High-Intensity Interval Training in Patients With Heart Failure With Reduced Ejection Fraction.

BACKGROUND: Small studies have suggested that high-intensity interval training (HIIT) is superior to moderate continuous training (MCT) in reversing cardiac remodeling and increasing aerobic capacity in patients with heart failure with reduced ejection fraction. The present multicenter trial compared 12 weeks of supervised interventions of HIIT, MCT, or a recommendation of regular exercise (RRE). METHODS: Two hundred sixty-one patients with left ventricular ejection fraction ≤35% and New York Heart Association class II to III were randomly assigned to HIIT at 90% to 95% of maximal heart rate, MCT at 60% to 70% of maximal heart rate, or RRE. Thereafter, patients were encouraged to continue exercising on their own. Clinical assessments were performed at baseline, after the intervention, and at follow-up after 52 weeks. Primary end point was a between-group comparison of change in left ventricular end-diastolic diameter from baseline to 12 weeks. RESULTS: Groups did not differ in age (median, 60 years), sex (19% women), ischemic pathogenesis (59%), or medication. Change in left ventricular end-diastolic diameter from baseline to 12 weeks was not different between HIIT and MCT (P=0.45); left ventricular end-diastolic diameter changes compared with RRE were -2.8 mm (-5.2 to -0.4 mm; P=0.02) in HIIT and -1.2 mm (-3.6 to 1.2 mm; P=0.34) in MCT. There was also no difference between HIIT and MCT in peak oxygen uptake (P=0.70), but both were superior to RRE. However, none of these changes was maintained at follow-up after 52 weeks. Serious adverse events were not statistically different during supervised intervention or at follow-up at 52 weeks (HIIT, 39%; MCT, 25%; RRE, 34%; P=0.16). Training records showed that 51% of patients exercised below prescribed target during supervised HIIT and 80% above target in MCT. CONCLUSIONS: HIIT was not superior to MCT in changing left ventricular remodeling or aerobic capacity, and its feasibility remains unresolved in patients with heart failure. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00917046.

Renal function and peak exercise oxygen consumption in chronic heart failure with reduced left ventricular ejection fraction.

BACKGROUND: Chronic kidney disease is associated with sympathetic activation and muscle abnormalities, which may contribute to decreased exercise capacity. We investigated the correlation of renal function with peak exercise oxygen consumption (V̇O2) in heart failure (HF) patients. METHODS AND RESULTS: We recruited 2,938 systolic HF patients who underwent clinical, laboratory, echocardiographic and cardiopulmonary exercise testing. The patients were stratified according to estimated glomerular filtration rate (eGFR). Mean follow-up was 3.7 years. The primary outcome was a composite of cardiovascular death and urgent heart transplantation at 3 years. On multivariable regression, eGFR was predictor of peakV̇O2(P<0.0001). Other predictors were age, sex, body mass index, HF etiology, NYHA class, atrial fibrillation, resting heart rate, B-type natriuretic peptide, hemoglobin, and treatment. After adjusting for significant covariates, the hazard ratio for primary outcome associated with peakV̇O2<12 ml·kg(-1)·min(-1)was 1.75 (95% confidence interval (CI): 1.06-2.91; P=0.0292) in patients with eGFR ≥60, 1.77 (0.87-3.61; P=0.1141) in those with eGFR of 45-59, and 2.72 (1.01-7.37; P=0.0489) in those with eGFR <45 ml·min(-1)·1.73 m(-2). The area under the receiver-operating characteristic curve for peakV̇O2<12 ml·kg(-1)·min(-1)was 0.63 (95% CI: 0.54-0.71), 0.67 (0.56-0.78), and 0.57 (0.47-0.69), respectively. Testing for interaction was not significant. CONCLUSIONS: Renal dysfunction is correlated with peakV̇O2. A peakV̇O2cutoff of 12 ml·kg(-1)·min(-1)offers limited prognostic information in HF patients with more severely impaired renal function.

