Peak Oxygen Uptake In Patients Research Articles

Determination of Peak Oxygen Uptake in Patients with Acute Myocardial Infarction: The Role of Arterial Stiffness in Cardio-Vascular-Skeletal Muscle Coupling.

The relationship between arterial stiffness and oxygen uptake (VO2) in patients with acute myocardial infarction (AMI) remains unclear. We aimed to investigate this relationship and factors contributing to VO2 in patients with AMI. The role of arterial stiffness in cardio-skeletal muscle coupling during exercise was then elucidated. Upon discharge, we measured exercise capacity using cardiopulmonary exercise testing (CPX), assessed arterial stiffness with the cardio-ankle vascular index (CAVI), and determined body composition to assess the skeletal muscle mass of 101 patients with AMI. Patients were categorized based on their CAVI scores into three groups: (i) normal (CAVI: ≤7.9), (ii) borderline (CAVI: 8.0-8.9), and (iii) abnormal (CAVI: ≥9.0). Subsequently, VO2 was compared among these groups. The relationship between the CAVI and VO2 Peak during CPX and factors contributing to VO2 Peak were investigated. The abnormal CAVI group had a significantly lower VO2 Peak than the normal and borderline groups. The CAVI was associated with VO2 Peak. Furthermore, the CAVI was found to be a factor contributing to VO2 Peak. These findings suggest that arterial stiffness in tissue blood distribution and blood supply causes systemic exercise limits in patients with AMI. This suggests that arterial stiffness plays a significant role in cardio-vascular-skeletal muscle coupling.

Depressive symptoms, right ventricular function, and muscular strength are associated with peak oxygen uptake in patients with implantable left ventricular assist devices.

Left ventricular assist device (LVAD) implantation is among the most effective treatment options for patients with severe heart failure. Although previous studies have examined the factors related to peak oxygen uptake (peak VO2 ), they were limited by the few patients involved and their focus on medical and physical functions. Therefore, this study comprehensively examined the factors associated with peak VO2 , which is an important prognostic factor in patients with implantable LVADs. Eighty-nine patients who underwent initial LVAD implantation and were eligible for cardiopulmonary exercise testing (CPX) between May 2014 and September 2021 were included. The patients' mean age was 48 ± 12 years, and 70% were males. Based on previous studies, the cut-off was set at 12 and 14 mL/kg/min for patients taking β-blocker and those not taking β-blockers, respectively. Furthermore, factors associated with peak VO2 were examined using multivariate logistic regression analysis. The mean time from surgery to CPX administration was 73 ± 40 days. The high group had a higher cardiac index, right ventricular stroke work index (RVSWI), and isometric knee extensor muscular strength and lower Patient Health Questionnaire-9 (PHQ-9) and B-type natriuretic peptide values than the low group. Multivariate logistic regression analysis showed that RVSWI and KEMS were positively correlated, whereas PHQ-9 was negatively associated with peak VO2 . Right ventricular function, depressive symptoms, and lower limb muscular strength were associated with exercise capacity in patients with implantable LVADs.

Cardiac output and arteriovenous oxygen difference contribute to lower peak oxygen uptake in patients with fibromyalgia

