Improved ventilatory response to exercise after cardioversion of chronic atrial fibrillation to sinus rhythm

Clinical outcomes after AF cardioversion in patients presenting left atrial sludge in trans-esophageal echocardiography

BACKGROUND

Direct-current cardioversion (DCC) for atrial fibrillation carries a risk of stroke, probably associated with the temporary atrial stunning following cardioversion. The presence of a cardiac thrombus, usually localized in the left atrial appendage (LAA), is recognized as a clear contra-indication to the cardioversion. However, the presence of atrial sludge without LAA thrombus in trans-esophageal echocardiography (TEE) remains, for many cardiologists, a relative contra-indication to the cardioversion. The aim of this study was to evaluate the safety of DCC in patients presenting atrial sludge without LAA thrombus.

METHODS

We prospectively included all consecutive patients demonstrating atrial sludge without LAA thrombus in TEE and undergoing DCC for persistent atrial fibrillation (AF). Safety of DCC was evaluated by the occurrence of clinical events at 1 month following cardioversion, i.e., up to the end of the atrial stunning period, as assessed by clinical examination and the standardized and validated Questionnaire for Verifying Stroke-Free Status (QVSFS).

RESULTS

Over a period of 2 years, 21 patients presenting atrial sludge without LAA thrombus underwent DCC for AF. During the follow-up period of 1 month after DCC, no clinical embolic event, cardiac event, or unscheduled consultations/hospitalizations occurred. At 1 month, 67% of the patients remained in sinus rhythm.

CONCLUSION

No clinical event occurred in patients demonstrating atrial sludge without thrombus and undergoing DCC for AF. These findings support current guidelines that only keep atrial thrombus as a contraindication to cardioversion, but warrant further investigation in large studies.

Impact of atrial fibrillation on exercise capacity in heart failure with preserved ejection fraction: a RELAX trial ancillary study

BACKGROUND

Atrial fibrillation (AF) is common among patients with heart failure and preserved ejection fraction (HFpEF), but its clinical profile and impact on exercise capacity remain unclear. RELAX (Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in HFpEF) was a multicenter randomized trial testing the impact of sildenafil on peak VO2 in stable outpatients with chronic HFpEF. We sought to compare clinical features and exercise capacity among patients with HFpEF who were in sinus rhythm (SR) or AF.

METHODS AND RESULTS

RELAX enrolled 216 patients with HFpEF, of whom 79 (37%) were in AF, 124 (57%) in SR, and 13 in other rhythms. Participants underwent baseline cardiopulmonary exercise testing, echocardiogram, biomarker assessment, and rhythm status assessment before randomization. Patients with AF were older than those in SR but had similar symptom severity, comorbidities, and renal function. β-blocker use and chronotropic indices were also similar. Despite comparable left ventricular size and mass, AF was associated with worse systolic (lower EF, stroke volume, and cardiac index) and diastolic (shorter deceleration time and larger left atria) function compared with SR. Pulmonary artery systolic pressure was higher in AF. Patients with AF had higher N-terminal pro-B-type natriuretic peptide, aldosterone, endothelin-1, troponin I, and C-telopeptide for type I collagen levels, suggesting more severe neurohumoral activation, myocyte necrosis, and fibrosis. Peak VO2 was lower in AF, even after adjustment for age, sex, and chronotropic response, and VE/VCO2 was higher.

CONCLUSIONS

AF identifies an HFpEF cohort with more advanced disease and significantly reduced exercise capacity. These data suggest that evaluation of the impact of different rate or rhythm control strategies on exercise tolerance in patients with HFpEF and AF is warranted.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00763867.

