Pharmacologic control of heart rate in atrial fibrillation

Atrial fibrillation is associated with a resting heart rate in excess of age-matched subjects in sinus rhythm, and there is an additional steep rise in rate during exertion. This article reviews the factors responsible for this tachycardia, the pharmacologic agents commonly used for heart rate control, and the effects of atrial antiarrhythmic agents on the heart rate during paroxysmal atrial fibrillation.     

Renal-hepatic-pancreatic dysplasia: an autosomal recessive malformation

BACKGROUND: Pharmacological conversion of paroxysmal atrial fibrillation is frequently necessary. The aim of this study was to compare intravenous propafenone, a class Ic antiarrhythmic agent, with placebo in paroxysmal atrial fibrillation (AF) of recent onset (< 72 h). PATIENTS AND METHODS: We randomly allocated 75 patients, aged 18 to 70 years, with paroxysmal AF to receive intravenous propafenone (2 mg/kg in 15 min followed by 1 mg/kg in 2 h) or the matching placebo. Patients were followed for 3 h. Exclusion criteria were the presence of one of the following: clinical heart failure, recent acute myocardial infarction, hypotension, atrioventricular block, Wolff-Parkinson-White syndrome, or current treatment with antiarrhythmic agents or digitalis. RESULTS: No sign of heart disease was found in 74.7% of the patients. Echocardiographically determined left atrium diameter was similar in the two groups. Conversion to sinus rhythm occurred in 24 of 41 patients allocated to propafenone and in 10 of 34 patients allocated to placebo (odds ratio 3.2, 95% confidence intervals 1.3-7.9; p < 0.01). Mean conversion time was 34 +/- 29 and 71 +/- 55 min, respectively, for propafenone and placebo. Mean heart rate in nonconverters decreased from 146 to 109 beats/min in patients treated with propafenone while it remained virtually unchanged in those treated with placebo. Only minor side effects were noted. CONCLUSIONS: Intravenous propafenone is an effective therapeutic option for restoring sinus rhythm in patients with paroxysmal AF of recent onset.     

Depressives'' future-event schemas and the social inference process

Atrial fibrillation (AF) is the most common, sustained, symptomatic tachyarrhythmia that clinicians are called upon to manage. Management strategies include ventricular rate control coupled with anticoagulation, versus restoration and maintenance of sinus rhythm. Rate control may be achieved pharmacologically, with agents that impair AV nodal conduction directly and/or by increasing parasympathetic/sympathetic balance, or by modifying or ablating the AV nodal region anatomically. Rhythm control may be achieved by electrical or pharmacologic conversion followed by maintenance of sinus rhythm by pharmacologic (or occasionally ablative) therapies. This article will present current approaches to rate and rhythm control issues in atrial fibrillation. Parts 1 and 2, published previously, dealt with rate control and with the restoration of sinus rhythm. Part 3, the current article, details the selection process of choosing a therapy to maintain sinus rhythm, including the likelihood of success, the risks of therapy, and individualization of therapy as dependent upon the nature of the structural heart disease present. It also discusses nonpharmacologic approaches that have been recently developed or are undergoing development. One suggested drug selection algorithm is provided.     

Drugs for conversion of atrial fibrillation

Atrial fibrillation is the most common arrhythmia in patients visiting a primary care practice. Although many patients with atrial fibrillation experience relief of symptoms with control of the heart rate, some patients require restoration of sinus rhythm. External direct current (DC) cardioversion is the most effective means of converting atrial fibrillation to sinus rhythm. Pharmacologic cardioversion, although less effective, offers an alternative to DC cardioversion. Several advances have been made in antiarrhythmic medications, including the development of ibutilide, a class III antiarrhythmic drug indicated for acute cardioversion of atrial fibrillation. Other methods of pharmacologic and nonpharmacologic cardioversion remain under development. Until the results of several large-scale randomized clinical trials are available, the decision to choose cardioversion or maintenance of sinus rhythm must be individualized, based on relief of symptoms and reduction of the morbidity and mortality associated with atrial fibrillation.     