BackgroundPatients with fibromyalgia (FM) exhibit low peak oxygen uptake (dot{text{V}}O2peak). We aimed to detect the contribution of cardiac output to (dot{text{Q}}) and arteriovenous oxygen difference [text{C}(text{a-v})text{O}_{2}] to dot{text{V}}text{O}_{2} from rest to peak exercise in patients with FM.MethodsThirty-five women with FM, aged 23 to 65 years, and 23 healthy controls performed a step incremental cycle ergometer test until volitional fatigue. Alveolar gas exchange and pulmonary ventilation were measured breath-by-breath and adjusted for fat-free body mass (FFM) where appropriate. dot{text{Q}} (impedance cardiography) was monitored. text{C}(text{a-v})text{O}_{2} was calculated using Fick’s equation. Linear regression slopes for oxygen cost (∆dot{text{V}}O2/∆work rate) and dot{text{Q}} to text{V}O2 (∆dot{text{Q}}/∆dot{text{V}}O2) were calculated. Normally distributed data were reported as mean ± SD and non-normal data as median [interquartile range].Resultsdot{text{V}}O2peak was lower in FM patients than in controls (22.2 ± 5.1 vs. 31.1 ± 7.9 mL∙min−1∙kg−1, P < 0.001; 35.7 ± 7.1 vs. 44.0 ± 8.6 mL∙min−1∙kg FFM−1, P < 0.001). dot{text{Q}} and C(a-v)O2 were similar between groups at submaximal work rates, but peak dot{text{Q}} (14.17 [13.34–16.03] vs. 16.06 [15.24–16.99] L∙min−1, P = 0.005) and C(a-v)O2 (11.6 ± 2.7 vs. 13.3 ± 3.1 mL O2∙100 mL blood−1, P = 0.031) were lower in the FM group. No significant group differences emerged in ∆dot{text{V}}O2/∆work rate (11.1 vs. 10.8 mL∙min−1∙W−1, P = 0.248) or ∆dot{text{Q}}/∆dot{text{V}}O2 (6.58 vs. 5.75, P = 0.122) slopes. ConclusionsBoth dot{text{Q}} and C(a-v)O2 contribute to lower dot{text{V}}O2peak in FM. The exercise responses were normal and not suggestive of a muscle metabolism pathology.Trial registrationClinicalTrials.gov, NCT03300635. Registered 3 October 2017—Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT03300635.

Six-minute walk test may be a reliable predictor of peak oxygen uptake in patients undergoing hemodialysis

BackgroundCardiorespiratory fitness seems to play an important role in the general health of patients undergoing hemodialysis (HD). However, the prediction of peak oxygen uptake (V̇O2peak) in a clinical setting is not widely adopted for these patients.ObjectivesEvaluate the agreement and reliability between directly and indirectly V̇O2peak measurements in patients undergoing HD.MethodsThis is a cross-sectional study with patients undergoing HD that performed a cardiopulmonary exercise test (CPET) with 5/10 watts incremental load in each minute using a cycle ergometry to directly evaluate the V̇O2peak, and the 6-min walk test (6MWT) in a 30-m corridor to indirect measures it. Both tests were performed on a midweek non-dialysis day. Bland–Altman analysis of agreement limits was used with direct and indirect V̇O2peak values. Intraclass correlation coefficient (ICC) and Cronbach’s Alpha was used to evaluate the reproducibility and reliability between direct and indirect V̇O2peak values.ResultsTwenty-six patients (54.4 ± 14.5 years, 53.8% of male) were evaluated. The V̇O2peak direct mean obtained through CPET was 15.91 ± 5.26 (ml/kg/min), while the indirect mean obtained through 6MWT was V̇O2peak of 14.89 ± 4.21 (ml/kg/min). There was a strong positive correlation between both V̇O2peak values (r = 0.734; p < 0.001). The Bland–Altman analysis demonstrated that the methods agreed with each other (p = 0.103). Also, the ICC (0.829) and Cronbach's Alpha (0.846) showed excellent reproducibility and reliability.Conclusions6MWT is a reliable tool for estimating V̇O2peak in patients undergoing HD.

Cardiopulmonary exercise responses in patients with non-ischemic heart failure and a mildly reduced ejection fraction.

Background: The cardiopulmonary response to exercise in patients with heart failure exhibiting a mildly reduced ejection fraction (41% ≤ EF ≤ 49%) remains unclear. Materials & methods: A total of 193 consecutive patients with heart failure (excluding those with coronary artery disease) who underwent cardiopulmonary exercise (CPX) tests were examined. CPX variables were compared among patients with reduced, mildly reduced, and preserved EF. Results: The CPX test responses of patients with mildly reduced EF were similar to those of patients with reduced or preserved EF; however, increases in systolic blood pressure during exercise differed significantly (32±26, 50±24, and 41±31mmHg, respectively; p =0.016). Grip strength and an increase in systolic blood pressure during exercise were independently associated with peak oxygen uptake in patients with mildly reduced EF (β=0.41, 0.35, respectively; p < 0.05). Conclusion: Measurements of grip strength and blood pressure during exercise are useful predictors of prognoses in patients with non-ischemic and mildly reduced EF.

