Maintenance of sinus rhythm after atrial defibrillation

Peak Early Diastolic Transmitral Velocity As A Surrogate Marker Of Short-Term Atrial Fibrillation Recurrence After Electrical Cardioversion

OBJECTIVES

The aim of this study was to assess if peak early diastolic transmitral velocity (E-wave) can be used as a surrogate marker of short-term atrial fibrillation (AF) recurrence.

METHODS

We prospectively studied 57 consecutive patients who underwent electrical cardioversion (ECV) for AF and successfully converted to sinus rhythm. N-terminal brain natriuretic peptide levels (BNP) before and after ECV was measured in all patients. The follow-up included physical examination and a 12-lead electrocardiogram 14 days and one month after the ECV.

RESULTS

In 42.1% patients AF recurred during one-month follow-up period. Gender, presence of mitral regurgitation, treatment with angiotensin II receptor blocker and left atrium diameter independently influenced E-wave velocity before ECV. E-wave velocity fell immediately after successful ECV (94.0±27 cm/s vs 79.7±23 cm/s, P<0.0001). E-wave velocity before ECV>94 cm/s and E-wave velocity after ECV >80 cm/s were predictors of one-month AF recurrence [(Hazard Ratio) HR=3.62 with 95% CI=1.49-8.78 and HR=3.76 with 95% CI=1.40-10.10, respectively]. E-wave velocity before and E-wave velocity after ECV remained predictors of AF recurrence but only in non-hypertensive patients (HR=1.01 with 95% C.I=1.01-1.03 and HR=1.03 with 95% C.I=1.01-1.06, respectively). Similarly, BNP levels before and after ECV were associated with an increased the risk of AF recurrence (HR=1.14 with 95% C.I 1.01-1.28 and HR= 1.16 with 95% C.I 1.03- 1.31, respectively). The addition of BNP levels to E-wave velocity before ECV appeared to have incremental value on short-term AF recurrence but at a marginally statistical significance (LR chi2=3.28, p=0.07).

CONCLUSIONS

E-wave velocity before and after ECV appears to be a marker of short-term recurrence of AF.

Spontaneous reversion from long-lasting atrial fibrillation to sinus rhythm

We have collected 23 cases with atrial fibrillation (AF) of 3-29 years' duration with spontaneous reversion to sinus rhythm (SR). We have also identified 22 similar cases in the literature. Several of our patients spent several years with different atrial arrhythmias before a stable SR was established. Of all the 45 cases, 39 had significant rheumatic mitral valve disease. In the majority of these patients the ECG shows first degree AV block after return to SR and a low-amplitude P-wave--as if the left atrial P component was lacking. There are no signs of left atrial mechanical activity after re-establishment of SR in our mitral valve disease group, as judged from phonocardiograms, apexcardiograms, echocardiograms and left atrial pressure recordings in selected patients. Heart muscle biopsy was obtained from two patients who underwent mitral valve surgery. Left atrial speciments showed almost complete lack of all muscle structures. There is thus electrical, mechanical and histological evidence of left atrial muscle deterioration. It is likely that the electrophysiological factors responsible for initiation and maintenance of AF have disappeared with this deterioration, thereby allowing SR to be re-established. The return of SR might indicate a progress of the heart disease although the patient may benefit from normalization of cardiac rate and regularity. The easy identification of our 23 patients makes us believe that the phenomenon of appearance of late SR is far more common than suggested up to now.

The effect of patient sex on recurrence of atrial fibrillation following successful direct current cardioversion

BACKGROUND

The effect of patient sex on recurrence of atrial fibrillation after a successful direct current cardioversion is unknown.

METHODS

This prospective study included 773 patients (486 [63%] men and 287 [37%] women) undergoing successful direct current cardioversion of atrial fibrillation between May 2000 and July 2003. Patient characteristics at presentation were recorded. The primary end point was the time between cardioversion and the first documented recurrence of arrhythmia.

RESULTS

At presentation, women were older and had a higher prevalence of hypertension and valvular disease compared with men. In addition, women had worse mechanical left atrial appendage function. Arrhythmia recurrence was more prevalent in women (50.0% at 1 year compared with 43.4% in men, and 75.8% at 2 years compared with 67.0% in men; P = .03). On the basis of multivariate analysis, patient sex was a significant predictor of arrhythmia recurrence. There was no significant difference in overall mortality between men and women.

CONCLUSIONS

Women were more likely than men to have recurrence of atrial fibrillation after successful direct current cardioversion. Patient sex should be taken into account with other clinical factors when making the decision about cardioversion for atrial fibrillation.

High-sensitivity C-reactive protein is predictive of successful cardioversion for atrial fibrillation and maintenance of sinus rhythm after conversion

BACKGROUND

Cardioversion for atrial fibrillation (AF) is the most effective treatment for the restoration of sinus rhythm (SR). Recently, an elevated level of hs-CRP has been shown to be associated with AF burden, suggesting that inflammation increases the propensity for persistence of AF. We examined whether the level of high-sensitivity C-reactive protein (hs-CRP) was predictive of the outcome of cardioversion for AF.

METHODS AND RESULTS

One hundred and six patients with a history of symptomatic AF lasting > or =1 day (age 63+/-14 years, mean+/-S.D.) underwent cardioversion. Echocardiography and hs-CRP assay were performed immediately prior to cardioversion. SR was restored in 84 patients (79%). By using selected cutoff values, multiple discriminant analysis revealed significant associations between successful cardioversion and a shorter duration of AF (AF duration< or =36 days, odds ratio (OR), 0.98; 95% confidence interval (CI), 0.97-0.99), smaller left atrial diameter (left atrial diameter< or =40 mm, OR 0.82, 95% CI 0.71-0.94), better-preserved left ventricular ejection fraction (left ventricular ejection fraction> or =60%, OR 0.92, 95% CI 0.86-0.99), and lower hs-CRP level (hs-CRP< or =0.12 mg/dL, OR 0.33, 95% CI 0.21-0.51). During a follow-up period of 140+/-144 days, AF recurred in 64 patients (76%). By using a cutoff value of hs-CRP> or =0.06 mg/dL, Cox proportional-hazards regression model found that only hs-CRP level was an independent predictor of AF recurrence (OR 5.30, 95% CI 2.46-11.5) after adjustment for coexisting cardiovascular risks. When patients were divided by the hs-CRP level of 0.06 mg/dL, percentage of maintenance of SR below and above the cutoff was 53% and 4%, respectively (log-rank test, p<0.0001).