EaRly-start ExerciSe training afTer acute hemodynAmic decompensation in patients with chRonic hearT failure (RE-START). A multicenter, randomized, controlled trial on short-term feasibility and impact on functional capacity, symptoms and neurohumoral activation .

RE-START is a multicenter, randomized, prospective, open, controlled trial aiming to evaluate the feasibility and the short- and medium-term effects of an early-start AET program on functional capacity, symptoms and neurohormonal activation in chronic heart failure (CHF) patients with recent acute hemodynamic decompensation. Study endpoints will be: 1) safety of and compliance to AET; 2) effects of AET on i) functional capacity, ii) patient-reported symptoms and iii) AET-induced changes in beta-adrenergic receptor signaling and circulating angiogenetic and inflammatory markers. Two-hundred patients, randomized 1:1 to training (TR) or control (C), will be enrolled. Inclusion criteria: 1) history of systolic CHF for at least 6 months, with ongoing acute decompensation with need of intravenous diuretic and/or vasodilator therapy; 2) proBNP > 1000 pg/mI at admission. Exclusion criteria: 1) ongoing cardiogenic shock; 2) need of intravenous inotropic therapy; 3) creatinine > 2.5 mg/dl at admission. After a 72-hour run-in period, TR will undergo the following 12-day early-start AET protocol: days 1-2: active/passive mobilization (2 sessions/day, each 30 minutes duration); days 3-4: as days 1-2 + unloaded bedside cycle ergometer (3 sessions/day, each 5-10 minutes duration); days 5-8: as days 1-2 + unloaded bedside cycle ergometer (3 sessions/day, each 15-20 minutes duration); days 9-12: as days 1-2 + bedside cycle ergometer at 10-20 W (3 sessions/day, each 15-20 minutes duration). During the same period, C will undergo the same activity protocol as in days 1-2 for TR. All patients will undergo a 6-min WT at day 1, 6, 12 and 30 and echocardiogram, patient-reported symptoms on 7-point Likert scale and measurement of lymphocyte G protein coupled receptor kinase, VEGF, angiopoietin, TNF alfa, IL-1, IL-6 and eNOS levels at day 1, 12 and 30.

Aerobic training and angiogenesis activation in patients with stable chronic heart failure: a preliminary report.

The pathophysiology of chronic heart failure (CHF) involves multiple hystologic and molecular alterations. To determine the effects of physical training on circulating endothelial progenitor cells (EPCs), angiogenesis (angiogenin, angiopoietin-1 and -2, VEGF, Tie-2, SDF-1α) and inflammation (IL-6, CRP), we compared data obtained from 11 CHF pts before and after 3 months aerobic exercise training, to those from 10 non trained CHF pts (CHF-C group, age 64 + 2 years, NYHA 2). At the end of the study, EPCs count and AP-2 serum levels significantly increased in the CHF-TR group. These preliminary data suggest a significant effect of even a short program of physical training on angiogenic activation and endothelial dysfunction.

Androgens and cardiac diseases.

Although androgens have been considered deleterious for the cardiovascular system, recent data have demonstrated favourable testosterone effects on cardiac and vascular remodeling and clinical outcome. However, the cardiovascular risk-benefit profile of testosterone therapy remains largely elusive due to lack of well-designed and adequately powered randomized clinical trials. In any case, a large body of clinical evidence underlines that low plasma testosterone levels should be considered a risk factor for cardiovascular disease, and that the evaluation of sex steroids should be included in the routine clinical evaluation of cardiac patients. A better understanding of the mechanism regulating the effects of testosterone on cardiovascular system could lead to novel therapeutic strategies in several cardiac patient populations, such as chronic heart failure patients and those who recently underwent cardiac surgery.

Reduced exercise capacity in early-stage amyotrophic lateral sclerosis: Role of skeletal muscle.

