[AV nodal reentrant tachycardias: what is the place of cryoablation?]. / Cryoablation : quel apport dans la prise en charge des tachycardies par réentrée intranodale ?

Radiofrequency ablation is the reference method for the interventional treatment of AV nodal reentrant tachycardias. Even if risks are low, one of the complications of radiofrequency ablation is auriculoventricular block. Cryoablation is an alternative to radiofrequency ablation. The most important advantage of this technique is a lack of permanent AV-block. This article reviews principles of cryotherapy, its main results in ablation of AV nodal reentrant tachycardias, its advantages and disadvantages. A proposal is made about its indications.

Transvenous cryo-ablation of the slow pathway for the treatment of atrioventricular nodal re-entrant tachycardia: a single-centre initial experience study.

AIMS: Within the last several years, transvenous cryo-ablation has become an alternative method to perform ablation of the slow-pathway. This study evaluated the acute and long-term safety and effectiveness of atrio-ventricular nodal re-entrant tachycardia (AVNRT) cryo-ablation. METHODS AND RESULTS: The first 69 consecutive patients with AVNRT (60 slow-fast, 4 fast-slow, and 5 slow-slow) who underwent slow-pathway cryo-ablation were included. Mean age was 37 +/- 15, body weight 68 +/- 14 kg, symptom duration 125 +/- 104 months, and number of ineffective antiarrhythmic (AA) drugs 1.8 +/- 1.4. A 7 Fr cryo-catheter (Cryocath(A)) was used, with initially 4-mm-tip and later with 6-mm-tip electrode. Cryo-mapping (n = 7.9 +/- 8.4 per pt) was performed at the temperature of -30 degrees C to test the effect on the target ablation site. Successful cryo-mapping was defined as abolition of nodal conduction jump or AV nodal refractory period prolongation. Cryo-ablation (n = 5.1 +/- 4.9 per pt) was then applied by freezing to -75 degrees C for 4 min in duration if no AV-block occurred. Acute procedural success (defined as AVNRT non-inducibility) after the first cryo-ablation attempt was achieved in 60/69 patients (87%). During cryo-ablation, inadvertent transient AV-block was encountered in 14 patients (five I AV-block and nine II-III AV-block). A mid-septal target site was the only variable correlated with inadvertent AV-block occurrence during cryo-ablation (P < 0.02). Long-term clinical success after cryo-ablation was globally achieved in 56/66 (85%) with a mean follow-up of 18 +/- 9 months (3 pts dropped-out). After the first procedure, 41/66 (62%) had no relapse, eight had a dramatic reduction in AVNRT duration-frequency and considered themselves cured, and five needed previously ineffective AA (with no relapse in three, drastic reduction in AVNRT duration-frequency in two). The five last patients needed one or more procedures, after which one had no recurrence and one had reduction in duration-frequency. Absence of recurrence after the first procedure was positively correlated with 6-mm-tip cryo-catheter use (<0.001) and negatively with acute procedural success (<0.001). At multivariate analysis, both were independently significant (<0.04 and <0.008, respectively). Long-term clinical success was correlated only with 6-mm-tip cryo-catheter use (<0.001). CONCLUSIONS: Slow pathway cryo-ablation is associated with an acute success but a higher recurrence rate. A 6-mm-tip cryo-catheter seems to assure during cryo-ablation a large acute and long-term success. AV-block seems non-guaranteed by a negative cryo-mapping, stressing on need of a careful surveillance. Nevertheless, the theoretical advantage of avoiding the risk of permanent AV-block when compared with radiofrequency needs larger series to be demonstrated.

[Long-term evaluation of endocavitary cryoablation of nodal reentry]. / Evaluation à long terme de la cryoablation endocavitaire dans le traitement des réentrées nodales.

Radiofrequency ablation is the reference treatment of refractory nodal reentry. Cryoablation has the advantage of having more modulable effects and minimises the risk of permanent atrioventricular block (AVB). Its immediate efficacy seems comparable to that of radiofrequency ablation but the long-term results are not well known. Endocavitary cryoablation of the slow pathway was undertaken in 26 patients (18 women) with an average age of 47.7 +/- 72.8 years with re-entrant nodal tachycardia refractory to medical therapy. The primary success rate was 92% (24 out of 26). On average, 2.6 +/- 2.2 (1 to 10) cryoablations at - 70 degrees C were delivered and were preceded by 6.4 +/- 4.5 (1 to 16) cryomappings to locate the site of the slow pathway. During cryomapping, 8 episodes of AVB were observed in 6 patients (6 second or third degree), all of which were revertible on rewarming. No cases of permanent AVB were observed. An oesophageal stimulation test of inducibility was performed on the 4th day in 21 patients, 16 of which were not reinducible. During follow-up of 355 +/- 194 days, 22 of the 26 patients (85%) had no recurrence of the arrhythmia. Two of the 24 primary successes had a recurrence, in addition to the two primary failures. Two of the four recurrences occurred in a non-sustained form which was less disabilitating for the patient and the recurrences were controlled in the 4 patients by antiarrhythmic therapy. These results suggest that cryoablation may be a reliable and effective long-term treatment of re-entrant nodal tachycardias. If confirmed in larger series in terms of efficacy and safety, cryoablation could become the treatment of choice of re-entrant nodal tachycardia.