CONCLUSIONS

hs-CRP level determined prior to cardioversion represents an independent predictor of both successful cardioversion for AF and the maintenance of SR after conversion.

Electrical cardioversion for persistent or chronic atrial fibrillation: Outcome and clinical factors predicting short and long term success rate

AIMS

To assess the effectiveness and to identify predictors for successful electrical cardioversion (ECV) and maintenance of sinus rhythm, in long term follow up of patients with persistent (PAF) and chronic atrial fibrillation (CAF).

METHODS AND RESULTS

Retrospective analysis of medical records of 68 patients with PAF or CAF, who underwent 91 cardioversions. ECV was successful in 86 attempts (94.5%). In obese (body mass index>30) and hypertensive patients (blood pressure >140/90 mm Hg), ECV was less successful in restoring sinus rhythm (p<0.05, p<0.021, respectively). Sinus rhythm was maintained more than half a year in 42 cardioversions (61%). Treatment with beta blockers prior to cardioversion and age younger than 75 were independent factors predicting long term success (p<0.013, p<0.034, respectively). Mild or moderate enlargement of left atrium (<6 cm) did not predict relapse of the arrhythmia. Second ECV was as or more effective than the first in 82.3% of patients that underwent more than one cardioversion.

CONCLUSIONS

Conversion of atrial fibrillation by DC shock was found to be safe and effective procedure. Patients should be treated with beta blockers prior to cardioversion, if possible. Mild or moderate enlargement of left atrium is not contraindication to cardioversion. Recurrent cardioversions may be recommended.

Assessing observational studies of medical treatments

BACKGROUND

Previous studies have assessed the validity of the observational study design by comparing results of studies using this design to results from randomized controlled trials. The present study examined design features of observational studies that could have influenced these comparisons.

METHODS

To find at least 4 observational studies that evaluated the same treatment, we reviewed meta-analyses comparing observational studies and randomized controlled trials for the assessment of medical treatments. Details critical for interpretation of these studies were abstracted and analyzed qualitatively.

RESULTS

Individual articles reviewed included 61 observational studies that assessed 10 treatment comparisons evaluated in two studies comparing randomized controlled trials and observational studies. The majority of studies did not report the following information: details of primary and ancillary treatments, outcome definitions, length of follow-up, inclusion/exclusion criteria, patient characteristics relevant to prognosis or treatment response, or assessment of possible confounding. When information was reported, variations in treatment specifics, outcome definition or confounding were identified as possible causes of differences between observational studies and randomized controlled trials, and of heterogeneity in observational studies.

CONCLUSION

Reporting of observational studies of medical treatments was often inadequate to compare study designs or allow other meaningful interpretation of results. All observational studies should report details of treatment, outcome assessment, patient characteristics, and confounding assessment.

Stunning of the Left Atrium after Conversion of Atrial Fibrillation: Predictor for Maintenance of Sinus Rhythm?

Recurrence of atrial fibrillation (AF) after cardioversion (CV) to sinus rhythm (SR) is determined by various clinical and echocardiographic parameters. The aim of this study was to determine the value of mitral inflow A-wave velocity, performed at 24 hours after CV in estimation of AF recurrence. The study group consisted of 187 consecutive patients with nonvalvular atrial fibrillation, who had been cardioverted to SR from 1998 to 2000. Transthoracic echocardiography was performed in all cases recruited for the study 24 hours after CV. Left atrial (LA) diameter, left ventricular ejection fraction, and mitral inflow A-wave velocity were measured. The patients were evaluated in five groups according to their recurrence time (<30 days, 31-90 days, 91-180 days, 181-365 days, and >365 days). Maintenance of SR was determined to have a negative linear correlation with age (r =-0.97, P = 0.006), LA diameter (r =-0.93, P = 0.02), and AF duration (r =-0.93, P = 0.02), while having a positive linear correlation with mitral inflow A-wave velocity (r = 0.96, P = 0.008). In the maintenance of sinus rhythm, age, LA diameter, and AF duration were not affected from the method of CV, while mitral inflow A-wave velocity was found to be affected with the method of CV. No relationship was determined between mitral inflow A-wave velocity and the maintenance of sinus rhythm in those performed electrical cardioversion, while frequency of recurrence was found to be higher in those with slow mitral inflow A-wave velocity who were performed pharmacological cardioversion (r = 0.89, P = 0.004). In conclusion, age, duration of AF, LA diameter, and the mitral inflow A-wave velocity can be used to predict the maintenance of SR after CV.

Persistent atrial fibrillation: a population based study of patients with their first cardioversion

BACKGROUND

Electrical cardioversion is effective in terminating even long standing atrial fibrillation (AF), but the relapse risk of AF is high. Data on long-term success of cardioversion in real life clinical practice are scant.

METHODS

Restoration and maintenance of sinus rhythm as well as acceptance of permanent AF was studied in a population based cohort (catchment area with a population of 440,000) of patients with persistent AF after first elective cardioversion.

