Management of the older person with atrial fibrillation

Function and dysfunction of human sinoatrial node

Sinoatrial node (SAN) automaticity is jointly regulated by a voltage (cyclic activation and deactivation of membrane ion channels) and Ca²⁺ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca²⁺ release). Using optical mapping in Langendorff-perfused canine right atrium, we previously demonstrated that the β-adrenergic stimulation pushes the leading pacemaker to the superior SAN, which has the fastest activation rate and the most robust late diastolic intracellular calcium (Ca_i) elevation. Dysfunction of the superior SAN is commonly observed in animal models of heart failure and atrial fibrillation (AF), which are known to be associated with abnormal SAN automaticity. Using the 3D electroanatomic mapping techniques, we demonstrated that superior SAN served as the earliest atrial activation site (EAS) during sympathetic stimulation in healthy humans. In contrast, unresponsiveness of superior SAN to sympathetic stimulation was a characteristic finding in patients with AF and SAN dysfunction, and the 3D electroanatomic mapping technique had better diagnostic sensitivity than corrected SAN recovery time testing. However, both tests have significant limitations in detecting patients with symptomatic sick sinus syndrome. Recently, we reported that the location of the EAS can be predicted by the amplitudes of P-wave in the inferior leads. The inferior P-wave amplitudes can also be used to assess the superior SAN responsiveness to sympathetic stimulation. Inverted or isoelectric P-waves at baseline that fail to normalize during isoproterenol infusion suggest SAN dysfunction. P-wave morphology analyses may be helpful in determining the SAN function in patients at risk of symptomatic sick sinus syndrome.

Catheter Ablation Of Atrial Fibrillation In The Elderly: Risk Benefit Analysis

Over the past decade, catheter ablation has emerged as an important therapeutic option and reserved for drug refractory symptomatic paroxysmal and persistent atrial fibrillation (AF). Although elderly population constitutes the significant amount of AF patients, literature data is inadequate regarding the use of catheter ablation for elderly AF patients. Since there has been significant improvement in efficacy and safety of the AF ablation in last decade, it has become widespread accross the whole world. As the life expectancy continues to grow in population and outcomes of catheter ablation for AF further improve, higher number of elderly patients are likely to undergo catheter ablation for AF. Therefore, in this paper we reviewed the published literature to date regarding the clinical efficacy and safety of catheter ablation for AF in elderly patients.

Chronic amiodarone therapy impairs the function of the superior sinoatrial node in patients with atrial fibrillation

BACKGROUND

The mechanisms underlying amiodarone-induced sinoatrial node (SAN) dysfunction remain unclear, so we used 3-dimensional endocardial mapping of the right atrium (RA) to investigate.

METHODS AND RESULTS

In a matched-cohort design, 18 patients taking amiodarone before atrial fibrillation (AF) ablation (amiodarone group) were matched for age, sex and type of AF with 18 patients who had undergone AF ablation without taking amiodarone (no-amiodarone group). The amiodarone group had a slower heart rate than the no-amiodarone group at baseline and during isoproterenol infusion. Only the amiodarone group had sick sinus syndrome (n=4, 22%, P=0.03) and abnormal (>550ms) corrected SAN recovery time (n=5, 29%; P=0.02). The median distance from the junction of the superior vena cava (SVC) and RA to the most cranial earliest activation site (EAS) was longer in the amiodarone group than in the no-amiodarone group at baseline (20.5 vs. 10.6mm, P=0.04) and during isoproterenol infusion (12.8 vs. 6.3mm, P=0.03). The distance from the SVC-RA junction to the EAS negatively correlated with the P-wave amplitudes of leads II (r=-0.47), III (r=-0.60) and aVF (r=-0.56) (P<0.001 for all).

CONCLUSIONS

In a quarter of the AF patients, amiodarone causes superior SAN dysfunction, which results in a downward shift of the EAS and reduced P-wave amplitude in leads II, III and aVF at baseline and during isoproterenol infusion.

