO(2) 10 to 14 mL/min per kg was identical to post-HTx survival. When patients with peak VO(2) 10 to 14 mL/min per kg were dichotomized by a cutoff value of BNP of 506 pg/mL, those with BNP<506 pg/mL was equivalent to post-HTx survival (1 year: 90.8% versus 87.2%; P=0.61), whereas those with BNP≥506 showed worse VAD-free or HTx-free survival (1 year: 79.7%; P<0.001 versus post-HTx). Patients with peak VO(2) <10 mL/min per kg showed worse survival compared with post-HTx survival, and there was a survival difference between those with BNP≥506 and <506 pg/mL (1 year: 77.2% versus 56.1%; P=0.01).

CONCLUSIONS

Patients with peak VO(2) 10 to 14 mL/min per kg and low BNP levels have a VAD-free or HTx-free survival similar to post-HTx survival in heart recipients, whereas high BNP levels indicate worse outcome in this group of patients.

Coronary artery bypass surgery with or without mitral valve annuloplasty in moderate functional ischemic mitral regurgitation: final results of the Randomized Ischemic Mitral Evaluation (RIME) trial

BACKGROUND

The role of mitral valve repair (MVR) during coronary artery bypass grafting (CABG) in patients with moderate ischemic mitral regurgitation (MR) is uncertain. We conducted a randomized, controlled trial to determine whether repairing the mitral valve during CABG may improve functional capacity and left ventricular reverse remodeling compared with CABG alone.

METHODS AND RESULTS

Seventy-three patients referred for CABG with moderate ischemic MR and an ejection fraction >30% were randomized to receive CABG plus MVR (34 patients) or CABG only (39 patients). The study was stopped early after review of interim data. At 1 year, there was a greater improvement in the primary end point of peak oxygen consumption in the CABG plus MVR group compared with the CABG group (3.3 mL/kg/min versus 0.8 mL/kg/min; P<0.001). There was also a greater improvement in the secondary end points in the CABG plus MVR group compared with the CABG group: left ventricular end-systolic volume index, MR volume, and plasma B-type natriuretic peptide reduction of 22.2 mL/m(2), 28.2 mL/beat, and 557.4 pg/mL, respectively versus 4.4 mL/m(2) (P=0.002), 9.2 mL/beat (P=0.001), and 394.7 pg/mL (P=0.003), respectively. Operation duration, blood transfusion, intubation duration, and hospital stay duration were greater in the CABG plus MVR group. Deaths at 30 days and 1 year were similar in both groups: 3% and 9%, respectively in the CABG plus MVR group, versus 3% (P=1.00) and 5% (P=0.66), respectively in the CABG group.

CONCLUSIONS

Adding mitral annuloplasty to CABG in patients with moderate ischemic MR may improve functional capacity, left ventricular reverse remodeling, MR severity, and B-type natriuretic peptide levels, compared with CABG alone. The impact of these benefits on longer term clinical outcomes remains to be defined.

Randomized controlled trial of ventricular elastic support therapy in the treatment of symptomatic heart failure: rationale and design

BACKGROUND

Despite the current drug and device therapies, heart failure remains associated with high rates of disability, morbidity, and mortality. There is a need for newer therapies. One investigational approach is the use of ventricular support devices. These devices reduce ventricular wall stress leading to decreases in left ventricular (LV) volumes, dimensions, and mass. Ventricular support devices have been shown to reverse pathological ventricular remodeling, improve systolic function, and improve symptoms of heart failure. The Prospective Evaluation of Elastic Restraint to LESSen the effects of Heart Failure (PEERLESS-HF) trial was designed to further evaluate the safety and efficacy of one such device, the HeartNet (Paracor Medical, Sunnyvale, CA).

METHODS

The HeartNet is an elastic ventricular restraint device formed from nitinol and covered in silicone, implanted using a minimally invasive approach. The aim of this randomized controlled trial is to compare optimal heart failure drug and device therapy plus the HeartNet (treatment group) to optimal drug and device therapy alone (control group) in patients with advanced systolic heart failure (LV ejection fraction ≤35% and LV end diastolic diameter <85 mm). Primary efficacy end points include the change in peak VO(2), quality of life score, and 6-minute hall walk distance from baseline to 6 months. The primary safety objective is to demonstrate noninferiority for all-cause mortality at 12 months. Planned enrollment is for 272 patients at approximately 35 centers in North America.

CONCLUSIONS

The PEERLESS-HF trial will evaluate the safety and efficacy of ventricular elastic support in advanced systolic heart failure, advancing our knowledge of this investigational approach to heart failure therapy.

Patients with heart failure in the "intermediate range" of peak oxygen uptake: additive value of heart rate recovery and the minute ventilation/carbon dioxide output slope in predicting mortality

PURPOSE

While patients with heart failure who achieve a peak oxygen uptake (peak VO2) of 10 mL·kg(-1)·min(-1) or less are often considered for intensive surveillance or intervention, those achieving 14 mL·kg(-1)·min(-1) or more are generally considered to be at lower risk. Among patients in the "intermediate" range of 10.1 to 13.9 mL·kg(-1)·min(-1), optimally stratifying risk remains a challenge.

METHODS

Patients with heart failure (N = 1167) referred for cardiopulmonary exercise testing were observed for 21 ± 13 months. Patients were classified into 3 groups of peak VO2 (≤10, 10.1-13.9, and ≥14 mL·kg(-1)·min(-1)). The ability of heart rate recovery at 1 minute (HRR1) and the minute ventilation/carbon dioxide output (VE/VCO2) slope to complement peak VO2 in predicting cardiovascular mortality were determined.

RESULTS

Peak VO2, HRR1 (<16 beats per minute), and the VE/VCO2 slope (>34) were independent predictors of mortality (hazard ratio 1.6, 95% CI: 1.2-2.29, P = .006; hazard ratio 1.7, 95% CI: 1.1-2.5, P = .008; and hazard ratio 2.4, 95% CI: 1.6-3.4, P < .001, respectively). Compared with those achieving a peak VO2 ≥ 14 mL·kg(-1)·min(-1), patients within the intermediate range with either an abnormal VE/VCO2 slope or HRR1 had a nearly 2-fold higher risk of cardiac mortality. Those with both an abnormal HRR1 and VE/VCO2 slope had a higher mortality risk than those with a peak VO2 ≤ 10 mL·kg(-1)·min(-1). Survival was not different between those with a peak VO2 ≤ 10 mL·kg(-1)·min(-1) and those in the intermediate range with either an abnormal HRR1 or VE/VCO2 slope.

