Brain natriuretic peptide predicts successful cardioversion in patients with atrial fibrillation and maintenance of sinus rhythm

BACKGROUND: Brain natriuretic peptide (BNP) is released from the heart by hemodynamically induced muscle stretch. Patients with atrial fibrillation have higher levels of BNP than those in sinus rhythm. OBJECTIVE: To assess the usefulness of BNP as a predictor of successful cardioversion in patients with persistent atrial fibrillation and subsequent maintenance of sinus rhythm. SUBJECTS AND METHODS: Twenty patients undergoing cardioversion for persistent atrial fibrillation were enrolled. BNP levels were measured before electric cardioversion, and 30 min and two weeks after cardioversion. Baseline echocardiograms and 12-lead electrocardiograms were obtained from all patients. Patients with valvular disease, previous mitral valve surgery or significant left ventricular dysfunction were excluded. RESULTS: The mean BNP level and the mean heart rate were significantly higher before cardioversion than 30 min after (197+/-132 pg/mL versus 164+/-143 pg/mL, P=0.02, and 77+/-17 beats/min versus 57+/-12 beats/min, P=0.0007, respectively). Patients who reverted back to atrial fibrillation after two weeks had a baseline BNP of 293+/-106 pg/mL, while those who remained in sinus rhythm for two weeks had a lower baseline BNP of 163+/-122 pg/mL (P=0.02). CONCLUSION: In patients with persistent atrial fibrillation, BNP levels are associated with successful cardioversion and maintenance of sinus rhythm two weeks after cardioversion.     

Functional capacity of patients with atrial fibrillation and controlled heart rate before and after cardioversion.

OBJECTIVE: To measure exercise duration (which frequently is diminished by atrial fibrillation) and to compare the gain in exercise duration achieved by heart rate control with the gain after cardioversion. METHODS AND RESULTS: Eighteen patients (10 with structural heart condition and eight with lone atrial fibrillation) did the treadmill exercise stress test using the Bruce protocol. Resting supine heart rate was lowered below 100 beats/min by verapamil (initial exercise stress test). An exercise stress test was then repeated as often as needed to achieve 'heart rate control' (less than 130 beats/min at the end of a 3 min walk at 10 degrees elevation and 2.74 km/h speed). This heart rate control was obtained by gradual increases in verapamil dose. Subsequently, the patients were converted to normal sinus rhythm chemically (seven patients) or electrically (11 patients) and an exercise stress test was repeated. At cardioversion, patients were on antiarrhythmic therapy and verapamil was discontinued in most. All patients had left atrial size measured by echocardiogram before and after cardioversion, and all were followed for four months. Upon achieving controlled heart rate, exercise duration increased in 16 patients (average gain was 164 s). After cardioversion to normal sinus rhythm, exercise duration further increased in 13 cases with an average additional gain of 90 s. The total increase in exercise duration after cardioversion was 254 s. Post cardioversion, all patients with lone atrial fibrillation improved. A decline in exercise performance occurred in four patients with fixed cardiac output. Average gain in exercise duration was independent of drugs used. Left atrial size remained increased post cardioversion (50.4 mm before and 52 mm after). During four months of follow-up, only eight patients could continue on the same medication given for cardioversion. Three patients did not maintain normal sinus rhythm. CONCLUSIONS: Conversion to normal sinus rhythm in patients with atrial fibrillation is associated with improved exercise tolerance except in cases with fixed cardiac output. Restoration of mechanical atrial function appears to be responsible for improved exercise performance following cardioversion.     

Improvement in exercise performance after successful cardioversion in patients with persistent atrial fibrillation and symptoms of heart failure