Our objective was to correlate skeletal muscle mass (SM) with cardiopulmonary exercise testing (CPET) descriptors of exercise capacity in patients with amyotrophic lateral sclerosis (ALS) and compare ALS CPET data with those of patients with mitochondrial myopathy (MM) and normal subjects (N). Twenty-four early-stage ALS patients (63±11 years) underwent bioelectrical impedance analysis of body composition, resting spirometry, and ramp CPET. Six MM and six N were used as controls (56 ± 7 and 63 ± 4 years, respectively). Results showed that ALS SM index was similar to that of N (9.0±2.1 kg/m(2) vs. 10.4±1.9 kg/m(2), respectively; p = n.s.), whereas peak VO(2)/kg SM was significantly lower (41.5 ± 11.6 ml/kg/min vs. 57.8 ± 7.5 ml/kg/min, respectively; p < 0.01). However, the heart rate/VO(2) slope did not differ between ALS and N, being significantly higher in MM than in both ALS and N (6.1 ± 1.4 beats/ml/kg/min vs. 4.2 ± 1.1 beats/ml/kg/min vs. 3.8 ± 2.0 beats/ml/kg/min, respectively; both p < 0.01), excluding a marked skeletal muscle metabolic impairment in ALS. Neither cardiovascular nor ventilatory dysfunction was detected in ALS. Early-stage ALS patients show a SM similar to N, but with a reduced peak VO(2)/kg SM. Such a reduced peripheral O(2) utilization is consistent with deconditioning as the main cause of impaired exercise capacity in this population.

Effects of n-3 polyunsaturated fatty acids on malignant ventricular arrhythmias in patients with chronic heart failure and implantable cardioverter-defibrillators: A substudy of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca (GISSI-HF) trial.

BACKGROUND: The antiarrhythmic effects of n-3 polyunsaturated fatty acids (n-3PUFA) in ischemic heart disease have been demonstrated; however, studies in patients surviving malignant ventricular arrhythmias of different etiologies treated with an implantable cardioverter-defibrillator (ICD) have given conflicting results. The purpose of this study was to assess the antiarrhythmic effect of n-3PUFA versus placebo in 566 patients with heart failure enrolled in the GISSI-HF trial who received an ICD for secondary or primary prevention of ventricular fibrillation (VF) or tachycardia (VT). METHODS: Clinical data and arrhythmic event recordings extracted from the device memory were obtained. We tested the treatment effect by a multivariate Cox model adjusting for all clinical parameters associated with the primary end point defined as time to first appropriate ICD discharge for VT/VF. RESULTS: In the 566 patients with at least one recorded follow-up visit, 1363 VT and 316 VF episodes were terminated by ICD pacing or shock over a median follow-up of 928 days. The incidence of the primary end point event was 27.3% in the n-3PUFA group and 34.0% in the placebo group (adjusted hazard rate = 0.80, 95% CI 0.59-1.09, P = .152). Patients who received 1, 2 to 3, or >3 ICD discharges were 8.9%, 7.1%, and 11.1% in the n-3PUFA group, compared with slightly higher rates of 11.1%, 10.7%, and 12.1% in the placebo group (overall P = .30). Patients with the highest 3-month increase in plasma n-3PUFA had a somewhat lower incidence of arrhythmic events. CONCLUSIONS: The results of this study, though not statistically significant, support prior evidences of an antiarrhythmic effect of n-3PUFA in patients with ICD, although they leave open the issue of whether this effect leads to a survival benefit.

Aerobic exercise training intensity in patients with chronic heart failure: principles of assessment and prescription.

Chronic heart failure (CHF) is a significant cause of worldwide mortality and morbidity, whose clinical picture is characterized by exercise intolerance and impaired quality of life. Aerobic exercise training is a well-established nonpharmacological tool improving the CHF's pathophysiological, clinical, and prognostic picture, and prescription of an adequate training intensity is crucial to obtain both exercise-induced benefits and a reasonable control of exercise-related risk. However, clarity is still lacking regarding the definition of exercise intensity domains and the lower and upper intensity limits of prescriptible aerobic exercise in CHF patients. The purpose of this review is to provide an update of the methods for the exercise intensity assessment and continuous aerobic training intensity prescription in the CHF population, furnishing indications useful for implementation of physical rehabilitation programs in these patients.