RESULTS

Of the 183 patients having their first electrical cardioversion during the 1-year study period, sinus rhythm was restored in 153 patients (84%). Only 39 of these (25%) maintained sinus rhythm for 1 year, even though 108 (71%) patients had anti-arrhythmic medication. Age, hypertension, coronary artery disease, heart failure and valvular disease, or absence of these known risk factors for AF were not associated with the outcome. The outcome was better if the cardioversion was performed earlier than the median delay (78 days) from the diagnosis of AF to cardioversion compared to longer delay (P=0.022 in multivariate modelling). The decision of acceptance of permanent AF was made in 74 cases (40%) during 1 year of follow-up.

CONCLUSIONS

Patients with persistent AF had a high tendency to remain in or relapse into AF, even though most patients had anti-arrhythmic medication after first cardioversion. Short history of arrhythmia was associated with better outcome. Acceptance of permanent AF was made in almost half of the cases during 1 year of follow-up.

Dynamic nature of atrial fibrillation substrate during development and reversal of heart failure in dogs

BACKGROUND

Clinical atrial fibrillation (AF) often results from pathologies that cause atrial structural remodeling. The reversibility of arrhythmogenic structural remodeling on removal of the underlying stimulus has not been studied systematically.

METHODS AND RESULTS

Chronically instrumented dogs were subjected to 4 to 6 weeks of ventricular tachypacing (VTP; 220 to 240 bpm) to induce congestive heart failure (CHF), followed by a 5-week recovery period leading to hemodynamic normalization at 5-week recovery (Wk5(rec)). The duration of burst pacing-induced AF under ketamine/diazepam/isoflurane anesthesia increased progressively during VTP and recovered toward baseline during the recovery period, paralleling changes in atrial dimensions. However, even at full recovery, sustained AF could still be induced under relatively vagotonic morphine/chloralose anesthesia. Wk5(rec) dogs showed no recovery of CHF-induced atrial fibrosis (3.1+/-0.3% for controls versus 10.7+/-1.0% for CHF and 12.0+/-0.8% for Wk5(rec) dogs) or local conduction abnormalities (conduction heterogeneity index 1.8+/-0.1 in controls versus 2.3+/-0.1 in CHF and 2.2+/-0.2 in Wk5(rec) dogs). One week of atrial tachypacing failed to affect the right atrial effective refractory period significantly in CHF dogs but caused highly significant effective refractory period reductions and atrial vulnerability increases in Wk5(rec) dogs.

CONCLUSIONS

Reversal of CHF is followed by normalized atrial function and decreased duration of AF; however, fibrosis and conduction abnormalities are not reversible, and a substrate that can support prolonged AF remains. Early intervention to prevent fixed structural abnormalities may be important in patients with conditions that predispose to the arrhythmia.

Prevalence and significance of focal sources of atrial arrhythmia in patients undergoing cardioversion of persistent atrial fibrillation

INTRODUCTION

Recent reports have high-lighted the importance of focal atrial arrhythmias as a curable cause for a group of patients with frequently recurrent paroxysmal atrial fibrillation (AF). The importance of this arrhythmia mechanism in the general population of patients with persistent AF is unknown.

METHODS AND RESULTS

After successful internal cardioversion of 50 consecutive patients with persistent AF (mean age 60 years, mean duration of AF 26 months), endocardial activity in the immediate postcardioversion period was analyzed for the presence of focal atrial activity. Postcardioversion atrial arrhythmias were considered to be focal if there was evidence of a localized source of repetitive early atrial activation, either in the form of (1) self-terminating monomorphic atrial tachycardia (at least five beats) or (2) recurrences of AF with an initial atrial activation sequence (first five beats) that was both monomorphic and reproducible with repeated recurrences. Evidence for a focal atrial arrhythmia was present in 20 of the total group of 50 patients (40%). Multivariate analysis of clinical characteristics revealed the diagnosis of lone AF as the only independent predictor of a focal source of AF (P = 0.028). Thirty-nine patients were discharged from hospital in sinus rhythm. At 1-month follow-up, 25 (64%) of these 39 patients had suffered AF recurrence. The only significant predictor of AF recurrence was evidence of a focal source of atrial arrhythmia immediately after cardioversion, with a relative risk of 1.73 (range 1.1 to 2.7; P = 0.015).

CONCLUSION

Focal atrial arrhythmias are common in patients presenting with "idiopathic" persistent AF, suggesting a possible causative role in the generation of this common arrhythmia.

Prospective randomized trial of external versus internal transcatheter cardioversion in patients with chronic atrial fibrillation

To evaluate the safety and long-term efficacy of internal transcatheter cardioversion, forty patients with chronic, lone atrial fibrillation were studied. The patients were randomised to internal transcatheter cardioversion or to conventional external cardioversion. In cases where the procedure was unsuccessful, cross-over to the alternate method was performed. Oral anticoagulation therapy was started three weeks prior to the procedure and was maintained for another three weeks following successful cardioversion. Sinus rhythm was restored in 16/18 patients (88%) in the internal cardioversion group, versus 9/22 patients (40%) in the external cardioversion group (p < 0.01). In addition, 8/13 (61%) patients who were crossed-over to internal cardioversion were successfully cardioverted to sinus rhythm. In contrast, both patients who were crossed-over to external cardioversion remained in atrial fibrillation. During a mean follow-up period of 23 months, 13 (39.3%) patients maintained sinus rhythm. Using the intention to treat principle, the recurrence rate was not statistically different between the two methods. It is concluded that internal cardioversion is more effective in acutely restoring sinus rhythm compared to external cardioversion. However, both methods have similar long-term recurrence rates.

