The effects of alpha and beta blockade on ventilatory responses to exercise in chronic heart failure

Impact of beta blockers on resting respiratory rate in older adults: A cross-sectional study

[Purpose] Beta blockers, commonly prescribed for older adults, affect heart rates and blood pressure and may reduce respiratory rates, which are used to evaluate patient status and predict outcomes. However, limited clinical evidence is available on the impact of beta blockers on respiratory rates. This study aimed to investigate the impact of beta blockers on respiratory rates in older adults. [Methods] This cross-sectional study included patients aged ≥60 years who underwent an annual checkup. Patients were excluded if they had a diagnosis of severe heart failure, chronic obstructive pulmonary disease, interstitial pneumonitis, severe anemia, or neurodegenerative disease. Doubly robust estimation with inverse probability weighting was applied to estimate the mean differences between beta blocker users and non-users. The dose-response relationship between the administered beta blockers and respiratory rates was examined using multivariable regression models. [Results] Of 637 participants, 108 had received beta blockers regularly. The adjusted mean differences (95% confidence interval, CI) in respiratory rates, pulse rates, systolic blood pressure, and diastolic blood pressure between beta blocker users and non-users were 0.35 (-0.68 to 1.37), -3.56 (-6.34 to -0.78), -5.53 (-8.53 to -2.52), and -4.70 (-8.27 to -1.14), respectively. The adjusted mean differences (95% CI) in respiratory rates per 1 mg of a carvedilol equivalent dose in all beta blocker users, liposoluble beta blocker users, and carvedilol users were -0.10 (-0.18 to -0.02), -0.35 (-0.59 to -0.11), and -0.29 (-0.54 to -0.06), respectively. [Conclusions] Beta blockers may dose-dependently reduce the respiratory rates of older adults. However, in clinical settings, the impact of beta-blocker use or non-use on the respiratory rate may not occur at a clinically important level. Clinicians should note the potentially suppressive impact of beta blockers on respiratory rates according to the situation.

Farnesoid X Receptor Activation in Brain Alters Brown Adipose Tissue Function via the Sympathetic System

The nuclear bile acid (BA) receptor farnesoid X receptor (FXR) is a major regulator of metabolic/energy homeostasis in peripheral organs. Indeed, enterohepatic-expressed FXR controls metabolic processes (BA, glucose and lipid metabolism, fat mass, body weight). The central nervous system (CNS) regulates energy homeostasis in close interaction with peripheral organs. While FXR has been reported to be expressed in the brain, its function has not been studied so far. We studied the role of FXR in brain control of energy homeostasis by treating wild-type and FXR-deficient mice by intracerebroventricular (ICV) injection with the reference FXR agonist GW4064. Here we show that pharmacological activation of brain FXR modifies energy homeostasis by affecting brown adipose tissue (BAT) function. Brain FXR activation decreases the rate-limiting enzyme in catecholamine synthesis, tyrosine hydroxylase (TH), and consequently the sympathetic tone. FXR activation acts by inhibiting hypothalamic PKA-CREB induction of TH expression. These findings identify a function of brain FXR in the control of energy homeostasis and shed new light on the complex control of energy homeostasis by BA through FXR.

Ventilatory response to exercise in cardiopulmonary disease: the role of chemosensitivity and dead space