Cox-Maze III procedure with valvular surgery in an autopneumonectomized patient

Destructive pulmonary inflammation can leave patients with only a single functional lung, resulting in anatomical and physiological changes that may interfere with subsequent cardiac surgeries. Such patients are vulnerable to perioperative cardiopulmonary complications. Herein, we report the first case, to our knowledge, of an autopneumonectomized patient who successfully underwent a modified Cox-Maze III procedure combined with valvular repairs. The three major findings in this case can be summarized as follows: (1) a median sternotomy with peripheral cannulations, such as femoral cannulations, can provide an optimal exposure and prevent the obstruction of vision that may occur as a result of multiple cannulations through a median sternotomy; (2) a modified septal incision combined with biatrial incisions facilitate adequate exposure of the mitral valve; and (3) the aggressive use of intraoperative ultrafiltration may be helpful for the perioperative managements as decreasing pulmonary water contents, thereby avoiding the pulmonary edema associated with secretion of inflammatory cytokines during a cardiopulmonary bypass. We also provide several suggestions for achieving similar satisfactory surgical outcomes in patients with a comparable condition.

Lung function and dyspnea in patients with permanent atrial fibrillation

BACKGROUND

Reduced forced expiratory volume in one second (FEV(1)) has been associated with new-onset atrial fibrillation (AF), and AF patients often complain of dyspnea. We hypothesized that patients with permanent AF had reduced lung function compared to subjects in sinus rhythm.

METHODS

The participants were 75year-olds from the general population. FEV(1), forced vital capacity (FVC), maximal voluntary ventilation (MVV), total lung capacity by single breath (TLC(SB)), single-breath diffusing capacity of the lung for carbon monoxide (DLCO(SB)) and exercise testing with peak oxygen uptake (VO(2) peak) were assessed. The slope of minute ventilation over carbon dioxide output defined ventilatory efficiency. The Symptom Checklist-frequency and severity questionnaire assessed dyspnea.

RESULTS

AF patients had significantly higher number (%) of subjects below the 5th percentile of predicted FEV(1) (7 (27) versus 3 (4), p=0.005), FVC (6 (23) versus 2 (3), p=0.006) and TLC(SB) (11 (42) versus 12 (18), p=0.014) compared to control subjects, also after adjustment for smoking and obesity, or if disregarding subjects with chronic heart failure. The dyspnea frequency and severity scores correlated with VO(2) peak (r=-0.6, p<0.01) in AF patients, and in control subjects with % predicted FEV(1), MVV and TLC(SB) (r=-0.3, p<0.05).

CONCLUSION

More patients with permanent AF had lung function below normal range than control subjects in sinus rhythm, irrespective of smoking, obesity or chronic heart failure. Dyspnea, however, was related to exercise capacity rather than to lung function in AF patients.

Exercise hyperventilation, dyspnea sensation, and ergoreflex activation in lone atrial fibrillation

Lone atrial fibrillation may be associated with daily life disability and exercise limitation. The extracardiac pathophysiology of these effects is poorly explored. In 35 subjects with lone atrial fibrillation (mean age 67 +/- 7 yr), we investigated pulmonary function, symptom-limited cardiopulmonary exercise performance, muscle ergoreflex (handgrip exercise) contribution to ventilation, and brachial artery flow-mediated dilation (as a measure of endothelial function) before and after (average interval 20 +/- 5 days) restoring sinus rhythm with external cardioversion. Respiratory volumes and lung diffusing capacity at rest were within normal limits during both atrial fibrillation and after restoring sinus rhythm. Cardioversion was associated with the following changes: a decrease of the slope of exercise ventilation vs. CO2 production (from 35 +/- 5 to 29 +/- 3; P <0.01) and of dyspnea sensation (Borg score from 4 to 2) and an increase of peak oxygen uptake (Vo2; from 16 +/- 4 to 20 +/- 5 ml.min(-1).kg(-1); P <0.01), Vo2 at anaerobic threshold (from 11 +/- 2 to 13 +/- 2 ml.min(-1).kg(-1); P <0.05), and O2 pulse (from 8 +/- 3 to 11 +/- 3 ml/beat; P <0.01). After cardioversion, the observed improvement in ventilatory efficiency was accompanied by a significant peak end-tidal CO2 increase (from 33 +/- 2 to 37 +/- 2 mmHg; P <0.01) and no changes in dead space-to-tidal volume ratio (from 0.23 +/- 0.03 to 0.23 +/- 0.02; P=not significant). In addition, the ergoreflex contribution to ventilation was remarkably attenuated, and the brachial artery flow-mediated dilatation was significantly augmented (from 0.32 +/- 0.07 to 0.42 +/- 0.08 mm; P <0.01). Ten patients had atrial fibrillation relapse and, compared with values after restoration of regular sinus rhythm, invariably showed worsening of endothelial function, exercise ventilatory efficiency, and muscle ergoreflex contribution to ventilation. In subjects with lone atrial fibrillation, an impairment in ventilatory efficiency appears to be involved in the pathophysiology of exercise limitation, and to be primarily related with a demodulated peripheral control of ventilation.