Stepwise increase of angiopoietin-2 serum levels is related to haemodynamic and functional impairment in stable chronic heart failure.

BACKGROUND: A reciprocal link between inflammation, oxidative/nitrosative stress, and endothelial dysfunction has been postulated in chronic heart failure (CHF). The endothelial repair mechanisms involved remain to be determined. Our aim was to investigate whether there are detectable signs of ongoing angiogenesis in serum of CHF patients and to evaluate the correlation with indexes of haemodynamic and functional impairment. METHODS AND RESULTS: Enzyme-linked immunosorbent assay tests were used to quantify angiogenin, angiopoietin-1, angiopoietin-2, vascular endothelial growth factor, Tie-2, and brain natriuretic peptide in serum of 87 patients with CHF of increasing severity according to New York Heart Association (NYHA; class I, n = 8; II, n = 45; and III, n = 34) and in 14 healthy subjects matched for age and sex. Angiogenin, angiopoietin-2, and Tie-2 were significantly increased in CHF of increasing severity (Kruskal-Wallis: p = 0.0004, p < 0.0001, and p = 0.017, respectively). Angiopoietin-2 was inversely correlated with the 6-min walking test (r = -0.65, p < 0.0001), peak oxygen consumption (VO(2max); r = -0.57, p = 0.0002), and deceleration time (r = -0.61, p < 0.0001). Multiple regression analysis showed that angiopoietin-2 was mainly associated with VO(2max) (p = 0.018). The angiopoietin-2 area under the receiver operating characteristic curve for CHF diagnosis was 0.94 (95% CI 0.88-0.99; p < 0.001). CONCLUSIONS: These data demonstrate that angiopoietin-2 and selected serum markers of angiogenesis progressively increase with haemodynamic and functional decline in CHF.

Cardiovascular evaluation of middle-aged/ senior individuals engaged in leisure-time sport activities: position stand from the sections of exercise physiology and sports cardiology of the European Association of Cardiovascular Prevention and Rehabilitation.

Regular aerobic exercise at moderate intensities and an increased physical fitness are associated with a reduced risk of fatal and nonfatal coronary events in middle-aged individuals. In contrast, moderate and vigorous physical exertion is associated with an increased risk for cardiac events, including sudden cardiac death in individuals harbouring cardiovascular disease. The risk-benefit ratio may differ in relation to the individual's age, fitness level, and presence of cardiovascular disease; sedentary individuals with underlying coronary artery disease are at greatest risk. The intention of the present position stand of the European Association of Cardiovascular Prevention and Rehabilitation is to encourage individuals to participate in regular physical activity and derive the benefits of physical exercise while minimizing the risk of cardiovascular adverse events. Therefore, the aim is to establish the most practical method of cardiovascular evaluation in middle-age/senior individuals, who are contemplating exercise or who are already engaged in nonprofessional competitive or recreational leisure sporting activity. These recommendations rely on existing scientific evidence, and in the absence of such, on expert consensus. The methodology of how middle-aged and older individuals should be evaluated appropriately before engaging in regular physical activity is both complex and controversial. On practical grounds the consensus panel recommend that such evaluation should vary according to the individual's cardiac risk profile and the intended level of physical activity. Self assessment of the habitual physical activity level and of the risk factors, are recommended for screening of large populations. Individuals deemed to be at risk require further evaluation by a qualified physician. In senior/adult individuals with an increased risk for coronary events, maximal exercise testing (and possibly further evaluations) is advocated. Hopefully, the recommendations in this paper provide a practical solution for facilitating safe exercise prescription in senior/adults.

Cardiovascular prevention and rehabilitation for patients with ventricular assist device from exercise therapy to long-term therapy. Part I: Exercise therapy.

