Cardiac resynchronization therapy in pacemaker-dependent patients with left ventricular dysfunction.

AIMS: Heart failure and left ventricular (LV) systolic dysfunction (LVSD) are common in patients with permanent pacemakers. The aim was to determine if cardiac resynchronization therapy (CRT) at the time of pulse generator replacement (PGR) is of benefit in patients with unavoidable RV pacing and LVSD. METHODS AND RESULTS: Fifty patients with unavoidable RV pacing, LVSD, and mild or no symptoms of heart failure, listed for PGR were randomized 1 : 1 to either standard RV-PGR (comparator) or CRT. The primary endpoint was the difference in change in LV ejection fraction (LVEF) between RV-PGR and CRT groups from baseline to 6 months. Secondary endpoints included peak oxygen consumption, quality of life, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels. At 6 months there was a difference in change in median (interquartile range) LVEF [9 (6-12) vs. -1.5 (-4.5 to -0.8)%; P < 0.0001] between the CRT and RV-PGR arms. There were also improvements in exercise capacity (P = 0.007), quality of life (P = 0.03), and NT-proBNP (P = 0.007) in those randomized to CRT. After 809 (729-880) days, 17 patients had died or been hospitalized (6 in CRT group and 11 in the comparator RV-PGR group) and two patients in the RV-PGR arm had required CRT for deteriorating heart failure. Patients with standard RV-PGR had more days in hospital during follow-up than those in the CRT group [4 (2-7) vs. 11 (6-16) days; P = 0.047]. CONCLUSION: Performing CRT in pacemaker patients with unavoidable RV pacing and LVSD but without severe symptoms of heart failure, at the time of PGR, improves cardiac function, exercise capacity, quality of life, and NT-pro-BNP levels.

Prognostic Significance of Incidental Nonsustained Ventricular Tachycardia Detected on Pacemaker Interrogation.

Symptomatic sustained ventricular tachycardia is a life threatening arrhythmia requiring prompt treatment. However, the risk associated with asymptomatic nonsustained ventricular tachycardia (NSVT) detected on routine permanent pacemaker (PPM) interrogation in patients with known cardiac conduction disease is unknown. Our aim is to determine if asymptomatic NSVT detected on PPM interrogation is associated with increased mortality. As part of a prospective observational cohort study, 582 patients with long-term pacemakers were recruited at a tertiary cardiac centre, and followed for 4 ± 1.96 years (mean ± standard deviation). At each subsequent pacemaker check, any symptoms and ventricular high-rate episodes were recorded. We excluded 17 patients due to incomplete data. In the remaining 565 patients (57% male, age 74.5 ± 19.2 years, left ventricular ejection fraction 50.0 ± 11.3%), NSVT was found in 125 (22.1%) patients with a higher prevalence in males (65% vs 54%; p = 0.033). Those with NSVT were more likely to have had coronary artery disease (p = 0) or previous myocardial infarction (p = 0.015). After correction for baseline variables, NSVT had no impact on survival (n = 52 [42%] vs n = 162 [37%]; log-rank p = 0.331, hazard ratio: 0.927, 95% confidence interval: 0.678 to 1.268, p = 0.697). In conclusion, asymptomatic NSVT identified on PPM interrogation does not appear to be associated with increased mortality, thus whether treatment to suppress this arrhythmia is of benefit remains unproven.

Dyspnoea versus fatigue: additional prognostic information from symptoms in chronic heart failure?