Right-sided maze procedure for right atrial arrhythmias in congenital heart disease

BACKGROUND: Atrial fibrillation and flutter, commonly associated with congenital heart anomalies that cause right atrial dilatation, may cause significant morbidity and reduction of quality of life, even after surgical repair of the anomalies. METHODS: In an effort to reduce the incidence of atrial tachyarrhythmias after repair of right-sided congenital heart disease, we performed a concomitant right-sided maze procedure. RESULTS: Eighteen patients with paroxysmal atrial fibrillation or flutter (n = 12) or chronic atrial fibrillation or flutter (n = 6) aged 10.9 to 68.4 years (mean 34.9 years) underwent a right-sided maze in association with repair of Ebstein's anomaly (n = 15), congenital tricuspid insufficiency (n = 2), and isolated atrial septal defect (n = 1). There were no early deaths, reoperations, or complete heart block. Discharge rhythm was sinus (n = 16) or junctional (n = 2). Follow-up was complete in all 18 patients and ranged from 3.1 to 17.2 months (mean 8.1 months); all are in New York Heart Association class I. Early postoperative arrhythmias developed in 3 patients (all were converted to sinus rhythm by antiarrhythmic drugs). There were no late deaths or reoperations. CONCLUSIONS: The inclusion of a right-sided maze procedure with cardiac repair in patients having congenital heart anomalies that cause right atrial dilatation and associated atrial tachyarrhythmias is effective in eliminating or reducing the incidence of those arrhythmias.     

CD34+-enriched donor lymphocyte infusions in a case of pure red cell aplasia and late graft failure after major ABO-incompatible bone marrow transplantation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Increased life expectancy will result in a higher prevalence of AF. Treatment of AF constitutes a persistent medical dilemma. Different multicenter trials have confirmed that oral anticoagulant therapy is the best choice for the prevention of systemic embolism. It must be recognized, however, that the incidence of systemic embolism in patients with AF varies according to the presence and type of underlying heart disease. Advanced age increases the risk of emboli in patients with AF. At the same time, older patients have a higher risk of hemorrhage when treated with oral anticoagulants. Thus, careful titrated individual oral anticoagulant therapy targeted to a safe and effective INR must be considered in patients with AF. Another dilemma in AF patients is the convenience of restoring sinus rhythm and indicating permanent antiarrhythmic therapy versus the alternative of heart rate control plus oral anticoagulants. Several multicenter trials now in progress have addressed this issue and most likely will answer these questions. Identification of patients with paroxysmal AF and risk of systemic embolism constitutes another dilemma, since only a small proportion of these patients evolve to chronic arrhythmia. Advanced age, history of hypertension and left atrial enlargement in 2D Echo are well recognized risk factors for embolism in patients with non valvular paroxysmal AF. A history of previous embolism constitutes another risk factor and supports the hypothesis that AF may activate systemic coagulation factors and left atrial thrombus formation in some patients.     

Actinic superficial folliculitis

BACKGROUND: The maze operation is effective for the restoration of sinus rhythm; however, restoration of atrial mechanical function has not been demonstrated in all patients. METHODS: Maze operations were performed in 32 patients (13 men, 19 women; mean age 47.1 +/- 9.0 years) combined with valvular surgery (n = 25), coronary artery bypass graft (CABG) (n = 3), and others (n = 4). At 1 week, 3 months, 6 months, and 1 year after the operation, prospective serial Doppler echocardiographic examination was carried out to determine the presence of atrial mechanical function. RESULTS: Sinus rhythm was restored and maintained during the follow-up period in 26 (81%) patients; in 22 patients this was due solely to the operation, whereas in four patients an antiarrhythmic agent was needed to maintain sinus rhythm. Another four patients showed paroxysmal atrial fibrillation (AF) despite treatment with an antiarrhythmic agent. Right atrial mechanical function was restored in all 30 patients with sinus rhythm or paroxysmal AF; in 19 (63%) of these, left atrial mechanical function was restored. In patients with restored left atrial mechanical function, peak A velocity (A) and A/E ratio (A/E) of mitral inflow were significantly lower than in the 16 postoperative control patients (A: 0.46 +/- 0.14 m/sec vs 0. 75 +/- 0.29 m/sec, p < 0.01; A/E: 0.40 vs 0.80, p < 0.01). In patients with left atrial mechanical function, the duration of AF was significantly shorter than in patients without left atrial mechanical function (1.9 +/- 2.9 years vs 7.1 +/- 3.0 years, p < 0. 01), but there were no significant differences in left atrial size and volume. CONCLUSIONS: The maze operation could be safely added to standard open heart surgery for the correction of underlying structural heart disease. The rate of conversion to sinus rhythm resulting solely from the operation might be lower than the rates previously reported with only the duration of AF adversely affecting the restoration of left atrial mechanical function. Considering the fact that not all patients converted to sinus rhythm show atrial mechanical function, the role of the maze operation in the prevention of systemic embolism, with subsequent improvement in survival, requires further study.     