BACKGROUND: Loss of atrial systolic function as well as fast and irregular ventricular response result in the impairment of hemodynamic function in patients with atrial fibrillation (AF). AF is considered to be a less efficient cardiac rhythm than sinus rhythm (SR), and accounts for the symptoms of reduced exercise tolerance, such as fatigue, tiredness or dyspnoea. In more severe cases, the hemodynamic alterations can result in heart failure. AIM: To assess exercise performance before and one month after cardioversion of persistent AF. METHODS: We studied 42 patients with mild to moderate clinically stable heart failure and persistent AF (median duration 7 months) with controlled ventricular rate. They underwent submaximal exercise testing 24 hours before cardioversion and one month after cardioversion. Exercise capacity was determined during symptom-limited exercise testing, according to a modified Bruce protocol with peak VO(2) analysis. RESULTS: Thirty-five (83%) patients were successfully cardioverted to SR. One month after cardioversion 29 patients remained in SR (SR group) while 6 had recurrence of AF, and, together with patients with unsuccessful cardioversion, formed the AF group (n=13). Baseline patient characteristics did not differ between the SR and AF groups. Left ventricular ejection fraction (52.7+/-10.2% vs 56.5+/-9.6%, NS) and exercise tolerance (peak VO(2) 19.85+/-3.5 ml/min/kg vs 22.2+/-3,4 ml/kg/min, NS; and exercise duration 9.5+/-3.4 min vs 10.6+/-2.4 min; NS) were similar in both groups before cardioversion. Successful cardioversion resulted in a mean decrease in resting heart rate of 28 beats/minute (94.7+/-10.3 vs 66.7+/-9.7 beats/min, p<0.05), measured 30 days after cardioversion, and a significant improvement in exercise tolerance in the SR group: exercise duration increased from 9.5+/-3.4 min to 13.7+/-3.2 min, p<0.05; and peak oxygen consumption increased from 19.85+/-3.5 ml/min/kg to 32.2+/-3.6 ml/min/kg, p<0.05. No improvement was observed in the AF group. CONCLUSIONS: Restoration of sinus rhythm in patients with persistent AF is associated with a significant improvement in exercise capacity one month after cardioversion.     

Effect of verapamil on immediate recurrence of atrial fibrillation

INTRODUCTION: The purpose of this study was to assess the effect of verapamil on immediate recurrences of atrial fibrillation occurring after successful electrical cardioversion. METHODS AND RESULTS: The effect of verapamil on the recurrence of atrial fibrillation within 5 minutes after successful transthoracic cardioversion was assessed in 19 (5%) of 364 patients undergoing electrical cardioversion. The mean duration of atrial fibrillation was 4.44+/-3.0 months. In the 19 patients, cardioversion was successful after each of three consecutive cardioversion attempts per patient; however, atrial fibrillation recurred 0.4+/-0.3 minutes after cardioversion. Verapamil 10 mg was administered intravenously and a fourth cardioversion was performed. Cardioversion after verapamil was successful in each patient, and atrial fibrillation did not recur in 9 (47%) of 19 patients (P < 0.001 vs before verapamil). In the remaining 10 patients in whom atrial fibrillation recurred, the duration of sinus rhythm was significantly longer compared with before verapamil (3.6+/-2.4 min, P < 0.001). The density of atrial ectopy occurring after cardioversion was significantly less after verapamil (21+/-14 ectopic beats per min) compared with before verapamil (123+/-52 ectopic beats per min, P < 0.001). CONCLUSION: Among patients with immediate recurrence of atrial fibrillation after electrical cardioversion, acute calcium channel blockade by verapamil reduces recurrence of atrial fibrillation and extends the duration of sinus rhythm.     

Functional capacity before and after cardioversion of atrial fibrillation: a controlled study.

OBJECTIVE--To evaluate the effect of cardioversion on peak oxygen consumption (peak VO2) in patients with long-standing atrial fibrillation, to assess the importance of underlying heart disease with respect to the response to exercise, and to relate functional capacity to long-term arrhythmia outcome. DESIGN--Prospective controlled clinical trial. SETTING--Tertiary referral centre. PATIENTS--63 consecutive patients with chronic atrial fibrillation accepted for treatment with electrical cardioversion. Before cardioversion all patients were treated with digoxin, verapamil, or a combination of both to attain a resting heart rate < or = 100 beats per minute. INTERVENTIONS--Electrical cardioversion. MAIN OUTCOME MEASURES--Peak VO2 measured before and 1 month after electrical cardioversion to compare patients who were in sinus rhythm and those in atrial fibrillation at these times. Maintenance of sinus rhythm for a mean follow up of 19 (7) months. RESULTS--Mean (1SD) peak VO2 in patients in sinus rhythm after 1 month (n = 37) increased from 21.4 (5.8) to 23.7 (6.4) ml/min/kg (+11%, P < 0.05), whereas in patients with a recurrence of atrial fibrillation 1 month after cardioversion (n = 26) peak VO2 was unchanged. In patients who were in sinus rhythm both those with and without underlying heart disease improved, and improvement was not related to functional capacity or left ventricular function before cardioversion. Baseline peak VO2 was not a predictive factor for long-term arrhythmia outcome. CONCLUSION--Restoration of sinus rhythm improved peak VO2 in patients with atrial fibrillation, irrespective of the presence of underlying heart disease. Peak VO2 was not a predictive factor for long-term arrhythmia outcome after cardioversion of atrial fibrillation. These findings suggest that cardioversion is the best method of improving functional capacity in patients with atrial fibrillation, whether or not they have underlying heart disease and whatever their functional state.     