CONCLUSIONS

HRR1 and the VE/VCO2 slope effectively stratify patients with peak VO2 within the intermediate range into distinct groups at high and low risk.

Reduced peak oxygen uptake and implications for cardiovascular health and quality of life in patients with schizophrenia

BACKGROUND

Peak oxygen uptake (VO(2peak)) is a strong predictor of cardiovascular disease (CVD) and all-cause mortality, but is inadequately described in patients with schizophrenia. The aim of this study was to evaluate treadmill VO(2peak), CVD risk factors and quality of life (QOL) in patients with schizophrenia (ICD-10, F20-29).

METHODS

33 patients, 22 men (33.7 ± 10.4 years) and 11 women (35.9 ± 11.5 years), were included. Patients VO(2peak) were compared with normative VO(2peak) in healthy individuals from the Nord-Trøndelag Health Study (HUNT). Risk factors were compared above and below the VO(2peak) thresholds; 44.2 and 35.1 ml·kg⁻¹·min⁻¹ in men and women, respectively.

RESULTS

VO(2peak) was 37.1 ± 9.2 ml·kg⁻¹·min⁻¹ in men with schizophrenia; 74 ± 19% of normative healthy men (p < 0.001). VO(2peak) was 35.6 ± 10.7 ml·kg⁻¹·min⁻¹ in women with schizophrenia; 89 ± 25% of normative healthy women (n.s.). Based on odds ratio patients were 28.3 (95% CI = 1.6-505.6) times more likely to have one or more CVD risk factors if they were below the VO(2peak) thresholds. VO(2peak) correlated with the SF-36 physical functioning (r = 0.58), general health (r = 0.53), vitality (r = 0.47), social function (r = 0.41) and physical component score (r = 0.51).

CONCLUSION

Men with schizophrenia have lower VO(2peak) than the general population. Patients with the lowest VO(2peak) have higher odds of having one or more risk factors for cardiovascular disease. VO(2peak) should be regarded as least as important as the conventional risk factors for CVD and evaluation of VO(2peak) should be incorporated in clinical practice.

Avaliação da capacidade máxima de exercício: uma revisão sobre os protocolos tradicionais e a evolução para modelos individualizados

Os ajustes fisiológicos ao exercício têm sido extensivamente estudados. Apesar do consenso sobre a importância de testes de exercício para a avaliação do consumo máximo de oxigênio (<img border=0 width=32 height=32 id="_x0000_i1065" src="../../../../img/revistas/rbme/v17n5/img01.jpg">O2máx), diferenças expressivas entre os protocolos utilizados podem comprometer a comparação de dados e sua utilização clínica ou funcional. A presente revisão analisou os principais protocolos correntemente utilizados na avaliação do <img border=0 width=32 height=32 id="_x0000_i1064" src="../../../../img/revistas/rbme/v17n5/img01.jpg">O2máx, destacando suas vantagens e limitações. Além disso, compararam-se as características de protocolos escalonados em estágios com aquelas de modelos individualizados, conhecidos como protocolos em rampa. Foram revisados 102 estudos publicados entre os anos 1955 e 2009. Os resultados indicaram que, apesar de a maior parte dos estudos apontar vantagens dos protocolos em rampa sobre os mais tradicionais, há uma evidente carência de recomendações sobre diversos aspectos de sua elaboração. São raros os estudos que analisaram a influência de variáveis dos protocolos em rampa sobre os desfechos pretendidos, como o consumo máximo de oxigênio e limiares de transição metabólica. Há dúvidas acerca da melhor maneira de se determinar a capacidade máxima de exercício, velocidade inicial do teste, razão de incremento, interação velocidade/inclinação e tempo de teste. Em suma, os testes em rampa vêm sendo aplicados com base na experiência dos avaliadores, sem que haja realmente um 'protocolo' que norteie a sua montagem. Estudos que possam contribuir para o desenvolvimento de critérios mais formais e precisos para a elaboração de protocolos em rampa, portanto, fazem-se necessários.

Relationship between peak cardiac pumping capability and selected exercise-derived prognostic indicators in patients treated with left ventricular assist devices

AIM

Exercise-derived variables have been used in the assessment of functional capacity and prognosis in patients with chronic heart failure. The aim of this study was to assess the relationship between cardiac pumping capability represented by peak cardiac power output and peak oxygen consumption, anaerobic threshold, ventilatory efficiency slope, and peak circulatory power in patients undergoing the 'Harefield Protocol'.

METHODS AND RESULTS

Haemodynamic and gas exchange measurements were undertaken during a graded treadmill exercise test. They were performed on 54 patients-18 implanted with left ventricular assist devices (LVADs), 16 explanted (recovered), and 20 moderate-to-severe heart failure patients. Peak oxygen consumption was only highly correlated with peak cardiac power output in explanted LVAD (r = 0.85, P< 0.01), but not in implanted LVAD and heart failure patients (r = 0.55 and 0.53, P< 0.05). The anaerobic threshold was only modestly correlated with peak cardiac power output in heart failure and explanted (r = 0.46 and 0.54, P< 0.05) and weakly in implanted LVAD patients (r = 0.37, P< 0.05). Peak cardiac power output was well correlated with peak circulatory power in LVAD explanted and implanted (r = 0.82, P< 0.01; r = 0.63, P< 0.01) but not in heart failure patients (r = 0.31, P> 0.05). Ventilatory efficiency slope was only moderately correlated with peak cardiac power output in LVAD-explanted patients (r = -0.52, P< 0.05).

CONCLUSION

Exercise-derived prognostic indicators demonstrate limited capacity in reflecting cardiac pumping capability in patients treated with LVADs and should therefore be used with caution in interpretation of cardiac organ function.