The Association of Field Test Outcomes with Peak Oxygen Uptake in Patients with Cystic Fibrosis: A Systematic Review

The Association of Field Test Outcomes with Peak Oxygen Uptake in Patients with Cystic Fibrosis: A Systematic Review

Prognostic Value of Peak Oxygen Uptake in Patients Supported With Left Ventricular Assist Devices (PRO-VAD)

ObjectivesThe purpose of this study was to examine whether peak oxygen uptake (pVO2) and other cardiopulmonary exercise test (CPET)-derived variables could predict intermediate-term mortality in stable continuous flow LVAD recipients. BackgroundpVO2 is a cornerstone in the selection of patients for heart transplantation, but the prognostic power of pVO2 obtained in patients treated with a left ventricular assist device (LVAD) is unknown. MethodsWe collected data for pVO2 and outcomes in adult LVAD recipients in a retrospective, multicenter study and evaluated cutoff values for pVO2 including: 1) values above or below medians; 2) grouping patients in tertiles; and 3) pVO2 ≤14 ml/kg/min if the patient was not treated with beta-blockers (BB) or pVO2 ≤12 ml/kg/min if the patient was taking BB therapy. ResultsNine centers contributed data from 450 patients. Patients were 53 ± 13 years of age; 78% were male; body mass index was 25 ± 5 kg/m2 with few comorbidities (stroke: 11%; diabetes: 18%; and peripheral artery disease: 4%). The cause of heart failure (HF) was most often nonischemic (66%). Devices included were the HeartMate II and 3 (Abbott); and Heartware ventricular assist devices Jarvik and Duraheart (Medtronic). The index CPET was performed at a median of 189 days (154-225 days) after LVAD implantation, and mean pVO2 was 14.1 ± 5 ml/kg/min (47% ± 14% of predicted value). Lower pVO2 values were strongly associated with poorer survival regardless of whether patients were analyzed for absolute pVO2 in ml/kg/min, pVO2 ≤12 BB/14 ml/kg/min, or as a percentage of predicted pVO2 values (P ≤ 0.001 for all). For patients with pVO2 >12 BB/14 and ventilation/carbon dioxide relationship (VE/VCO2) slope <35, the 1-year survival was 100%. ConclusionsEven after LVAD implantation, pVO2 has prognostic value, similar to HF patients not supported by mechanical circulatory support devices. (PROgnostic Value of Exercise Capacity Measured as Peak Oxygen Uptake [pVO2] in Recipients of Left Ventricular Assist Devices [PRO-VAD]; NCT04423562)

Impact of worsening renal function on peak oxygen uptake in patients with acute myocardial infarction.

Worsening renal function (WRF) induced by acute myocardial infarction (AMI) is a strong predictor of cardiovascular events and mortality. Peak oxygen uptake may contribute to prognosis in AMI patients with WRF, however, the impact of WRF on peak oxygen uptake is unclear. Among 154 patients with AMI who underwent emergency percutaneous coronary intervention and participated in phase II cardiac rehabilitation, those who underwent cardiopulmonary exercise testing were consecutively enrolled. WRF was defined as a ≥20% decrease in estimated glomerular filtration rate (eGFR [ml/min/1.73 m2 ]) from admission to that at cardiopulmonary exercise testing. The association of WRF with peak oxygen uptake was evaluated by multivariate regression analysis. The non-WRF group was divided into two subgroups according to eGFR <60/≥60 at cardiopulmonary exercise testing, and eGFR at cardiopulmonary exercise testing and peak oxygen uptake of all three groups were compared. Ninety-four patients were enrolled in the final analysis. Multiple linear regression analysis showed that WRF was associated with peak oxygen uptake (p = .003). Comparing the non-WRF group with eGFR at cardiopulmonary exercise testing <60 and the WRF group, although eGFR at cardiopulmonary exercise testing was similar (p = 1.000), peak oxygen uptake in the WRF group was significantly lower (p = .026). WRF, not eGFR at cardiopulmonary exercise testing was significantly associated with peak oxygen uptake in patients with AMI. This result suggests that when considering the relationship between renal function and peak oxygen uptake, WRF must be taken into account.