Factors influencing long term persistence of sinus rhythm after a first electrical cardioversion for atrial fibrillation

It is conventionally thought that electrical cardioversion in patients with atrial fibrillation (AF) of longstanding duration or with a large left atrial diameter, only seldom results in long term success. Recurrence is common, although antiarrhythmic drugs often effectively decrease the number and duration of recurrent AF episodes. We analysed clinical, functional and pharmacological variables which could possibly influence the long term outcome after a first electrical cardioversion for AF in a retrospective study on 85 patients. Univariate and multivariate analysis was used to identify factors predicting maintenance of sinus rhythm at 100 days, and absence of recurrence during the entire follow-up. In univariate analysis, the only significant predictor for maintenance of sinus rhythm at 100 days was the duration of the preceding AF episode. Multivariate analysis with persistence of sinus rhythm at 100 days as endpoint confirmed this as a prognostic factor (p < 0.03), but sotalol treatment also contributed to maintenance of sinus rhythm (p < 0.05). When considering the entire observation period, class III antiarrhythmic drugs, i.e. sotalol and amiodarone, were useful in preventing recurrence (p < 0.01 and < 0.02). High age (above 75 years) was a predictor of recurrence. In conclusion, class III antiarrhythmic drugs, the duration of atrial fibrillation and high age were the most important determinants of long term outcome, while echocardiographic parameters and the presence of heart disease played no role.

Pharmacologic management of atrial fibrillation

In an era when many electrophysiologic problems are routinely treated with invasive procedures or implantable devices, drugs remain the cornerstones of treatment for atrial fibrillation. Atrial fibrillation may present as an episodic rhythm in patients who are primarily in sinus rhythm or it may be manifested as rhythm disorder that is permanent. Patients who appear to have an episodic rhythm disorder may be found to be in atrial fibrillation permanently when followed for long periods of time, and prognosis in the two forms is similar. It is, therefore, useful to consider them different manifestations in the same spectrum of disease. This review will address pharmacologic approaches designed to: (1) slow ventricular response; (2) restore sinus rhythm; (3) reduce occurrences of atrial fibrillation; and (4) prevent thromboembolic complications. Nonpharmacologic approaches to treating atrial fibrillation will be briefly reviewed.

Restoring Sinus Rhythm in Patients With Atrial Flutter and Fibrillation: Pharmacologic or Electrical Cardioversion?

Atrial fibrillation and atrial flutter, the most frequently encountered tachyarrhythmias requiring treatment, have become a major focus for clinical and basic research in recent years. Restoration and maintenance of sinus rhythmn, having been shown to improve exercise capacity, alleviate symptoms, and reduce the incidence of thromboembolic events, may be the optimal management strategy. Identification of the safest, most efficacious and cost-effective means of restoring sinus rhythm is necessary prior to the institution of optimal antiarrhythmic therapy to maintain sinus rhythm. Potential advantages of pharmacologic compared with electrical cardioversion include lack of need for general anesthesia and likely lower cost. Pharmacologic conversion include lack of need for general anesthesia and likely lower cost. Pharmacologic conversion has been accomplished with drugs that prolong atrial refractorinerss, including class Ia (quinidine, procainamide, disopyramide), class Ic (flecainide, propafenone), and class II (sotalol, amiodarone) compounds. The so-called pure class III agents were created to overcome the blocker side effects of sotalol and the complex pharmacodynamic profile of amiodarone. Two such agents are dofetilide, which selectively blocks the rapid component of the delayed rectifier current (Ikr) and ibutilide, which augments the slow inward sodium current, with a smaller component of action mediated by the block of Ikr. Reported overall conversion rates for recent onset atrial fibrillation and atrial flutter were 31% and 54% for difetilide, respectively, and 29-31% and 38-63%, respectively, for ibutilide. Proarrhythmia, manifested as polymorphic ventricular tachycardia requiring cardioversion, was a significant early side effect of both agents. Data from clinical trtials with these new agents, combined with increasing nowledge of the electrophysiologic substrate for these arrhythmias, has renewed initerest in the development of safer, more efficacious class IIIdrugs for atrial fibrillation and atrial flutter conversion.

Long-term management of atrial fibrillation

In the past decade, catheter ablation techniques and implantable devices have revolutionized the treatment of ventricular arrhythmias, junctional arrhythmias, and atrial flutter. For most patients presenting with atrial fibrillation (AF), the treatment available today is similar to that used a century ago, although nonpharmacologic strategies of therapy have begun to emerge for selected cases. There have been important recent advances in our understanding of the pathophysiology of AF and its complications, and it may be possible to improve patient management by refinement of the way in which current drugs are used.

Prediction of outcome of electrical cardioversion by left atrial appendage flow velocities in atrial fibrillation

We evaluated the usefulness of left atrial appendage (LAA) flow velocity during atrial fibrillation as an objective measure for prediction of the outcome of electrical cardioversion. Left atrial appendage peak velocities were measured by transesophageal echocardiography before cardioversion in 56 patients. Left atrial thrombus was demonstrated in 6 (11%) of these patients. Cardioversion was then performed in the 50 patients who did not have a thrombus and in 1 patient whose left atrial thrombus disappeared after anticoagulant therapy (n = 51). Thirty-eight patients converted to sinus rhythm which remained stable until discharge (initial success group). Of these, long-term (> 6 months) maintenance of sinus rhythm was achieved in 31 patients (82%). Five patients with almost no detectable appendage contractions during atrial fibrillation were classified in the initial failure group. The peak LAA flow velocity was significantly higher in patients with the initial success group compared with the patients in the initial failure group (25.6 +/- 12.0 vs 15.3 +/- 10.7 cm/s, respectively; p < 0.01). Left atrial appendage flow velocity during atrial fibrillation may be useful for identifying candidates for electrical cardioversion.

Atrial fibrillation pearls and perils of management

Atrial fibrillation, a common arrhythmia, is responsible for considerable cardiovascular morbidity. Its management demands more than antiarrhythmic therapy alone, but must address the causes and consequences of the arrhythmia. Although remediable causes are infrequently found, a thorough search for associated heart disease or its risk factors results in better-informed patient management. Controlling the ventricular response and protecting from thromboembolic complications are important initial goals of therapy and may include the administration of aspirin in younger, low-risk patients. Older patients and those with risk factors for systemic embolism are not adequately protected from stroke complications by aspirin therapy alone. It remains controversial whether all high-risk patients should receive warfarin and at what intensity. Whether and how sinus rhythm should be restored and maintained poses the greatest therapeutic controversy for atrial fibrillation. The mortal risk of antiarrhythmic therapy is substantially greater in patients with evidence of heart failure. In such persons, the risks and benefits of maintaining normal sinus rhythm with antiarrhythmic medications should be weighted carefully. A definitive cure for atrial fibrillation remains elusive, but promising surgical and catheter ablation therapies are being developed.