Electrophysiological characteristics of the atrium in sinus node dysfunction with and without postpacing atrial fibrillation.

In patients with sinus node dysfunction (SND) with or without associated paroxysmal atrial fibrillation (AF), the effectiveness of atrial pacing in reducing the incidence of AF is not definitive. In addition, despite several studies involving large populations of implanted patients, little attention has been paid to the electrophysiological (EP) atrial substrate and the effect of permanent atrial pacing. The aim of this study is to correlate EP data and the risk of AF after DDD device implantation. We reviewed EP data of 38 consecutive patients with SND, mean age 70 +/- 8 years, who were investigated free of antiarrhythmic treatment, for the evaluation of the atrial substrate. We also considered as control group 25 subjects, mean age 63 +/- 14 years, referred to our EP laboratory for unexplained syncope or various atrioventricular disturbances. Following pharmacological washout and at a drive cycle length of 600 ms, effective and functional refractory periods (ERP, FRP), S1-A1 and S2-A2 latency, A1 and A2 conduction duration, and latent vulnerability index (ERP/A2) were measured. AF induction was tested with up to three extrastimuli at paced cycle lengths of 600 and 400 ms in 20 patients. Induction of sustained AF (> 30 seconds) was considered as the endpoint. P wave duration on the surface ECG in lead II/V1 was also measured. DDD pacing mode was chosen in all patients with the minimal atrial rate programmed between 60 and 75 beats/min (mean 64 +/- 4 beats/min). After implantation, the patients were followed-up for 29 +/- 17 months and clinically documented occurrence of AF was determined. When comparing patients with SND and subjects of the control group, we did not find any significant statistical differences in terms of ERP (237 +/- 33 vs 250 +/- 29 ms), FRP (276 +/- 30 vs 280 +/- 32 ms) and S1-A1 (39 +/- 16 vs 33 +/- 11 ms) and S2-A2 latency (69 +/- 24 vs 63 +/- 25 ms). In contrast, we observed significant differences regarding A1 (55 +/- 19 vs 39 +/- 13 ms; P < 0.001), A2 (95 +/- 34 vs 57 +/- 18 ms; P < 0.001) and P wave duration (104 +/- 18 vs 94 +/- 15 ms; P < 0.05), and ERP/A2 (2.8 +/- 1.2 vs 4.8 +/- 1.6; P < 0.001). When comparing patients with (n = 11) or without (n = 27) postpacing AF occurrence, we did not find any difference with reference to ERP, FRP, S1-A1, S2-A2, A1 duration, or follow-up duration. In patients with postpacing AF occurrence, A2 was longer (116 +/- 41 vs 87 +/- 27 ms; P < 0.01), ERP/A2 lower (2.1 +/- 0.4 vs 3.1 +/- 1.4; P < 0.05), P wave more prolonged (116 +/- 22 vs 99 +/- 14 ms; P < 0.01), and preexisting AF history predominant (6/11 vs 5/27 patients; P < 0.05). No difference was observed between patients with (n = 8) and without (n = 12) AF induction during the EP study. In patients with SND, the atrial refractoriness appears normal and the most important abnormality concerns conduction slowing disturbances. Persistence of AF despite pacing stresses the importance of mechanisms responsible for AF not entirely brady-dependent. In this setting, more prolonged atrial conduction disturbances, responsible for a low vulnerability index, and a preexisting history of AF enable us to identify a high risk patient group for AF in the follow-up.

Electrophysiologic characteristics of the atrium in sinus node dysfunction: atrial refractoriness and conduction.