Prevention of and medical therapy for atrial arrhythmias in heart failure

A large proportion of heart failure patients suffer from atrial arrhythmias, prime amongst them being atrial fibrillation (AF). Ventricular dysfunction and the syndrome of heart failure can also be a concomitant pathology in up to 50% of patients with AF. However this association is more than just due to shared risk factors, research from animal and human studies suggest a causal relationship between AF and heart failure. There are numerous reports of tachycardia-induced heart failure where uncontrolled ventricular rate in AF results in heart failure, which is reversible with cardioversion to sinus rhythm or ventricular rate control. However the relationship extends beyond tachycardia-induced cardiomyopathy. Optimal treatment of AF may delay progressive ventricular dysfunction and the onset of heart failure whilst improved management of heart failure can prevent AF or improve ventricular rate control. Prevention and treatment of atrial arrhythmias, and in particular atrial fibrillation, is therefore an important aspect of the management of patients with heart failure. This review describes the incidence and possible predictors of AF and other atrial arrhythmias in patients with heart failure and discusses the feasibility of primary prevention. The evidence for the management of atrial fibrillation in heart failure is systematically reviewed and the strategies of rate versus rhythm control discussed in light of the prevailing evidence.

Excessive ventilation after acute myocardial infarction and its improvement in 4 months

The relationship between ventilation (VE) and CO2 output (VCO2) is fitted linearly. The steeper gradient implies excessive ventilation. Through an evaluation of the VE-VCO2 slopes, this study investigated whether patients with acute myocardial infarction (AMI) have excessive ventilation and whether it improved in 4 months. The VE-VCO2 slopes were determined in exercise tests at 1 and 4 months in 131 patients with AMI. Patients were divided into 3 groups according to the 1 month VE-VCO2 slope value: (i) normal (<30); (ii) intermediate (30-32); and (iii) excessive (>32). In the normal group (n=76), at 4 months, the slope decreased in 10, increased in 5 and remained unchanged in 61 patients; in the intermediate (n=31) group, 9, 2 and 20; and in the excessive (n=24) group, 15, 3 and 6, respectively, showing that the slope reduction was greater in the excessive group (p<0.01). The slope correlated with age and acute phase heart failure. The percent reduction of the slope did not correlate with these parameters. In conclusion, a substantial fraction of patients with AMI have excessive ventilation that improves in 4 months. The improvement is greater in patients with greater excessive ventilation but is not associated with an improvement in exercise capacity nor hemodynamics.