[Flecainide acetate utilisation review among general practitioners and hospital or office-based cardiologists in France. Obepine: observational study of flecainide]

A pharmacoepidemiological cross-sectional observational study was performed among a representative sample of French general practitioners and cardiologists. The aim of this study was to describe the prescription modalities of flecainide acetate, an Ic class antiarrhythmic, and how these modalities match the marketing authorization and the current summary of product characteristics. A total of 941 physicians participated in the study, 496 GPs and 445 cardiologists, and 1116 patients treated with flecainide for more than one month were included. On average, the patients were 68.7-years-old and 54% of them were women. Most of the initial flecainide prescriptions came from cardiologists (96%) and the check-up included an electrocardiogram (98%), a Holter monitoring (56%) and/or an echocardiography (71%). The preferred indication was supraventricular rhythm disorders (95%) and mostly atrial fibrillation (63%). A small proportion of coronary patients (7%) and of patient suffering from cardiac insufficiency (4%) was found. Flecainide was prescribed with a median posology of 150 mg per day, mostly as LP form (64%). Overall, the indications specified in the summary of product characteristics were respected in 90% of the cases, the contraindications in 91% of the cases and the patient follow-up was appropriate in 99% of the cases. In conclusion, the study showed that the prescription's conditions of flecainide in France complied with the summary of product characteristics data for most of the prescribing physicians with a respect of the indications, contraindications and management recommendations in 84% of the cases.

Atrial fibrillation in the elderly: facts and management

Although atrial fibrillation is not widely known by the general public, in developed countries it is the most common arrhythmia. The incidence increases markedly with advancing age. Thus, with the growing proportion of elderly individuals, atrial fibrillation will come to represent a significant medical and socioeconomic problem. The consequences of atrial fibrillation have the greatest impact. The risk of thromboembolism is well known; other outcomes of atrial fibrillation are less well recognised, such as its relationship with dementia, depression and death. Such consequences are responsible for diminished quality of life and considerable economic cost. Atrial fibrillation is characterised by rapid and disorganised atrial activity, with a frequency between 300 and 600 beats/minute. The ventricles react irregularly, and may contract rapidly or slowly depending on the health of the conduction system. Clinical symptoms are varied, including palpitations, syncope, dizziness or embolic events. Atrial fibrillation may be paroxysmal, persistent or chronic, and a number of attacks are asymptomatic. Suspicion or confirmation of atrial fibrillation necessitates investigation and, as far as possible, appropriate treatment of underlying causes such as hypertension, diabetes mellitus, hypoxia, hyperthyroidism and congestive heart failure. In the evaluation of atrial fibrillation, cardiac exploration is invaluable, including electrocardiogram (ECG) and echocardiography, with the aim of detecting cardiac abnormalities and directing management. In elderly patients (arbitrarily defined as aged >75 years), the management of atrial fibrillation varies; it requires an individual approach, which largely depends on comorbid conditions, underlying cardiac disease, and patient and physician preferences. This management is essentially based on pharmacological treatment, but there are also nonpharmacological options. Two alternatives are possible: restoration and maintenance of sinus rhythm, or control of ventricular rate, leaving the atria in arrhythmia. Pharmacological options include antiarrhythmic drugs, such as class III agents, beta-blockers and class IC agents. These drugs have some adverse effects, and careful monitoring is necessary. The nonpharmacological approach to atrial fibrillation includes external or internal direct-current cardioversion and new methods, such as catheter ablation of specific foci, an evolving science that has been shown to be successful in a very select group of atrial fibrillation patients. Another serious challenge in the management of chronic atrial fibrillation in older individuals is the prevention of stroke, its primary outcome, by choosing an appropriate antithrombotic treatment (aspirin or warfarin). Several risk-stratification schemes have been validated and may be helpful to determine the best antithrombotic choice in individual patients.

Amiodarone and the risk of bradyarrhythmia requiring permanent pacemaker in elderly patients with atrial fibrillation and prior myocardial infarction

OBJECTIVES

The aim of this study was to determine whether the use of amiodarone in patients with atrial fibrillation (AF) increases the risk of bradyarrhythmia requiring a permanent pacemaker.

BACKGROUND

Reports of severe bradyarrhythmia during amiodarone therapy are infrequent and limited to studies assessing the therapy's use in the management of patients with ventricular arrhythmias.

