Prophylactic treatment after electroconversion of atrial fibrillation

Dietary sodium intake is associated with long-term risk of new-onset atrial fibrillation

BACKGROUND

The association between dietary salt intake and hypertension has been well documented. We evaluated the association between dietary sodium intake and the incidence of new-onset atrial fibrillation (AF) during a mean follow-up of 19 years among 716 subjects from the Oulu Project Elucidating Risk of Atherosclerosis (OPERA) cohort.

MATERIAL AND METHODS

Dietary sodium intake was evaluated from a seven-day food record. The diagnosis of AF (atrial flutter included) was made if ICD-10 code I48 was listed in the hospital discharge records during follow-up.

RESULTS

In the Kaplan-Meier curves, when quartiles of sodium consumption were considered, the cumulative proportional probabilities for AF events were higher in the highest (4th) quartile (16.8%) than in the lower quartiles (1st 6.7%, 2nd 7.3% and 3rd 10.6%) (p = .003). In the Cox regression analysis, sodium consumption (g/1000 kcal) as a continuous variable was independently associated with AF events (Hazard Ratio = 2.1 (95% CI, 1.2 to 3.7) p =.015) when age, body mass index, smoking (pack-years), office systolic blood pressure, left atrium diameter, left ventricular mass index and the use of any antihypertensive therapy were added as covariates.

CONCLUSIONS

These findings indicate that sodium intake is associated with the long-term risk of new-onset AF. Further confirmatory studies are needed. Key messages Sodium consumption correlated positively with CV risk factors: age, smoking, SBP, BMI and LDL-cholesterol. When quartiles of sodium consumption were considered, the AF incidence was higher in the highest quartile compared to lower quartiles. Sodium consumption as a continuous variable was independently associated with AF events when age, BMI, smoking, SBP, LAD, LVMI and the use of any antihypertensive therapy were considered.

Prediction of the recurrence of atrial fibrillation after successful cardioversion with P wave signal-averaged ECG

BACKGROUND

The recurrence of atrial fibrillation (AF) was often observed after cardioversion.

METHODS

In our study, a P wave triggered P wave signal-averaged ECG (P-SAECG) was performed on 118 consecutive patients 1 day after successful electrical cardioversion in order to evaluate the utility of this method to predict AF after cardioversion. We measured the filtered P wave duration (FPD) and the root mean square voltage of the last 20 ms of the P wave (RMS 20).

RESULTS

During a 1-year follow-up, a recurrence was observed in 57 patients (48%). Patients with recurrence of AF had a larger left atrial size (41.9 +/- 4.0 vs 39.3 +/- 3.1 mm, P < 0.0003), a longer FPD (139.6 +/- 16.0 vs 118.2 +/- 14.1 ms, P < 0.0001), and a lower RMS 20 (2.57 +/- 0.77 vs 3.90 +/- 0.99 microV, P < 0.0001). A cutoff point (COP) of FPD > or =126 ms and RMS 20 < or =3.1 microV could predict AF with a specificity of 77%, a sensitivity of 72%, a positive value of 75%, a negative predictive value of 75%, and an accuracy of 75%. A stepwise logistic regression analysis of variables identified COP (odds ratio 9.97; 95% CI, 4.10-24.24, P < 0.0001) as an independent predictor for recurrence.

CONCLUSIONS

We conclude that the probability of recurrence of AF after cardioversion could be predicted by P-SAECG. This method seems to be appropriate to demonstrate a delayed atrial conduction that might be a possible risk factor of reinitiation of AF.

Efficacy of dofetilide in the treatment of atrial fibrillation-flutter in patients with reduced left ventricular function: a Danish investigations of arrhythmia and mortality on dofetilide (diamond) substudy

BACKGROUND

In patients with left ventricular dysfunction, atrial fibrillation and flutter (AF and AFl, respectively) are common arrhythmias associated with increased morbidity and mortality. The present study investigated the potential of dofetilide in AF-AFl patients with left ventricular dysfunction to restore and maintain sinus rhythm, which might reduce mortality and hospitalizations.