Effects of Exercise Training on Cardiac and Skeletal Muscle Functions in Patients with Chronic Heart Failure.

The primary symptom in patients with chronic heart failure (CHF) is exercise intolerance. Previous studies have reported that reduced exercise tolerance in CHF can be explained not only by cardiac output (a central factor) but also by reduced skeletal muscle aerobic capacity (a peripheral factor). Although exercise training in CHF improves exercise tolerance, few studies have evaluated the effects of exercise training on each specific central and peripheral factor in CHF. The aim of this study was to investigate the central and peripheral aerobic functions in CHF and the effects of exercise training in CHF on cardiac output and skeletal muscle deoxygenation during exercise. We assessed peak oxygen uptake (VO2) during cardiopulmonary exercise testing, peak cardiac output (CO) using noninvasive hemodynamic monitoring, and muscle oxygen saturation (SmO2) using near-infrared spectroscopy (NIRS). Patients with CHF were trained for 12weeks and performed ramp cycling exercise until exhaustion before and after the exercise training. Peak VO2, peak CO, and SmO2 changes from rest to peak exercise (ΔSmO2) were significantly lower in CHF than those in healthy subjects. As a result of exercise training, peak oxygen uptake in patients with CHF was improved and positively associated with change in ΔSmO2. In contrast, there was no change in peak cardiac output. The results of this study indicate that both cardiac and skeletal muscle functions in patients with CHF were lower than those in healthy subjects. Further, the results suggest that the improvement of exercise capacity in patients with CHF by exercise training was related to the improved utilization of oxygen (a peripheral factor) in skeletal muscle.

The association between normal lung function and peak oxygen uptake in patients with exercise intolerance and coronary artery disease.

In coronary artery disease (CAD), exercise intolerance with reduced oxygen uptake at peak exercise (VO2peak) is assumed to primarily reflect cardiovascular limitation. However, oxygen transport and utilization depends on an integrated organ response, to which the normal pulmonary system may influence overall capacity. This study aimed to investigate the associations between normal values of lung function measures and VO2peak in patients with exercise intolerance and CAD. We hypothesized that forced expiratory lung volume in one second (FEV1), transfer factor of the lung for carbon monoxide (TLCO) and TLCO/alveolar volume (TLCO/VA) above lower limits of normal (LLN) are associated with VO2peak in these patients. We assessed patients with established CAD (n = 93; 21 women) referred for evaluation due to exercise intolerance from primary care to a private specialist clinic in Norway. Lung function tests and cardiopulmonary exercise testing (CPET) were performed. Z-scores of FEV1, FEV1/forced vital capacity (FVC), TLCO and TLCO/VA were calculated using the Global Lung Function Initiative (GLI) software and LLN was defined as the fifth percentile (z = -1.645). Non-obstructive patients, defined by both FEV1 and FEV1/FVC above LLN, were assessed. The associations of FEV1Z-score, TLCOZ-score and TLCO/VAZ-score above LLN with VO2peak were investigated using linear regression models. Mean VO2peak ± standard deviation (SD) was 23.8 ± 6.4 ml/kg/min in men and 19.7 ± 4.4 ml/kg/min in women. On average, one SD increase in FEV1, TLCO and TLCO/VA were associated with 1.4 (95% CI 0.2, 2.6), 2.6 (95% CI 1.2, 4.0) and 1.3 (95% CI 0.2, 2.5) ml/kg/min higher VO2peak, respectively. In non-obstructive patients with exercise intolerance and CAD, FEV1, TLCO and TLCO/VA above LLN are positively associated with VO2peak. This may imply a clinically significant influence of normal lung function on exercise capacity in these patients.