METHODS

A study cohort of 8,770 patients age > or =65 years with a new diagnosis of AF was identified from a provincewide database of Quebec residents with a myocardial infarction (MI) between 1991 and 1999. Using a nested case-control design, 477 cases of bradyarrhythmia requiring a permanent pacemaker were matched (1:4) to 1,908 controls. Multivariable logistic regression was used to estimate the odds ratio (OR) of pacemaker insertion associated with amiodarone use, controlling for baseline risk factors and exposure to sotalol, Class I antiarrhythmic agents, beta-blockers, calcium channel blockers, and digoxin.

RESULTS

amiodarone use was associated with an increased risk of pacemaker insertion (OR: 2.14, 95% confidence interval [CI]: 1.30 to 3.54). This effect was modified by gender, with a greater risk in women versus men (OR: 3.86, 95% CI: 1.70 to 8.75 vs. OR: 1.52, 95% CI: 0.80 to 2.89). Digoxin was the only other medication associated with an increased risk of pacemaker insertion (OR: 1.78, 95% CI: 1.37 to 2.31).

CONCLUSIONS

This study suggests that the use of amiodarone in elderly patients with AF and a previous MI increases the risk of bradyarrhythmia requiring a permanent pacemaker. The finding of an augmented risk of pacemaker insertion in elderly women receiving amiodarone requires further investigation.

Amiodarone and mortality among elderly patients with acute myocardial infarction with atrial fibrillation

BACKGROUND

Amiodarone has been shown to be safe in patients with acute myocardial infarction (AMI) who are at risk for sudden cardiac death. However, there is limited data concerning the safety of amiodarone in patients who experience AMI complicated by atrial fibrillation.

METHODS

To determine the safety of amiodarone therapy, we conducted a retrospective analysis of elderly patients hospitalized with AMI who experienced atrial fibrillation and had survived to hospital discharge (n = 17,597). Amiodarone prescribed at discharge was evaluated for its association with short-term and long-term mortality in crude and adjusted analyses employing propensity score methods.

RESULTS

Of the 17,597 patients, 550 patients (3.1%) were prescribed amiodarone, 2317 patients (13.2%) were prescribed other antiarrhythmic agents (excluded from analysis), and 14,730 (83.7%) were prescribed no antiarrhythmic medication at discharge. Thirty-day mortality rates were similar for patients prescribed amiodarone and those not prescribed amiodarone (6.8% amiodarone vs 5.4% no amiodarone, P =.21), but mortality at 1 year was higher among patients prescribed amiodarone (35.6% vs 31.6%, P =.001). However, amiodarone was not associated with mortality at 30 days (odds ratio 0.80, 95% CI 0.53-1.20) or at long-term follow-up (mean duration 612 days, hazard ratio 1.04, 95% CI 0.92-1.18) after multivariable modeling.

CONCLUSIONS

Amiodarone was not independently associated with short-term or long-term mortality in elderly patients discharged after a hospitalization for AMI complicated by atrial fibrillation. Although our data suggest that amiodarone may be safe to use in this population, randomized controlled trial data are needed to confirm this finding.

Does advanced age affect the immediate and long-term results of direct-current external cardioversion of atrial fibrillation?

OBJECTIVES

To determine whether advanced age affects the immediate and long-term results of direct-current external cardioversion (ECV) of atrial fibrillation (AF), the sustained arrhythmia most commonly encountered in older patients.

DESIGN

Retrospective analysis of medical records.

SETTING

Intensive care unit.

PARTICIPANTS

Two hundred fifty consecutive patients(age 34-100) with AF who underwent ECV following a standardized protocol in an intensive care unit.

MEASUREMENTS

Immediate efficacy of ECV, defined as recovery of sinus rhythm, and maintenance of sinus rhythm over the follow-up were study outcomes. The univariate and multivariate associations of immediate efficacy of ECV and long-term results with clinical variables were analyzed.