The lungs and heart are irrevocably linked in their oxygen (O₂) and carbon dioxide (CO₂) transport functions. Functional impairment of the lungs often affects heart function and vice versa The steepness with which ventilation (V'_E) rises with respect to CO₂ production (V'_CO2 ) (i.e. the V'_E/V'_CO2 slope) is a measure of ventilatory efficiency and can be used to identify an abnormal ventilatory response to exercise. The V'_E/V'_CO2 slope is a prognostic marker in several chronic cardiopulmonary diseases independent of other exercise-related variables such as peak O₂ uptake (V'_O2 ). The V'_E/V'_CO2 slope is determined by two factors: 1) the arterial CO₂ partial pressure (P_aCO2 ) during exercise and 2) the fraction of the tidal volume (V_T) that goes to dead space (V_D) (i.e. the physiological dead space ratio (V_D/V_T)). An altered P_aCO2 set-point and chemosensitivity are present in many cardiopulmonary diseases, which influence V'_E/V'_CO2 by affecting P_aCO2 Increased ventilation-perfusion heterogeneity, causing inefficient gas exchange, also contributes to the abnormal V'_E/V'_CO2 observed in cardiopulmonary diseases by increasing V_D/V_T During cardiopulmonary exercise testing, the P_aCO2 during exercise is often not measured and V_D/V_T is only estimated by taking into account the end-tidal CO₂ partial pressure (P_ETCO2 ); however, P_aCO2 is not accurately estimated from P_ETCO2 in patients with cardiopulmonary disease. Measuring arterial gases (P_aO2 and P_aCO2 ) before and during exercise provides information on the real (and not "estimated") V_D/V_T coupled with a true measure of gas exchange efficiency such as the difference between alveolar and arterial O₂ partial pressure and the difference between arterial and end-tidal CO₂ partial pressure during exercise.

[Physical training with beta-blockers in chronic heart failure]

In patients with chronic heart failure, the efficacy of beta-blocker therapy on mortality and the multiple benefits observed with physical training justify the association of the both. The effects of betablockade on different systems solicited in the exercise, particularly on the cardiocirculatory response during exercise test, rise many questions about the impact of beta blocker treatment on the changes induced by physical training. The cardioselective and vasodilating properties of beta-blockers play a role. It seems that the improved performance assessed by peak oxygen uptake (peak VO2) resulting from physical training is not limited by the beta-blocker treatment in patients with chronic heart failure. Synergistic effects have been observed, but many issues remain unsolved.

Chronotropic incompentence and functional capacity in chronic heart failure: no role of β-blockers and β-blocker dose

AIM

To assess the effect of chronotropic incompetence on functional capacity in chronic heart failure (CHF) patients, as evaluated as NYHA and peak oxygen consumption (pVO(2) ), focusing on the presence and dose of β-blocker treatment.

METHODS

Nine hundred and sixty-seven consecutive CHF patients were evaluated, 328 of whom were discarded because they failed to meet the study criteria. Of the 639 analyzed, 90 were not treated with β-blockers whereas the other 549 were. The latter were further subdivided in high (n = 184) and low (n = 365) β-blockers daily dose group in accordance with an arbitrary cut-off of 25 mg for carvedilol and of 5 mg for bisoprolol. Failure to achieve 80% of the percentage of maximum age predicted peak heart rate (%Max PHR) or of HR reserve (%HRR) constituted chronotropic incompetence.

RESULTS

No differences were found in NYHA or pVO2 between patients with and without β-blockers and, similarly, between high and low β-blocker dose groups. Twenty and sixty-nine percent of not β-blocked patients showed chronotropic incompetence according to %Max PHR and %HRR, respectively, whereas this prevalence rose to 61% and 84% in those on β-blocker therapy. Patients taking β-blockers without chronotropic incompetence, as inferable from both %Max PHR and %HRR, showed higher NYHA and pVO2 regardless of drug dose, whereas, in not β-blocked patients, only %HRR revealed a difference in functional capacity. At multivariable analysis, HR increase during exercise (ΔHR) was the variable most strongly associated to pVO2 (β: 0.572; SE: 0.008; P < 0.0001) and NYHA class (β: -0.499; SE: 0.001; P < 0.0001).

CONCLUSIONS

ΔHR is a powerful predictor of CHF severity regardless of the presence of β-blocker therapy and of β-blocker daily dose.

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.

Muscle sympathetic nerve activity and ventilation during exercise in subjects with and without chronic heart failure

BACKGROUND

Changes within skeletal muscle, including augmentation of its capacity to elicit reflex increases in both efferent muscle sympathetic nerve activity (MSNA) and ventilation during work, contribute significantly to exercise intolerance in heart failure (HF). Previously, we demonstrated that peak oxygen uptake (pVO(2)) in HF relates inversely to MSNA at rest and during exercise.