BACKGROUND: In non-heart failure populations, dyspnoea reported by the patient as the reason for stopping an exercise test is associated with a worse prognosis than fatigue. Patients with chronic heart failure (CHF) have exercise limitation due to breathlessness or fatigue, but it is unclear whether one symptom confers an adverse prognosis over the other. METHODS: Consecutive CHF patients underwent exercise testing with metabolic gas exchange. Upon stopping exercise the dominant symptom reported by the patients was recorded. Survival analyses were performed to establish predictors of mortality and relationships between symptoms and objective measures of exercise capacity. RESULTS: Data were analysed on 271 patients (219 men), mean age 67 (10) years, mean left ventricular ejection fraction 32 (8)%, and median follow-up 59 months (interquartile range 38). There were no differences in exercise variables, sex, NYHA class, body mass index and medical therapy between fatigued and dyspnoeic patients. At the censor date 92 (34%) patients had died. Deceased patients had a lower peak oxygen consumption (17.2 (4.6) versus 20.3 (5.6); p=0.0028). Although NYHA class was related to death at 36 months (chi2 value=7.3, p=0.026), reason for stopping was not (chi2 value=0.57, p=0.45). CONCLUSION: Unlike in non-heart failure populations, dyspnoea as the reason for stopping an exercise test in CHF subjects is not associated with increased mortality. CHF patients should be assessed for treatments such as cardiac resynchronisation therapy by the degree of exercise intolerance, not the nature of their symptoms.

Epidemiology, associated factors, and prognostic outcomes of renal artery stenosis in chronic heart failure assessed by magnetic resonance angiography.

Our aim was to determine the prevalence, morbidity, and mortality associated with the presence of significant renal artery stenosis (RAS) in patients with chronic heart failure (HF), and to explore the use of angiotensin-converting enzyme (ACE) inhibitors and diuretics in this population during a 3-year follow-up period. We identified 97 patients with significant renal dysfunction (RD, defined as a calculated glomerular filtration rate of <60 ml/min) and 38 patients without RD, with ejection fractions of <40%. A stenosis of >50% using magnetic resonance angiography of the renal arteries was used to define significant RAS. Seventy-three (54%) patients had significant RAS of >or=1 artery. Mean follow-up time was 37.3 (+/- 7.9) months. Compared with patients with no significant RAS, these patients were on higher doses of diuretics, lower doses of ACE inhibitors, had prolonged hospital admissions, were admitted with exacerbation of HF, and had a higher mortality (p = 0.007 for mortality). In conclusion, RAS is common in patients with chronic HF, especially among patients with RD and is a predictor of a poor clinical outcome. Interventional trials on renal revascularization are underway that contain subsets of patients with HF that may provide evidence on how best to manage RAS in this setting.

Effects of applying a standardised management algorithm for moderate to severe renal dysfunction in patients with chronic stable heart failure.

BACKGROUND: No specific guidelines exist on how to manage renal dysfunction (RD) in patients with chronic heart failure (CHF). AIMS: To identify the proportion of patients with moderate to severe RD and CHF who showed an improvement in their renal function in response to a systematic management algorithm. METHODS: Stable patients with CHF and RD (defined by a serum creatinine (SCr) of >130 micromol/l (>1.5 mg/dl)) were enrolled into a systematic management algorithm. The following changes were implemented: switching aspirin to clopidogrel, halving the dose of both diuretics and angiotensin converting enzyme (ACE) inhibitors and switching between bisoprolol and carvedilol. RESULTS: Two thirds of patients in whom diuretics were reduced, and one fifth of patients in whom ACE inhibitors were reduced, improved their SCr by >25.5 micromol/l (0.3 mg/dl). All these changes were more marked in the presence of bilateral renal artery stenosis. Compared to a reference group, in whom no changes were implemented, the treatment group showed an improvement in their mean SCr by 35 micromol/l (0.4 mg/dl), p<0.001. CONCLUSION: Manipulation of pharmacological therapy for patients with CHF and RD results in a substantial recovery of renal function in a minority of patients.

The effect of altering heart rate on ventricular function in patients with heart failure treated with beta-blockers.