Resting measures and physiological responses to exercise for the determination of prognosis in patients with chronic heart failure: useful tools for clinical decision-making

Despite recent advances in the management of chronic heart failure (CHF), the prognosis of many of these patients remains dire. The need for an accurate prognosis in these patients has led to the identification of several indicators purported to represent the impact of the disease. Such indicators often are obtained at rest and are not always accurate at determining the clinical status of CHF patients. As a result, the relationship between prognostic indicators and clinical outcomes is frequently weak. On the other hand, physiological responses to acute exercise may unmask patients with the worst clinical status and identify those at increased risk of poor outcomes. Therefore, the present review appraises the value of several prognostic indicators for patients with CHF collected at rest and in response to exercise. In particular, it contrasts the value and accuracy of predictors of mortality widely used in clinical settings, such as oxygen uptake, ventilatory efficiency, and left ventricular ejection fraction, with new and more direct indicators of ventricular systolic and diastolic function.

Cardiopulmonary Exercise Testing in Patients with Chronic Heart Failure: Prognostic Comparison from Peak VO2 and VE/VCO2 Slope

BACKGROUND

Cardiopulmonary exercise testing with ventilatory expired gas analysis (CPET) has proven to be a valuable tool for assessing patients with chronic heart failure (CHF). The maximal oxygen uptake (peak V02) is used in risk stratification of patients with CHF. The minute ventilation-carbon dioxide production relationship (VE/VCO2 slope) has recently demonstrated prognostic significance in patients with CHF.

METHODS

Between January 2006 and December 2007 we performed CPET in 184 pts (146 M, 38 F, mean age 59.8 +/- 12.9 years), with stable CHF (96 coronary artery disease, 88 dilated cardiomyopathy), in NYHA functional class II (n.107) - III (n.77), with left ventricular ejection fraction (LVEF)

RESULTS

Peak VO2 and VE/VCO2 slope were demonstrated with univariate Cox regression analysis both to be significant predictor of cardiac-related mortality and hospitalization (p < 0.0001, respectively). Non survivors had a lower peak VO2 (10.49 +/- 1.70 ml/kg/min vs. 14.41 +/- 3.02 ml/kg/min, p < 0.0001), and steeper Ve/VCO2 slope (41.80 +/- 8.07 vs. 29.84 +/- 6.47, p < 0.0001) than survivors. Multivariate survival analysis revealed that VE/VCO2 slope added additional value to VO2 peak as an independent prognostic factor (chi2: 56.48, relative risk: 1.08, 95% CI: 1.03 - 1.13, p = 0.001). The results from Kaplan-Meier analysis revealed a 1-year cardiac-related mortality of 75% in patients with VE/VCO2 slope >/= 35.6 and 25% in those with VE/VCO2 slope < 35.6 (log rank chi2: 67.03, p < 0.0001) and 66% in patients with peak VO2 12.2 ml/kg/min (log rank chi2: 50.98, p < 0.0001). One-year cardiac-related hospitalization was 77% in patients with VE/VCO2 slope >/= 32.5 and 23% in those with VE/VCO2 slope < 32.5 (log rank chi2: 133.80, p < 0.0001) and 63% in patients with peak VO2 12.3 ml/kg/min (log rank chi2: 72.86, p < 0.0001). The VE/VCO2 slope was demonstrated with receiver operating characteristic curve analysis to be equivalent to peak VO2 in predicting cardiac-related mortality (0.89 vs. 0.89). Although area under the receiver operating characteristic curve for the VE/VCO2 slope was greater than peak VO2 in predicting cardiac-related hospitalization (0.88 vs 0.82), the difference was no statistically significant (p = 0.13).

CONCLUSION

These results add to the present body of knowledge supporting the use of CPET in CHF patients. The VE/VCO2 slope, as an index of ventilatory response to exercise, is an excellent prognostic parameter and improves the risk stratification of CHF patients. It is easier to obtain than parameters of maximal exercise capacity and is of equivalent prognostic importance than peak VO2.

Collapse

Key Words

• Congestive heart failure
• exercise capacity
• gas exchange
• prognosis.
• ventilation

Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Filippo Maria Sarullo Division of Cardiology, Buccheri La Ferla Fatebenefratelli Hospital Palermo, Italy
Giovanni Fazio Department of Cardiology, University of Palermo, Italy
Ignazio Brusca Clinical Phatology Service, Buccheri La Ferla Fatebenefratelli Hospital Palermo, Italy
Sergio Fasullo Division of Cardiology “P. Borsellino”, G.F. Ingrassia Hospital - Palermo – Italy
Salvatore Paterna Department of Internal Medicine, University of Palermo - Italy
Pamela Licata Department of Cardiology, University of Palermo, Italy
Giuseppina Novo Department of Cardiology, University of Palermo, Italy
Salvatore Novo Department of Cardiology, University of Palermo, Italy
Pietro Di Pasquale Division of Cardiology “P. Borsellino”, G.F. Ingrassia Hospital - Palermo – Italy

Collapse

What is treatment success in cardiac resynchronization therapy?

Cardiac resynchronization therapy (CRT) is an established treatment for symptomatic patients with heart failure, a prolonged QRS duration, and impaired left ventricular (LV) function. Identification of ‘responders’ and ‘non-responders’ to CRT has attracted considerable attention. The response to CRT can be measured in terms of symptomatic response or clinical outcome, or both. Alternatively, the response to CRT can be measured in terms of changes in surrogate measures of outcome, such as LV volumes, LV ejection fraction, invasive measures of cardiac performance, peak oxygen uptake, and neurohormones. This review explores whether these measures can be used in assessing the symptomatic and prognostic response to CRT. The role of these parameters to the management of individual patients is also discussed.

Are scores useful in advanced heart failure?

Advanced heart failure (HF) is becoming an increasingly challenging problem as more patients with this disease are living longer, yet experiencing its inexorable progression. Adding to this complex matter, there are different views on how to define advanced HF, whereby an acute decompensation episode does not necessarily indicate advanced disease. Several scores have been described aiming at a better prognostic performance across the HF spectrum. These include the Heart Failure Survival Score, the Seattle Heart Failure Model, the Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients With Heart Failure predictive schemes, the Acute Decompensated Heart Failure National Registry regression tree discrimination, among others. Most scoring systems have been built based on outpatient populations or recently hospitalized HF subjects. The setting of advanced HF has not gained much attention as far as prognostication is concerned, and yet there lies potentially challenging decision-making situations where issues, such as heart transplantation, use of costly devices and end-of-life questions, are raised.