Knee extensor muscle strength as a predictor of peak oxygen uptake in patients with heart disease.

[Purpose] The mortality rate increases when peak oxygen uptake is less than 5 metabolic equivalents, and peak oxygen uptake correlates with knee extensor muscle strength. This study aimed to determine the knee extensor muscle strength at peak oxygen uptake corresponding to 5 metabolic equivalents. [Participants and Methods] We enrolled 45 consecutive patients (29 males and 16 females; average age, 63.6 ± 13.7 years) with heart disease receiving outpatient rehabilitation with us. We performed cardiopulmonary exercise testing with a bicycle ergometer to measure peak oxygen uptake. We investigated the relationship between peak oxygen uptake and isometric knee extensor muscle strength divided by the body weight (kgf/kg). The cutoff value for knee extensor muscle strength with peak oxygen uptake corresponding to 5 metabolic equivalents was calculated. [Results] Knee extensor muscle strength was significantly positively associated with peak oxygen uptake. The cutoff value for knee extensor muscle strength at peak oxygen uptake corresponding to 5 metabolic equivalents was 0.46 kgf/kg. [Conclusion] In this study, the cutoff value for knee extensor muscle strength for achieving peak oxygen uptake corresponding to 5 metabolic equivalents in patients with heart disease was 0.46kgf/kg.

Determinants of Peak Oxygen Uptake in Patients with Chronic Obstructive Pulmonary Disease: Looking Beyond the Lungs

Peak oxygen uptake (V̇O2peak), a primary determinant of prognosis, mortality, and quality of life, is diminished in patients with chronic obstructive pulmonary disease (COPD). Of importance, even after lung function is restored, by lung transplant, V̇O2peak remains markedly attenuated, emphasizing the critical importance of peripheral dysfunction in this pathology. However, the peripheral determinants of V̇O2peak in patients with COPD remain poorly understood. Therefore, the purpose of this investigation was to assess the peripheral determinants of V̇O2peak in patients with COPD, to better understand disease‐related peripheral adaptations. Oxygen transport and utilization at peak single‐leg knee‐extensor exercise were assessed from arterial and femoral venous oxygenation measurements and leg blood flow (by thermodilution) in 8 patients with COPD (FEV1 = 0.9 ± SE 0.1 L, 30% of predicted) and 8 well‐matched control subjects. This exercise modality was utilized to minimize cardiopulmonary exercise limitations. Muscle convective O2 delivery (0.44 ± 0.06 vs. 0.69 ± 0.07 l/min, p&lt;0.05) and muscle diffusive O2 conductance (6.6 ± 0.8 vs. 10.4 ± 0.9 ml/min/mmHg, p&lt;0.05) were both ~1/3 lower in COPD patients than control subjects, resulting in a significantly attenuated leg V̇O2peak in the patients (0.27 ± 0.04 vs. 0.42 ± 0.05 l/min, p&lt;0.05). Thus, in an exercise paradigm that minimizes cardiopulmonary limitations, the convective and diffusive components of oxygen transport within skeletal muscle, key determinants of V̇O2peak, are markedly diminished in patients with COPD. These findings emphasize the importance of peripheral factors, beyond the lungs, that limit exercise capacity, exacerbate inactivity, and increase the risk for cardiovascular disease in patients with COPD.Support or Funding InformationSupported by National Heart, Lung, and Blood Institute Grant HL‐091830This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Left ventricular end-diastolic dimension and septal e\u2032 are predictors of cardiac index at rest, while tricuspid annular plane systolic excursion is a predictor of peak oxygen uptake in patients with pulmonary hypertension