Effects of altered site of electrical activation on myocardial performance during inotropic stimulation

The effects of altering the site of electrical activation on responses to isoproterenol (ISO) and treadmill exercise were examined in mongrel dogs instrumented for long-term measurement of left ventricular pressure, left ventricular dP/dt, coronary blood flow, cardiac output, left ventricular diameters, and mean arterial pressure and O2 content in the coronary sinus and aorta. During spontaneous rhythm, 0.2 micrograms/kg/min ISO increased heart rate by 90 +/- 7 beats/min, left ventricular dP/dt by 2479 +/- 301 mm Hg/sec, cardiac output by 3.5 +/- 0.9 liters/min, coronary blood flow by 30.4 +/- 3.9 ml/min, and myocardial oxygen consumption (MVO2) by 3.91 +/- 0.84 ml/min. During right atrial pacing at 193 +/- 7 beats/min, the effects of ISO were not different from the effects during spontaneous rhythm, with the exception of a lesser increase in coronary blood flow and lesser reductions in coronary resistance and left ventricular end-diastolic diameter and pressure. During right ventricular pacing at an identical rate, ISO increased left ventricular dP/dt (1140 +/- 158 mm Hg/sec) and cardiac output (2.2 +/- 0.5 liters/min) significantly less (p less than .025) than during either sinus rhythm or right atrial pacing, while MVO2 rose to a higher value. During right ventricular pacing the changes in mean arterial pressure and left ventricular end-diastolic diameters with ISO were not significantly different from those during right atrial pacing. Treadmill exercise induced significantly smaller (p less than .025) increases in left ventricular dP/dt during right ventricular pacing as compared with during either right atrial pacing or sinus rhythm, while MVO2 rose to a higher value.(ABSTRACT TRUNCATED AT 250 WORDS)     

Absence of atrial contraction and exercise in patients with isolated atrial fibrillation

The aim of the study was to assess the effect of absence of atrial contraction during exercise. During the incremental ergometer exercise tests, heart rate, oxygen uptake, and oxygen pulse in patients with isolated atrial fibrillation were compared with those in control subjects at rest, at the exercise level of gas exchange anaerobic threshold, and at peak exercise. The study population consisted of 51 subjects aged 40 years or more: 12 patients with isolated atrial fibrillation and 39 control subjects with normal sinus rhythm. Heart rate in control subjects was lower than that in patients with isolated atrial fibrillation, at rest, anaerobic threshold, and peak exercise (74 +/- 12 vs 85 +/- 8 beats/min at rest, 108 +/- 16 vs 134 +/- 18 beats/min at anaerobic threshold, and 151 +/- 16 vs 173 +/- 22 beats/min at peak exercise, all p less than 0.01). During exercise, oxygen uptake in patients with isolated atrial fibrillation was not significantly different from that in control subjects. Oxygen pulse in patients with isolated atrial fibrillation was lower than that in control subjects during exercise (6.45 +/- 2.04 vs 7.84 +/- 1.63 ml/beat at anaerobic threshold, 7.79 +/- 2.28 vs 9.16 +/- 1.79 ml/beat at peak exercise, both p less than 0.05). In patients with isolated atrial fibrillation, the oxygen pulse might be reduced due to the lack of atrial contraction during exercise. However, the oxygen uptake that represents the exercise capacity would be preserved with the increase in heart rate.     