Is there a difference between patients with peak oxygen consumption below 10 ml/kg/min versus between 10 and 14 ml/kg/min? Does the "Grey Zone" really exist?

BACKGROUND

Cardiopulmonary exercise testing is an important component of evaluation when orthotopic heart transplantation (OHT) is considered for chronic heart failure (CHF) patients. However there is a question about the accuracy of interpretations of peak oxygen consumption (VO(2)max) used at present.

MATERIALS AND METHODS

We analyzed 302 CHF patients stratified into 3 groups according to VO(2)max (mL/kg/min): group 1 = <10 (n = 37); group 2 = 10-14 (n = 121) and group 3 = >14 (n = 144). We compared the mortality rate, the OHT rate, time to OHT, time to death and pulmonary function tests (PFT) among the groups using ANOVA Kruskal-Wallis tests for analysis in Statistica 7.1.

RESULTS

No important differences were observed between groups 1 and 2 (P > .05), but first in comparison with group 3 (P < .05) in terms of mortality (48.6% vs 33.1% vs 21.5%), number of OHT (24.3% vs 32.2% vs 14.6%), time to death (15.4 vs 16.6 vs 34.4 months) or PFT results (forced expiratory volume in the first second forced vital capacity and peak expiratory flow, all as direct or as percent of normal values). In contrast, time to OHT (4.6 vs 6.9 vs 10.9 months) and percent of normal vital capacity (72% vs 81% vs 91%) differed significantly among all groups (P < .05).

CONCLUSION

Patients with VO(2)max between 10 and 14 or <10 mL/kg/min are at similar risk of death.

Influence of etiology of heart failure on the obesity paradox

Several investigations have demonstrated that higher body weight, as assessed by the body mass index, is associated with improved prognosis in patients with heart failure (HF). The purpose of the present investigation was to assess the influence of HF etiology on the prognostic ability of the body mass index in a cohort undergoing cardiopulmonary exercise testing. A total of 1,160 subjects were included in the analysis. All subjects underwent cardiopulmonary exercise testing, at which the minute ventilation/carbon dioxide production slope and peak oxygen consumption were determined. In the overall group, 193 cardiac deaths occurred during a mean follow-up of 30.7 +/- 25.6 months (annual event rate 6.0%). The subjects classified as obese consistently had improved survival compared to those classified as normal weight (overall survival rate 88.0% vs <or=81.1%, p <0.001). Differences in survival according to HF etiology were observed for those classified as overweight. In the ischemic subgroup, the survival characteristics for the overweight subjects (75.5%) were similar those for subjects classified as normal weight (81.1%). The converse was true for the nonischemic subgroup, for whom the survival trends for the obese (86.4%) and overweight subjects (88.4%) were similar. The minute ventilation/carbon dioxide production slope was the strongest prognostic marker (chi-square >or=43.4, p <0.001) for both etiologies, and the body mass index added prognostic value (residual chi-square >or=4.7, p <0.05). In conclusion, these results further support the notion that obesity confers improved prognosis in patients with HF, irrespective of the HF etiology. Moreover, the body mass index appears to add predictive value during the cardiopulmonary exercise testing assessment. However, survival appears to differ according to HF etiology in subjects classified as overweight.

Importance of treadmill exercise time as an initial prognostic screening tool in patients with systolic left ventricular dysfunction

BACKGROUND

We sought to determine whether treadmill exercise time may be of value as an initial prognostic screening tool in ambulatory patients with impaired systolic function who are referred for cardiopulmonary exercise testing.

METHODS AND RESULTS

We studied 2231 adult systolic heart failure patients (27% of whom were women) who underwent cardiopulmonary stress testing using a modified Naughton protocol. We assessed the value of treadmill exercise time for prediction of all-cause death and a composite of death or United Network for Organ Sharing status 1 heart transplantation. During a mean follow-up of 5 years, 742 patients (33%) died. There were 249 United Network for Organ Sharing status 1 heart transplants (11%). Treadmill exercise time was predictive of death and the composite outcome in both women and men, even after accounting for peak oxygen consumption and other clinical covariates (adjusted hazard ratio of lowest versus high sex-specific quartile for prediction of death 1.70, 95% confidence interval 1.05 to 2.75, P=0.03; for prediction of the composite outcome, 1.75, 95% confidence interval 1.15 to 2.66, P=0.009). For a 1-minute change in exercise time, there was a 7% increased hazard of death (eg, comparing 480 to 540 seconds, hazard ratio =1.07, 95% confidence interval 1.02 to 1.12, P=0.004).

CONCLUSIONS

Because cardiopulmonary stress testing is not available in every hospital, treadmill exercise time with a modified Naughton protocol may be of value as an initial prognostic screening tool.

End-tidal CO2 pressure and cardiac performance during exercise in heart failure

INTRODUCTION

In patients with heart failure (HF), end-tidal CO2 pressure (PetCO2) is related to ventricular function at rest and has been shown to predict prognosis. However, little is known about the association between ventricular performance and PetCO2 responses to exercise.

METHODS

Forty-eight patients with HF and 13 normal subjects underwent cardiopulmonary exercise testing (CPX), while cardiac output and other hemodynamic measurements at rest and during exercise were obtained using a novel, noninvasive, bioreactance device based on assessment of relative phase shifts of electric currents injected across the thorax, heart rate, and ventricular ejection time. CPX responses and indices of cardiac performance were compared between normal subjects and HF patients achieving above and below a PetCO2 of 36 mm Hg at the ventilatory threshold (PetCO2@VT).