Little is known regarding a correlation of hemodynamics at rest or exercise capacity with echocardiographic parameters in patients with pulmonary hypertension (PH). To clarify these potential correlations, we performed transthoracic echocardiography, right heart catheterization, and cardiopulmonary exercise testing in 53 patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Left ventricular end-diastolic dimension (LVDd), early diastolic velocity of the septal mitral annulus (septal e′), tricuspid regurgitation peak gradient (TRPG), and tricuspid annular plane systolic excursion (TAPSE) were significantly correlated with cardiac index (LVDd; r = 0.477, P < 0.001, septal e′; r = 0.463, P = 0.001, TRPG; r = − 0.455, P = 0.001 and TAPSE; r = 0.406, P = 0.003, respectively). Multiple regression analysis revealed that LVDd and septal e′ were significantly associated with cardiac index (CI) and stroke volume index at rest. Among the exercise capacity markers evaluated, TAPSE, TRPG, and LVDd were significantly correlated with peak oxygen uptake (TAPSE; r = 0.534, P < 0.001, TRPG; r = − 0.466, P = 0.001 and LVDd; r = 0.411, P = 0.002, respectively). Multiple regression analysis showed that TAPSE was significantly associated with peak oxygen uptake (VO2). In PAH and CTEPH patients, LVDd and septal e′ were significantly associated with CI at rest, whereas TAPSE was significantly associated with peak VO2. Echocardiographic parameters may predict the prognostic factors of PAH and CTEPH patients.

Prediction of peak oxygen uptake in patients with Chagas heart disease: Value of the Six-minute Walk Test

Prediction of peak oxygen uptake in patients with Chagas heart disease: Value of the Six-minute Walk Test

Peak oxygen uptake after cardiac rehabilitation: a randomized controlled trial of a 12-month maintenance program versus usual care.

BackgroundExercise capacity is a strong predictor of survival in patients with coronary artery disease (CAD). Exercise capacity improves after cardiac rehabilitation exercise training, but previous studies have demonstrated a decline in peak oxygen uptake after ending a formal rehabilitation program. There is a lack of knowledge on how long-term exercise adherence can be achieved in CAD patients. We therefore assessed if a 12-month maintenance program following cardiac rehabilitation would lead to increased adherence to exercise and increased exercise capacity compared to usual care.Materials and MethodsTwo-centre, open, parallel randomized controlled trial with 12 months follow-up comparing usual care to a maintenance program. The maintenance program consisted of one monthly supervised high intensity interval training session, a written exercise program and exercise diary, and a maximum exercise test every third month during follow-up. Forty-nine patients (15 women) on optimal medical treatment were included following discharge from cardiac rehabilitation. The primary endpoint was change in peak oxygen uptake at follow-up; secondary endpoints were physical activity level, quality of life and blood markers of cardiovascular risk.ResultsThere was no change in peak oxygen uptake from baseline to follow-up in either group (intervention group 27.9 (±4.7) to 28.8 (±5.6) mL·kg (-1) min (−1), control group 32.0 (±6.2) to 32.8 (±5.8) mL·kg (−1) min (−1), with no between-group difference, p = 0.22). Quality of life and blood biomarkers remained essentially unchanged, and both self-reported and measured physical activity levels were similar between groups after 12 months.ConclusionsA maintenance exercise program for 12 months did not improve adherence to exercise or peak oxygen uptake in CAD patients after discharge from cardiac rehabilitation compared to usual care. This suggests that infrequent supervised high intensity interval training sessions are inadequate to improve peak oxygen uptake in this patient group.Trial RegistrationClinicalTrials.gov NCT01246570

The Reliability of 6-Minute Walk Test to Predict Peak Oxygen Uptake in Patients with Pulmonary Hypertension