In the present context of an aging population, limited donor heart availability, improved reliability of mechanical cardiac support and improved patient outcomes, ventricular assist device (VAD) options to support end-stage heart failure patients are rapidly expanding. In addition, both the smaller size and lighter weight of the pumps now produced and early evidence that these third generation devices may be associated with lower risk of infection and right ventricular failure will probably lead to greater physician and patient acceptability. This is the first of a two-part review on the role of cardiovascular prevention and rehabilitation in patients with VAD. In this first part, we will discuss the role of exercise therapy in VAD patients, while the second will focus on long-term management. One of the prerequisites for use of a VAD--whether permanent (as destination therapy) or semi-permanent (as an alternative to heart transplantation)--is that exercise capacity, although not normal, must be adequate for daily life activities. An intensive multidisciplinary rehabilitation program has the potential to increase exercise performance and improve the quality of life of VAD patients. Both early progressive mobilization and exercise training may improve the overall condition of VAD patients, and favorably impact their clinical course.

Age-related prolongation of phase I of VO2 on-kinetics in healthy humans.

Data are lacking regarding age-related modifications of phase I (PhI) of pulmonary Vo(2) on-kinetics during moderate-intensity exercise. We studied three groups (aged 20-30, 40-50, and 60-70 years) of 10 normal subjects, who underwent one incremental and four below-gas exchange threshold constant-power cardiopulmonary exercise tests. Data from constant-power tests were time-aligned and averaged, and the PhI-phase II transition (PhI-IItr) determined when a sharp decrease from baseline of respiratory exchange ratio occurred. The Vo(2) phase II time constant (tau) was obtained by an exponential fitting starting 1) from PhI-IItr ("experimental" fitting strategy) and 2) after 20 s from exercise onset ("fixed-duration" fitting strategy). Assuming estimated arterial-venous O(2) concentration difference not to change with respect to resting value, cardiac output (CO) values at rest and PhI-IItr were obtained according to Fick's principle. Average pulmonary flow acceleration (AFA) during PhI was calculated as the ratio between CO increase during PhI and PhI duration. PhI duration was related to age (r = 0.74, P < 0.0001), increasing from 21 +/- 3 s to 27 +/- 3 s to 32 +/- 4 s in the 20-30, 40-50, and 60-70 age groups, respectively, and to AFA (r = -0.60, P < 0.001), but not to CO increase during PhI. With respect to the experimental fitting strategy, the fixed-duration strategy overestimated Vo(2) phase II tau the more the higher the subject's age, with a lower goodness of fit in the 60-70 group (SE 0.035 vs. 0.056, P < 0.01). In conclusion, PhI duration is related to age in healthy male humans and is linked to CO acceleration-rather than to increase-during PhI. A significant overestimation of phase II tau thus may occur in healthy elderly subjects and patients with a pathologically induced longer PhI duration when fitting data where the PhI-PhIItr was not experimentally determined but assumed to be a set value (i.e., 20 s).

Assessment of physical activity - a review of methodologies with reference to epidemiological research: a report of the exercise physiology section of the European Association of Cardiovascular Prevention and Rehabilitation.

Physical activity has a fundamental role in the prevention and treatment of chronic disease. The precise measurement of physical activity is key to many surveillance and epidemiological studies investigating trends and associations with disease. Public health initiatives aimed at increasing physical activity rely on the measurement of physical activity to monitor their effectiveness. Physical activity is multidimensional, and a complex behaviour to measure; its various domains are often misunderstood. Inappropriate or crude measures of physical activity have serious implications, and are likely to lead to misleading results and underestimate effect size. In this review, key definitions and theoretical aspects, which underpin the measurement of physical activity, are briefly discussed. Methodologies particularly suited for use in epidemiological research are reviewed, with particular reference to their validity, primary outcome measure and considerations when using each in the field. It is acknowledged that the choice of method may be a compromise between accuracy level and feasibility, but the ultimate choice of tool must suit the stated aim of the research. A framework is presented to guide researchers on the selection of the most suitable tool for use in a specific study.

Exercise haemodynamic variables rather than ventilatory efficiency indexes contribute to risk assessment in chronic heart failure patients treated with carvedilol.