RESULTS

HF patients with an abnormal PetCO2@VT (<36 mm Hg) had a lower exercise capacity, a lower .VO2@VT, a higher .V_E/.VCO2 slope, and lower oxygen uptake efficiency slope (OUES) values compared with normal subjects and patients achieving a normal PetCO2@VT. Patients with reduced PetCO2@VT had lower peak cardiac output responses to exercise (20.0 +/- 10, 17.8 +/- 6, and 13.7 +/- 7 L x min for normal subjects and HF patients with normal and abnormal PetCO2 responses to exercise, respectively, P = 0.04). PetCO2@VT was inversely related to the .V_E/.VCO2 slope (r = -0.78, P < 0.001) and directly related to the OUES (r = 0.55, P < 0.001).

CONCLUSION

Reduced PetCO2 reflects impairments in the functional, ventilatory, and cardiac performance response to exercise in patients with HF. PetCO2 can supplement other clinical and CPX indices in the functional and prognostic evaluation of patients with HF.

Prognostic characteristics of cardiopulmonary exercise testing in caucasian and African American patients with heart failure

Peak oxygen consumption (VO(2)) and ventilatory efficiency (minute ventilation/carbon dioxide output [VE/VCO(2)] slope) are prognostically important in heart failure (HF). The purpose of the present study was to compare the prognostic characteristics of these variables between Caucasian and African American patients. A total of 662 HF patients (455 Caucasian/207 African American) underwent cardiopulmonary exercise testing and were tracked for major cardiac events. The VE/VCO(2) slope was the strongest prognostic marker (chi-square >or=18.9, P<.001), irrespective of race. While peak VO(2) was a significant univariate predictor in both Caucasian (chi-square 42.0, P<.001) and African American (5.2, P=.02) subgroups, it was only retained in the Caucasian multivariate regression. The lack of predictive value of peak VO(2) in the African American subgroup was due to its lack of prognostic significance in female patients. While the VE/VCO(2) slope was the most robust prognostic marker in both Caucasian and African American patients, the predictive ability of peak VO(2) seems to be influenced by race and sex.

Prognostic value of myocardial perfusion-gated SPECT in patients with ischemic cardiomyopathy

BACKGROUND

There are no extensive series in which risk stratification of patients with ischemic cardiomyopathy (IC) is based on their rest and exercise and scintigraphic characteristics. The purpose of our study was to analyze rest and exercise myocardial perfusion-gated SPECT variables for prognosis in patients with ischemic IC.

METHODS AND RESULTS

Prospective cohort study. A study was performed in 167 patients with IC who consecutively underwent rest myocardial perfusion-gated SPECT. In addition, stress SPECT was performed on 137 of these patients. During an average follow-up of 2.3 +/- 1.2 years, cardiac mortality (CM) was 17.4%. Independent predictors of CM in rest-gated SPECT were the positive criteria for myocardial viability (P = 0.027; Hazard risk, HR: 5.1; 95% CI: 1.2-21.4). In the 137 patients who underwent stress-gated SPECT, predictors were scintigraphic criteria for viability plus ischemia (P = 0.026; HR: 3.6; 95% CI: 1.16-11.2) and exercise duration < or = 5 minutes (P = 0.04; HR: 2.7; 95% CI: 1.01-7.36). Coronary angiography variables, performed in 111 patients, did not significantly modify the prognostic value of non-invasive testing.

CONCLUSION

Myocardial perfusion-gated SPECT improves prognostic stratification of patients with IC.

High plasma adiponectin is related to low functional capacity in patients with chronic heart failure

We evaluated the association between plasma adiponectin and functional capacity in patients with chronic heart failure (CHF). Similarly to NT-proBNP, plasma adiponectin was elevated in CHF compared to healthy controls. Adiponectin correlated inversely with peak oxygen consumption and 6-minute walking distance and was able to identify CHF patients with impaired exercise capacity. Our findings support a role of adiponectin as an index of heart failure severity.

Exercise oscillatory breathing in diastolic heart failure: prevalence and prognostic insights

AIMS

Exercise intolerance occurs in both systolic and diastolic heart failure (HF). Exercise oscillatory breathing (EOB) is a powerful predictor of survival in patients with systolic HF. In diastolic HF, EOB prevalence and prognostic impact are unknown.

METHODS AND RESULTS

A total of 556 HF patients (405 with systolic HF and 151 with diastolic HF) underwent cardiopulmonary exercise testing (CPET). Diastolic HF was defined as signs and symptoms of HF, a left ventricular ejection fraction > or =50%, and a Doppler early (E) mitral to early mitral annulus ratio (E') > or =8. CPET responses, EOB prevalence and its ability to predict cardiac-related events were examined. EOB prevalence in systolic and diastolic HF was similar (35 vs. 31%). Compared with the patients without EOB, patients with EOB and either systolic or diastolic HF had a higher New York Heart Association class, lower peak VO(2) and higher E/E' ratio (all P < 0.01). Univariate Cox regression analysis demonstrated that peak VO(2), VE/VCO(2) slope and EOB all were significant predictors of cardiac events in both systolic and diastolic HF. Multivariable analysis revealed that EOB was retained as a prognostic marker in systolic HF and was the strongest predictor of cardiac events in diastolic HF.

CONCLUSION

EOB occurrence is similar in diastolic and systolic HF and provides relevant clues for the identification of diastolic HF patients at increased risk of adverse events.

Heart rate recovery and prognosis in heart failure patients

The aim of this study is to evaluate the usefulness of heart rate recovery (HRRec) for assessing risk of death in heart failure (HF) patients. Echocardiographic and clinical exercise data were analyzed retrospectively on 712 HF patients (EF < or = 45%). HRRec was calculated as peak exercise heart rate - heart rate at 1 min of active recovery. Patients were followed for all-cause mortality (5.9 +/- 3.3 years follow-up). Groups were identified according to HRRec: group-1 (HRR < or = 4 bpm), group-2 (5 < or = HRR < or = 9 bpm), and group-3 (HRR > or = 10). Kaplan-Meier analysis estimated survival of 91, 64, and 43% (group-1); 94, 76, and 63% (group-2); and 92, 82, and 70% (group-3) at 1, 5, and 10 years, respectively. Ranked HRRec independently predicted mortality after adjusting for age, gender, NYHA class, LVEF and BMI, but was not independent of exercise time, peak V(O)(2) and V(E)/V(CO)(2) at nadir. HRRec is a useful prognostic marker in patients with HF, particularly when gas exchange measures are not available.