METHODS AND RESULTS

In the Danish Investigations of Arrhythmia and Mortality ON Dofetilide (DIAMOND) studies, 506 patients were in AF-AFl at baseline. Over the course of study, cardioversion occurred in 148 (59%) dofetilide- and 86 (34%) placebo-treated patients. In these patients, the probability of maintaining sinus rhythm for 1 year was 79% with dofetilide versus 42% with placebo (P<0.001). Dofetilide had no effect on all-cause mortality, but restoration and maintenance of sinus rhythm was associated with significant reduction in mortality (risk ratio [RR], 0.44; 95% CI, 0.30 to 0.64; P<0.0001). In addition, dofetilide therapy was associated with a significantly lower risk ratio versus placebo for either all-cause (RR, 0.70; 95% CI, 0.56 to 0.89; P</=0.005) or congestive heart failure (RR, 0.69; 95% CI, 0.51 to 0.93; P</=0.02) rehospitalization.

CONCLUSIONS

Dofetilide is safe and increases the probability of obtaining and maintaining sinus rhythm in patients with structural heart disease. The present study suggests that restoration of sinus rhythm is associated with improved survival.

Atrial fibrillation: a review of mechanism, etiology, and therapy

The prevalence of elderly individuals in the populations of developed countries is increasing rapidly, and atrial fibrillation (AF) is quite common in these elderly patients: currently, 11% of the U.S. population is between the ages of 65 and 85 years; 70% of people with AF are between the ages of 65 and 85 years. AF causes symptoms secondary to hemodynamic derangements that are the result of increased ventricular response and loss of atrial booster function. AF can lead to reversible impairment of left ventricular function, cardiac chamber dilatation, clinical heart failure, and thromboembolic events. AF requires treatment in order to prevent these potential complications. Type Ia, Ic, and III antiarrhythmics are capable of converting AF to normal sinus rhythm (NSR). Amiodarone has the greatest efficacy and safety for converting AF and maintaining NSR while digoxin and verapamil are ineffective in restoring NSR. Quinidine, flecainide, disopyramide, and sotalol have also been shown to maintain NSR after conversion of AF. Proarrhythmia is a definite concern with the latter four agents. Alternative therapy for AF includes anticoagulation with warfarin or aspirin for the prevention of thromboembolic events, and a variety of agents to control the ventricular response. All medications used to treat AF carry significant risks in the elderly, whether from proarrhythmia, overdosing because of compliance errors, or hemorrhage secondary to anticoagulation. Treatment of AF must be based on a careful risk-benefit evaluation. The physician must know the capability of the particular patient as well as drug mechanisms and effects in the elderly. The decision to convert patients from AF to NSR or to leave the patient in AF and control the ventricular response represents a complex intellectual challenge. Factors favoring one or the other of these two clinical strategies are discussed. Multicenter clinical trials, for example, the Atrial Fibrillation Follow-up Investigation Rhythm Management (AFFIRM) trial, are currently underway to assess various clinical strategies for maintenance of NSR following conversion from AF. Amiodarone is one of the drugs under investigation.

Propafenone versus disopyramide for maintenance of sinus rhythm after electrical cardioversion of chronic atrial fibrillation: a randomized, double-blind study. PRODIS Study Group

Safety and efficacy of propafenone and disopyramide for long-term maintenance of sinus rhythm after electrical cardioversion was studied in 56 patients with chronic atrial fibrillation (median arrhythmia duration, 5 months). After cardioversion, patients were randomly assigned to receive double-blind propafenone 300 mg tid (25 patients) or disopyramide 250 mg tid (31 patients). Downward dose adjustment was allowed in case of intolerable side effects. The endpoints were arrhythmia recurrence; and side effects not amenable to dose reduction. For patients randomized to propafenone (mean dose, 878 +/- 65 mg/day), 66% [95% confidence interval [(CI) 46-85%] and 55% (95% CI, 34-76%) remained in sinus rhythm at 3 and 6 months, respectively (Kaplan-Meier method). Similar figures were found with disopyramide (mean dose, 704 +/- 81 mg/day): 71% (95% CI, 54-87%) and 67% (95% CI, 50-84%) at 3 and 6 months, respectively (p = NS). In the patients with a relapse of atrial fibrillation, the ventricular rate while still using the prophylactic agents did not increase significantly compared with precardioversion. However, one patient on disopyramide had an excessively high relapse heart rate (170 vs. 100 beats/min). Side effects were more frequent on disopyramide. Side effects necessitating drug discontinuation occurred in 12 patients: 4 patients (16%) on propafenone and 8 (26%) on disopyramide. Severe adverse effects occurred in two patients, who developed heart failure while on disopyramide. There were no proarrhythmic events or deaths. Thus, propafenone and disopyramide are equally effective for maintaining sinus rhythm after cardioversion of atrial fibrillation. Propafenone is, however, better tolerated than disopyramide, which may cause heart failure.