Atrial fibrillation: maintenance of sinus rhythm versus rate control

Atrial fibrillation represents a common and challenging arrhythmia. A rational approach to management of the individual case depends on careful assessment of the temporal of the arrhythmia, any associated cardiovascular disease, and any particular features suggesting the advisability or risks of any particular treatment regimen. The nature of an arrhythmia and of individual patient factors change over time, requiring a flexible approach to long-term treatment that may be defined only after months or years. While new treatment options such as catheter ablation techniques and implantable atrial defibrillators are being tested, old therapies (e.g., low-dose amiodarone) are undergoing reappraisal. Increasing recognition of the dangers of antiarrhythmic therapy used to maintain sinus rhythm is focusing attention on nonpharmacologic methods. All patients with persistent atrial fibrillation merit serious consideration for direct current cardioversion before accepting that atrial fibrillation is permanent, and many patients may benefit from more than one attempt to restore and maintain sinus rhythm.

Effectiveness of amiodarone and electrical cardioversion for chronic rheumatic atrial fibrillation after mitral valve surgery

Thirty consecutive patients with chronic rheumatic atrial fibrillation (AF) > or = 3 months after successful mitral valve surgery and left atrial diameter < or = 60 mm were treated with oral amiodarone. Protocol included high loading dosages of amiodarone for 4 weeks, and if conversion to sinus rhythm (SR) was not achieved then electrical cardioversion was performed. Patients converted to SR were maintained on low-dose amiodarone for another 4 weeks when treatment was discontinued. Overall, 23 patients (77%) converted to SR after 4 weeks of therapy: 12 (40%) taking amiodarone alone and 11 (37%) with the addition of electrical cardioversion. The duration of AF > 48 months was an adverse factor in the ability to restore SR. Sixteen patients (70%) remained in SR at a mean follow-up of 17 months. The duration of AF < or = 48 months alone or in combination with left atrial diameter < or = 45 mm were the best predictors for long-term maintenance of SR. Thus, short-term amiodarone with or without electrical cardioversion is effective and safe in the treatment of chronic rheumatic AF after mitral valve surgery. The duration of AF and left atrial size can be used to identify patients with successful outcome.

Recurrence of paroxysmal atrial fibrillation or flutter after successful cardioversion in patients with normal left ventricular function

One hundred twenty-four consecutive patients (85%) with paroxysmal atrial fibrillation (AF) and 21 (15%) with atrial flutter (AFI) were studied immediately after pharmacologic or electrical cardioversion to sinus rhythm. Mean age was 59 +/- 13 years (range 23 to 79). Patients with reduced left ventricular function were excluded from the study. After restoration to sinus rhythm, the clinical course of all patients was followed for the first recurrence of paroxysmal AF or AFI irrespective of the therapeutic approach. Mean follow-up was 23 +/- 16 months. After 12 months of follow-up, 50% of all patients remained in sinus rhythm. Univariate analysis indicated that coronary artery disease (relative risk 1.9; 95% confidence interval 0.9-3.9), history of paroxysmal AF or AFI (2.3; 1.1-5.0), female sex (2.3; 1.1-4.6), pulmonary disease (3.9; 1.9-7.6) and valvular heart disease (4.4; 2.2-8.8) were associated with an increased risk for recurrent or frequent episodes of paroxysmal AF or AFI. No predictors were found to be associated with a decrease in length of the recurrence-free period after successful conversion to sinus rhythm. Multivariate analysis identified history of AF or AFI (odds ratio 2.5; 95% confidence interval 0.9-6.4), coronary artery disease (3.1; 1.1-8.2) and female sex (3.4; 1.3-8.9) as independent predictors for recurrent or frequent episodes of paroxysmal AF or AFI. The presence of these risk factors should be taken into account when prophylactic therapy with antiarrhythmic drugs is being considered in the treatment of paroxysmal AF or AFI.

Assessment of the efficacy and safety of antiarrhythmic therapy for chronic atrial fibrillation: observations on the role of trial design and implications of drug-related mortality

The findings in clinical trials of antiarrhythmic drug efficacy and safety are frequently difficult to compare, since study design often has an important effect on trial outcome. To explore this problem further, we compared three designs--randomized control, nonrandomized control, and uncontrolled--collectively enrolling 2415 patients in 21 trials reporting on the role of quinidine in the prevention of chronic atrial fibrillation. The proportion of patients remaining in sinus rhythm at 3, 6, and 12 months after cardioversion was calculated by means of Kaplan-Meier techniques, and the data were pooled for each trial design. For the randomized control trials the difference in the absolute percentage of patients remaining in sinus rhythm in the quinidine and control groups was 24% at each of the three follow-up intervals. Contrary to findings in the randomized control trials, the magnitude of the treatment benefit in nonrandomized trials was smaller and declined markedly over time. The percentage of patients remaining in sinus rhythm in the uncontrolled trials was intermediate to the percentages in the other two trial designs. When the data from all three trial designs were pooled, the crude mortality rate was 2.0% in quinidine-treated patients and 0.6% in control patients. Sudden cardiac death or ventricular fibrillation was the cause of death in 13 of 19 patients for whom the cause of death was known, highlighting the potential risk of quinidine-induced proarrhythmia. Although quinidine is effective in maintaining sinus rhythm, estimates of the treatment effect vary among trial types.(ABSTRACT TRUNCATED AT 250 WORDS)