OBJECTIVE

To test the hypothesis that there is an independent positive relationship between resting MSNA and the ratio of ventilation to carbon dioxide output during exercise (VE/VCO(2)) that is augmented in HF.

METHODS

MSNA at rest and VE/VCO(2)) during stationary cycling were measured in 30 patients (27 men) with HF (mean +/- SD ejection fraction 20+/-6%) and in 31 age-matched controls (29 men).

RESULTS

MSNA was higher in HF patients than in controls (51.5+/-14.3 bursts/min versus 33.0+/-11.1 bursts/min; P<0.0001). The VE/VCO(2) slope was also higher in HF patients than in controls (33.7+/-5.7 versus 26.0+/-3.5; P<0.0001), whereas pVO(2) was lower in HF patients than in controls (18.6+/-6.6 versus 31.4+/-8.4 mL/kg/min; P<0.0001). There were significant relationships between MSNA and VE/VCO(2) in both HF (r=0.50; P=0.005) and control subjects (r=0.36; P=0.046). The slope of this regression equation was steeper in HF (0.20 versus 0.11 x MSNA; P=0.001). An analysis of covariance for main effects, including age and pVO(2), identified a significant independent relationship between MSNA burst frequency and VE/VCO(2) (P=0.013) that differed between HF and controls (P<0.01).

CONCLUSIONS

The magnitude of resting sympathetic activity correlates positively with the VE/VCO(2) slope. Augmentation of this relationship in HF patients is consistent with the concept that enhanced mechanoreceptor reflex activity exaggerates their ventilatory response to exercise.

Why does chronic heart failure cause breathlessness and fatigue?

Traditional explanations for the symptoms of fatigue and breathlessness experienced by patients with chronic heart failure (CHF) focus on how reduced cardiac output on exercise leads to impaired skeletal muscle blood supply, thus causing fatigue, and on how the requirement for a raised left ventricular filling pressure to maintain cardiac output results in reduced pulmonary diffusion owing to interstitial edema, thus causing breathlessness. However, indices of left ventricular function relate poorly to exercise capacity and symptoms, suggesting that the origin of symptoms may lie elsewhere. There is a specific heart failure myopathy that is present early in the condition which may contribute largely to the sensation of fatigue. Receptors present in skeletal muscle sensitive to work (ergoreceptors) are overactive in patients with CHF, presumably as a consequence of the myopathy, and their activity is related both to the ventilatory response to exercise and breathlessness, and to the sympathetic overactivity of CHF. In the present paper, we review the systemic consequences of left ventricular dysfunction to understand how they relate to the symptoms of heart failure.

Theoretical rationale and practical recommendations for cardiopulmonary exercise testing in patients with chronic heart failure

The syndrome of chronic heart failure (CHF) becomes increasingly prevalent in older patients, and while mortality rates are declining in most cardiovascular diseases, both prevalence and mortality in CHF remain high. The heart is unable to meet the demands of the skeletal musculature, and symptoms manifest as dyspnoea and signs of fatigue during exercise. The cardiopulmonary exercise test (CPET) can provoke symptoms which may be useful in improving the accuracy of diagnosis in CHF in a non-invasive setting. CPET also provides important information on the pathophysiology of exercise limitation, risk stratification and can establish exercise-training protocols. The information provided by the CPET allows suitable pharmacological or device-based adjustments to be considered in the management of CHF, which can be crucial in maintaining a patient's quality of life. This manuscript provides a useful insight into the theoretical rationale and practical recommendations for CPET in patients with CHF. Prior to CPET, it is important to consider the mode of exercise, as cycle ergometry or treadmill protocols will yield different outcomes in patients with CHF. We discuss how pre-CPET set-up procedures should be conducted and also the significance of electrocardiographic abnormalities found in CHF patients, and how these should be interpreted. The assessment of lung function is integral to the underlying pathophysiological basis of exercise limitation and we explain how this should be performed. CHF patients display the following abnormal exercise responses which can be identified by CPET: peak oxygen uptake ( [Formula: see text] peak), anaerobic threshold (AT), DeltaVO(2)/Delta work rate (WR), peak oxygen pulse, estimated peak stroke volume and predicted peak heart rate are reduced. The [Formula: see text] slope is abnormally high and the breathing reserve is normal or high. An immediate post-exercise increase in O(2) pulse is evident, and/or a regular oscillatory breathing pattern has been observed at lower exercise intensities in some CHF patients. Symptoms of breathlessness, fatigue, and/or leg pain occur earlier during CPET and may cause the CPET to be aborted early. We explain the significance of the 9-panelled array, and how it can help to determine the underlying pathophysiology of exercise intolerance in these patients.