Analysis of obstetric complications reported to the National Patient Insurance Association in Finland from 1987 to 1995

OBJECTIVE: To review comparative studies evaluating oral propafenone for restoring sinus rhythm in recent onset atrial fibrillation. DATA SOURCES: A MEDLINE search of the English-language literature (1966 to 1996) along with any referenced articles not identified by MEDLINE. STUDY SELECTION: Because intravenous propafenone is not marketed in Canada, only studies evaluating oral propafenone were included. Studies were selected if they compared oral propafenone with placebo or other antiarrhythmic agents for converting recent onset atrial fibrillation to normal sinus rhythm. DATA SYNTHESIS: Propafenone is often used as a first-line agent for pharmacological cardioversion of atrial fibrillation. In earlier studies, the efficacy of propafenone in restoring sinus rhythm was reported to be low with conversion rates of 6% to 62%. Many of these studies were noncomparative and often included patients with refractory, chronic atrial fibrillation or employed suboptimal doses of propafenone. More recently propafenone has been evaluated in the treatment of recent onset atrial fibrillation by using a single 600 mg oral loading dose. Success rates of 76% at 8 h and 83% at 12 h following the loading dose are reported. The incidence of atrial flutter during active treatment was similar to that with placebo, with the majority exhibiting 2:1 or greater atrioventricular conduction ratios and heart rates 150 beats/min or less. CONCLUSIONS: A single 600 mg oral dose of propafenone is highly effective at restoring sinus rhythm in patients with acute onset atrial fibrillation with few adverse effects. The small studies reviewed cannot lead to definitive conclusions about the safety of propafenone without prior administration of agents for rate control.     

Atrioverter: an implantable device for the treatment of atrial fibrillation

BACKGROUND: During atrial fibrillation, electrophysiological changes occur in atrial tissue that favor the maintenance of the arrhythmia and facilitate recurrence after conversion to sinus rhythm. An implantable defibrillator connected to right atrial and coronary sinus defibrillation leads allows prompt restoration of sinus rhythm by a low-energy shock. The safety and efficacy of this system, called the Atrioverter, were evaluated in a prospective, multicenter study. METHODS AND RESULTS: The study included 51 patients with recurrent atrial fibrillation who had not responded to antiarrhythmic drugs, were in New York Heart Association Heart failure class I or II, and were at low risk for ventricular arrhythmias. The atrial defibrillation threshold had to be 相似文献   

Spontaneous reinitiation of atrial fibrillation following transvenous atrial defibrillation

