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Independent Predictors of Long Term
Success in Treatment of Persistent
Atrial Fibrillation

Potpara, Tatjana; Marinkovic, Jelena; Grujic, Miodrag;
Radojkovic, Biljana; Vujisic, Bosiljka

Institute for Cardiovascular Diseases, Clinical Centre of Serbia, Belgrade, Yugoslavia

SUMMARY
Objetives: This study evaluates whether clinical and/or echocardiographic parameters registered at patient's presentation could predict the long-term treatment outcome in patients with first persistent atrial fibrillation (PAF) ever experienced.
Background: Although AF is the most common cardiac arrhythmia it is still not clear if possibilities for long-term maintenance of sinus rhythm (SR) could be predicted in advance, i.e. in time of arrhythmia recognition.
Material and Methods: Using multiple logistic regression model with a 95% confidence interval we analysed the influence of clinical and echocardiographic parameters listed bellow on long-term outcome (1-15, mean 5 years) of 335 patients with first PAF.
Results: In the multiple logistic regression model dependent variable was cardiac rhythm at the end of follow-up (SR-237 or 70.7% patients, permanent AF-98 or 29.3%). Independent clinical variables were: age (mean 54 years), gender (69.9% males), arrhythmia duration before cardioversion at the beginning of the study (mean 8.5 months, over 48 hours in 83% of patients), lone AF (37%) and previous heart failure (9.9%). Independent echocardiographic variables in the same model were: left atrial enlargement (59% of patients) and left ventricular ejection fraction (normal in 80% of patients). Model identified heart failure, arrhythmia duration over 48 hours before cardioversion and left atrial enlargement as independent predictors of increased risk of permanent AF at the end of the study (correspondent relative risks are 5, 4 and 2.3).
Discussion:
AF duration before cardioversion and left atrial dimension exert powerful impact on treatment outcome in patients with PAF, as many investigators previously reported. Opinions differ regarding heart failure and rigid algorhythm of treatment of PAF does not exist.
Conclusions: Long-term successful treatment of PAF can be predicted by baseline parameters at patient's presentation. Maintaining SR is likely in patients with normal left atrium, without heart failure and with AF lasting less than 48 hours before cardioversion.

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OBJECTIVES
   This study evaluates whether clinical and/or echocardiographic parameters registered at patient's presentation could predict the long-term treatment outcome in patients with first episode of persistent atrial fibrillation ever experienced.

BACKGROUND
   Although atrial fibrillation is the most common cardiac arrhythmia it is still not clear if possibilities for long-term maintenance of sinus rhythm could be predicted in advance, i.e. in time of arrhythmia recognition and before any therapy has been started. Because of the certain risk of proarrhythmic action of antiarrhythmic drugs used for conversion of atrial fibrillation and maintenance of sinus rhythm that should not be neglected, it seems reasonable to try to define the subset of patients in whom rhythm control is worth attempting at all and in whom acceptable chances for successful therapy exceeds known risks of antiarrhythmic therapy. During 1903 year Lewis and Rothberger almost simultaneously reported the first clinical description of atrial fibrillation in humans. Nearly one century later there still does not exist a rigid, complete algorhythm for management of patients with this cardiac arrhythmia.

MATERIAL AND METHODS
   Using multiple logistic regression model with a 95% confidence interval we analysed the influence of clinical and echocardiographic parameters listed bellow on long-term outcome (follow up of 1-15, mean 5 years) in a cohort of 335 patients with first episode of persistent atrial fibrillation.

   Patients with acute causes of atrial fibrillation such as hyperthyroidism, patients with advanced valvular heart disease and/or significant left ventricular systolic dysfunction (left ventricular ejection fraction = 30%), patients with heart conduction system diseases and/or permanent artificial pacing devices, as well as patients with Wolff-Parkinson-White syndrome were excluded from the study.

   Besides detailed history, clinical examination, biochemistry and routine 12-lead electrocardiogram each patient underwent transthoracic echocardiography in M-mode, Two-dimensional and Continuous and Colour Doppler techniques. Other diagnostic procedures were performed if necessary and cardiac or other diseases were diagnosed according to known accepted criteria.

