Atrial fibrillation

A comparison of rate control and rhythm control in patients with atrial fibrillation

BACKGROUND

There are two approaches to the treatment of atrial fibrillation: one is cardioversion and treatment with antiarrhythmic drugs to maintain sinus rhythm, and the other is the use of rate-controlling drugs, allowing atrial fibrillation to persist. In both approaches, the use of anticoagulant drugs is recommended.

METHODS

We conducted a randomized, multicenter comparison of these two treatment strategies in patients with atrial fibrillation and a high risk of stroke or death. The primary end point was overall mortality.

RESULTS

A total of 4060 patients (mean [+/-SD] age, 69.7+/-9.0 years) were enrolled in the study; 70.8 percent had a history of hypertension, and 38.2 percent had coronary artery disease. Of the 3311 patients with echocardiograms, the left atrium was enlarged in 64.7 percent and left ventricular function was depressed in 26.0 percent. There were 356 deaths among the patients assigned to rhythm-control therapy and 310 deaths among those assigned to rate-control therapy (mortality at five years, 23.8 percent and 21.3 percent, respectively; hazard ratio, 1.15 [95 percent confidence interval, 0.99 to 1.34]; P=0.08). More patients in the rhythm-control group than in the rate-control group were hospitalized, and there were more adverse drug effects in the rhythm-control group as well. In both groups, the majority of strokes occurred after warfarin had been stopped or when the international normalized ratio was subtherapeutic.

CONCLUSIONS

Management of atrial fibrillation with the rhythm-control strategy offers no survival advantage over the rate-control strategy, and there are potential advantages, such as a lower risk of adverse drug effects, with the rate-control strategy. Anticoagulation should be continued in this group of high-risk patients.

A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation

BACKGROUND

Maintenance of sinus rhythm is the main therapeutic goal in patients with atrial fibrillation. However, recurrences of atrial fibrillation and side effects of antiarrhythmic drugs offset the benefits of sinus rhythm. We hypothesized that ventricular rate control is not inferior to the maintenance of sinus rhythm for the treatment of atrial fibrillation.

METHODS

We randomly assigned 522 patients who had persistent atrial fibrillation after a previous electrical cardioversion to receive treatment aimed at rate control or rhythm control. Patients in the rate-control group received oral anticoagulant drugs and rate-slowing medication. Patients in the rhythm-control group underwent serial cardioversions and received antiarrhythmic drugs and oral anticoagulant drugs. The end point was a composite of death from cardiovascular causes, heart failure, thromboembolic complications, bleeding, implantation of a pacemaker, and severe adverse effects of drugs.

RESULTS

After a mean (+/-SD) of 2.3+/-0.6 years, 39 percent of the 266 patients in the rhythm-control group had sinus rhythm, as compared with 10 percent of the 256 patients in the rate-control group. The primary end point occurred in 44 patients (17.2 percent) in the rate-control group and in 60 (22.6 percent) in the rhythm-control group. The 90 percent (two-sided) upper boundary of the absolute difference in the primary end point was 0.4 percent (the prespecified criterion for noninferiority was 10 percent or less). The distribution of the various components of the primary end point was similar in the rate-control and rhythm-control groups.

CONCLUSIONS

Rate control is not inferior to rhythm control for the prevention of death and morbidity from cardiovascular causes and may be appropriate therapy in patients with a recurrence of persistent atrial fibrillation after electrical cardioversion.

Atrial fibrillation: current surgical options and their assessment

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with morbidity and mortality. Traditional surgical treatment of AF is the Cox-Maze III procedure, a complicated operation. New surgical approaches include alternate energy sources (radiofrequency, microwave, cryothermy) and simplified left atrial lesion sets. These operations cure AF in 70% to 80% of patients. This review describes contemporary and emerging surgical approaches to AF, synthesizes results of these operations, and proposes new standards for reporting results of AF treatment.

Long-term Anticoagulation Therapy in Prevention of Stroke

Long-term anticoagulation continues to be used and investigated as a means to prevent new or recurrent stroke. The best-established indications for long-term anticoagulation are cardiac abnormalities capable of producing intracardiac thrombi that may embolize into the brain or systemic circulation. The firmest cardiac indications are mechanical prosthetic heart valves, mitral stenosis with atrial fibrillation, and atrial fibrillation with additional features placing them at increased risk for stroke. These and other "major" cardiac potential sources of emboli should be considered as anticoagulation candidates unless the estimated risk of bleeding is prohibitive. A number of noncardiac potential causes of stroke are generally managed with long-term anticoagulation. These include arterial dissections, cerebral venous sinus thrombosis, the antiphospholipid antibody syndrome, and congenital and acquired coagulopathies. Recent randomized studies do not support the use of long-term anticoagulation for the prevention of recurrent stroke in patients with noncardioembolic stroke that is not due to the previously outlined disorders. Whether long-term anticoagulation is beneficial in the specific population of patients with major documented intracranial atherosclerotic stenosis is currently under investigation.