Carvedilol reduces exercise-induced hyperventilation: A benefit in normoxia and a problem with hypoxia

AIMS

To evaluate whether carvedilol influences exercise hyperventilation and the ventilatory response to hypoxia in heart failure (HF).

METHODS AND RESULTS

Fifteen HF patients participated to this double blind, randomised, placebo controlled, cross-over study. Patients were evaluated by quality of life questionnaire, echocardiography, pulmonary function and cardiopulmonary exercise tests (ramp and constant workload) both in normoxia (FiO2 = 21%) and hypoxia (FiO2 = 16%, equivalent to a simulated altitude of 2000 m). Carvedilol improved clinical condition and reduced left ventricle size, but had no effect on lung mechanics. In normoxia during exercise, ventilation was lower, V(CO2) unchanged and PaCO2 (constant workload) or PetCO2 (ramp) higher with carvedilol, exercise capacity was unchanged (peak workload 92+/-22 and 90+/-22W for placebo and carvedilol, respectively). Abnormal V(E)/V(CO2) slope was reduced by carvedilol. Hypoxia increased ventilation but less with carvedilol; exercise capacity decreased to 87+/-21W (placebo) and to 80+/-11 W (carvedilol, p < 0.01). With hypoxia, carvedilol decreased V(E)/V(CO2) slope. At constant workload exercise with hypoxia, PaO2 decreased to 69+/-6 mm Hg (placebo) and to 64+/-5 (carvedilol, p < 0.01).

CONCLUSION

Carvedilol reduced hyperventilation possibly by reducing peripheral chemoreflex sensitivity as suggested by PaCO2 increase with normoxia and PaO2 decrease with hypoxia without V(CO2) and V(D)/V(T) changes. Lessening hyperventilation is beneficial when breathing normally, but detrimental when hyperventilation is needed for exercise at high altitude.

Changes in exercise capacity, ventilation, and body weight following heart transplantation

AIMS

Peak oxygen uptake adjusted to body weight (peak VO(2)) and ventilatory efficiency (VE/VCO(2)-slope) are important prognostic parameters in chronic heart failure. Our study prospectively examined changes in these parameters over 24 months following heart transplantation (HTx) and evaluated the potentially confounding effects of weight gain.

METHODS AND RESULTS

One hundred patients with chronic heart failure (16 female, mean age at HTx 53.9+/-9.6 years) underwent cardiopulmonary exercise testing before and 3, 6, 12 and/or 24 months after HTx. Twenty-five healthy individuals served as matched normals. VE/VCO(2)-slope during exercise improved significantly at 6 (-23.7%), 12 (-21.3%), and 24 months (-32.3%; all p<0.002 vs. baseline). At 6 months, VE/VCO(2)-slopes were similar to the matched normals (31.8+/-4.3), 46 of 78 patients achieved values within the 95% confidence interval of normal. Peak VO(2) increased significantly after HTx at 6 (+31.8%), 12 (+36.2%), and 24 months (+42.2%; all p<0.005). None of the patients reached values within the 95% CI of normal. Although VE/VCO(2)-slope and peak VO(2) were correlated inversely at every time point (p<0.03), reduction in VE/VCO(2)-slope did not correlate with increase in peak VO(2). Symptoms that limited exercise changed from dyspnoea before HTx to leg fatigue after HTx.

CONCLUSION

Following HTX, VE/VCO(2)-slope returns to normal values in the majority of patients; however, despite improvement, peak VO(2) remains abnormal in all patients. Symptoms causing patients to stop exercising change from dyspnoea to leg fatigue.