BACKGROUND: Beta-blockers are effective for the treatment of heart failure, but their mechanism of action is unresolved. Heart rate reduction may be a central mechanism or a troublesome side effect. METHODS: A randomized, double-blind, parallel group study comparing chronic higher-rate (80 pulses per minute) with lower-rate (60 pulses per minute) pacing in pacemaker-dependent patients with symptomatic left ventricular (LV) systolic dysfunction, receiving beta-blockers. Gated radionuclide ventriculography (RNVG) was performed at baseline and after at least 9 months. The primary outcome was change in LV volumes, as a marker of beneficial reverse remodeling, from baseline to follow-up. RESULTS: Forty-nine patients were randomized. Mean age was 74 +/- 6 years and with LV ejection fraction of 26% +/- 9% at baseline. During 14 +/- 13 months of follow-up, 21 patients (43%) died and 25 (51%) completed the study protocol: 12 in the higher-rate and 13 in the lower-rate group. Mean LV end-diastolic (higher rate +20 +/- 104 mL vs lower rate -65 +/- 92 mL, P = .03) and systolic (higher rate +29 +/- 83 mL vs lower rate -60 +/- 74 mL, P = .006) volumes increased with higher-rate versus lower-rate pacing, whereas LV ejection fraction declined (higher rate -4.2% +/- 4.4% vs lower rate +2.2% +/- 5.4%, P = .002). CONCLUSION: Reversal of beta-blocker-induced bradycardia has deleterious effects on ventricular function, suggesting heart rate reduction is an important mediator of their effects. The prognosis of patients with pacemakers and heart failure is poor.

Anemia, renal dysfunction, and their interaction in patients with chronic heart failure.

Anemia and renal dysfunction (RD) are frequent complications seen in chronic heart failure (HF). However, the prevalence and interaction of these co-morbidities in a representative population of outpatients with chronic HF is poorly described. In this study, it was sought to determine the association between RD and anemia in patients with HF enrolled in a community-based HF program. Nine hundred fifty-five patients with HF due to left ventricular systolic dysfunction were investigated for the prevalence of anemia and its cause and followed for a median of 531 days. Anemia was defined as hemoglobin < 12.0 g/dl in women and < 13.0 g/dl in men. RD was defined as a calculated glomerular filtration rate of < 60 ml/min. The prevalence of anemia was 32%. Fifty-three percent of patients with and 27% of those without anemia had > or = 1 test suggesting hematinic deficiency. The prevalence of RD was 54%. Forty-one percent of patients with and 22% of patients without RD had anemia, with similar proportions associated with iron deficiency in the presence or absence of RD. Anemia and RD independently predicted a worse outcome, and this effect was additive. In conclusion, in outpatients with chronic HF, anemia and RD are common and co-exist but confer independent prognostic information. A deficiency of conventional hematinic factors may cause about 1/3 of anemia in this clinical setting.

Biventricular pacemaker upgrade in previously paced heart failure patients--improvements in ventricular dyssynchrony.

BACKGROUND: Cardiac resynchronization therapy (CRT) reduces symptoms and mortality in patients with left bundle branch block (LBBB) and severe chronic heart failure. There are few data demonstrating the effects of CRT on contemporary dyssynchrony variables in patients with advanced heart failure who have been chronically paced from the right ventricle (RV). METHODS AND RESULTS: We reviewed baseline and follow-up clinical and echocardiographic data on patients receiving CRT in a single centre. Indices of global left ventricular (LV) function and dyssynchrony before and after CRT were measured. Patients were then divided into those receiving their first device (n = 39) and those receiving CRT as an upgrade to existing RV pacemakers (n = 32). Baseline demographic variables, indices of global LV function, symptomatic status, renal function, hemodynamics, and diuretic requirements were not different between previously paced patients and nonpaced patients. Mean length of RV pacing in the previously paced patients was 59 months (range 12-167 months). Patients in the previously paced group had a broader QRS complex than patients with intrinsic LBBB. Aortopulmonary delay of longer than 40 ms was present in 68% of all subjects, 67% had intraventricular septal and posterior wall motion delay longer than 130 ms, and 59% had an intraventricular delay as measured by tissue Doppler imaging of longer than 65 ms. There was no difference between paced and nonpaced patients for any of these measures of dyssynchrony. QRS duration was reduced to a greater extent in the previously paced patients than those with no previous device therapy. CRT led to important reductions in each dyssynchrony variable in both patients with previous RV pacing and those with intrinsic LBBB. The magnitude of these changes in measures of dyssynchrony was not different between the 2 groups. In all patients undergoing CRT, 50% had a reduction in furosemide dose at 3 months, 56% an improvement of at least 1 grade in New York Heart Association status, and 66% an improvement of at least 5% in LVEF. Divided by group, previously paced patients were no more or less likely than newly implanted patients to achieve one or more of these clinical outcomes. CONCLUSION: Our data suggest that patients with RV pacing and heart failure have similar dyssynchrony as patients with intrinsic LBBB. CRT leads to improvements in LV global function, dyssynchrony variables and symptoms in patients chronically paced from the RV that are similar to those observed in patients with LBBB without preexisting devices.