Middle cerebral artery blood velocity during exercise in patients with atrial fibrillation

Atrial fibrillation limits the ability to increase cardiac output during exercise and may, in turn, affect the exercise-associated elevation in cerebral perfusion. In nine patients with atrial fibrillation (AF) and in five age-matched healthy subjects, middle cerebral artery blood velocity (MCA Vmean) was measured during incremental exercise using the transcranial Doppler. The AF patient group exhibited a lower aerobic capacity than the control group [peak work rate: 106 W (71-153 W; median and range) vs. 129 W (118-1.9 W) and maximal oxygen uptake: 1.4 l min-1 (1.0-1.9 l min-1) vs. 1.7 l min-1 (1.4-2.2 l min-1); P = 0.05]. At rest, MCA Vmean was not significantly different between the two groups [43 cm s-1 (39-56 cm s-1) vs. 52 cm s-1 (40-68 cm s-1)]. During intense cycling, the increase in MCA Vmean was to 51 cm s-1 (40-78 cm s-1) (9%) in the AF group and lower than in the healthy subjects [to 62 cm s-1 (50-81 cm s-1) 23%; P < 0.05], which corresponded with the smaller than expected increase in cardiac output [156% (130-169%) vs. 180%]. Thus, there was a correlation between the increase in MCA Vmean and the ability to increase cardiac output (r2 = 0.55, P < 0.01). We suggest that, during exercise with a large muscle mass, atrial fibrillation affects the ability to elevate cerebral perfusion, and this results from an impaired ability to increase cardiac output.

Hemodynamic and cardiorespiratory function following internal atrial defibrillation for chronic atrial fibrillation

Internal atrial defibrillation (IAD) is able to restore sinus rhythm in patients with chronic atrial fibrillation (AF) and failed external electrical and/or pharmacologic cardioversion. To assess whether cardiorespiratory and hemodynamic function improve after IAD, 35 patients were prospectively investigated during constant workload exercise by spiroergometry and Doppler echocardiography before IAD, and 1 day and 1 month after IAD. Oxygen uptake kinetics, ventilation, left atrial mechanical function, and pulmonary artery pressure were determined simultaneously at rest and during steady state. During the serial follow-up, 20 patients maintained sinus rhythm. The time interval for achieving the steady state (146 +/- 53 vs 132 +/- 42 seconds; p = 0.5) and the oxygen deficit (645 +/- 190 vs 670 +/- 174 ml; p = 0.7) were not different before and 1 day after IAD, but decreased significantly after 1 month (98 +/- 16 seconds, p = 0.01 and 487 +/- 72 ml, p = 0.02). Exercise pulmonary artery systolic pressures were 38 +/- 13 mm Hg before IAD, increased significantly to 46 +/- 11 mm Hg on day 1 (p = 0.03), and decreased below baseline values at 1 month to 31 +/- 12 mm Hg (p = 0.07). Peak A-wave velocities increased from 0.51 +/- 0.1 m/s after 1 day to 0.67 +/- 0.2 m/s after 1 month (p = 0.03). Restoration of sinus rhythm in patients with AF resistant to external electrical and/or pharmacologic cardioversion improves hemodynamic and cardiorespiratory function at daily activity exercise levels.

Prevention of relapse in patients with congestive heart failure: the role of precipitating factors

Relapse of congestive heart failure (CHF) frequently occurs and has serious consequences in terms of morbidity, mortality, and health care expenditure. Many studies have investigated the aetiological and prognostic factors of CHF, but there are only limited data on the role of precipitating factors that trigger relapse of CHF. Knowledge of potential precipitating factors may help to optimise treatment and provide guidance for patients with CHF. The literature was reviewed to identify factors that may influence haemodynamic homeostasis in CHF. Precipitating factors that may offer opportunities for preventing relapse of CHF were selected. Potential precipitating factors are discussed in relation to the pathophysiology of CHF: alcohol, smoking, psychological stress, uncontrolled hypertension, cardiac arrhythmias, myocardial ischaemia, poor treatment compliance, and inappropriate medical treatment. Poor treatment compliance in particular is frequently encountered in patients with CHF. Furthermore, studies of medical treatment under everyday circumstances indicate that some aspects of the management of CHF can be improved. In conclusion, the identification of precipitating factors for relapse of CHF may strongly contribute to optimal treatment. Improvement of treatment compliance and optimalisation of medical treatment may offer important possibilities to clinicians to reduce the number of relapses in patients with CHF.