Exercise heart rate acceleration patterns during atrial fibrillation and sinus rhythm

Background: Patients with atrial fibrillation sustain a significant lower exercise tolerance compared to those in sinus rhythm, even while seemingly in adequate rate‐control. Methods: Exercise testing was performed during atrial fibrillation and after electric cardioversion for 30 patients who were initially treated with AV modifying agents and were considered in adequate rate control. Heart rate parameters were obtained during all exercise stages, and a graphic display of heart rate acceleration was obtained. For those patients who remained in sinus rhythm, an additional exercise test was performed after 1 month. Results: During atrial fibrillation, heart rate at the completion of Bruce stage 1 and the peak exercise heart rate were significantly higher when compared to sinus rhythm (120 ± 10 bpm vs. 98 ± 11 bpm and 164 ± 16 bpm vs. 129 ± 11 bpm respectively, p < 0.001 for both). The time to peak exercise heart rate was significantly shorter during atrial fibrillation (3.5 ± 1 min vs. 6.5 ± 1.5 min, p < 0.001), and the total exercise duration was subsequently shorter as well (6 ± 2 min vs. 8.5 ± 2 min, p < 0.001). Treatment with beta‐blockers prior to exercise did not affect the earlier peaking of the heart rate. After 1 month, similar time to peak heart rate and similar exercise performance were observed among patients, who remained in sinus rhythm, when compared to to the post‐cardioversion exercise test. Conclusions: In patients with atrial fibrillation, exercise heart rate acceleration displays a specific pattern of early peaking. Earlier heart rate peaking occurs regardless of ample rate control while at rest or mild physical activity and contributes to overall lower exercise performance. Ann Noninvasive Electrocardiol 2011;16(4):357–364     

Effect of restoring sinus rhythm on sleep apnea in patients with atrial fibrillation or flutter

Sleep apnea (SA) is more prevalent in patients with atrial fibrillation (AF), but the impact of cardioversion on disordered breathing is unknown. Thus, we investigated the influence of restoring sinus rhythm in patients with AF and atrial flutter (AFlut) on SA. The 16 patients (mean age 63.1 +/- 11.2) with AF (n = 6) or AFlut (n = 10) and SA (apnea-hypopnea index >10) received cardioversion or ablation of cavotricuspid isthmus. We compared the severity of SA by sleep polygraphy under AF/Aflut with the first night after restoring sinus rhythm and after 4 weeks. Apnea-hypopnea index before and immediately after restoring sinus rhythm was similar (31.7 +/- 13.2 vs 30.1 +/- 15.7, p = NS) despite a significantly reduced heart rate (86.7 +/- 26.5 vs 67.8 +/- 11.9 beats/min, p <0.02). After 4 weeks, apnea-hypopnea index remained unchanged (38.1 +/- 18.1, p = NS) although heart rate was further reduced (61.8 +/- 8.8 beats/min, p <0.003). In our study, SA could not be improved by cardioversion of AF/AFlut. Therefore, although it is well known that SA leads to AF, eliminating AF does not cure or improve SA. In conclusion, our study shows that AF should be regarded more as an innocent bystander than a causative or aggravating condition in SA.     

Use of metoprolol CR/XL to maintain sinus rhythm after conversion from persistent atrial fibrillation: a randomized, double-blind, placebo-controlled study

OBJECTIVES: The primary objective of the present study was to assess the efficacy of metoprolol CR/XL to reduce the risk of relapse after cardioversion of persistent atrial fibrillation to sinus rhythm. BACKGROUND: Indirect data from studies with d,l sotalol provide evidence that the beta-blocking effects of the compound are important in maintaining sinus rhythm after cardioversion of atrial fibrillation. METHODS: After successful conversion to sinus rhythm, 394 patients with a history of persistent atrial fibrillation were randomly assigned to treatment with metoprolol CR/XL or placebo. The two treatment groups were similar with respect to all pretreatment characteristics. Patients were seen on an outpatient basis for recording of resting electrocardiogram (ECG) after one week, one, three and six months of follow-up or whenever they felt that they had a relapse into atrial fibrillation or experienced an adverse event. RESULTS: In the metoprolol CR/XL group, 96 patients (48.7%) had a relapse into atrial fibrillation compared with 118 patients (59.9%) in the placebo group (p = 0.005). Heart rate in patients after a relapse into atrial fibrillation was significantly lower in the metoprolol group (98 +/- 23 beats/min) than in the placebo group (107 +/- 27 beats/min). The rate of adverse events reported was similar in both groups when the difference in follow-up time was taken into account. CONCLUSIONS: The results of this double-blind, placebo-controlled study in patients after cardioversion of persistent atrial fibrillation showed that metoprolol CR/XL was effective in preventing relapse into atrial fibrillation or flutter.     