The initial slope of the VCO2/VO2-curve (s1) in cardiopulmonary exercise testing is a strong and independent predictor of outcome in patients with previous myocardial infarction

BACKGROUND

Detecting heart failure (HF) patients at risk is a relevant clinical problem. Our goal was to define associations of clinical HF-markers and exercise parameters with respect to their prognostic power in HF-patients.

METHODS

We performed cardiopulmonary exercise testing (CPET) in 103 ischemic HF-patients. CPET-parameters included peak VO(2), VO(2) at AT, peak oxygen pulse, minimal CO(2) and O(2) equivalents, VE/VCO(2) and s1, a motivation-independent and submaximal parameter representing the initial slope of the VCO(2)/VO(2)-curve that has not been described in HF-patients so far.

RESULTS

Median follow-up was 668 days. The combined endpoint of cardiovascular death and rehospitalization due to HF occurred in 14 patients. Patients with/without events differed significantly regarding their age, NYHA-class, LVEF and NT-proBNP serum-levels. Patients with events had significantly lower peak VO(2)- and higher s1-values. NT-proBNP serum-levels, NYHA-class and LVEF were significantly correlated with peak VO(2). Only age, peak VO(2) and s1 were independent predictors of adverse events. Using multivariate analysis, s1 was a strong and independent parameter with good sensitivity and specificity.

CONCLUSION

s1 is an independent and powerful predictor in HF-patients. Since s1 is independent of maximal exercise capacity, s1 might be more accurate for the evaluation of HF-patients not willing or unable to perform maximal exercise.

Low-intensity exercise training delays heart failure and improves survival in female hypertensive heart failure rats

Exercise training improves functional capacity and quality of life in patients with heart failure. However, the long-term effects of exercise on mortality associated with hypertensive heart disease have not been well defined. In the present study, we investigated the effect of low-intensity exercise training on disease progression and survival in female spontaneously hypertensive heart failure rats. Animals with severe hypertension (16 months old) were treadmill trained (14.5 m/min, 45 min/d, 3 d/wk) until they developed terminal heart failure or were euthanized because of age-related complications. Exercise delayed mortality resulting from heart failure (P<0.001) and all causes (P<0.05) and transiently attenuated the systolic hypertension and contractile dysfunction observed in the sedentary animals but had no effect on cardiac morphology or contractile function in end-stage heart failure. Training had no effect on terminal myocardial protein expression of antioxidant enzymes, calcium handling proteins, or myosin heavy chain isoforms but was associated with higher cytochrome oxidase activity in cardiac mitochondria (P<0.05) and a greater mitochondrial content of cardiolipin, a phospholipid that is essential for optimal mitochondrial energy metabolism. In conclusion, low-intensity exercise training significantly delays the onset of heart failure and improves survival in female hypertensive heart failure rats without eliciting sustained improvements in blood pressure, cardiac function, or expression of several myocardial proteins associated with the cardiovascular benefits of exercise. The effects of exercise on cytochrome oxidase and cardiolipin provide novel evidence that training may improve prognosis in hypertensive heart disease by preserving mitochondrial energy metabolism.

Association between heart rate recovery and severity of obstructive sleep apnea syndrome

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is associated with autonomic dysfunction and metabolic abnormalities including obesity, dyslipidemia, and insulin resistance. Heart rate recovery at 1min after exercise termination (HRR-1) is a marker of vagal tone. We hypothesized that patients with more severe OSAS would have a lower HRR-1, either due to the co-existing metabolic abnormalities or OSAS.

METHODS

Sixty-three patients with untreated OSAS (49.2+/-9.8years) without glucose- or lipid-lowering or negatively chronotropic drugs underwent cardiopulmonary exercise testing including HRR-1 measurement and assessment of several metabolic parameters. Patients with severe OSAS (apnea-hypopnea index [AHI]>30h(-1); n=32) were compared to patients with mild to moderate OSAS (AHI 5-30h(-1); n=31).

RESULTS

Patients with severe OSAS were more likely to be male (25 vs. 3%; p=0.01) and to have hypertension (72 vs. 39%; p=0.01); they also had higher fasting glucose (5.4+/-0.5 vs. 5.1+/-0.4mmol/l; p=0.016) and C-peptide [905 (651-1353) vs. 749 (597-919)pmol/l; p=0.028] levels compared to patients with mild to moderate OSAS. The groups did not differ with respect to peak heart rate (p=0.2) or peak oxygen consumption (p=0.9), but HRR-1 was significantly lower in patients with severe OSAS compared to patients with mild and moderate OSAS [20 (15-25) vs. 24 (18-34)bpm; p=0.022]. Higher AHI (p=0.01) and lower peak heart rate (p=0.02), but not body mass index or insulin resistance, were independently associated with lower HRR-1.

CONCLUSIONS

The severity of OSAS expressed as higher AHI is independently associated with lower HRR-1, a measure of autonomic dysfunction.

Reproducibility of maximum aerobic power (VO2max) among soccer players using a modified heck protocol

OBJECTIVE

To determine the degree of reproducibility of maximum oxygen consumption (VO2max) among soccer players, using a modified Heck protocol.

METHODS

2 evaluations with an interval of 15 days between them were performed on 11 male soccer players. All the players were at a high performance level; they were training for an average of 10 hours per week, totaling 5 times a week. When they were evaluated, they were in the middle of the competitive season, playing 1 match per week. The soccer players were evaluated on an ergometric treadmill with velocity increments of 1.2 km.h-1 every 2 minutes and a fixed inclination of 3% during the test. VO2max was measured directly using a breath-by-breath metabolic gas analyzer.

RESULTS

The maximum running speed and VO2max attained in the 2 tests were, respectively: (15.6 +/- 1.1 vs. 15.7 +/- 1.2 km.h-1; [P = .78]) and (54.5 +/- 3.9 vs. 55.2 +/- 4.4 ml.kg-1.min-1; [P = .88]). There was high and significant correlation of VO2max between the 2 tests with a 15-day interval between them [r = 0.97; P < .001].

CONCLUSION

The modified Heck protocol was reproducible, and the 15-day interval between the ergospirometric testing was insufficient to significantly modify the soccer players' VO2max values.