Prediction of uneventful cardioversion and maintenance of sinus rhythm from direct-current electrical cardioversion of chronic atrial fibrillation and flutter

The present study was undertaken to reassess prospectively the immediate and long-term results of direct-current electrical cardioversion in chronic atrial fibrillation or atrial flutter, and to determine factors predicting clinical outcome of the arrhythmia after direct-current cardioversion. Two-hundred forty-six patients underwent direct-current electrical cardioversion and were followed during a mean of 260 days. Multivariate analysis was used to identify factors predicting short- and long-term arrhythmia outcome. Cardioversion was achieved in 70% of patients with atrial fibrillation and in 96% of patients with atrial flutter. Stepwise logistic regression analysis revealed that arrhythmia duration (p less than 0.001), type of arrhythmia (fibrillation vs flutter, p less than 0.02) and age (p less than 0.05) independently influenced conversion rate. On an actuarial basis, 42 and 36% of patients remained in sinus rhythm during 1 and 2 years, respectively. Multivariate regression analysis revealed that the type of arrhythmia (p = 0.0008), low precardioversion functional class (p = 0.002) and the presence of nonrheumatic mitral valve disease (p = 0.03) independently increased the length of the arrhythmia-free episode. Rheumatic heart disease shortened this period (p = 0.03). In conclusion, patients having a high probability of conversion together with a prolonged post-shock arrhythmia-free episode can be identified. This may improve the cost-benefit ratio of cardioversion.

Sotalol versus quinidine for the maintenance of sinus rhythm after direct current conversion of atrial fibrillation

This open, parallel-group study compares quinidine and sotalol treatment for maintenance of sinus rhythm after direct current conversion of patients with chronic atrial fibrillation. The patients from 15 centers in Sweden were randomized to sotalol (98 patients) or quinidine (85 patients) after 2 hours of sinus rhythm after direct current conversion. According to primary efficacy assessment, 52% of the patients in the sotalol group and 48% of the patients in the quinidine group remained in sinus rhythm during the following 6-month treatment period (NS). Furthermore, 34% of the patients treated with sotalol and 22% of the patients treated with quinidine relapsed into atrial fibrillation (NS). Heart rate after relapsing into atrial fibrillation was higher in the patients treated with quinidine (109 beats/min) than in the patients treated with sotalol (78 beats/min, p less than 0.001). Patients treated with sotalol were found to be less symptomatic at the time of relapse compared with relapsing patients in the quinidine group. In terms of safety, more patients were withdrawn from quinidine than from sotalol treatment (26% vs. 11%, p less than 0.05), and sotalol was generally better tolerated than quinidine. Twenty-eight percent of the patients treated with sotalol and 50% of the patients treated with quinidine reported side effects (p less than 0.01). The difference was primarily a result of early (within the first month of treatment) gastrointestinal and skin side effects in the group of patients treated with quinidine.(ABSTRACT TRUNCATED AT 250 WORDS)

Return of atrial mechanical function following electrical conversion of atrial dysrhythmias

The return of atrial mechanical function and its relationship to embolic events following cardioversion of atrial arrhythmias is controversial. Fourteen patients with atrial arrhythmias were evaluated with pulsed Doppler echocardiography before and after direct current (DC) cardioversion. The atrial filling fraction increased significantly: 1.14 +/- 4.3% at baseline versus 14.9 +/- 13.3%, 13.4 +/- 11.4%, and 21.9 +/- 13.5% at 5 minutes, 30 minutes, and 24 hours, respectively, following cardioversion. Absent atrial mechanical activity was noted in four patients immediately after cardioversion. Mechanical activity resumed by 30 minutes in one patient and at 24 hours in two others. Those with delayed atrial function had lower stroke volumes and atrial filling fractions following cardioversion. An embolic event occurred in one patient who had immediate return of atrial mechanical activity. This patient also had the largest atrial filling fraction of any patient at 24 hours (41%). These data suggest that the degree of atrial mechanical activity following cardioversion is variable and that embolic episodes are not necessarily related to delayed return of atrial mechanical activity following cardioversion.

Risk-benefit assessment of amiodarone in the treatment of cardiac arrhythmias

Cardiac arrhythmias are a cause of significant morbidity and mortality in patients with cardiac disease, and thus represent a major management problem. The recognition that antiarrhythmic drugs have the potential to aggravate as well as to attenuate arrhythmias has prompted clinicians to reconsider treatment strategies and weight the benefits of treatment against the risks. In this context, amiodarone has emerged as an effective antiarrhythmic agent and when used at the lowest effective dose has an acceptable side effect profile. This review focuses on the current clinical usage of amiodarone in a broad variety of cardiac arrhythmias, and addresses the risk-benefits arising from its use. It further discusses the current position of amiodarone in the management of sudden cardiac death.

Prophylactic treatment after electroconversion of atrial fibrillation

Atrial fibrillation is a common arrhythmia. Sinus rhythm can often be restored by electroconversion, but the relapse rate is high. Various antiarrhythmic drugs have been used to maintain sinus rhythm after electroconversion. This article reviews the experience with these drugs and suggests a treatment strategy.