Left ventricular morphology, global and longitudinal function in normal older individuals: a cardiac magnetic resonance study.

BACKGROUND: The heart transforms structurally and functionally with age but the nature and magnitude of reported changes appear inconsistent. This study was designed to assess left ventricular (LV) morphology, global and longitudinal function in healthy older men and women using cardiac magnetic resonance (CMR). METHODS: Ninety-five healthy subjects (age 62+/-16 years, range 22-91 years) underwent breath-hold cine CMR. LV end-diastolic volume (EDV), end-systolic volume (ESV), myocardial mass, ejection fraction (EF), mass-to-volume ratio, mean midventricular wall motion, thickness and thickening were calculated from short-axis data sets. Average mitral annular displacement was measured to assess longitudinal LV function. RESULTS: Subjects were divided according to age (< 65 and > or = 65 years) and sex. EDV and ESV indices (corrected for body surface area) decreased whilst EF increased with age. There was no difference in LV myocardial mass index between the age groups, but midventricular wall thickness was significantly higher in older people. Mass-to-volume ratio also increased with age. In contrast to EF, mitral annular displacement declined with age. Midventricular LV wall thickness, myocardial mass index and mass-to-volume ratio were higher in men than in women but there were no differences in measures of global and longitudinal LV systolic function. CONCLUSIONS: Due to smaller LV volumes but higher wall thickness, myocardial mass remains unchanged with age. We have found an age-related increase in EF and reduction in longitudinal LV function in apparently normal subjects. This must be borne in mind when assessing older patients with possible heart failure and normal LV systolic function. Men have higher myocardial mass than women.

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.

Metabolic gas kinetics depend upon the level of exercise performed.

BACKGROUND: The kinetics of oxygen and carbon dioxide at the onset of and recovery from exercise are slowed in patients with chronic heart failure (CHF). The aim of the present study was to establish whether the kinetics of O2 are influenced by the work rate. METHODS: Thirteen CHF patients and 12 control subjects underwent bicycle-based peak exercise testing with metabolic gas exchange analysis. Each subject then exercised at 15%, 25% and 50% of the maximal workload achieved until reaching steady state. Time constants for onset (T(onset)) and offset (T(offset)) for O2 uptake and CO2 output were correlated to the workload and the percentage of peak V(O2) performed during the steady state tests. RESULTS: Patients had lower peak oxygen uptake (pV(O2)) and the relation between ventilation and carbon dioxide output was steeper in patients than controls. T(offset) for both oxygen (O2) and carbon dioxide (CO(2)) from peak exercise was significantly greater in the patients than the controls and correlated with peak V(O2) (r=0.56, p<0.005 and r=0.58, p<0.005). T(onset) and T(offset) for O2 were increased in patients for each of the steady state tests and peak V(O2) correlated with T for recovery of O2 (r=0.44; p<0.05 from 15%, r=0.35; p= or <0.05 from 25%, and r=0.54; p<0.01 from 50%). There was a correlation between the T(onset) (r=0.42; p<0.0005 for O2 and r=0.23; p<0.05 for CO2) and T(offset) (r=0.49; p<0.0001 for O2 and r=0.42; p<0.0005 for CO2) and oxygen uptake as a percentage of peak exercise. CONCLUSIONS: This study demonstrates that the time constants of onset and offset for oxygen are dependent upon the degree of exertion performed relative to the individual's peak capacity.

Deployment of left ventricular lead from the ipsilateral side of central vein obstruction.