RESULTS

At univariate analysis, immediate efficacy of ECV (overall, 91.2%) was lower in older patients and in those with chronic obstructive pulmonary disease, higher for a 3- to 90-day pre-ECV duration of AF than for a duration of 2 days or less or more than 90 days, and independent of underlying cardiac disease, hypertension, diabetes mellitus, previous AF, and left atrial dimension. However, pre-ECV duration of AF was the only multivariate predictor of ECV immediate success. Major complications occurred in only three patients. Of 220 patients discharged in sinus rhythm, 211 were followed up for a mean period +/- standard deviation of 34 +/- 25 months. AF relapsed in 45.5% of them. At multivariate analysis, underlying cardiac disease was the only predictor of the relapse rate, and relapse rate was lower in coronary heart disease than in valvular heart disease, congestive heart failure, or lone AF.

CONCLUSION

Immediate and long-term results of ECV of AF, an effective and safe procedure, are unaffected by age,at least after adjusting for several covariates.

Baseline characteristics of patients with atrial fibrillation: the AFFIRM Study

BACKGROUND

Although anticoagulation therapy is accepted for most patients with atrial fibrillation, 2 different strategies exist for management of the cardiac rhythm: atrial fibrillation is allowed to persist while the ventricular rate is controlled; and atrial fibrillation is converted, and an attempt is made to maintain sinus rhythm.

METHODS

The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) Study was a randomized clinical trial that compared these 2 strategies. We report the baseline characteristics of the patients enrolled in the AFFIRM Study.

RESULTS

More than 7400 patients at more than 200 North American hospitals and clinics qualified for enrollment in the AFFIRM Study. A total of 4060 patients were enrolled in the AFFIRM Study. The average age of patients enrolled was 70 years, with 39% female and 89% white. Hypertension was present in 71%. Coronary artery disease was present in 38%. Echocardiography was performed in 3311 patients, and results showed normal ventricular function in 68% and normal left atrial size in 33%. Most patients with recurrent episodes had symptoms with atrial fibrillation. Approximately one third of patients were enrolled with a first episode of atrial fibrillation.

CONCLUSION

The AFFIRM Study enrolled 4060 predominantly elderly patients with atrial fibrillation to compare ventricular rate control with rhythm control. The patients in the AFFIRM Study were representative of patients at high risk for complications from atrial fibrillation, which indicates that the results of this large clinical trial will be relevant to patient care.

Inappropriate use of digoxin in older hospitalized heart failure patients

BACKGROUND

Older adults are more likely to suffer from the adverse effects of digoxin. Studies have described the inappropriate use of digoxin in various populations. The objective of this study was to determine the correlates of inappropriate digoxin use in older heart failure patients.

METHODS

We studied older hospitalized heart failure patients with documented left ventricular (LV) function evaluation and electrocardiography. Digoxin use was considered inappropriate if patients had preserved LV systolic function (ejection fraction greater > or =40%) or if they had no atrial fibrillation (AF). We compared baseline patient characteristics by indication for digoxin and tested statistical significance using Pearson's chi-square analysis and Student's t tests. Using logistic regression, we determined the correlates of inappropriate use and initiation of digoxin.

RESULTS

Subjects (N = 603) had a mean age of 79 (+/-7) years; 59% were women, and 18% were African American. A total of 376 patients (62%) were discharged on digoxin, and 223 (37%) had no indication for its use. Half of the patients without an indication for digoxin received the drug. Of 132 patients without an indication and not already on digoxin, 38 (29%) were initiated on it. After adjustment for various patient and care characteristics, prior digoxin use (adjusted odds ratio [OR] 11.47, 95% confidence interval [CI] 5.72-23.02) and pulse > or =100/min (adjusted OR 2.33, 95% CI 1.10-4.94) were associated with inappropriate digoxin use. Pulse > or =100/min was also associated with inappropriate initiation of the drug (adjusted OR 2.95, 95% CI 1.28-6.78).

CONCLUSIONS

Inappropriate use of digoxin was common and was associated with prior use. Tachycardia was associated with inappropriate use and initiation. Electrocardiography and echocardiography should be performed in all older heart failure patients. Digoxin therapy should not be initiated or continued in patients without any evidence of LV systolic dysfunction or chronic AF.