Central haemodynamics and peripheral muscle function during exercise in patients with chronic heart failure

In this narrative review of the current literature, we examine the central and peripheral mechanisms responsible for the exercise intolerance of chronic heart failure and highlight briefly the benefits of exercise training in the treatment of this debilitating disorder. Specifically, we identify the common finding of reduced cardiac output reserve during exercise conditions leading to decreased exercise tolerance. We also reveal that the stroke volume response to exercise varies depending on the individual patient, the presence of mitral regurgitation, and the aetiology of heart failure. Chronic heart failure patients with left ventricular systolic dysfunction appear able to use the Frank-Starling mechanism to compensate (in part) for their decreased contractile reserve. Patients with left ventricular diastolic dysfunction have normal contractile function; however, they are unable to make use of the Frank-Starling mechanism during exercise conditions. We also reveal that pericardial constraint may limit diastolic filling and exercise capacity in patients with chronic heart failure. It appears that interventions that reduce pericardial constraint and mitral regurgitation enhance diastolic filling and increase exercise tolerance. A series of peripheral muscle changes also occur, including changes in muscle mass, cellular structure, energy metabolism, and blood flow. Each of these factors is associated with decreased exercise capacity and the symptoms of chronic heart failure. Exercise training has been shown to improve both central haemodynamics and peripheral muscle function leading to improvements in exercise capacity, functional status, and overall quality of life in patients with chronic heart failure.

The Prognostic Value of Ventilatory Efficiency with Beta-Blocker Therapy in Heart Failure

PURPOSE

Beta-blockade (BB) has been shown to improve outcomes among patients with heart failure (HF). The impact this pharmacological approach has on the prognostic information gained from cardiopulmonary exercise testing (CPX) is, however, unclear.

METHODS

Four hundred seventeen subjects diagnosed with HF underwent CPX. The numbers of subjects prescribed and not prescribed a BB agent were 167 and 250, respectively. Subjects were tracked for cardiac-related mortality after CPX.

RESULTS

Values are reported for the no-BB versus the BB group throughout. Age (57.9 +/- 13.3 vs 55.6 +/- 12.5), peak VO2 (16.2 +/- 5.7 vs 16.5 +/- 5.5 mL x kg(-1) x min(-1)), VE/VCO2 slope (34.2 +/- 9.0 vs 33.2 +/- 7.4), and peak RER (1.07 +/- 0.16 vs 1.05 +/- 0.14) were similar between groups (P > 0.05). Multivariate Cox regression analysis revealed that the VE/VCO2 slope was the superior predictor of death in both groups (chi-square: 71.9, P < 0.001; and 18.4, P < 0.001). The optimal threshold values for VE/VCO2 slope in the no-BB and BB groups were 36.0 and 34.3, respectively.

CONCLUSIONS

The results of the present study indicate that BB does not alter the prognostic value/characteristics of the VE/VCO2 slope. Findings from previous investigations examining the prognostic significance of CPX predominantly using HF groups not receiving a BB agent may, therefore, still be applicable in modern-day clinical practice.

Comparison of the prognostic value of cardiopulmonary exercise testing between male and female patients with heart failure

BACKGROUND

Cardiopulmonary exercise testing (CPX) clearly holds prognostic value in the heart failure (HF) population. Studies investigating the prognostic value of CPX in individuals with HF have consistently examined predominantly male groups. The purpose of the present study was to examine the prognostic value of CPX in a female HF group.

METHODS

Seventy-five female and 337 male subjects diagnosed with HF participated in this study. The ability of peak oxygen consumption (VO(2)) and the minute ventilation/carbon dioxide production (VE/VCO(2)) slope to predict cardiac-related events were assessed.

RESULTS

In the year following CPX, the female group suffered 26 cardiac-related events (8 deaths/18 hospitalizations), while the male group suffered 89 cardiac-related events (20 deaths/69 hospitalizations). The hazard ratios for peak VO(2) and the VE/VCO(2) slope were 4.0 (95% confidence interval: 2.6-6.1, p<0.001) and 4.2 (95% confidence interval: 2.7-6.6, p<0.001) in the male group and 3.8 (95% confidence interval: 1.7-8.5, p<0.001) and 4.3 (95% confidence interval: 1.8-9.8, p<0.001) in the female group. In both the male and female groups, Cox multivariate analysis revealed VE/VCO(2) slope was the strongest predictor of cardiac-related events while peak VO(2) added significant predictive value and was retained in the regression.

CONCLUSION

The results of the present study indicate that the prognostic value of peak VO(2) and the VE/VCO(2) slope are similar in men and women diagnosed with HF. In both men and women, the prognostic power of the VE/VCO(2) slope is greater than that of peak VO(2).

Limitations of the New York Heart Association functional classification system and self-reported walking distances in chronic heart failure

BACKGROUND

Two ways to evaluate the symptoms of heart failure are the New York Heart Association (NYHA) classification and asking patients how far they can walk (walk distance). The NYHA system is commonly used, although it is not clear how individual clinicians apply it.

AIM

To investigate how useful these measures are to assess heart failure and whether other questions might be more helpful.

METHODS

30 cardiologists were asked what questions they used when assessing patients with heart failure. To assess interoperator variability, two cardiologists assessed a series of 50 patients in classes II and III using the NYHA classification. 45 patients who had undergone cardiopulmonary testing were interviewed using a specially formulated questionnaire. They were also asked how far they could walk before being stopped by symptoms, and then tested on their ability to estimate distance.

RESULTS

The survey of cardiologists showed no consistent method for assessing NYHA class and a literature survey showed that 99% of research papers do not reference or describe their methods for assigning NYHA classes. The interoperator variability study showed only 54% concordance between the two cardiologists. 70% of cardiologists asked patients for their walk distance; however, this walk distance correlated poorly with actual exercise capacity measured by cardiopulmonary testing (rho = 0.04, p = 0.82).

CONCLUSION

No consistent method of assessing NYHA class is in use and the interoperator study on class II and class III patients gave a result little better than chance. Some potential questions are offered for use in assessment. Walking distance, although frequently asked, does not correlate with formally measured exercise capacity, even after correction for patient perception of distance, and has never been found to have prognostic relevance. Its value is therefore doubtful.