Effects of lisinopril in patients with heart failure and chronic atrial fibrillation

Although atrial fibrillation is common in patients with heart failure, patients with atrial fibrillation are often excluded from congestive heart failure trials or are not analyzed separately. Consequently, while the effect of angiotensin-converting enzyme inhibitors in patients with sinus rhythm is well established, the effect on patients with atrial fibrillation is unknown. The authors hypothesized that these agents might be particularly effective in this patient category, given their antiadrenergic properties and the importance of adequate rate control. Therefore, the effects of lisinopril 10 mg once daily were evaluated in 30 patients with congestive heart failure and chronic atrial fibrillation (mean age, 68 +/- 6 years) in a double-blind, randomized, placebo-controlled trial. All patients were in New York Heart Association class II or III and were stable on conventional therapy (digoxin, diuretics, nitrates). After 6 weeks, mean peak oxygen consumption increased from 14.7 +/- 3.4 to 15.9 +/- 2.9 mL/min/kg in the lisinopril group (P = .034). Plasma norepinephrine levels during exercise and at peak exercise tended to be lower when the patients were taking lisinopril (10.8 +/- 4.2 to 8.9 +/- 4.4 nmol/L and 16.3 +/- 9.2 to 14.3 +/- 7.7 nmol/L, P < .1). Heart rate during exercise and ambulatory monitoring was not significantly affected. Left ventricular fractional shortening tended to increase after lisinopril (23 +/- 7 to 27 +/- 9%, P = .073). Left atrial volume was unchanged, as were plasma atrial natriuretic peptide levels. After subsequent electrical cardioversion, treatment was continued for 6 more weeks, allowing assessment of the effect of lisinopril on maintenance of sinus rhythm; maintenance of sinus rhythm was 71% in the lisinopril group and 36% in the placebo group (P = NS). This study shows that treatment with an angiotensin- converting enzyme inhibitor improves peak oxygen consumption in patients with congestive heart failure and chronic atrial fibrillation. Attenuation of adrenergic drive during exercise may play a role in mediating this effect.     

Amiodarone in restoration and maintenance of sinus rhythm in patients with chronic atrial fibrillation after unsuccessful direct-current cardioversion

Background: When direct-current (DC) cardioversion is used, sinus rhythm can be restored, at least temporarily, in 80–90% of patients with atrial fibrillation. However, there is a small but significant group of patients with chronic atrial fibrillation in whom DC cardioversion has failed to restore sinus rhythm. The value of antiarrhythmic drug pretreatment before DC cardioversion is still controversial. Hypothesis: The aim of our study was to assess (1) the effecti veness of repeat DC cardioversion in patients with chronic atrial fibrillation after pretreatment with amiodarone, and (2) the efficacy of amiodarone in maintaining sinus rhythm after repeat cardioversion. Methods: Forty-nine patients with chronic atrial fibrillation after ineffective DC cardioversion were included in the study. Repeat DC cardioversion was performed after loading with oral amiodarone, 10–15 mg/kg body weight/day for a period necessary to achieve the cumulative dose of over 6.0 g. Results: Spontaneous conversion to sinus rhythm during amiodarone pretreatment was achieved in 9 of 49 patients (18%). Direct-current cardioversion was performed in 39 patients and sinus rhythm was achieved in 23 of these patients (59%). Mean heart rate decreased from 95 beats/min before to 68 beats/min after DC cardioversion (p<0.001). Systolic blood pressure significantly (p<0.05) decreased from 126 ± 23 to 108 ± 25 mmHg. Complications occurring in four patients just after electroconversion were well tolerated and of short duration. After 12 months, 52% of patients maintained sinus rhythm on low dose (200 mg/day) amiodarone therapy. Conclusion: Pretreatment with amiodarone and repeat DC cardioversion allows for restoration of sinus rhythm in about 65% of patients with chronic atrial fibrillation after first ineffective DC cardioversion. Direct-current cardioversion can be performed safely with the use of standard precautions in patients who are receiving amiodarone. At 12 months' follow-up, more than 50% of patients maintain sinus rhythm on low-dose amiodarone after successful repeat cardioversion.     