Spontaneous reinitiation of atrial fibrillation (AF) has not been systematically looked at in patients undergoing transvenous AF. This study involved 11 patients, the mean age 60 +/- 8 years, 3 male and 8 female, in whom transvenous atrial defibrillation successfully converted AF to sinus rhythm. Eight patients had paroxysmal AF and three patients had chronic persistent AF for 4 weeks or more. Four patients were taking antiarrhythmic medications at the time of testing. Multipolar transvenous catheters were positioned inside the coronary sinus, right atrium, and the right ventricle. Atrial defibrillation testing was performed using the METRIX atrial defibrillation system in nine patients and the Ventritex HVSO2 in the remaining two patients. A total of 64 therapeutic shocks (range 3-11) were delivered in the 11 patients, and 31 of these successfully converted AF to sinus rhythm. In four patients spontaneous AF was reinitiated following 12 successful transvenous atrial defibrillation episodes. The mean time to reinitiation of AF following shock delivery and restoration of sinus rhythm was 8.26 +/- 5.25 seconds, range 1.8-19.9 seconds. All 12 episodes of spontaneous AF were preceded by a spontaneous premature atrial complex. The coupling interval of the premature atrial complexes was 443 +/- 43 ms, range 390-510 ms. None of the patients taking antiarrhythmic medications or those demonstrating no premature atrial complexes had spontaneous reinitiation of AF. In conclusion, spontaneous reinitiation of AF can occur in a significant proportion of patients with AF undergoing transvenous atrial defibrillation. This phenomenon is preceded by the occurrence of atrial premature complex. Findings of this study may have significant clinical implications.     

Paroxysmal atrial fibrillation

Paroxysmal atrial fibrillation is the most frequent of cardiac arrhythmias and its frequency increases with age. Its diagnosis is difficult since the symptoms are often absent or misleading. It is based on electrocardiogram performed during the attack, and this has been made easier by the Holter technique or by sequential recordings triggered by the patient himself. It is only in special cases, when percritical recordings could not be made that intracavitary electrophysiological study is used to obtain indirect arguments in favour of the diagnosis. All heart diseases can be attended by this cardiac rhythm disorder which usually marks an unfavourable turn in the course of the disease, with an increased risk of sudden death in the end. But in most cases the only disorder found is a common arterial hypertension. Atrial fibrillation carries a risk of peripheral, and in particular cerebral, embolism evaluated at 5% per annum. This risk is high in patients with cardiopathy, but it also exists even with a normal heart. The value of anticoagulants has been demonstrated by large controlled studies, but it is important to know that a very strong anticoagulant treatment is unnecessary to reduce the risk of embolism. Only antiarrhythmic agents can maintain the patients in sinus rhythm for as long as possible before the passage to permanent fibrillation. Although no beneficial effect on mortality has been proved, these drugs are indicated for patients who have very marked symptoms or a major cardiopathy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Retrospective study of auricular fibrillation of recent onset in a hospital emergency service: frequency, clinical presentation, and predictive factors of early conversion to sinus rhythm

AIM: To evaluate the proportion of emergencies due to recent-onset atrial fibrillation (AF), its clinical characteristics and in-hospital follow-up. The clinical predictors of conversion to sinus rhythm within the first 24 hours were analyzed. PATIENTS AND METHODS: 34,445 consecutive reports from patients presenting themselves at the emergency room of a community hospital during 15 months were retrospectively studied. The clinical reports of all patients (n = 186) with symptoms of recent onset AF (< 15 days) were reviewed. RESULTS: Hypertension (n = 77.41%) and lone AF (52 patients, 28%) were the most common etiologies. Forty seven patients (25%) presented with heart failure and the onset time was > 24 hours in 77 cases (41%). Conversion to sinus rhythm was observed in 71 out of 166 patients with at least 24 hours of follow-up (42.8%). Age < 60 years, the absence of cardiac disease, a NYHA functional class I, the absence of heart failure at the emergency room and the time from onset < 24 hours were significantly associated with conversion to sinus rhythm. The last two variables were selected as independent predictors by logistic regression analysis (sensitivity: 80%, specificity: 68%). CONCLUSIONS: We conclude that recent-onset AF represents 0.54% of all the hospital emergencies. The time from onset and the presence of heart failure predict the probability of conversion to sinus rhythm within the first 24 hours.     