Effectiveness of percutaneous device occlusion for atrial septal defect in adult patients with pulmonary hypertension

BACKGROUND

Adult patients with atrial septal defect (ASD) and pulmonary hypertension have a more advanced degree of disease, frequently having functional class deterioration and atrial arrhythmias when they are aged >40 years. Surgery at this age prolongs life expectancy and limits functional deterioration. Although percutaneous ASD device occlusion is an accepted alternative to surgery, there is limited information on the immediate and long-term effects of device occlusion in middle-aged and elderly patients with ASD and pulmonary hypertension.

METHODS

From a total of 101 patients with secundum ASD who were receiving treatment with percutaneous device occlusion, we selected for analysis 29 adult patients (mean age 56 +/- 14 years) with a baseline peak pulmonary pressure of >40 mm Hg (mean 65 +/- 23 mm Hg). Three of the patients had suprasystemic pulmonary pressure and a bidirectional shunt. Six patients were asymptomatic at treatment. The remaining 23 had different degrees of dyspnea; 14 of them had an advanced New York Heart Association functional class (III-IV). Twelve patients had chronic atrial fibrillation. At cardiac catheterization, the mean ratio of pulmonary to systemic flow was 1.8 +/- 0.5, and the pulmonary-to-systemic pressure ratio was 0.66 +/- 0.22. The mean diameter of the defect, as evaluated by the stretching balloon method, was 26 +/- 7 mm. All patients received an Amplatzer septal occluder (Golden Valley, Minn). Seven patients had combined therapeutic procedures for associated anomalies before the implant: mitral balloon valvuloplasty (n = 1), stent coronary revascularization (n = 1), stent in pulmonary vein stenosis (n = 1), and internal catheter defibrillation (n = 4). After treatment, patients were followed up by clinical and echocardiographic Doppler studies every 6 months.

RESULTS

Immediately after the implantation, the peak systolic pulmonary pressure significantly decreased to 54 +/- 21 mm Hg (P <.001). A clear improvement in functional status was observed after the treatment in all symptomatic patients, especially in those with refractory heart failure. There were no major complications. Six patients who had atrial fibrillation at baseline study recovered to a stable sinus rhythm after treatment, and it was maintained at discharge. Complete ASD occlusion by echocardiographic Doppler at discharge was observed in 28 patients (97%). After a mean follow up of 21 +/- 14 months, clinical improvement persisted in all previously symptomatic patients, and the peak systolic pulmonary pressure, obtained by echocardiographic Doppler, further decreased to 31 +/- 11 mm Hg (P <.001) compared with baseline and immediately after hemodynamic measurements.

CONCLUSIONS

Our findings suggest that percutaneous device occlusion of ASD in adult patients with pulmonary hypertension is safe and effective and provides significant and prolonged relief.

Impact of atrial fibrillation on tricuspid and mitral annular dilatation and valvular regurgitation

To investigate the effects of atrial fibrillation (AF) on the mitral and tricuspid valves, the corresponding annular dilatation and valvular regurgitation were compared with 2-dimensional and Doppler echocardiography in 31 consecutive patients with lone AF and 28 normal controls. Mid-systolic mitral and tricuspid annular areas were measured from 2 diameters in 2 orthogonal apical echocardiograms. Percent (%) mitral regurgitant (MR) or tricuspid regurgitant (TR) jet area to the left or right atrial area was evaluated and % MR or TR jet area >20% was considered moderate or significant. Both the mitral and tricuspid annular areas in patients with lone AF were significantly larger compared with the controls (mitral: 9.5 +/- 1.2 vs 6.6 +/- 0.9 cm2, lone AF vs control, p < 0.01) (tricuspid: 12.0 +/- 2.0 vs 7.5 +/- 0.9 cm2, p < 0.01). The % increase in the annular area relative to the mean normal value was significantly greater in the tricuspid valve (44 +/- 18 vs 60 +/- 28%, p < 0.01). Moderate or severe MR was not observed and the incidence of moderate or severe valve regurgitation (% jet area >20%) was significantly higher in the tricuspid valve (0/31 vs 11/31, MR vs TR, p < 0.01) in patients with lone AF. The % TR jet area showed significant correlation with tricuspid annular area (r2 = 0.65, p < 0.001). Lone AF is associated with annular dilatation of both mitral and tricuspid valves, but the annular dilatation and valvular regurgitation are significantly greater in the tricuspid valve.