Serial evaluation of left atrial dimension after cardioversion for atrial fibrillation and relation to atrial function

The size of the left atrium is usually increased during atrial fibrillation (AF). The aim of the present study was to evaluate changes in left atrial (LA) dimension after cardioversion for AF, and the relation between LA dimension and atrial function. The initial study population included 171 consecutive patients. Patients who had spontaneous cardioversion to sinus rhythm (56 patients) were compared with patients who had random cardio-version with drugs (50 patients) or direct-current (DC) shock (50 patients). Echocardiographic evaluations included LA size and volume. LA passive and active emptying volumes were calculated, and LA function was assessed. Atrial stunning was observed in 18 patients reverted with DC shock and in 7 patients reverted with drugs. The left atrium was dilated in all patients during AF (48 +/- 5 mm). The size of the left atrium decreased after restoration of sinus rhythm in all patients with spontaneous reversion to sinus rhythm, in 73% of patients reverted with drugs, and in 50% of patients reverted with DC shock. The comparison between patients with a normal mechanical atrial function and patients with reduced atrial function showed that a higher atrial ejection force was associated with a more marked reduction in LA size after restoration of sinus rhythm. A relation between LA volumes and atrial ejection force was observed in the group of patients with depressed atrial mechanical function (r = -0.78; p <0.001). The active emptying fraction was lower, although not significantly, in this group, whereas the conduit volume was increased. Thus, a depressed atrial mechanical function after cardioversion for AF was associated with a persistence of LA dilation.     

Atrial pacing for cardioversion of atrial flutter in digitalized patients

To test the safety and reliability of atrial pacing as a conversion technique in patients with atrial flutter who are receiving digitalis therapy, atrial pacing conversion was attempted for 49 episodes of atrial flutter in 32 consecutive patients. All patients except one were receiving digitalis. To control ventricular rates most patients had received larger than usual therapeutic doses of digitalis glycoside before pacing. Fourteen of the 25 patients whose serum levels were measured had glycoside concentrations greater than 2 ng/ml. Before atrial pacing the mean atrial and ventricular rates were, respectively, 290 +/- 20.6 and 134 +/- 27.9/min (mean +/- standard deviation). Successful rhythm conversion was achieved on 48 occasions (98%) in 31 patients. One patient required transthoracic direct current synchronized countershock cardioversion. With atrial pacing, the atrial flutter rhythm reverted immediately to sinus mechanism in 23 instances, and there were 25 episodes of atrial fibrillation. Among those who experienced atrial fibrillation, the rhythm spontaneously reverted to sinus mechanism within 24 hours on 14 occasions; on 11 occasions; the rhythm reverted to atrial flutter and repeat pacing was required. Sinus mechanism was eventually established in all 31 patients.     

Efficacy of intravenous amiodarone in the management of paroxysmal or new atrial fibrillation with fast ventricular response

We tested the efficacy of intravenous amiodarone (5 mg/kg) in slowing ventricular response and/or restoring sinus rhythm in 26 patients with paroxysmal or new atrial fibrillation with fast ventricular response. There were 16 men and 10 women with ages ranging from 35 to 84 years, mean 63 years. Intravenous amiodarone initially slowed the ventricular response in all patients from 143 +/- 27 to 96 +/- 10 beats/min (P less than 0.001). Twelve patients (46%) reverted to sinus rhythm within the first 30 min (range 5 to 30 min, mean 14 +/- 9 min). One patient reverted to atrial flutter after 10 min and 40 min later to sinus rhythm. Six patients (23%) converted to sinus rhythm after 2 to 8 hr and in these 6 cases, the initial slowing in ventricular response obtained with amiodarone persisted until conversion. Seven patients (27%) did not convert to sinus rhythm following amiodarone administration and they required further medical therapy to slow the ventricular response and/or to convert to sinus rhythm. No serious side effects from drug administration were noted. Intravenous amiodarone appears as a highly effective medication in the conversion or control of new onset atrial fibrillation with fast ventricular response.     