Aging and retirement: a difficult issue for individual psychoanalysts and organized psychoanalysis

Atrial fibrillation (AF) remains a challenge to medical therapy. Over the past several years, a variety of experimental models of AF have been developed. These have provided insights into mechanisms underlying AF and antiarrhythmic drug action against the arrhythmia. A variety of drugs effective against clinical AF, including flecainide, propafenone, procainamide, and sotalol, have been found to terminate experimental AF. All of these agents appear to act by prolonging the wavelength for atrial reentry at rapid rates, thereby increasing the size and decreasing the number of functional circuits maintaining the arrhythmia. While the ability to terminate AF is determined by refractoriness prolongation at rapid rates, refractoriness prolongation at slow rates (e.g., sinus rhythm) can prevent AF induction by premature beats. Thus, drugs with strong reverse use-dependence (like sotalol) may be much more effective in preventing than in terminating AF. Spacial heterogeneity in refractoriness is an important contributor to AF occurrence in some models, particularly vagal AF, and is reduced by some (but not all) drugs that terminate AF. New insights are being gained into mechanisms of electrical remodeling, which promotes AF maintenance when rapid atrial rates are maintained, such as during AF. This electrical remodeling may be an interesting novel target for therapy of AF. Insights into AF mechanisms obtained in experimental models of AF should help in the development of new and improved therapeutic approaches.     

Monetary compensation for plasma donors: a record of safety

BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia after open heart surgery. Traditional treatment with a range of antiarrhythmic drugs and electrical cardioversion is associated with considerable side effects. The aim of this study was to examine the feasibility and efficacy of low-energy atrial defibrillation with temporary epicardial defibrillation wire electrodes. METHODS AND RESULTS: Epicardial defibrillation wire electrodes were placed at the left and right atria during open heart surgery in 100 consecutive patients (age 65+/-9 years; male to female ratio 67:23). Electrophysiological studies performed postoperatively revealed a test shock (0.3 J) impedance of 96+/-12 omega (monophasic) and 97+/-13 omega (biphasic). During their hospital stay, AF occurred in 23 patients (23%) at 2.1+/-1.3 days postoperatively. Internal atrial defibrillation was performed in 20 patients. Of these patients, 80% (16/20) were successfully cardioverted with a mean energy of 5.2+/-3 J. Early recurrence of AF (< or =60 seconds after defibrillation) developed in 8 patients. Five patients had multiple episodes of AF. In total, 35 episodes of AF were treated, with an 88% success rate. Only 6 patients (30%) required sedation. No complications were observed with shock application or with lead extraction. CONCLUSIONS: Atrial defibrillation with temporary epicardial wire electrodes can be performed safely and effectively in patients after cardiac operations. The shock energy required to restore sinus rhythm is low. Thus, patients can be cardioverted without anesthesia.     

The Brevibacterium albidum gene encoding the arginine tRNACCG complements the growth defect of an Escherichia coli strain carrying a thermosensitive mutation in the rnpA gene at the nonpermissive temperature

Antiarrhythmic drug prophylaxis in patients with atrial fibrillation (AF) is associated with a high incidence of arrhythmic recurrence. Uncontrolled studies have suggested that low-dose amiodarone may be superior in terms of efficacy to other antiarrhythmic drugs while having an acceptable side effect profile. The Canadian Trial of Atrial Fibrillation (CTAF) is a 25-center study sponsored by the Medical Research Council of Canada to determine the best treatment strategy to maintain sinus rhythm in patients with persistent or paroxysmal AF. Recruitment began in November 1996 and will continue for 1.5 years. Patients are randomized to receive either low-dose amiodarone or conventional antiarrhythmic drug therapy. Patients assigned to the amiodarone group will receive an oral loading regimen of 10 mg/kg/day during a minimum 14-day period. Patients assigned to conventional antiarrhythmic therapy will receive 1 of 2 agents commonly used in AF prophylaxis: sotalol or propafenone. Drug selection and loading, and electrical cardioversion, if necessary, will be performed within 21 days of randomization. The long-term maintenance dose of amiodarone is 200 mg/day. We have planned a minimum follow-up period of 1 year. The primary end point is the time to the first relapse of AF. Data will be analyzed on an intention-to-treat basis. Secondary outcomes are medication toxicity, mortality, major clinical events, costs of each approach, and quality of life. For the purpose of sample size calculations, it is anticipated that recurrence of AF at 1 year will occur in 50% of patients on conventional treatment compared with 35% in those receiving amiodarone. In order to have an 80% power and a 2-tailed type I error of 0.05, assuming a 15% loss to follow-up rate, a total sample size of 400 patients will be required. A pilot study done at the Montreal Heart Institute has shown that the research protocol is feasible.     