Combined atrial fibrillation and mitral valve surgery using microwave technology

Atrial fibrillation is associated with a significant morbidity and mortality and is typically related to patients with mitral valve disease. Microwave ablation is a new option for surgical treatment of chronic atrial fibrillation. We present our experience with surgical treatment of mitral valve disease and microwave ablation in patients with chronic atrial fibrillation. In 105 patients (73 women, 32 men, 68.6 +/- 8 years of age from 45 to 83 years, ejection fraction 28% to 80%, left atrial diameter 56 +/- 9.1 mm from 35 to 97 mm) with mitral valve disease, chronic atrial fibrillation was documented for 8.6 +/- 6.8 years. Microwave ablation was performed using a continuous ablation line starting at the posterior mitral valve annulus and incorporating the interior of all pulmonary veins. In 33 patients, mitral valve reconstruction was performed. Ten patients received biologic valve replacement; 3 of them got a stentless quattro mitral valve prosthesis. Survival rate was 99.1% (n = 104). In the 6-month follow-up, 42 of 69 patients were in sinus rhythm (61%); in the 1-year follow-up, 37 of 64 patients were in sinus rhythm (57.8%). Microwave ablation is a safe and efficient method for surgical treatment of chronic atrial fibrillation in patients with mitral valve disease.

Combined atrial fibrillation and mitral valve surgery using radiofrequency technology

Recently, intraoperative radiofrequency ablation of the left atrium combined with mitral valve surgery has become widely used. In our center, 30 patients underwent this combined procedure; median sternotomy was used in 16 patients, and port access was used in 14 patients. At hospital discharge, 18 patients (60%) were no longer in atrial fibrillation, and at 6 months, 19 patients (65%) remained in sinus rhythm. All sinus rhythm patients had a well-defined transmitral A wave detectable by echocardiography. One patient sustained a major stroke. Two patients required pacemaker implantation. Such encouraging preliminary results have triggered worldwide interest in the percutaneous and surgical treatment of atrial fibrillation. However, the excellent long-term results with the classic Cox-Maze III operation have not yet been achieved with these newer approaches. Further basic and clinical research is required before a predictable simple and safe technique can be introduced as a new standard for the surgical treatment of atrial fibrillation in patients with or without structural heart disease.

Personal health care services through digital television

Personal health care has obtained increasing importance in the field of health care as the populations' age in the industrialised countries and resources available for health care remain limited. Personal health care through digital television is an exiting possibility in the realisation of new types of services answering to this demand for increased personal action and responsibility in health care. The possibilities of digital television in health care are studied in the Health Care Television (HCTV) research project of the Digital Media Institute at Tampere University of Technology. In this paper personal health care services are studied mainly from the perspective of the interactive service infrastructure of digital television. Firstly we present the general infrastructure of digital television and the different interactive service types of digital television. The usage of these service types in personal health care applications is also discussed. Finally, a web-based application based on chronic atrial fibrillation and its test use is presented. The application is used as a research platform for personal health care applications in digital television.

Hyperthyroidism and the management of atrial fibrillation

Atrial fibrillation is often induced in patients with hyperthyroidism and may trigger heart failure. Its prevalence and outcome were examined to obtain up-to-date information. Persistent atrial fibrillation was observed in approximately 1.7% of new hyperthyroid patients. It occurs more frequently in males (2.86%) than in females (1.36%), even though the number of male hyperthyroid patients is only one fifth of female patients. The rate increased with age, being 8% in the patients older than 70 years old. The initial treatment is to control the heart rate with routine pharmacologic therapy and to start antithyroid therapy as quickly as possible. Attempted cardioversion should be deferred until approximately the fourth month of maintaining a euthyroid state, because more than 56% of atrial fibrillation spontaneously reverts to sinus rhythm when the thyroid hormone levels start to decline. Elective cardioversion for those whose atrial fibrillation persists is highly effective and sinus rhythm maintenance rates were 56.7% and 47.6% at the 10th and the 14th year, respectively, even though the duration of atrial fibrillation prior to cardioversion was extremely long (35.0 +/- 29.0 months).