Internal cardioversion with low-energy shocks in atrial fibrillation resistant to external electric cardioversion

BACKGROUND AND OBJECTIVE: Although external electrical cardioversion is effective in most patients with atrial fibrillation, there are cases refractory to external cardioversion. This study is aimed at showing our initial experience with an internal cardioversion system in patients with previous unsuccessful external cardioversion. PATIENTS AND METHODS: Between February, 1997 and September, 1998 nine consecutive patients with spontaneous chronic or persistent atrial fibrillation that failed external cardioversion, were included. Internal cardioversion was performed under sedation with two electrodes that had a 5.5 cm coil placed in the lateral right atrium and coronary sinus. Both electrodes were connected to an external defibrillator capable of delivering R-wave synchronized low-energy biphasic shocks following a minimum RR interval of 500 ms. Energy between 2 J and 10 J was applied until the restoration of sinus rhythm or a maximum of 2 shocks of 10 J. RESULTS: Sinus rhythm was achieved in the nine patients, but in two of them atrial fibrillation recurred after a few beats. Both had underlying structural heart disease. The other 7 patients, 5 of them without structural heart disease, were in sinus rhythm at discharge. No mechanic complications or ventricular arrhythmias were observed. Six patients are in sinus rhythm after 4 +/- 3 months of follow-up. CONCLUSIONS: Low-energy intracardiac cardioversion is useful in some patients with atrial fibrillation that had failed external cardioversion and can be performed without general anesthesia.     

Combination of quinidine and verapamil in auricular fibrillation

The efficacy of the association of verapamil plus quinidine in 70 patients with atrial fibrillation, 64 of them after having cardiac surgery, was assessed. Oral dosage ranged from 825 mg to 1,100 mg for quinidine polygalacturonate and 240 mg to 320 mg for verapamil. All patients but two reached a good control of heart rate (mean heart rate less than 110 beats/min) while arrhythmia persisted. Sixty patients (85.7%) reverted to normal sinus rhythm in a period of 2.4 +/- 1.5 days (mean +/- SD). According to the atrial fibrillation duration three subsets of patients with different conversion rates to sinus rhythm were established (p less than 0.01): group A (lasting from 1 day to 3 months) 31/39 (96%); group B (lasting 3 to 6 months) 18/21 (85.7%) and group C (lasting 6 to 12 months) 5/10 (50%) (p less than 0.01). Plasma quinidine levels were maintained at either near to or therapeutic range (2.6 +/- 0.94 micrograms/ml). Adverse effects comprised one ventricular arrhythmia-induced syncope (quinidine syncope) and two cases of systemic hypotension. Quinidine-verapamil association is a good alternative in the treatment of atrial fibrillation, particularly in those of recent onset, according to the high rates of conversion to normal sinus rhythm, affording control of heart rate while atrial fibrillation persists. Adverse reactions did not differ in severity from those observed with quinidine monotherapy.     

Low-energy internal cardioversion in patients with long-lasting atrial fibrillation refractory to external electrical cardioversion: results and long-term follow-up.

AIM: Low-energy internal cardioversion is a new electrical treatment for patients with persistent atrial fibrillation. This paper evaluates the efficacy and safety of low-energy internal cardioversion in patients with long-lasting atrial fibrillation refractory to external electrical cardioversion, and the clinical outcome of such patients. METHOD AND RESULTS: The study population consisted of 55 patients [32 male, mean age 65 +/- 10 years, 48 (87%) with underlying heart disease] with long-lasting (mean 18 +/- 34 months) atrial fibrillation in whom external cardioversion had failed to restore sinus rhythm. Two custom-made catheters were used: one positioned in the right atrium and one in the coronary sinus or the left pulmonary artery. A standard catheter was inserted into the right ventricular apex to provide R wave synchronization. Sinus rhythm was restored in 52 patients (95%) with a mean defibrillating energy of 6.9 +/- 2.6 J (320 +/- 60 V). No complications were observed. During follow-up (mean 18 +/- 9 months), 16 patients (31%) suffered early recurrence (< or = 1 week) of atrial fibrillation and 20 patients (38%) had late recurrence (> 1 week, mean 3.5 +/- 3.6 months) of atrial fibrillation. Six patients with a late recurrence again underwent cardioversion and five of these maintained sinus rhythm. Therefore, a total of 21/52 patients (40%) were in sinus rhythm at the end of follow-up. No clinical difference was found between patients with and without recurrences. CONCLUSIONS: Low-energy internal cardioversion is a useful means of restoring sinus rhythm in patients with long-lasting atrial fibrillation refractory to external electrical cardioversion. More than one-third of patients maintained sinus rhythm during long-term follow-up.     