Cardiorespiratory Fitness and Short-term Complications After Bariatric Surgery

BACKGROUND

Morbid obesity is associated with reduced functional capacity, multiple comorbidities, and higher overall mortality. The relationship between complications after bariatric surgery and preoperative cardiorespiratory fitness has not been previously studied.

METHODS

We evaluated cardiorespiratory fitness in 109 patients with morbid obesity prior to laparoscopic Roux-en-Y gastric bypass surgery. Charts were abstracted using a case report form by reviewers blinded to the cardiorespiratory evaluation results.

RESULTS

The mean age (+/- SD) was 46.0 +/- 10.4 years, and 82 patients (75.2%) were female. The mean body mass index (BMI) was 48.7 +/- 7.2 (range, 36.0 to 90.0 kg/m(2)). The composite complication rate, defined as death, unstable angina, myocardial infarction, venous thromboembolism, renal failure, or stroke, occurred in 6 of 37 patients (16.6%) and 2 of 72 patients (2.8%) with peak oxygen consumption (Vo(2)) levels < 15.8 mL/kg/min or > 15.8 mL/kg/min (lowest tertile), respectively (p = 0.02). Hospital lengths of stay and 30-day readmission rates were highest in the lowest tertile of peak Vo(2) (p = 0.005). There were no complications in those with BMI < 45 kg/m(2) or peak Vo(2) > or= 15.8 mL/kg/min. Multivariate analysis adjusting for age and gender found peak Vo(2) was a significant predictor of complications: odds ratio, 1.61 (per unit decrease); 95% confidence interval, 1.19 to 2.18 (p = 0.002).

CONCLUSIONS

Reduced cardiorespiratory fitness levels were associated with increased, short-term complications after bariatric surgery. Cardiorespiratory fitness should be optimized prior to bariatric surgery to potentially reduce postoperative complications.

Early heart rate recovery after exercise predicts mortality in patients with chronic heart failure

BACKGROUND

Patients with chronic heart failure (CHF) have multiple abnormalities of autonomic regulation that have been associated to their high mortality rate. Heart rate recovery immediately after exercise is an index of parasympathetic activity, but its prognostic role in CHF patients has not been determined yet.

METHODS

Ninety-two stable CHF patients (83M/9F, mean age: 51+/-12 years) performed an incremental symptom-limited cardiopulmonary exercise testing. Measurements included peak O2 uptake (VO2p), ventilatory response to exercise (VE/VCO2 slope), the first-degree slope of VO2 for the 1st minute of recovery (VO2/t-slope), heart rate recovery [(HRR1, bpm): HR difference from peak to 1 min after exercise] and chronotropic response to exercise [%chronotropic reserve (CR, %)=(peak HR-resting HR/220-age-resting HR)x100]. Left ventricular ejection fraction (LVEF, %) was also measured by radionuclide ventriculography.

RESULTS

Fatal events occurred in 24 patients (26%) during 21+/-6 months of follow-up. HRR1 was lower in non-survivors (11.4+/-6.4 vs. 20.4+/-8.1; p<0.001). All cause-mortality rate was 65% in patients with HRR112 bpm (log-rank: 32.6; p<0.001). By multivariate survival analysis, HRR1 resulted as an independent predictor of mortality (chi2=19.2; odds ratio: 0.87; p<0.001) after adjustment for LVEF, VO2p, VE/VCO2 slope, CR and VO2/t-slope. In a subgroup of patients with intermediate exercise capacity (VO2p: 10-18, ml/kg/min), HRR1 was a strong predictor of mortality (chi2: 14.3; odds ratio: 0.8; p<0.001).

CONCLUSIONS

Early heart rate recovery is an independent prognostic risk indicator in CHF patients and could be used in CHF risk stratification.

VE/VCO2 slope is associated with abnormal resting haemodynamics and is a predictor of long-term survival in chronic heart failure

BACKGROUND

Patients with chronic heart failure (CHF) present with exercise-induced hyperpnea, but its pathophysiological mechanism has not been thoroughly investigated. We aimed to determine the relationship between exercise-induced hyperpnea, resting haemodynamic measurements and the validity of ventilatory response (V(E)/V(CO(2)) slope) as a mortality predictor in CHF patients.

METHODS

Ninety-eight CHF patients (90M/8F) underwent a symptom-limited treadmill cardiopulmonary exercise test (CPET). Right heart catheterization and radionuclide ventriculography were performed within 72 h of CPET.

RESULTS

Twenty-seven patients died from cardiac causes during 20+/-6 months follow-up. Non-survivors had a lower peak oxygen consumption (V(O(2)p)), (16.5+/-4.9 vs. 20.2+/-6.1, ml/kg/min, p=0.003), a steeper V(E)/V(CO(2)) slope (34.8+/-8.3 vs. 28.9+/-4.8, p<0.001) and a higher pulmonary capillary wedge pressure (PCWP) (19.5+/-8.6 vs. 11.7+/-6.5 mm Hg, p=0.008) than survivors. By multivariate survival analysis, the V(E)/V(CO(2)) slope as a continuous variable was an independent prognostic factor (chi(2): 8.5, relative risk: 1.1, 95% CI: 1.03-1.18, p=0.004). Overall mortality was 52% in patients with V(E)/V(CO(2)) slope > or =34 and 18% in those with V(E)/V(CO(2)) slope <34 (log rank: 18.5, p<0.001). In a subgroup of patients (V(O(2)p): 10-18 ml/kg/min), V(E)/V(CO(2)) slope was a significant predictor of mortality (relative risk: 6.2, 95% CI: 1.7-22.2, p=0.002). Patients with high V(E)/V(CO(2)) slope had higher resting PCWP (19.9+/-9.1 vs. 11.3+/-5.7 mmHg, p<0.001) and V(E)/V(CO(2)) slope correlated significantly with PCWP (r: 0.57, p<0.001).

CONCLUSIONS

The V(E)/V(CO(2)) slope, as an index of ventilatory response to exercise, improves the risk stratification of CHF patients. Interstitial pulmonary oedema may be a pathophysiological mechanism of inefficient ventilation during exercise in these patients.