A randomized double-blind crossover study comparing the efficacy and tolerability of flecainide and quinidine in the control of patients with symptomatic paroxysmal atrial fibrillation

Patients with paroxysmal atrial fibrillation (PAF) are prone to recurrence. We compared the efficacy and tolerability of flecainide acetate in the control of PAF by means of conventional treatment with quinidine in 19 patients without structural heart disease. A randomized, placebo-controlled, crossover protocol consisting of 8 weeks of treatment with either agent was used. The recurrence of PAF was documented in a symptom diary and confirmed by event ECG recording. Complete control of symptoms was achieved in 4 of 19 and 2 of 11 of patients with flecainide and quinidine, respectively. Both agents prolonged the time to the first recurrence and significantly reduced the total duration of PAF recurrence by 40% and 47%, respectively (p less than 0.05 compared with placebo). Compared with quinidine, flecainide significantly reduced the frequency of recurrence and the rate of PAF during a recurrent episode. However, treatment with flecainide was associated with a higher incidence of symptomatic sinus pauses and visual disturbances compared with a higher incidence of gastrointestinal side effects with quinidine. During a follow-up period of 32 months, satisfactory control was achieved in 74% of patients with the use of these two antiarrhythmic agents.

Short- and long-term efficacy and safety of flecainide acetate for supraventricular arrhythmias

This report summarizes efficacy and safety data on the use of flecainide acetate for supraventricular arrhythmias. For this purpose, 60 original articles were identified by a literature search representing data from 1,835 treatment courses. In 18 trials, flecainide was administered intravenously; in 19, orally; and in 23, both forms of therapy were applied. There were 5 placebo-controlled and 12 comparative studies, whereas data from uncontrolled studies were represented in 43 articles. Short-term flecainide administration terminated atrial fibrillation in 65% of attempts and terminated atrial flutter in 28%. The drug was effective during long-term therapy for atrial fibrillation in 49% of patients, with similar efficacy rates in 11 comparative trials and in 16 uncontrolled studies. In randomized, placebo-controlled studies in patients with paroxysmal atrial fibrillation, flecainide was shown to reduce significantly the number of attacks, to prolong the time between attacks, and to improve quality of life. In patients with atrioventricular (AV) reciprocating tachycardias, acute drug administration was successful in 72%; 83% of patients with AV nodal reentrant tachycardias and 74% exhibiting arrhythmias associated with the Wolff-Parkinson-White syndrome responded acutely. During long-term therapy, efficacy rates were 70%, 78%, and 69%, respectively. Ectopic atrial tachycardia responded in 86% and 95% of patients treated with flecainide acutely or chronically. Data concerning drug-related side effects were available for 1,794 of 1,835 treatment courses (98%). Overall, 352 of 1,794 patients (20%) reported at least one non-cardiac or cardiac adverse experience.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacologic treatment of supraventricular tachycardia: the German experience

Tachyarrhythmias that originate above the bifurcation of the bundle of His or in tissue proximal to it are classified as supraventricular tachyarrhythmias (SVTs). Primary treatment of SVT tries to influence the underlying disease. Symptomatic therapy is subdivided into drug therapy, electrotherapeutic tools (e.g., antitachycardia pacemakers, catheter ablation), and antiarrhythmic surgery. Antiarrhythmic agents that slow conduction and suppress premature beats are efficient for emergency and long-term treatment of SVTs. We evaluated some of the most relevant antiarrhythmic drugs in SVT, including propafenone, diprafenone, cibenzoline, sotalol, and diltiazem; in addition, usage and efficacy of quinidine/verapamil, disopyramide, amiodarone, ajmaline, adenosine, and flecainide are summarized. In 1990, the case load of supraventricular arrhythmias per physician in Germany was more than 30 patients seen per month. About 50% of them were treated with drug therapy; i.e., approximately 17 patients were treated with antiarrhythmic drugs per month per physician for supraventricular arrhythmias. The most important antiarrhythmic agents used in Germany are propafenone (40%), combination of quinidine and verapamil (23%), sotalol (12%), disopyramide (6%), flecainide (6%), and other (13%).