Prescribing for seniors: it's a balancing act

PURPOSE

To present a rational approach to prescribing for seniors, balancing the need for and number of medications.

DATA SOURCES

Selected evidence-based reviews and research articles and the author's own experience.

CONCLUSIONS

Whenever possible, alternatives to medication therapy should be considered as the initial treatment of choice; however, medications should be prescribed when indicated and not withheld due to a patient's age. Reducing the number of medications reduces the risk for adverse drug reactions and drug-to-drug interactions.

IMPLICATIONS FOR PRACTICE

Careful review of an older patient's medication list prior to initiating new therapy is necessary. Follow-up care to review the efficacy and monitor any potential side effects is crucial. Timely discontinuation of a drug when therapeutic usefulness is surpassed is equally important.

Internal low energy atrial cardioversion: efficacy and safety in older patients with chronic persistent atrial fibrillation

BACKGROUND

Low-energy internal atrial cardioversion is a relatively new technique based on delivery of intracardiac shocks through transvenous catheters placed into the atria or the vessels.

OBJECTIVE

The aim of this study was to assess in older and younger patients with chronic persistent atrial fibrillation (AF) the efficacy and safety of transvenous low-energy internal atrial cardioversion performed without routine administration of sedatives or anesthetics.

DESIGN

A prospective longitudinal study.

SETTING

A cardiological university hospital.

PARTICIPANTS

82 patients, divided into older (> or = 60 years) (n = 49) and younger (n = 33) subjects.

MEASUREMENTS

Atrial defibrillation threshold for internal cardioversion, measured as leading edge voltage (V) and delivered energy (J) of effective shocks, percentage of patients maintaining sinus rhythm at short-term (within 3 days) and at long-term follow-up.

METHODS

Patients with chronic persistent AF, treated with oral anticoagulants for at least 3 to 4 weeks, were admitted to hospital. Following a clinical work-up, patients were subjected to low-energy internal atrial cardioversion with shock delivery according to a step-up protocol.

RESULTS

Internal cardioversion was effective in restoring sinus rhythm in 90% (44/49) of the older patients and in 94% (31/33) of the younger patients. Shocks were effective at a mean energy between 6 and 8 joules (range 0.9-23) and administration of sedatives or anesthetics was required during the procedure in 22% (11/49) of older and in 48% (16/33) of younger patients (P = .026 at chi-square). No major complications occurred during the procedure. Pharmacological prophylaxis of AF recurrences was instituted immediately following the procedure. During inhospital stay and during the follow-up (mean 12 +/- 9 months for older patients and 15 +/- 10 months for younger patients), AF recurred in 39% (17/44) of older patients and in 16% (5/31) of younger subjects (P = .064 at chi-square).

CONCLUSIONS

Internal low energy cardioversion is a very effective procedure for restoring sinus rhythm in patients with AF; it can be performed in older patients, and administration of sedatives or anesthetics can be avoided or minimized in a substantial proportion of subjects. Recurrences of AF in the long term tend to be higher in older subjects and intensive prophylaxis with antiarrhythmic drugs is required.

Heart failure complicating acute myocardial infarction

Older people with congestive heart failure associated with acute myocardial infarction should be treated with loop diuretic therapy. Class I indications for the use of early intravenous beta blockade in patients with acute myocardial infarction are patients without a contraindication to beta blockers who can be treated within 12 hours of onset of myocardial infarction; patients with continuing or recurrent ischemic pain; and patients with tachyarrythmias, such as atrial fibrillation with a rapid ventricular rate. Class I indications for the use of angiotensin-converting enzyme inhibitors during acute myocardial infarction are (1) patients within the first 24 hours of onset of a suspected acute myocardial infarction with ST segment elevation in two or more anterior precordial leads or with clinical heart failure in the absence of significant hypotension or contraindications to the use of angiotensin-converting enzyme inhibitors, (2) patients with myocardial infarction and a left ventricular ejection fraction of less then 40%, (3) and patients with clinical heart failure on the basis of systolic pump dysfunction during and after convalescence from acute myocardial infarction. No class I indications exist for using calcium channel blockers or magnesium during acute myocardial infarction.