Atrial fibrillation: overview of therapeutic trials

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia treated by physicians, and a plethora of therapeutic trials deal with selected aspects of its management. This overview attempts to categorize and summarize the available studies. A key to management of AF is a clinical classification schema that provides a framework for application of the available treatment modalities. Such a classification is provided. Antithrombotic trials have demonstrated the remarkable efficacy of warfarin and more modest effect of acetylsalicylic acid for prevention of stroke; these data are summarized. Cardioversion to restore sinus rhythm is an important aspect of management of AF, particularly of persistent and new onset AF. In this review pharmacological cardioversion is emphasized. The data concerning the use of various drugs for pharmacological cardioversion are reviewed. Many, but not all, agents have been shown to have efficacy in this regard, but efficacy with drugs is lower than that with electrical cardioversion and, in the case of amiodarone, may be delayed. For recurrent AF, the two major rhythm management approaches are maintenance of rhythm and heart rate control. Trials of pharmacological and nonpharmacological therapies for these purposes are reviewed and summarized. Management of AF is an active area of research, and the present review is intended as a foundation upon which new information can be added.     

Radiofrequency catheter ablation in type I atrial flutter: preliminary experience of 10 cases

Common atrial flutter results from macroreentry in the right atrium. Catheter ablation of slow conduction, between tricuspid annulus and inferior vena cava (TA-IVC) or tricuspid annulus and coronary sinus ostium (TA-CS os) has been reported to terminate and prevent recurrence of this arrhythmia. We reported 10 consecutive patients, 7 men and 3 women, who underwent radiofrequency catheter ablation of common atrial flutter. The mean age was 59.4 +/- 11.2 years (range 42-82 years). During the paroxysmal atrial flutter, all patients had palpitation, 4 had dyspnea on exertion, 3 patients had syncope and 1 patient had presyncope. The mean duration of symptoms was 5.7 +/- 4.9 years (range 0.5-13 years). Two patients had dilated cardiomyopathy, 1 Ebstein's anomaly and 1 chronic obstructive pulmonary disease. Four patients (40%) had history of atrial fibrillation (AF) before ablation. The mean cycle length of atrial rhythm was 257.2 +/- 36.6 ms. Ablation was done by anatomical approach and could terminate arrhythmia in 9 patients (90%), 7 from TA-IVC, 2 from TA-CS os without major complication. The mean number of applications was 20.4 +/- 16.9 and turned atrial flutter to normal sinus rhythm in 13.5 +/- 10.7 seconds. Fluoroscopic and procedure times were 38.4 +/- 31.4 and 157.2 +/- 68.8 minutes, respectively. During the follow-up period of 24.0 +/- 28.7 weeks, 2 patients had recurrent atrial arrhythmia, 1 atrial fibrillation and 1 atrial flutter type I, giving the final success rate of 70 per cent. All patients who had recurrence or failure had a history of paroxysmal AF before ablation. In conclusion, radiofrequency catheter ablation in atrial flutter type I, using anatomical approach, is an effective treatment to terminate and prevent this arrhythmia in short term follow-up. It may be considered as an alternative treatment in patients with atrial flutter who were refractory to antiarrhythmic agents.     

Effects of beta-blockade on atrial and atrioventricular nodal refractoriness, and atrial fibrillatory rate during atrial fibrillation in pigs