Therapy of refractory symptomatic atrial fibrillation and atrial flutter: a staged care approach with new antiarrhythmic drugs

One hundred nine patients with recurrent episodes of symptomatic atrial fibrillation or flutter, or both, who had failed one to five previous antiarrhythmic drug trials were treated with propafenone and, subsequently, sotalol if atrial fibrillation recurred. The clinical profile of the study group was as follows: age 63 +/- 13 years, left atrial anteroposterior dimension 4.4 +/- 0.9 cm and left ventricular ejection fraction 57 +/- 14%. Paroxysmal atrial fibrillation occurred in 56 patients (51%) and chronic atrial fibrillation occurred in 53 patients (49%). After loading and dose titration phases were completed, the maintenance doses of drugs were 450 to 900 mg/day for propafenone and 160 to 960 mg/day for sotalol. Life table estimates of the duration of freedom from atrial fibrillation were constructed for each drug trial. The percent of patients free of recurrent symptomatic arrhythmia at 6 months was 39% for propafenone and 50% for sotalol. The cumulative proportion of patients successfully treated with propafenone or sotalol, or both, by 6 months was 55% and remained relatively constant beyond that point. The incidence of intolerable side effects necessitating discontinuation of therapy ranged from 7% to 8%. Thus, despite previous unsuccessful drug trials, a substantial proportion of patients with recurrent symptomatic atrial fibrillation refractory to conventional therapy can be treated successfully and safely with newer antiarrhythmic drugs. Treatment failures tend to occur early in the course of follow-up, permitting easy identification of candidates for alternative therapeutic approaches.

Efficacy and safety of flecainide acetate in the maintenance of sinus rhythm after electrical cardioversion of chronic atrial fibrillation or atrial flutter

The efficacy and safety of flecainide were studied in the maintenance of sinus rhythm after electrical cardioversion for chronic atrial fibrillation or atrial flutter. Eighty-one patients were randomized to flecainide treatment or no treatment. Baseline characteristics of both groups were comparable. Compared to previous studies, patients could be classified as difficult-to-treat patients. Multiple regression analysis showed New York Heart Association class I for exercise tolerance (p = 0.0004) and flecainide treatment (p = 0.01) to be the main factors increasing the arrhythmia-free episode. However, Mantel-Cox lifetable analysis did not reveal significant differences between arrhythmia-free survival curves of both treatment groups. In the flecainide-treated group, 9% of patients experienced side effects, mostly related to negative dromotropic effects. The incidence of ventricular proarrhythmia in this group of patients was low. Thus, flecainide may be effective in postponing arrhythmia recurrence, even in difficult-to-treat patients. Caution should be excercised in treating patients with underlying conduction disturbances, sick sinus syndrome or characteristics favoring development of ventricular proarrhythmia.

Factors determining maintenance of sinus rhythm after chronic atrial fibrillation with left atrial dilatation

Successful therapy of atrial fibrillation (AF) has been reportedly influenced by a variety of factors including patient age, type of underlying heart disease, duration of arrhythmia, left ventricular function and left atrial (LA) size. To determine which of these factors are associated with maintenance of sinus rhythm after conversion, 43 patients with symptomatic chronic AF in the setting of a dilated left atrium (greater than or equal to 45 mm, range 45 to 78) were followed for at least 6 months after the return of sinus rhythm. Class IA drugs, IC drugs or amiodarone were used for therapy. Life table analysis showed sinus rhythm to be maintained in 81% for 6 months, 79% for 12 months and 60% for 24 months. Factors positively associated with success were conversion with drug therapy alone, duration of chronic AF less than or equal to 1 year, absence of mitral valve disease and LA dimension less than or equal to 60 mm (all p less than 0.05). Patient age, left ventricular function and presence of coronary disease were not associated with outcome. Thus, patients with moderate LA dilatation (45 to 60 mm) and a short duration of chronic AF can often be maintained in sinus rhythm, especially if they convert with pharmacologic intervention alone.

Echocardiographic and clinical predictors for outcome of elective cardioversion of atrial fibrillation

Previous studies have suggested that success of elective direct-current cardioversion for atrial fibrillation (AF) can be predicted from clinical features and M-mode echocardiographic left atrial diameter. We evaluated clinical variables as well as M-mode and 2-dimensional echocardiographic measurements of atrial size in 85 patients undergoing electrical cardioversion for AF. Of 65 patients who were initially converted to sinus rhythm, 45 (69%) and 38 (58%) remained in sinus rhythm at 1 and 6 months, respectively. No historical feature predicted initial success, although patients with cardiomyopathy or pulmonary disease underlying their AF had significantly lower success rates compared with those having other etiologies. Furthermore, no M-mode or 2-dimensional echocardiographic measurements of atrial size predicted initial success of cardioversion. Maintenance of sinus rhythm at 1 month was related to short duration of AF before cardioversion (less than 3 months vs greater than 12 months, p less than 0.05). Left atrial area and long axis dimension by 2-dimensional echocardiography were significantly larger in patients remaining in sinus rhythm than in those who had reverted to AF at 1 month (28 +/- 7 vs 24 +/- 5 cm2 and 65 +/- 9 vs 59 +/- 8 mm, respectively, both p less than 0.05), but overlap was great. No significant difference in atrial dimensions was noted at 6-month follow-up. It appears that, although no clinical or echocardiographic variable predicts initial success for cardioversion of AF, duration of AF does predict maintenance of sinus rhythm 1 month after initial success.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler echocardiographic predictors of recurrence of atrial fibrillation after cardioversion

To determine if the return of atrial contraction as evidenced by progressive return of the A wave on the Doppler atrial profile could better predict long-term success of cardioversion than other clinical and echocardiographic parameters, 50 patients were studied 4 hours, 24 hours and, if sinus rhythm persisted, up to 180 days after cardioversion. Recurrence of atrial fibrillation (AF) was 64% at 6 months. Age, sex, prior episodes of AF, presence of mitral valve disease or magnitude of mitral valve gradient did not predict recurrence, but duration of AF was significantly longer in the failure group (p less than 0.01). Left atrial dimension greater than or equal to 45 mm had a positive predictive value of 66%, with a sensitivity of 59% and a specificity of 61%. Presence or magnitude of the A wave at 4 hours did not predict long-term success of cardioversion. Percent increase of the A wave from 4 to 24 hours less than 10% had the highest positive predictive value (80%) for recurrence of AF (sensitivity 71% and specificity 71%) and can be obtained in the immediate post-cardioversion period to better establish prognosis and adjust therapeutic regimens.