Does the 6-minute walk test predict the prognosis in patients with NYHA class II or III chronic heart failure?

BACKGROUND

We prospectively evaluated the potential of the 6-minute walk test compared with peak VO2 in predicting outcome of patients with New York Heart Association (NYHA) class II or III heart failure.

METHODS AND RESULTS

Patients with a history of heart failure caused by systolic dysfunction were included. The combined final outcome (death or hospitalization for heart failure) was used as the judgment criterion. One hundred twenty-one patients (age 59+/-11 years; left ventricular ejection fraction 29.6%+/-13%) were included and followed for 1.53+/-0.98 years. Patients were separated into two groups according to outcome: group 1 (G1, 74 patients), without events, and group 2 (G2, 47 patients), who reached the combined end point. Peak VO2 was clearly different between G1 and G2 (18.5+/-4 vs. 13.9+/-4 ml/kg/min, p=0.0001) but not the distance walked (448+/-92 vs 410+/-126 m; p=0.084, not significant). Survival analysis showed that unlike peak VO2, the distance covered was barely distinguishable between the groups (p < 0.08). However, receiver operating characteristic curves revealed that the best performances for the 6-minute walk test were obtained for subjects walking < or =300 m. These patients had a worse prognosis than those walking farther (p=0.013). In this subset of patients, there was a significant correlation between distance covered and peak VO2 (r=0.65, p=0.011). Thus it appears that the more severely affected patients have a daily activity level relatively close to their maximal exercise capacity. Nevertheless, the 300 m threshold suggested by this study needs to be validated in an independent population.

CONCLUSIONS

A distance walked in 6 minutes < or =300 m can predict outcome. Moreover, in these cases there is a significant correlation between the 6-minute walk test and peak VO2 demonstrating the potential of this simple procedure as a first-line screening test for this subset of patients.

Acute treatment of atrial fibrillation: why and when to maintain sinus rhythm

Although not usually immediately life threatening, atrial fibrillation (AFib) poses a significant long-term risk to health. The best-documented and probably largest long-term risk in this condition is from thromboembolic complications, but this has been shown to be largely overcome by moderate intensity anticoagulation. In addition, however, AFib has significant detrimental effects on exercise capacity and overall quality of life, can cause or exacerbate heart failure, and imposes significant health-care burdens. Cardioversion, usually by transthoracic direct current shock, restores sinus rhythm in > 80% of patients, but recurrence of AFib over the weeks and months that follow decreases the value of this strategy. Antiarrhythmic drugs lessen the recurrence rate and add to the overall efficacy of achieving the treatment goal of restoring and maintaining sinus rhythm, rather than accepting permanent AFib with ventricular rate control and long-term thromboembolic prophylaxis. Whereas clear evidence exists that abolishing AFib makes patients feel better in the short-to-medium term, data on the economic viability or long-term efficacy of such a strategy are sparse. Management trials in AFib currently ongoing will provide some answers, but the decision as to whether restoring sinus rhythm is feasible and realistic in individual patients will remain a decision to be made on a case-by-case basis.

Cardioversion of atrial fibrillation in the setting of mild to moderate heart failure