AIMS: To evaluate the prognostic significance of traditional cardiopulmonary exercise testing (CPET) parameters in chronic heart failure (CHF) patients treated with beta-blockers. METHODS AND RESULTS: A total of 631 CHF patients were followed for cardiovascular death over 3.8 +/- 1.4 years; among them 79 (13%) died. All prognostic CPET parameters were related to outcome at univariate analysis, with haemodynamic-derived parameters [peak systolic blood pressure (SBP), peak circulatory power (CP) = peak oxygen consumption (pVO2) x peak SBP] and exertional oscillatory ventilation (EOV) reaching the highest chi2 (46.5, 40.9, and 22.6, respectively, all with P < 0.0001). Exertional oscillatory ventilation, although associated with high mortality rate (43 vs. 11%, P < 0.001), was detected in 42 (7%) patients. In non-EOV, again both peak SBP and peak CP reached the highest chi2 (30.6, and 21.6, respectively, all with P < 0.0001). Regarding CPET parameters, at multivariable analysis, peak SBP was the strongest risk index both in total and non-EOV populations, with 11% risk reduction every 5 mmHg increase. CONCLUSION: All traditional CPET risk parameters were informative in beta-blockers CHF patients, but peak SBP, peak CP, and EOV were the most predictive. In this low-risk population, EOV, although underrepresented, considerably enhanced risk stratification, although other ventilatory efficiency indexes provided less impressive predictive content. In large majority of non-EOV patients, peak SBP improved risk evaluation beyond other CPET parameters.

Baseline and Exercise Predictors of V˙O2peak in Systolic Heart Failure Patients: Results from SMARTEX-HF.

PURPOSE: This study aimed to investigate baseline, exercise testing, and exercise training-mediated predictors of change in peak oxygen uptake (V˙O2peak) from baseline to 12-wk follow-up (ΔV˙O2peak) in a post hoc analysis from the SMARTEX Heart Failure trial. METHODS: We studied 215 patients with heart failure with left ventricular ejection fraction (LVEF) ≤35%, and New York Heart Association (NYHA) classes II-III who were randomized to either supervised high-intensity interval training with exercise target intensity of 90%-95% of peak heart rate (HRpeak) or supervised moderate continuous training (MCT) with target intensity of 60%-70% of HRpeak, or who received a recommendation of regular exercise on their own. Predictors of ΔV˙O2peak were assessed in two models: a logistic regression model comparing highest and lowest tertiles (baseline parameters) and a multivariate linear regression model (test/training/clinical parameters). RESULTS: The change in V˙O2peak in response to the interventions (ΔV˙O2peak) varied substantially, from -8.50 to +11.30 mL·kg·min. Baseline NYHA (class II gave higher odds vs III; odds ratio (OR), 7.1 (2.0-24.9); P = 0.002), LVEF (OR per percent, 1.1 (1.0-1.2); P = 0.005), and age (OR per 10 yr, 0.5 (0.3-0.8); P = 0.003) were associated with ΔV˙O2peak.In the multivariate linear regression, 34% of the variability in ΔV˙O2peak was explained by the increase in exercise training workload, ΔHRpeak between baseline and 12-wk posttesting, age, and ever having smoked. CONCLUSION: Exercise training response (ΔV˙O2peak) correlated negatively with age, LVEF, and NYHA class. The ability to increase workload during the training period and increased ΔHRpeak between baseline and the 12-wk test were associated with a positive outcome.

Standards for the use of cardiopulmonary exercise testing for the functional evaluation of cardiac patients: a report from the Exercise Physiology Section of the European Association for Cardiovascular Prevention and Rehabilitation.

Cardiopulmonary exercise testing (CPET) is a methodology that has profoundly affected the approach to patients' functional evaluation, linking performance and physiological parameters to the underlying metabolic substratum and providing highly reproducible exercise capacity descriptors. This study provides professionals with an up-to-date review of the rationale sustaining the use of CPET for functional evaluation of cardiac patients in both the clinical and research settings, describing parameters obtainable either from ramp incremental or step constant-power CPET and illustrating the wealth of information obtainable through an experienced use of this powerful tool. The choice of parameters to be measured will depend on the specific goals of functional evaluation in the individual patient, namely, exercise tolerance assessment, training prescription, treatment efficacy evaluation, and/or investigation of exercise-induced adaptations of the oxygen transport/utilization system. The full potentialities of CPET in the clinical and research setting still remain largely underused and strong efforts are recommended to promote a more widespread use of CPET in the functional evaluation of cardiac patients.