Long-term oral propafenone therapy for suppression of refractory symptomatic atrial fibrillation and atrial flutter

Sixty patients who had recurrent episodes of symptomatic atrial fibrillation or flutter, or both, and who had failed one to five prior drug trials were treated with open label oral propafenone hydrochloride. On a mean maximal tolerated dose of 795 +/- 180 mg/day, actuarial estimates of the percent of individuals free of recurrences of symptomatic atrial fibrillation/flutter during propafenone treatment were: 1 month, 54%; 3 months, 44% and 6 months, 40%. No individual baseline characteristic achieved statistical significance as a correlate of poor response to propafenone. Drug-related adverse reactions were reported in 22% of patients but were severe enough to require termination of propafenone in only 5%. Thus, oral propafenone is a useful and well tolerated drug for long-term suppression of symptomatic recurrences of atrial fibrillation/flutter despite a history of unresponsiveness to prior antiarrhythmic drug treatment.

Amiodarone for maintenance of sinus rhythm after conversion of atrial fibrillation in the setting of a dilated left atrium

Previous reports suggest that the finding of left atrial (LA) dilatation (greater than 45 mm) by echocardiography identifies patients not likely to maintain sinus rhythm after conversion of atrial fibrillation (AF). However, these studies antedate the availability of amiodarone, an antiarrhythmic agent that reportedly is effective in patients with AF in whom other drug therapy has failed. To analyze the relation between LA size and the ability to maintain sinus rhythm with amiodarone therapy, 28 patients, aged 32 to 87 years (mean 61), with an LA dimension greater than 45 mm (range 46 to 78, mean 57) were studied. Thirteen patients (46%) had valvular heart disease, 10 (36%) dilated cardiomyopathy and 5 (18%) miscellaneous disorders. In 25 patients (89%) quinidine therapy had failed. After therapy with amiodarone, sinus rhythm returned in all patients and was maintained. Therapy was judged completely successful in 10 patients (alive and still in sinus rhythm with at least 1 year of follow-up), partially successful in 11 (maintaining sinus rhythm for at least 6 months before a change in status) and failed in 7. Completely successful therapy was accomplished in 9 of 18 patients with an LA dimension between 46 and 60 mm, but in only 1 of 10 patients with an LA dimension greater than 60 mm (p less than 0.05). Thus, patients with LA dimensions between 46 and 60 mm who are significantly compromised by AF can often be maintained in sinus rhythm with amiodarone therapy. However, in patients with larger LA dimensions. AF is likely to return despite aggressive antiarrhythmic therapy with amiodarone, a drug with potentially serious side effects.

Strategies for the management of tachyarrhythmias

Conversion of atrial fibrillation or flutter is electrical and, if drugs fail to prevent recurrence, low energy His bundle ablation with implantation of a rate responsive pacemaker is our routine. For re-entry tachycardia, antitachycardia pacers are often the method of choice. We use bipolar automatically actuated systems exclusively, functioning either as burst overdrive or critically timed stimulation. His bundle, or accessory pathway ablation, is considered a later choice. Ventricular arrhythmias are initially terminated by by Class I agents or cardioversion and then a trial of suppressive drugs used. If this fails, a combination of an antitachycardia pacemaker plus an automatic implantable defibrillator is implanted. Alternative options are ablation of the arrhythmogenic site, endomyocardial stripping, or an encircling ventriculotomy with cardiac transplantation as the final option considered.

Persistent lone atrial fibrillation--its prognosis after clinical diagnosis

Eighty-three patients whose atrial fibrillation appeared to be permanent and the sole cardiac abnormality at the time of diagnosis were followed for one to 19 years (mean 7.5 years). None suffered systemic embolism. Three died, none of cardiac disease. Sinus rhythm returned in seven. Another six developed features suggestive of other heart disease. In the remaining 67, the initial diagnosis of persistent lone atrial fibrillation remained tenable and they remained well.The medium-term prognosis for patients with this disorder seems good.

Comparative efficacy of short-acting and long-acting quinidine for maintenance of sinus rhythm after electrical conversion of atrial fibrillation

Forty patients with chronic atrial fibrillation, apparently unrelated to any overt heart disease, were randomly allocated to two groups after restoration of sinus rhythm by direct current shock. The patients in group A were given 4 daily doses of quinidine polygalacturonate, while those in group B were given 2 daily doses of a long-acting quinidine preparation, quinidine arabogalactan sulphate. The percentage of early relapses (within the first month following DC shock) was not significantly different in the two groups: 44-4% in group A and 35% in group B (P greater than 0-50). On the other hand, there were fewer late relapses with long-acting quinidine. After 18 months of treatment, 27-8% of patient in group A remained in sinus rhythm, compared with 61% in group B (P less than 0-05). The average amount of quinidine actually ingested by the patients in group A was smaller than that in group B. However, this could not entirely account for the difference observed in the incidence of relapse since with short-acting quinidine the proportion of patients remaining in sinu rhythm was similar whether the dose was decreased or not. The incidence of gastrointestinal side-effects was the same in the two groups and there were no seriou complications that could be attributed to treatment. It is concluded that long-acting quinidine preparations are more effective than conventional quinidine in preventing late relapses of atrial fibrillation.

Effect of quinidine on maintaining sinus rhythm after conversion of atrial fibrillation or flutter. A multicentre study from Stockholm

In a controlled study comprising 176 patients, quinidine in the form of Kinidin Durules was found to reduced significantly the recurrence of the atrial fibrillation during a 1-year follow-up period after successful electric shock conversion. After one year, 51 per cent (52/101) of the patients in the quinidine group, and 28 per cent (21/75) in the control group remained in sinus rhythm (P smaller than 0.001). No less than 43 per cent of the patients converted to sinus rhythm during treatment with maintenance doses of quinidine sulphate before intended DC conversion. Gastrointestinal side-effects were not uncommon, and caused interruption of quinidine treatment in some cases.