INTRODUCTION: Clinical electrophysiology (EP) has focused attention on the EP properties of atrial muscle in patients with atrial fibrillation (AF). Patients with sinus node dysfunction (SND) sometimes are included in these studies, but the characteristics of these patients with SND alone appear less well investigated. METHODS AND RESULTS: We reviewed EP data of 46 patients (mean age 70 +/- 8 years) with SND, who underwent EP study for evaluation of the atrial substrate. In 16 patients, a history of paroxysmal AF was documented, but not in the remaining 30 patients who had SND alone. We considered as control a group of 25 subjects (mean age 63 +/- 14 years), who were referred to our EP laboratory for unexplained syncope or AV conduction disturbances. Following pharmacologic washout and at a drive cycle of 600 msec, effective (ERP) and functional refractory periods (FRP), S1-A1 and S2-A2 latency, A1 and A2 width, latent vulnerability index (ERP/A2), and P wave duration on the surface ECG were measured. Intra-atrial conduction times were measured from the stimulus artifact by pacing the high right atrium (HRA), to the corresponding atriograms at the AV node (HRA-AVN), low lateral atrium (HRA-LLA), and low interatrial septum close to the coronary sinus ostium (HRA-CSO). Compared with the control group, SND patients did not show differences in ERP (238 +/- 26 msec vs 250 +/- 29 msec), FRP (274 +/- 25 msec vs 280 +/- 32 msec), S1-A1 (38 +/- 15 msec vs 33 +/- 11 msec) and S2-A2 latency (67 +/- 24 msec vs 63 +/- 25 msec), or HRA-AVN (81 +/- 24 msec vs 65 +/- 19 msec), HRA-LLA (36 +/- 30 msec vs 40 +/- 27 msec), and HRA-CSO (77 +/- 17 msec vs 80 +/- 15 msec) conduction times. In contrast, we observed strong differences in atriogram durations A1 (59 +/- 19 msec vs 39 +/- 13 msec; P < 0.001) and A2 (92 +/- 28 msec vs 57 +/- 18 msec; P < 0.001), as well as in the latent vulnerability index ERP/A2 (2.8 +/- 1.2 msec vs 4.8 +/- 1.7; P < 0.001). Also, the P wave was slightly longer (104 +/- 18 msec vs 94 +/- 45 msec; P < 0.05). No significant statistical difference in EP parameters was found between SND patients with or without documented AF. CONCLUSION: In patients with SND, atrial refractoriness appears similar to that of control subjects. The most important EP abnormality appears to be local conduction slowing disturbances, with prolonged basal and postextrastimuli atriograms, responsible for a lower vulnerability index. This could explain, at least in part, the tendency of patients with SND to develop AF during their natural history. Normality of atrial refractoriness, in contrast to atrial conduction disorders, might explain why atrial pacing shows a preventative effect on the development of AF and why antiarrhythmic drugs often are ineffective.

Electrophysiological determinants of atrial fibrillation in sinus node dysfunction despite atrial pacing.