Cardiac resynchronisation therapy improves symptoms and reduces mortality in patients with chronic heart failure. In patients with previously implanted devices, particularly automatic defibrillators, central venous stenoses provide a challenge to upgrading to resynchronisation devices. We present a patient with central venous obstruction secondary to previously implanted defibrillator leads, in whom we achieved coronary sinus pacing through the ipsilateral internal jugular vein.

Chronic heart failure and multiple micronutrient supplementation: realistic hope or idealistic conjecture?

Recent studies have demonstrated the inefficacy of nutritional supplements containing various combinations of vitamins and minerals for otherwise healthy elderly people and patients with ischemic heart disease. However, patients with chronic heart failure (CHF) have, up until recently, been excluded from such studies. CHF has a high mortality and morbidity and patients are often elderly with poor general nutrition and high levels of micronutrient deficiency. It is in this population that nutritional supplementation has the most potential benefit. Evidence is accumulating that a strategy of long-term highdose multiple micronutrient supplementation might improve symptoms and cardiac function in elderly patients with CHF. In this article, we review the effects of individual micronutrients and how they might impact on CHF, and present recent data that dietary supplementation might offer an addition to standard therapy for CHF.

Calcium, phosphate and calcium phosphate product are markers of outcome in patients with chronic heart failure.

BACKGROUND: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). METHODS: Unselected, consecutive patients with CHF (left ventricular ejection fraction, LVEF ≤45%) were enrolled in a prospective observational study for the occurrence of hospitalisation and mortality. Blood samples were collected at the time of recruitment and analysed immediately. RESULTS: Patients (n = 713) were on contemporary optimal treatment and mean (standard error, SE) follow-up was 765 (18.9) days. Mean (SE) Ca was 2.29 (0.004) mmol/l. Median (interquartile range, IQR) Pi was 1.11 (0.98-1.23) mmol/l and median CPP 2.53 (2.21-2.88) mmol(2)/l(2). LVEF correlated inversely with Ca, natural log-transformed (Ln)Pi, and LnCPP. There was no difference in CPP between classes of symptom severity or diabetes status. Ca and LnCPP (but not LnPi) were associated with total mortality. Ca was significantly associated with progressive HF and non-cardiovascular death but not with sudden death. Binary logistic regression analyses showed that LnPi and LnCPP were associated with risk of hospitalisation. CONCLUSIONS: Ca, Pi and CPP could be useful additional variables in determining risk in CHF patients. Further work is required to elucidate the mechanisms underlying the adverse influence and determine whether lowering phosphate levels per se in CHF patients is of benefit.

Patients with long-term permanent pacemakers have a high prevalence of left ventricular dysfunction.

INTRODUCTION: Patients with right ventricular pacemakers are at increased risk of left ventricular systolic dysfunction (LVSD). We aimed to establish the prevalence, degree and associations of LVSD in patients with long-term right ventricular pacemakers listed for pulse generator replacement (PGR). METHODS: All patients listed for PGR at Leeds General Infirmary were invited to attend for an assessment during which we recorded medical history, symptomatic status, medical therapy, date and indication of first implantation, the percentage of right ventricular pacing (% RVP) and an echocardiogram. RESULTS: We collected data on 491 patients. A left ventricular ejection fraction less than 50% was observed in 40% of our cohort, however, this was much higher (59%) in those with more than 80% RVP than in those with less than 80% RVP (22%) (P < 0.0001). Multivariable analysis revealed % RVP, (but not complete heart block at baseline), serum creatinine and previous myocardial infarction to be independently related to the presence of LVSD. A model combining % RVP and previous myocardial infarction has a c-statistic of 0.74 for predicting LVSD. After a mean follow-up time of 668 days, 56 patients (12%) were dead or had been hospitalized for heart failure. In multivariable analysis, previous myocardial infarction and high % RVP were independently associated with a worse survival. CONCLUSION: Patients with right ventricular pacemakers have a high prevalence of LVSD, and this is greater in those exposed to more RVP. Those with LVSD and high amounts of RVP are at higher risk of hospitalization or death. Simple variables can identify those patients who might benefit from a more comprehensive review.