We investigated the effect of electrical cardioversion of atrial fibrillation in patients with heart failure. The study group consisted of 24 patients with mild to moderate heart failure [13 men, mean age 67+/-7 years, mean peak oxygen consumption (peak VO2) 16.3+/-2.8 ml/min/kg] and chronic atrial fibrillation (median duration 19 (1-228) months). Patients were stable on digoxin, diuretics, nitrates and angiotensin converting enzyme inhibitors; no prophylaxis with antiarrhythmics was started after cardioversion. Cardioversion was unsuccessful in 6 patients; of the 18 patients in whom sinus rhythm was obtained 9 had a relapse of atrial fibrillation within 6 weeks after cardioversion. The remaining 9 patients with maintenance of sinus rhythm and the 15 (6+9) patients with atrial fibrillation at follow-up after 6 weeks did not differ with respect to any baseline characteristic, including age, peak VO2, duration of atrial fibrillation, echocardiographic left ventricular and left atrial dimensions, plasma atrial natriuretic peptide and norepinephrine. In the patients with maintenance of sinus rhythm, baseline measurements were repeated at follow-up. Peak VO2 did not change significantly (16.7+/-2.8 to 17.6+/-3.3 ml/min/kg, P=0.29); also, echo parameters, atrial natriuretic peptide and norepinephrine were not significantly affected. These results indicate that it is difficult to achieve lasting sinus rhythm through electrical cardioversion in patients with atrial fibrillation and mild to moderate heart failure. Moreover, in patients with maintenance of sinus rhythm after cardioversion no significant benefit in terms of peak VO2, cardiac dimensions, and neurohumoral status is to be expected. Hence, indiscriminate cardioversion of atrial fibrillation in the setting of heart failure does not appear to be useful.

Atrial fibrillation is associated with a lower exercise capacity in male chronic heart failure patients

OBJECTIVE

To study the influence of atrial fibrillation on peak oxygen uptake (peak VO2) in chronic heart failure. An unfavourable effect of atrial fibrillation has been shown in several patient populations, but the results have not been consistent in chronic heart failure.

METHODS

Data were analysed from male heart transplant candidates who were able to perform graded bicycle ergometry until exhaustion with respiratory gas analysis and measurement of heart rate. Patients in atrial fibrillation (n = 18) were compared with patients in sinus rhythm (n = 93).

RESULTS

Age, weight, height, and aetiology of chronic heart failure did not differ significantly between the two groups. Cardiac catheterisation at supine rest showed that heart rate was comparable, but that stroke volume and cardiac output were lower (p < 0.05) in atrial fibrillation. Systolic and diastolic left ventricular function, assessed by radionuclide angiography at rest, were not significantly different. Peak VO2 (mean (SD): 13.8 (3.6) v 17.1 (5.6) ml/kg/min; p < 0.01) and peak work load (78 (27) v 98 (36) W; p < 0.05) were lower in the patients with atrial fibrillation, though respiratory gas exchange ratio and Borg score were similar in the two groups. Patients with atrial fibrillation had a higher heart rate sitting at rest before exercise (93 (16) v 84 (16) beats/min) and at peak effort (156 (23) v 140 (25) beats/min) (p < 0.05).

CONCLUSIONS

Atrial fibrillation is associated with a 20% lower peak VO2 in patients with chronic heart failure, suggesting that preserved atrial contraction or a regular rhythm, or both, are critical to maintain cardiac output and exercise performance.

Effect of percutaneous transluminal coronary angioplasty on exercise ventilation in patients with coronary artery disease and normal left ventricular function

We evaluated the ventilatory response to exercise before and after percutaneous transluminal coronary angioplasty (PTCA) in 22 patients with coronary artery disease (CAD) and normal left ventricular systolic function to determine the effect of exercise-induced myocardial ischemia on the ventilatory response. Subjects performed a symptom-limited maximal ergometer exercise test in the sitting position. The ventilatory response was evaluated in terms of the slopes of minute ventilation (VE) and carbon dioxide production (VCO2) during exercise (slope 1 and slope 2, defined as below and above the respiratory compensation threshold, respectively). Slope 1 of the correlation between (VE) and (VCO2) was significantly greater in patients with CAD (27.3 +/- 2.6) than in the age-matched control group (23.7 +/- 2.6; p < 0.01). Slope 2 was also significantly greater in patients (41.0 +/- 4.8) than in the control group (29.7 +/- 2.9; p < 0.01). Slope 1 of the correlation between (VE) and (VCO2) decreased significantly in the 14 patients in whom PTCA was successful but did not decrease in the 8 patients in whom PTCA failed. Our results suggest that myocardial ischemia increases exercise ventilation in patients with CAD and normal left ventricular systolic function and that its effect is reversible.