Permanent atrial fibrillation affects exercise capacity in chronic heart failure patients.

AIMS: The influence of permanent atrial fibrillation on exercise tolerance and cardio-respiratory function during exercise in heart failure (HF) is unknown. METHODS AND RESULTS: We retrospectively compared the results of 942 cardiopulmonary exercise tests, performed consecutively at seven Italian laboratories, in HF patients with atrial fibrillation (n = 180) and sinus rhythm (n = 762). By multivariable logistic regression analysis, peak VO(2) (OR 0.376, 95% CI 0.240-0.588, P < 0.0001), O(2)pulse (VO(2)/heart rate, HR) (OR 0.236, 95% CI 0.152-0.366, P < 0.0001), VCO(2) (OR 3.97, 95% CI 2.163-7.287, P < 0.0001), and ventilation (OR 1.38, 95% CI 1.045-1.821, P = 0.0231) were independently associated with atrial fibrillation. Anaerobic threshold (AT) was identified in 132 of 180 (73%) atrial fibrillation and in 649 of 762 (85%) sinus rhythm patients (P = 0.0002). By multivariable logistic regression analysis, only peak VO(2) (OR 0.214, 95% CI 0.155-0.296, P < 0.0001) was independently associated with unidentified AT. At AT, atrial fibrillation HF patients had higher HR (P < 0.0001) and higher VO(2) (P < 0.001) compared with sinus rhythm HF patients. Among AT variables, by multivariable logistic regression analysis, only HR was an independent predictor of atrial fibrillation. CONCLUSION: In HF patients with permanent atrial fibrillation, exercise performance is reduced as reflected by reduced peak VO(2). The finding of unidentified AT is associated with a poor performance. In atrial fibrillation patients, VO(2) is higher at AT whereas lower at peak. This last observation raises uncertainties about the use of AT data to define performance and prognosis of HF patients with atrial fibrillation.

Anaerobic and aerobic relative contribution to total energy release during supramaximal effort in patients with left ventricular dysfunction.

Energetic metabolism during effort is impaired in patients with left ventricular dysfunction (Dysf), but data have been lacking up to now on the relative anaerobic vs. aerobic contribution to total energy release during supramaximal effort. Recently, the maximal accumulated oxygen deficit (MAOD) has been shown to be measurable in Dysf patients, making it possible to evaluate the anaerobic/aerobic interaction under conditions of maximal stress of both anaerobic and aerobic metabolic pathways in this population. Nineteen Dysf patients and 17 normal patients (N) underwent one ramp cardiopulmonary, three moderate-intensity constant-power, and three supramaximal constant-power (1- to 2-min, 2- to 3-min, and 3- to 4-min duration) exercise tests. MAOD was the difference between accumulated O(2) demand (accO(2)dem; estimated from the moderate-intensity O(2) uptake/watt relationship) and uptake during supramaximal tests. Percent anaerobic (%Anaer) and aerobic (%Aer) energetic release were [(MAOD/accO(2)dem).100] and 100 - %Anaer, respectively. MAOD did not vary between 1-2, 2-3, and 3-4 min supramaximal tests, whereas accO(2)dem increased significantly with and was linearly related to test duration in both Dysf and N. Consequently, %Anaer and %Aer decreased and increased, respectively, with increasing test duration but did not differ between Dysf and N in 1-2 min, 2-3 min, and 3-4 min tests. Our study demonstrates a similar relative anaerobic vs. aerobic contribution to total energy release during supramaximal effort in Dysf and N. This finding indicates that energetic metabolism during supramaximal exercise is exercise tolerance independent and that relative anaerobic vs. aerobic contribution in this effort domain remains the same within the physiology- or pathology-induced limits to individual peak exercise performance.