Are hematinic deficiencies the cause of anemia in chronic heart failure?

BACKGROUND: Anemia in chronic heart failure (CHF) is common, varying in prevalence between 14.4% and 55%, and is more frequent in patients with more severe heart failure. Patients with CHF who have anemia have a poorer quality of life, higher hospital admission rates, and reduced exercise tolerance. We explored the relation between hematinic levels and hemoglobin (Hb) levels and exercise tolerance in a group of patients with CHF. METHODS: We analyzed data from 173 patients with left ventricular systolic dysfunction (LVSD), 123 patients with symptoms of heart failure, but preserved left ventricular (LV) systolic function ("diastolic dysfunction"), and 58 control subjects of similar age. Each underwent echocardiography, a 6-minute walk test, and blood tests for renal function and Hb and hematinic levels (vitamin B12, iron, and folate). We classified patients as having no anemia (Hb level >12.5 g/dL), mild anemia (Hb level from 11.5-12.5 g/dL), or moderate anemia (Hb level <11.5 g/dL). RESULTS: Of patients with LVSD, 16% had moderate anemia and 19% had mild anemia. Of patients with preserved LV function, 16% had moderate anemia and 17% had mild anemia. Four control subjects had a Hb level <12.5 g/dL. Of all patients, 6% were vitamin B12 deficient, 13% were iron deficient, and 8% were folate deficient. There was no difference between patients with LVSD and the diastolic dysfunction group. In patients with LVSDS, the average Hb level was lower in New York Heart Association class III than classes II and I. The distance walked in 6 minutes correlated with Hb level in both groups of patients with CHF (r = 0.29; P <.0001). Patients with anemia achieved a lower pVO2 (15.0 [2.3] vs 19.5 [4.4], P <.05). Peak oxygen consumption correlated with Hb level (r = 0.21, P <.05) in the patients, but not in the control subjects. In patients with anemia, the mean creatinine level was higher than in patients with a Hb level >12.5 g/dL, but there was no clear relationship with simple regression. Hematocrit level and mean corpuscular volume were not different in the patients with diastolic dysfunction, patients with LV dysfunction, or the control subjects. Hematocrit levels were not influenced by diuretic dose. Patients with anemia were not more likely to be hematinic deficient than patients without anemia. CONCLUSIONS: Patients with symptoms and signs of CHF have a high prevalence of anemia (34%) whether they have LV dysfunction or diastolic dysfunction, but few patients have hematinic deficiency. Hemoglobin levels correlate with subjective and objective measures of severity and renal function.

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.

Is the elevated slope relating ventilation to carbon dioxide production in chronic heart failure a consequence of slow metabolic gas kinetics?

OBJECTIVE: Patients with heart failure have slow metabolic gas exchange kinetics, which may contribute to the elevated slope of the relationship between ventilation and carbon dioxide production (Ve/Vco(2) slope). SETTING: A tertiary referral centre for cardiology. SUBJECTS: Eleven patients with stable chronic heart failure and 11 age-matched controls. DESIGN: Each subject underwent maximal bicycle-based peak exercise testing with metabolic gas exchange analysis and three further repeated tests at 15%, 25% and 50% of the load achieved at peak exercise. The ventilation and carbon dioxide production from each of these steady-state tests was used to re-calculate the Ve/Vco(2) slope and compared with the Ve/Vco(2) slope derived from the maximal test. RESULTS: Peak oxygen consumption [mean (S.D.)] was lower in heart failure patients [18.2 (4.0) vs. 31.2 (6.3) ml/kg per min; P<0.001] than in controls. The Ve/Vco(2) slope was steeper in patients than controls [32.7 (8.3) vs. 27.1 (1.6); P<0.05]. There was no difference between the Ve/Vco(2) slope reconstructed from the three steady state tests and resting data and that gained from the maximal test [35.3 (7.8) vs. 25.9 (3.2); P=0.43]. CONCLUSIONS: The elevated slope of the relationship between ventilation and carbon dioxide production is not a consequence of the short stages of a standard incremental exercise test combined with delayed metabolic gas kinetics in heart failure patients.