respectively, and reported as a standardized uptake value (SUV). This data was correlated with in vivo functional measurements with echocardiography and multi gated acquisition scans. Results: The Sugen-hypoxia (SuHx) model resulted in a progressive increase in RV FDG uptake over 8 weeks (SUV baseline: 1.80, PAH week 5: 3.81, PAH week 8: 3.69, p!0.05 between baseline and PAH week 8). RV FTHA uptake significantly increased from baseline to week 5 with the SuHx model (SUV baseline: 1.50, PAH week 5: 2.97, p!0.05). Macitentan significantly decreased RV/LV FDG uptake (SUV PAH week 8 untreated: 1.09 vs. PAH week 8 treated: 0.66, p!0.05). This was associated with improved RV ejection fraction (PAH week 8 untreated: 53.15% vs PAH week 8 treated: 73.22%, p!0.01) and with an improvement in pulmonary artery pressures measured by pulmonary artery acceleration time (PAH week 8 untreated: 17.32 ms vs. PAH week 8 treated: 24.38 ms, p! 0.001) Conclusion: PAH is associated with metabolic changes in the RV, characterized by increased fatty acid and glucose utilization with a proportionally greater increase in glucose uptake, likely representing increased glycolysis. Macitentan attenuated RV/LV FDG uptake and significantly improved RV function and hemodynamics. Clinical studies evaluating the link between metabolic and functional alterations in the RV and the effects of therapy are warranted

Effect of Right Ventricular Outflow Tract Obstruction on Right Ventricular Volumes and Exercise Capacity in Patients With Repaired Tetralogy of Fallot

Patients with tetralogy of Fallot and combined right ventricular outflow tract obstruction (RVOTO) and pulmonary regurgitation (PR) have a less dilated right ventricular (RV) and better RV function compared with patients without RVOTO. It is not known whether RVOTO is associated with improved exercise capacity. We compared cardiac magnetic resonance imaging, echocardiography, and exercise tests in 12 patients with RVOTO (Doppler peak RVOT gradient ≥30 mm Hg) and 30 patients without RVOTO. RV end-systolic and end-diastolic volumes were smaller in patients with RVOTO compared with patients without RVOTO (50 ± 16 vs 64 ± 18 ml/m(2) and 117 ± 24 vs 135 ± 28 ml/m(2), respectively) and patients with RVOTO had a higher RV mass (52 ± 14 vs 42 ± 11 ml/m(2)), p <0.05. RV ejection fraction was marginally significantly different between both groups (58 ± 8% vs 53 ± 7%), p = 0.051. Degree of PR, left ventricular volumes, and function did not differ significantly between both groups. Peak oxygen uptake in patients with RVOTO was significantly lower (25 ± 3 vs 32 ± 8 ml/kg/min) than in patients without RVOTO, as was the percentage of predicted peak oxygen uptake (63 ± 7% vs 79 ± 14%), p <0.001. Multivariate analysis showed that the peak RVOT gradient was the only independent predictor of exercise capacity. In conclusion, exercise capacity is lower in patients with RVOTO compared with those without RVOTO despite a less dilated RV and comparable degree of PR. Therefore, exercise capacity may be of importance and should additionally be taken in consideration to RV volumes and function in patients with tetralogy of Fallot and PR.

Determinants of peak oxygen uptake in patients with hypertrophic cardiomyopathy: a single-center study

Most patients with hypertrophic cardiomyopathy (HCM) usually complain of a reduced exercise capacity, and several factors have been advocated as possible causes of this clinical feature. The present single-center study was designed to investigate exercise capacity and its main clinical determinants in HCM patients. One hundred ninety seven patients of 223 evaluated underwent a complete clinical assessment, including Doppler echocardiography, cardiopulmonary exercise test (CPET) and, in most cases, cardiac magnetic resonance. The HCM population (male 75%; age 47±16years; NYHA class I or II 95%; left ventricular ejection fraction 61±3%; resting left ventricular outflow tract gradient ≥30mmHg 22%; late gadolinium enhancement presence 58%) showed slightly reduced mean peak oxygen uptake values (pVO2 75±15%, 23.2±6.7ml/kg/min) with a significant reduction of the achieved percentage of peak heart rate reserve (%pHRR 65±20%). Adopting a pVO2 <80% cut-off value, 59% of HCM patients showed a reduced exercise capacity. Age, male gender, left atrial size, chronotropic and systolic blood pressure response, ventilatory efficiency, late gadolinium enhancement presence and β-blocker therapy were independently associated with pVO2 (R (2)-adjusted index 0.738). A %pHRR cut-off value of 74% appeared to most accurately predict an impaired exercise capacity (area under curve 0.90). A great prevalence of reduced exercise capacity is present in NYHA class I-II HCM patients. Notwithstanding its multifactorial genesis, few parameters might be adopted in identifying this feature. In this context, %pHRR value might represent a reliable and easy-to-obtain tool for the clinical evaluation of HCM patients.