Exercise response before and after termination of atrial tachycardia after congenital heart disease surgery

We studied exercise performance before and after conversion of atrial tachycardia to sinus rhythm, atrial bradycardia, or junctional rhythm in 10 patients 9-25 years of age 8-20 years after congenital heart disease surgery (complete transposition of the great arteries, seven of 10 patients). The same maximal cycle (five of 10 patients) or treadmill (five of 10 patients) exercise protocol was performed in atrial tachycardia and sinus rhythm 1-232 days after atrial tachycardia (mean, 34 days). Electrocardiogram, heart rate, and pulmonary gas exchange were recorded. Sinus rhythm exercise increased peak VO2 (mean, 28.7 [sinus rhythm] vs. 24.7 [atrial tachycardia], p less than 0.01), exercise time (p less than 0.01), and O2 pulse at rest (p less than 0.01) and at peak exercise (NS). Mean resting heart rate decreased from 109 to 70 beats/min (p less than 0.01). In atrial tachycardia, peak exercise heart rate was low (80-163 beats/min) because of fixed conduction (six of 10 patients) or high as conduction approached 1:1 (176-252 beats/min) (four of 10 patients). In sinus rhythm, rest to peak exercise heart rate increased in six of 10 patients (p less than 0.05). The data show improved exercise performance in sinus rhythm primarily because of improved heart rate adaptation to exercise, by either permitting increased heart rate response or eliminating excessively high heart rate with inadequate diastolic filling.     

Echocardiographic factors predictive of restoration and maintenance of sinus rhythm after reduction of atrial fibrillation

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia. While the arrhythmia was initially thought to be little more than a nuisance, it is now clear that AF has a significant negative impact on quality of life and a corresponding increase in both morbidity and mortality. OBJECTIVE: The aim of this study was to identify Doppler echographic patterns that allow prediction of atrial fibrillation reduction and maintenance of sinus rhythm within 12 months. PATIENTS AND METHODS: One hundred and thirty patients having permanent atrial fibrillation, recent (51) or chronic (79) are included in the study, excepting those with valvular heart disease or thyroid dysfunction. The mean age was 63.5 +/- 11.3 years. Both transthoracic and transoesophageal echocardiography was performed using a Philips SONOS 5500 Echograph, before cardioversion. Were studied: end diastolic and systolic left ventricular diameters, left ventricular ejectionnal fraction, left atrial area (LAA), left atrial diameter, left atrial appendage area and peak emptying velocities of the left atrial appendage (PeV). Sinus rhythm was re-established in 102 patients (44 having recent and 58 chronic atrial fibrillation). Sinus rhythm was maintained for 12 months in 79 patients. RESULTS: Within the echographic parameters studied, the left atrial area (LAA) and peak emptying velocities of left atrial appendage (PeV) before cardioversion were the best predictors of restoration of sinus rhythm. On monovariate analysis, SOG is significantly lower and PicV is significantly higher in patients whose sinus rhythm had been restored in comparison with those with permanent atrial fibrillation. (Mean SOG: 27.7 +/- 7.62 vs. 34 +/- 7,6 cm2, p<0.0001; Mean PicV: 44 +/- 15.8 vs. 31.4 +/- 13,7 cm/s, p<0.0001). This difference was maintained on multivariate analysis (p=0.002 for SOG and p=0.005 for PicV). In patients with recent atrial fibrillation, only left atrial area can predict on mono and multivariate analysis (p=0.05, OR=0.5, IC=0.36 à 3.56), re-establishing of sinus rhythm whereas in patients with chronic atrial fibrillation, peak emptying velocity of left atrial appendage predict better re-establishing of sinus rhythm (p=0.04, OR=1.29, IC=0.12 à 4.23). The threshold values of LAA and PeV for conversion of atrial fibrillation into sinus rhythm are respectively 25 cm2 and 20 cm/sec. In patients who converted into sinus rhythm; LAA predict maintenance of sinus rhythm at the end of 12 months of survey (p=0.04) with a threshold value of 25 cm2. In the subgroup of patients admitted with chronic atrial fibrillation, PeV predicts better the maintenance of sinus rhythm (p=0.05) with a threshold value of 60 cm/sec, p=0.06; whereas LAA remains better in patients with a recent atrial fibrillation. (p=0.02). CONCLUSION: In addition to the anatomic study of cardiac structure and the search of intracavitary thromboses before reduction of atrial fibrillation, echocardiography allows prediction of cardioversion success (LAA and PeV) and maintenance of sinus rhythm within 12 months.