Presentation and management of patients admitted with atrial fibrillation: a review of 291 cases in a regional hospital

Two hundred and ninety one patients admitted with atrial fibrillation through the emergency room of a regional hospital in the year 1993 were reviewed to evaluate the presenting features and in-hospital treatment of patients with symptomatic atrial fibrillation. The incidence of atrial fibrillation increased with age (mean age was 73 +/- 12 years) and the ratio of female to male was 1.8:1. The commonest presenting features were palpitation (42.3%), dyspnoea (38.1%) and heart failure (16.4%). The most frequently associated cardiac conditions were hypertension (28.9%), atherosclerotic cardiovascular disease (24.7%) and rheumatic heart disease (17.5%). Pulmonary diseases (18.6%), diabetes mellitus (12.7%) and thyrotoxicosis (6.2%) were the principal associated non-cardiac conditions. Thromboembolic complications were found in 15 patients at presentation (5.2%). Cardiac enzyme assessment was investigated in two thirds of the patients (68.1%), while thyroid function test (59.5%) and echocardiography (29.6%) were less commonly investigated. Digoxin was still the most popular drug used for ventricular rate control, and cardioversion was performed in only 6.9% of patients. Antithrombotic therapy was used in 5.8% of patients only although it was clinically indicated in more than half of the patients (52%). Contraindications of anticoagulation were found in 23 patients (7.9%), including a history of gastrointestinal or cerebrovascular bleeding, active bleeding, chronic renal failure and poor drug compliance. The mean hospital stay was 5 +/- 4 days, compared to a mean stay of 2.7 days for other medical patients. Fourteen patients (4.8%) died during hospitalisation.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional capacity before and after cardioversion of atrial fibrillation: a controlled study

OBJECTIVE

To evaluate the effect of cardioversion on peak oxygen consumption (peak VO2) in patients with long-standing atrial fibrillation, to assess the importance of underlying heart disease with respect to the response to exercise, and to relate functional capacity to long-term arrhythmia outcome.

DESIGN

Prospective controlled clinical trial.

SETTING

Tertiary referral centre.

PATIENTS

63 consecutive patients with chronic atrial fibrillation accepted for treatment with electrical cardioversion. Before cardioversion all patients were treated with digoxin, verapamil, or a combination of both to attain a resting heart rate < or = 100 beats per minute.

INTERVENTIONS

Electrical cardioversion.

MAIN OUTCOME MEASURES

Peak VO2 measured before and 1 month after electrical cardioversion to compare patients who were in sinus rhythm and those in atrial fibrillation at these times. Maintenance of sinus rhythm for a mean follow up of 19 (7) months.

RESULTS

Mean (1SD) peak VO2 in patients in sinus rhythm after 1 month (n = 37) increased from 21.4 (5.8) to 23.7 (6.4) ml/min/kg (+11%, P < 0.05), whereas in patients with a recurrence of atrial fibrillation 1 month after cardioversion (n = 26) peak VO2 was unchanged. In patients who were in sinus rhythm both those with and without underlying heart disease improved, and improvement was not related to functional capacity or left ventricular function before cardioversion. Baseline peak VO2 was not a predictive factor for long-term arrhythmia outcome.

CONCLUSION

Restoration of sinus rhythm improved peak VO2 in patients with atrial fibrillation, irrespective of the presence of underlying heart disease. Peak VO2 was not a predictive factor for long-term arrhythmia outcome after cardioversion of atrial fibrillation. These findings suggest that cardioversion is the best method of improving functional capacity in patients with atrial fibrillation, whether or not they have underlying heart disease and whatever their functional state.