The effects of advanced age on the incidence of supraventricular arrhythmias after pneumonectomy in dogs

Because advanced age is the strongest independent risk factor for the development of supraventricular arrhythmias after lung resection, we compared the incidence and premorbid events of supraventricular arrhythmias after pneumonectomy in young and elderly dogs with the aim of better understanding potential age-related arrhythmogenic mechanisms. Right pneumonectomy was performed in 15 male mongrel dogs ("old" > or =8 yr [n = 8], "young" <4 yr [n = 7]) and the electrocardiogram continuously recorded by an implantable telemetry system for 1 wk before euthanizing. After surgery, 7 of 8 older animals (88%) developed a total of 23 episodes of sustained (>30 s) paroxysmal supraventricular tachycardia (SVT), compared with 0 of 7 (0%) young dogs, P = 0.0014. Analysis of heart rate over the 60 min preceding the onset of SVT revealed a progressive increase in sinus rhythm beginning 15 min before the arrhythmia. Comparison of the heart rate and rhythm obtained in younger animals from the corresponding postoperative hour demonstrated that although older animals developed more atrial (P = 0.03) and ventricular premature contractions (P = 0.056) and episodes of nonsustained ventricular tachycardia (P = 0.01), heart rate was similar for both groups until the increase in elderly dogs preceding the onset of SVT. Histologic examination of the atria showed interstitial fibrosis in old but not young animals. In addition, 4 of 8 (50%) elderly animals exhibited an inflammatory response within the atria consistent with acute myo- and epicarditis. We conclude that elderly dogs have an increased supraventricular arrhythmogenic potential within the first week after pneumonectomy than younger animals, perhaps because of increased atrial fibrosis and inflammation. Heart rate analysis before SVT onset suggests that adrenergic predominance was a probable responsible trigger.

IMPLICATIONS

In this canine pneumonectomy model, advanced age was associated with an increased incidence of supraventricular arrhythmias, perhaps because of increased atrial fibrosis and inflammation.

An emergency department observation unit protocol for acute-onset atrial fibrillation is feasible

STUDY OBJECTIVE

We sought to describe the feasibility of an emergency department observation unit (EDOU) treatment protocol for the management of uncomplicated acute-onset atrial fibrillation (AAF).

METHODS

This descriptive case series took place at a major suburban, university-affiliated teaching hospital. Patients were prospectively enrolled in an EDOU treatment protocol if they had uncomplicated AAF that failed initial ED attempts to convert to sinus rhythm. In the EDOU, patients underwent ECG monitoring, serial creatine kianse MB measurements, and further rate control with optional electrical cardioversion. Primary outcomes measured were EDOU rate of conversion to sinus rhythm, rate of discharge home, length of stay, positive diagnostic outcomes, complications of AAF, and 7-day return visits.

RESULTS

Sixty-seven patients were studied. Patients were symptomatic for a median of 4.0 hours, had mean initial ED pulse rates of 137+/-23 beats/min, and spent 4.7+/-2.2 hours in the ED before transfer to the EDOU. While in the EDOU, 55 (82%) patients converted to sinus rhythm. Five (7%) patients were admitted because of positive test results: 2 for myocardial infarction, 2 for fever, and 1 for ventricular tachycardia. Twelve (18%) patients remained in atrial fibrillation, with 9 admitted and 3 discharged. Overall, 81% of patients were discharged in 11.8+/-7.0 hours, and 19% were admitted after 17.6+/-9.5 hours of observation. Three discharged patients returned within 7 days, 2 for uncomplicated recurrent AAF and 1 for chest pain subsequently found to be noncardiac in origin. There were no major complications attributable to the EDOU protocol.

CONCLUSION

Selected patients with AAF for whom initial ED management fails can subsequently be managed in an EDOU with a high short-term conversion and discharge rate.

Postoperative atrial fibrillation

Postoperative atrial fibrillation is associated with significant morbidity, longer hospital stay, and higher related costs. Although the etiologic mechanism of postoperative atrial fibrillation and its optimum method of prophylaxis or management are not well defined, progress has been made during the past decade. This review focused on recent findings leading to a better understanding of the mechanisms and management of atrial fibrillation after surgery and current approaches directed at prevention of thromboembolic sequelae. Because postoperative atrial fibrillation is a frequent complication, preoperative risk assessment algorithms are being proposed to minimize the number of patients in whom an intervention to prevent atrial fibrillation is undertaken, and thus, reduce toxicity due to antiarrhythmic drug therapy. Finally, current data suggest that once atrial fibrillation has occurred, a rate-control strategy during the first 8 to 12 hours is reasonable because 50% of those episodes will resolve during this period. Beyond this period, a more aggressive approach using class IC or III antiarrhythmic drugs will hopefully reduce the number of patients requiring anticoagulation and prolonged drug therapy.