The effects of long-term beta-blockade on the ventilatory responses to exercise in chronic heart failure

AIMS

Chronic heart failure (CHF) patients complain of breathlessness and fatigue. Beta-blockers improve symptoms, echocardiograpahic variables and prognosis in CHF, but their effect on exercise capacity remains unclear. The aim of this study was to describe the effects of long-term beta-blocker therapy on metabolic gas exchange variables and ventilation during exercise in CHF patients.

METHODS

42 patients with symptomatic heart failure due to left ventricular systolic dysfunction (ejection fraction 33.2 (8.2)) on loop diuretics and angiotensin-converting enzyme inhibitors or angiotensin II antagonists, underwent exercise testing with metabolic gas exchange. They were then initiated onto and uptitrated to the maximum tolerated dose of beta-blockers. After 1 year of follow-up, patients were invited back for repeat testing.

RESULTS

35 patients attended for repeat exercise testing. Four patients had died, and three had not tolerated beta-blockade. After 1 year, exercise time was increased (487 (221) vs. 500 (217), p<0.05), and peak oxygen consumption and V(E)/V(CO(2)) slope were unchanged (20.9 (5.0) vs. 20.0 (5.4), p=0.15 and 36.7 (8.3) vs. 37.3 (7.8), p=0.70). Peak ventilation, (61.5 (12.9) vs. 57.1 (13.4), p<0.05), peak carbon dioxide production (1629 (404) vs. 1496 (375), p<0.02) and hence respiratory exchange ratio (1.02 (0.08) vs. 0.98 (0.06) p<0.02) and p<0.05) were reduced. Submaximal oxygen consumption and carbon dioxide production were lower at matched workloads. The slope relating symptoms to ventilation (Borg/V(E) slope) was less steep following beta-blockade (0.18 (0.09) vs. 0.15 (0.06), p<0.05).

CONCLUSION

Long term beta-blocker therapy increases exercise time but not peak oxygen consumption, and reduces peak carbon dioxide production. CHF patients are less symptomatic for a given ventilation during exercise following beta-blocker treatment.

Chronic heart failure, chronotropic incompetence, and the effects of beta blockade

OBJECTIVE

To establish the prevalence of chronotropic incompetence in a cohort of patients with chronic heart failure (CHF) taking modern medications for heart failure, and whether this affected exercise capacity and predicted prognosis.

METHODS

Heart rate response to exercise was examined in 237 patients with CHF in sinus rhythm, who were compared with 118 control volunteers. The percentage of maximum age predicted peak heart rate (%Max-PPHR) and percentage heart rate reserve (%HRR) were calculated, with a cut off of < 80% as the definition of chronotropic incompetence for both. Patients were followed up for an average (SD) of 2.8 (9) years. Mortality was related to peak oxygen consumption (pVo2), and the presence or absence of chronotropic incompetence.

RESULTS

%Max-PPHR < 80% identified 103 (43%) and %HRR < 80% identified 170 patients (72%) as having chronotropic incompetence. Chronotropic incompetence was more common in patients taking beta blockers than in those not taking beta blockers as assessed by both methods (80 (49%) v 23 (32%) by %Max-PPHR and 123 (75%) v 47 (64%) by %HRR, respectively). Patients with chronotropic incompetence by either method had a lower pVo2 than those without. These differences remained significant for both patients taking and not taking a beta blocker. %HRR, Max-PPHR%, and HRR were related to New York Heart Association class and correlated with pVo2. There was no difference in the slopes relating heart rate to pVo2 between patients with and those without chronotropic incompetence (6.1 (1.7) v 5.1 (1.8), p = 0.34). During an average 2.8 year follow up 40 patients (17%) died. In Cox proportional hazard models, pVo2 was the most powerful predictor of survival and neither measure of chronotropic incompetence independently predicted outcome.

CONCLUSIONS

pVo2 is a powerful marker of prognosis for patients with CHF whether they are taking beta blockers or not. A low heart rate response to exercise in patients with CHF correlates with worse exercise tolerance but is unlikely to contribute to exercise impairment.