Despite their widespread use in atrial fibrillation, the effects of beta-adrenoceptor blockers on atrial and atrioventricular (AV) nodal refractoriness, and atrial fibrillatory rate during atrial fibrillation have been incompletely characterised. In particular, it is unknown whether additional sodium channel (class I) blocking effects play a role. Effects of bisoprolol (no class I effect) and metoprolol (mild class I effect) were therefore compared in 12 open-chest pigs. Atrial and AV-nodal effective refractory periods were determined at pacing cycle length 500 ms and 300 ms. Atrial fibrillation was then induced by premature stimulation and topical application of metacholine, and atrial fibrillatory intervals and ventricular intervals were recorded. After resumption of sinus rhythm, bisoprolol 0.1 mg/kg or metoprolol 0.3 mg/kg was administered, and measurements were repeated. Also, effects on plasma catecholamines and signal-averaged QRS duration were determined. Both bisoprolol and metoprolol prolonged atrial and AV-nodal effective refractory periods at both pacing cycle lengths, however, no differences were noted between the two drugs. No significant effects were observed on atrial and ventricular intervals during atrial fibrillation. Plasma catecholamines were low and unaffected by either drug, as was the QRS duration. It is concluded that the mild class I effect of metoprolol does not play a role in atrial fibrillation. Also, the results confirm the clinical notion that beta-blockers exert insignificant effects during atrial fibrillation in the setting of low sympathetic tone.     

Can 1/1 atrial flutter be foreseen by class I anti-arrhythmics?

1/1 atrial tachycardia or "quinidine" flutter under class I antiarrhythmic drugs is a serious complication of these agents which, unfortunately, cannot be anticipated. The aim of this study was to review the cases of 11 patients who had suffered this complication of class I antiarrhythmic therapy to see if it could have been prevented. All drugs of this class were included. The 11 subjects were aged 57 to 78: 7 had no apparent underlying cardiac disease and the others had valvular (n = 1), hypertensive (n = 1) and ischaemic (n = 2) heart disease. They were treated for episodes of paroxysmal atrial fibrillation or tachycardia. In the absence of treatment, 7 patients had a short PR interval on the ECG (PR between 0.11 and 0.14 s). In the other 4, the PR interval was normal (0.16 to 0.20 s), but the P wave was widened with appearances of left atrial hypertrophy or an intra-atrial conduction defect. High amplification ECG performed in 3 patients showed continuity of atrial and ventricular depolarisation. Atrial stimulation showed excellent nodal conduction with a Wenckebach point of 200/min. The authors conclude that a short PR interval is predisposing factor to 1/1 atrial tachycardia with class I antiarrhythmics. High amplification ECG which allows identification of the end of the P wave with respect to the QRS complex could help identify subjects at risk when the P wave is widened and that, consequently, the PR interval appears to be normal.     

Oral propafenone to convert recent-onset atrial fibrillation in patients with and without underlying heart disease. A randomized, controlled trial

BACKGROUND: The effectiveness of oral propafenone in converting recent-onset atrial fibrillation to sinus rhythm has been established by controlled trials. However, it is not clear whether the effectiveness of propafenone is affected by the presence or absence of underlying heart disease. OBJECTIVES: To investigate the safety and effectiveness of oral propafenone and the role of underlying heart disease. DESIGN: Randomized, single-blind, controlled study. SETTING: 3 teaching hospitals. PATIENTS: 240 hospitalized patients with recent-onset atrial fibrillation. INTERVENTION: Propafenone (one 500-mg oral dose) or placebo. MEASUREMENTS: Conversion rates at 3 and 8 hours. RESULTS: Propafenone was more effective than placebo for converting atrial fibrillation to sinus rhythm at 3 hours: Fifty-four of 119 patients (45%) receiving propafenone and 22 of 121 patients (18%) receiving placebo had conversion (P < 0.001). It was also more effective at 8 hours: Ninety-one of 119 patients (76%) receiving propafenone and 45 of 121 patients (37%) receiving placebo had conversion (P < 0.001). Subgroup analysis showed that among patients without heart disease, 78% of those receiving propafenone and 56% of those receiving placebo converted to sinus rhythm within 8 hours (P = 0.02). In those with hypertension, the rate was 70% for those receiving propafenone and 27% for those receiving placebo (P < 0.001); in patients with structural heart disease, the rate was 81% for those receiving propafenone and 17% for those receiving placebo (P < 0.001). CONCLUSIONS: Oral loading of propafenone was more effective than placebo for conversion to sinus rhythm within 8 hours and had a favorable safety profile. The rate of spontaneous conversion to sinus rhythm was higher in patients without structural heart disease; this finding has important implications for the assessment of drug effectiveness in recent-onset atrial fibrillation.