[The efficacy of scheduled cardioversion in atrial fibrillation. Comparison of two schemes of treatment: electrical versus pharmacological cardioversion]

INTRODUCTION AND OBJECTIVES

Atrial fibrillation is an arrhythmia with high morbidity and mortality. Restoring sinus rhythm is one of the principle objectives in its management. The present study aimed to assess the efficacy of scheduled cardioversion on atrial fibrillation by comparing two different therapeutic approaches: electrical vs. pharmacological cardioversion.

PATIENTS AND METHOD

Two hundred thirty patients with atrial fibrillation of more than 48 hours duration and requiring sinus rhythm restoration were included. One hundred forty-four patients underwent external electrical cardioversion and 86 patients received quinidine. We analyzed the rate of success, duration of hospital stay, complications and clinical and echocardiographic variable that might predict success.

RESULTS

Sinus rhythm was restored in 181 of 230 patients (79%). The rate of success was 77% (111/144 patients) in the electrical group and 81% (70 of 86 patients) in the pharmacological group (ns). In 13 pharmacological group patients for whom the first attempt failed attempt, a second attempt with electrical cardioversion was made and was successful in 8 patients (61%). No embolic complication was recorded and only two electrical disturbances were seen. Only atrial fibrillation lasting less than 8 weeks was associated with a higher success rate (p < 0.01).

CONCLUSIONS

Scheduled cardioversion in atrial fibrillation is an effective technique with a high success rate and a very low rate of complication. Electrical cardioversion and pharmacological cardioversion with quinidine are similarly effective, although the latter involves a longer hospital stay.

Postoperative atrial fibrillation in noncardiothoracic surgical patients

BACKGROUND

Atrial fibrillation is a common arrhythmia whose prevalence increases with age. It is a well-known complication of cardiothoracic surgery, but the incidence and contributing factors to the development of atrial fibrillation in noncardiothoracic surgical patients are less well known. This study was undertaken to investigate the incidence, association with known risk factors, treatment, and outcome of atrial fibrillation in postoperative noncardiac, nonthoracic surgical patients.

METHODS

A 2-year retrospective review was performed of all noncardiac, nonthoracic surgical patients that developed atrial fibrillation within 30 days of operation. Incidence, risk factors, treatment and outcome related to the development of this arrhythmia were analyzed.

RESULTS

Fifty-one patients developed atrial fibrillation during this study period for an incidence of 0.37%. Most had preexisting cardiac risk factors, a positive fluid balance, or had electrolyte or arterial oxygen saturation abnormalities. Two thirds were discharged home on new cardiac medications, 16% remained in atrial fibrillation, and 12% died.

CONCLUSIONS

New onset atrial fibrillation in this group of noncardiothoracic surgical patients is an uncommon problem that is a morbid event associated with significant mortality.

Pharmacologic conversion of atrial fibrillation: a systematic review of available evidence

This report reviews the efficacy of currently available antiarrhythmic agents for conversion of atrial fibrilation (AF) to normal sinus rhythm (NSR). A systematic search of literature in the English language was done on computerized databases, such as MEDLINE, EMBASE, and Current Contents, in reference lists, by manual searching, and in contact with expert informants. Published studies involving humans that described the use of antiarrhythmic therapy for conversion of AF to NSR were considered and only studies that examined the use of agents currently available in the United States were included. Studies exclusively describing antiarrhythmic therapy for conversion of postsurgical AF were excluded. The methodology and results of each trial were assessed and attempts were made to acquire additional information from investigators when needed. Assessment of methodological quality was incorporated into a levels-of-evidence scheme. Eighty-eight trials were included, of which 34 (39%) included a placebo group (level I data). We found in recent-onset AF of less than 7 days, intravenous (i.v.) procainamide, high-dose i.v. or high-dose combination i.v. and oral amiodarone, oral quinidine, oral flecainide, oral propafenone, and high-dose oral amiodarone are more effective than placebo for converting AF to NSR. In recent-onset AF of less than 90 days, i.v. ibutilide is more effective than placebo and i.v. procainamide. In chronic AF, oral dofetilide converts AF to NSR within 72 hours, and oral propafenone and amiodarone are effective after 30 days of therapy. We conclude than for conversion of recent-onset AF of less than 7 days, procainamide may be considered a preferred i.v. agent and propafenone a preferred oral agent. For conversion of recent-onset AF of longer duration (less than 90 days), i.v. ibutilide may be considered a preferred agent. For patients with chronic AF and left ventricular dysfunction, direct current cardioversion is the preferred conversion method. Larger, well-designed randomized controlled trials with clinically important endpoints in specific populations of AF patients are needed.