Effects of Modality Change and Transplant on Peak Oxygen Uptake in Patients With Kidney Failure

Exercise capacity as measured by peak oxygen uptake (Vo₂(peak)) is low in hemodialysis patients. The present study assesses determinants of VO₂(peak) in patients with chronic kidney failure who either changed kidney replacement modality to frequent hemodialysis therapy or received a kidney transplant. Cohort study with assessment at baseline and 6 months after modality change. Participants included nondiabetic individuals receiving conventional hemodialysis who: (1) remained on conventional hemodialysis therapy (n = 13), (2) changed to short daily hemodialysis therapy (n = 10), or (3) received a transplant (n = 5) and (4) individuals who underwent a pre-emptive transplant (n = 15). Additionally, 34 healthy controls were assessed at baseline only. Modality change. Exercise capacity, assessed using the physiologic components of the Fick equation (Vo₂ = cardiac output × a-vo₂(dif), where a-vo₂(dif) is arterial to venous oxygen difference) was determined using measurement of Vo₂(peak) and cardiac output during symptom-limited exercise testing. Analysis of covariance was used to compare differences in changes in Vo₂(peak), cardiac output, heart rate, stroke volume, and a-vo₂(dif) at peak exercise between participants who remained on hemodialysis therapy and those who underwent transplant. Transplant was the only modality change associated with a significant change in Vo₂(peak), occurring as a result of increased peak cardiac output and reflecting increased heart rate without a change in peak a-vo₂(dif) despite increased hemoglobin levels. There were no differences in participants who changed to daily hemodialysis therapy compared with those who remained on conventional hemodialysis therapy. Small nonrandomized study. Vo₂(peak) increases significantly after kidney transplant, but not with daily hemodialysis; this improvement reflects increased peak cardiac output through increased peak heart rate. Despite statistical significance, the increase in Vo₂(peak) was not clinically significant, suggesting the need for interventions such as exercise training to increase Vo₂(peak) in all patients regardless of treatment modality.

Reducing Psychosocial Stress: A Novel Mechanism of Improving Survival from Exercise Training

Background Exercise training reduces mortality in patients with coronary artery disease. Behavioral characteristics, including depression, hostility, and overall psychosocial stress, have been shown to be independent risk factors for recurrent myocardial infarction and death in these patients. Exercise training can reduce these high-risk behaviors, but it remains uncertain as to what extent the health benefits of exercise training can be attributed to improving these behaviors. Methods We evaluated the impact of exercise training during cardiac rehabilitation on mortality in 53 patients with coronary artery disease with high levels of psychosocial stress and in 469 patients with coronary artery disease with low levels of psychosocial stress and compared them with 27 control patients with high psychosocial stress who did not undergo formal cardiac rehabilitation and exercise training. Results Mortality was approximately 4-fold greater in patients with high psychosocial stress than in those with low psychosocial stress (22% vs 5%; P = .003). Exercise training decreased the prevalence of psychosocial stress from 10% to 4% ( P < .0001) and similarly improved peak oxygen uptake in patients with high and low psychosocial stress. Mortality in patients who improved exercise capacity by ≥ 10% (high exercise change) was 60% lower than in patients who had < 10% improvement in exercise capacity (low exercise change) ( P = .009). Mortality was lower in patients with high psychosocial stress with high exercise change compared with patients with high psychosocial stress with low exercise change (0% vs 19%; P = .009). In contrast, there was no significant improvement in mortality in patients with high versus low exercise change with low psychosocial stress (4% vs 8%; P = .14). Conclusion Psychosocial stress is an independent risk factor for mortality in patients with coronary artery disease, and exercise training can effectively reduce its prevalence. Exercise training reduces mortality in patients with coronary artery disease, and this effect seems to be mediated in part because of the salutary effects of exercise on psychosocial stress.