    Upon admission to hospital, all patients received some medication for slowing atrioventricular conduction (digitalis, beta blockers or verapamil) orally or intravenously. Conversion of atrial fibrillation was then attempted pharmacologically and/or by external DC shock. The restoration of sinus rhythm was documented electrocardiographically and conversion of atrial fibrillation was considered to be successful if sinus rhythm lasted at least 12 hours after last administered dose of antiarrhythmic drug or at least 1 hour after electrocardioversion. After conversion of atrial fibrillation each patient received some antiarrhythmic drug for prevention of atrial fibrillation, according to current clinical practice (class IA, IC or class III antiarrhythmics). During follow up patients underwent routine check-up monthly and if atrial fibrillation recurred we performed new cardioversion in the absence of contraindications. Cardioversion during follow up was not repeated if patient have already tried at least three different antiarrhythmics or the last administered medication was amiodarone.

   All continuous variables are expressed as mean values with correspondent standard deviations. Database is recorded in Microsoft Excel 97 programme and all statistical analyses are performed using SPSS (Statistical Package for Social Sciences).

RESULTS
   In the multiple logistic regression model dependent variable was cardiac rhythm at the end of follow-up: sinus rhythm persisted in 237 patients or 70.7%, while atrial fibrillation became permanent in 98 patients or 29.3%. Independent clinical variables in the model were: age (mean 54 years), gender (69.9% males), arrhythmia duration before cardioversion at the beginning of the study (mean 8.5 months, over 48 hours in 83% of patients), lone AF (37%) and previous heart failure (9.9%). Independent echocardiographic variables in the same model were: left atrial enlargement with anteroposterior diameter over 40mm (59% of patients) and left ventricular ejection fraction (normal in 80% of patients). Model identified previous heart failure, arrhythmia duration over 48 hours before cardioversion and left atrial enlargement as independent predictors of increased risk for development of permanent atrial fibrillation at the end of the study (correspondent relative risks are 5, 4 and 2.3 with 95% CI).

DISCUSSION
   In contrast to other supraventricular cardiac arrhythmias which are now almost completely solved by nonpharmacological techniques, predominantly by radiofrequent catheter ablation, atrial fibrillation is usually not suitable for this kind of therapy and it became the most common cause of repeated admissions to hospital among cardiac arrhythmias. It is clear that there is no definite cure for atrial fibrillation yet and that it is rather reducing the frequency of repeated episodes of atrial fibrillation that may be considered as the successful treatment of those patients.

    According to our results the duration of atrial fibrillation before cardioversion and left atrial dimension exert a powerful impact on treatment outcome in patients with persistent atrial fibrillation, as many investigators previously reported. Opinions differ regarding heart failure but in our study it appeared that patients who ever experienced symptoms and signs of heart failure before current cardioversion at the beginning of the study have 5 times greater relative risk of developing permanent atrial fibrillation as compared to other patients, independently of other clinical and echocardiographic characteristics included in the analysis. The question could be raised whether those patients should be exposed to potential proarrhythmic risks of long-term antiarrhythmics therapy if we already know that their chances for successful prevention of permanent atrial fibrillation are significantly reduced, especially when we are aware that the proarrhythmic effects of antiarrhythmic drugs are the most pronounced in this subset of patients.
Obviously the treatment of atrial fibrillation and different proposed algorhythms for therapy need further investigations.

CONCLUSIONS
   Long-term successful treatment of persistent atrial fibrillation can be predicted by baseline parameters at patient's presentation. Maintaining sinus rhythm is the most likely in patients with normal left atrium, without heart failure and with atrial fibrillation lasting less than 48 hours before cardioversion.

 

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2nd Virtual Congress of Cardiology

Dr. Florencio Garófalo
Steering Committee
President
Dr. Raúl Bretal
Scientific Committee
President
Dr. Armando Pacher
Technical Committee - CETIFAC
President
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