β-Blockers and Inspiratory Pulmonary Function in Chronic Heart Failure

BACKGROUND

Chronic heart failure (CHF) patients complain of breathlessness and fatigue. Respiratory muscle function is impaired in CHF patients and may contribute to their symptoms. Beta-blockers cause fatigue but have become part of the standard management of CHF. We explored the relation between respiratory muscle power in CHF and the effects of long-term beta-blockade.

METHODS AND RESULTS

A total of 52 CHF patients and 25 control subjects underwent echocardiography, peak exercise testing with metabolic gas exchange analysis, and measurement of forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak inspiratory flow (PIF), and forced inspiratory volume in 1 second (FIV1). Of the patients, 35 started beta-blocker therapy and were tested again at 1 year. Patients had lower peak oxygen consumption (pV(O2) (19.3 [4.5] versus 37.3 [8.4] mL/kg/min, P < .0001), exercise time (414 [134] versus 817 [193] seconds, P < .0001), and anaerobic threshold (13.8 [3.8] versus 27.2 [8.2] mL/kg/min, P < .0001). Patients also had a steeper relationship between ventilation (V(E)) and carbon dioxide (CO2 ) (V(E)/V(CO2)) (40.0 [6.8] versus 26.4 [2.0], P < .0001); lower FEV1, FVC, and FIV1 (89 [15] versus 111 [24]% expected, P < .0001, 80 [20] versus 94 [21]% expected, P < .001 and 2.5 [1.6] versus 3.0 (0.9) L, P < .02); and there was a correlation between pV(O2) and FIV1 (r = 0.24, P < .05) for the patients. The slope relating symptoms of breathlessness (Borg score) to ventilation (Borg/V(E) slope) also correlated with FIV1 (r = 0.36, P < .02). Beta-blocker therapy improved echocardiographic variables, but not pV(O2). There was no change in PIF or FIV1. There was a significant reduction in FEV 1 after beta-blocker treatment (P < .01).

CONCLUSION

Inspiratory flows are impaired in patients with chronic heart failure and correlate with the degree of functional impairment. This may be due to a combination of respiratory muscle weakness and reduced lung compliance. The reduction in inspiratory capacity is not influenced by long-term beta-blockade.

The effect of aspirin on the ventilatory response to exercise in chronic heart failure

INTRODUCTION

Patients with chronic heart failure (CHF) experience breathlessness and fatigue on exercise. One of the abnormalities seen on maximal exercise testing is an increased ventilatory response to exercise (VE/VCO(2) slope). The cause of this is unknown, but is likely to be due to a combination of interacting peripheral and central factors. Recent data have demonstrated a relation between VE/VCO(2) slope and prostaglandin levels in contracting muscles. The present study examined the influence of the presence of a potent non-selective prostaglandin inhibitor, aspirin, on the ventilatory response to exercise in a group of patients with CHF.

METHODS

We investigated the ventilatory response to exercise of 120 consecutive patients in sinus rhythm attending a specialist heart failure clinic. We excluded those taking clopidogrel (six patients) and those on both warfarin and aspirin or taking other non-steroidal anti-inflammatory agents (five patients). The other 109 patients were grouped according to whether they were taking aspirin (n=52 (48%)) or not (n=57 (52%)). Each patient underwent echocardiography to assess left ventricular function, and exercise testing with metabolic gas exchange to derive peak oxygen consumption (pVO(2)) and the VE/VCO(2) slope.

RESULTS

The groups were similar in terms of age, (67 (13) vs. 66 (12) years; P=0.34) drug use, heart failure aetiology, left ventricular function (ejection fraction; 33.3 (9.4) vs. 31.8 (9.9)%; P=0.05)) and exercise tolerance (pVO(2); 20.4 (5.3) vs. 19.9 (6.0); P=0.68, and VE/VCO(2) slope; 35.4 (6.2) vs. 35.7 (9.3); P=0.73). There was no difference in the ventilatory response to exercise or the symptoms of breathlessness between the two groups.

CONCLUSIONS

Aspirin does not appear to affect exercise performance in CHF.