AIMS: The effectiveness of atrial pacing in reducing the incidence of atrial fibrillation in patients with sinus node dysfunction is incomplete, and the correlation between electrophysiological atrial properties and the effect of permanent atrial pacing has been poorly investigated. Accordingly, the aim of the present study was to correlate electrophysiological data, in terms of atrial refractoriness, conduction parameters, and propensity to atrial fibrillation induction, and the likelihood of atrial fibrillation after DDD device implantation. METHODS AND RESULTS: The authors reviewed electrophysiological data of 41 patients with sinus node dysfunction (mean age 70 +/- 8 years, who were investigated free of anti-arrhythmic treatments before pacemaker implantation. At a drive cycle length of 600 ms, effective and functional refractory periods, S1-A1 and S2-A2 latency, A1 and A2 width, and latent vulnerability index (effective refractory period [ERP] A2), were measured. Atrial fibrillation induction was tested with up to three extrastimuli in 34 patients. Induction of sustained atrial fibrillation (> 1 min) was considered as the end-point. P-wave duration on the surface ECG in lead II/V1 was also measured. Minimal atrial rate was programmed between 60 and 75 bpm (mean: 64 +/- 4 bpm). After implantation, the patients were followed-up for 28 +/- 17 months, and ECG-documented occurrence of atrial fibrillation was determined. Electrophysiological characteristics of patients with (n = 12) or without (n = 29) paroxysmal atrial fibrillation before implantation were similar. When comparing patients with (n = 11) or without (n = 30) post-pacing atrial fibrillation occurrence, no differences were found in age, underlying heart disease, left atrial size, minimal pacing rate, and follow-up duration. Additionally, between the two former groups, there was no significant difference in terms of effective refractory periods (233 +/- 47 ms vs 239 +/- 25 ms), functional refractory periods (280 +/- 48 ms vs 272 +/- 21 ms), S1-A1 (44 +/- 20 ms vs 37 +/- 13 ms) and S2-A2 latency (77 +/- 28 ms vs 66 +/- 22 ms), and A1 duration (60 +/- 23 ms vs 53 +/- 16 ms). In contrast, in patients with post-pacing atrial fibrillation occurrence, the P wave was more prolonged (116 +/- 22 ms vs 98 +/- 13 ms; P < 0.01), A2 was longer (116 +/- 41 ms vs 87 +/- 27 ms; P < 0.01), effective refractory periods/A2 was lower (2.1 +/- 0.4 cm vs 3.1 +/- 1.4 cm; P < 0.05), and rate of atrial fibrillation induction was higher (8/11 patients vs 8/23 patients; P < 0.05). Electrophysiological characteristics of patients free of post-pacing atrial fibrillation with associated (n = 6) or unassociated (n = 24) paroxysmal atrial fibrillation history before implantation were quite similar. In patients with post-pacing atrial fibrillation with associated (n = 6) or unassociated atrial fibrillation history (n = 5) before implantation, effective refractory periods was statistically different (207 +/- 23 ms vs 264 +/- 46 ms; P < 0.05). Values of effective refractory periods < 220 ms were significantly more frequent in patients with post-pacing atrial fibrillation than in patients without (4/11 patients vs 2/30 patients; P < 0.05). When comparing patients with post-pacing atrial fibrillation with effective refractory periods > or = 220 ms (n = 7) and < 220 ms (n = 4), A2 duration was remarkably prolonged (145 +/- 42 ms vs 90 +/- 11 ms; P < 0.05) in those with effective refractory periods > or = 220 ms. By contrast, between the two groups, effective refractory periods/A2 were identical (2.08 +/- 0.6 cm vs 2.15 +/- 0.3 cm; P = n.s.). CONCLUSION: Prolonged atrial refractoriness, lesser degrees of conduction disturbance and a lower rate of atrial fibrillation induction seem to be predictive of stable sinus rhythm. In contrast, patients with persistence of atrial fibrillation despite pacing have a more abnormal and inhomogeneous atrial substrate, as well as a higher rate of atrial fibrillation induction. Prolonged P wave, shortened refractoriness, or remarkably abnormal conduction disturbances in the presence of prolonged refractoriness limit the effectiveness of standard atrial pacing in atrial fibrillation prevention. Identification of predictive criteria of failure of single-site atrial pacing may be used to consider dual-site atrial pacing in such patients with sinus node dysfunction.

Is dual site better than single site atrial pacing in the prevention of atrial fibrillation?

Long-term prevention of atrial fibrillation is not constantly realized by single-site right atrial pacing, and the beneficial role of multisite atrial pacing is still being studied. Accordingly, we compared the effectiveness of dual site and single site atrial pacing in 83 patients (50 men, 33 women, aged 69 +/- 10 years), who received a DDD device for primary sinus node dysfunction or bradycardia with documented atrial fibrillation. Inclusion criteria for dual site pacing were a sinus P wave > or = 120 ms and at least two episodes of documented paroxysmal AF in the 6 months preceding implantation. Dual site atrial pacing (high right atrium-coronary sinus ostium) was performed in 30 cases, and was compared to 53 single site paced patients, 21 with a P wave > or = 120 ms and 32 with a P wave < 120 ms. The basic pacing rate was programmed at 68 +/- 4 beats/min (range 60-75 beats/min). Sinus P wave (133 +/- 20 vs 95 +/- 9 ms; P < 0.001), paced P wave (107 +/- 14 vs 99 +/- 15; P < 0.05), number of antiarrhythmic drugs used (2.4 +/- 1.2 vs 1.6 +/- 1.5, P < 0.05), and the duration of symptoms (8.1 +/- 4.5 vs 3.8 +/- 2.4 years; P < 0.001) were significantly higher in dual site patients. The other characteristics were similar. During the follow-up of 18 +/- 15 months (range 3-30 months), paroxysmal AF was documented in 33 patients. Among these patients, 13 developed permanent AF following at least one episode of paroxysmal AF. When comparing dual site patients and single site patients with a P wave duration > or = 120 ms, paroxysmal AF incidence was lower in the dual site group (9/30 patients vs 15/21 patients, P < 0.01), as well as permanent AF (1/30 patients vs 8/21 patients, P < 0.01). By contrast, comparison between dual site patients and the group of single site patients with a P wave duration < 120 ms did not evidence any significant differences in paroxysmal (9/30 patients vs 9/32 patients) and permanent (1/30 patients vs 4/32 patients) AF incidences. Dual site seems better able than single site atrial pacing to improve the natural history of patients with a prolonged P wave, reducing the incidence of paroxysmal and permanent AF. No benefit could be expected in patients with a normal P wave duration.

Sick sinus syndrome with and without atrial fibrillation: atrial refractoriness and conduction characteristics.

BACKGROUND: Clinical electrophysiology has focused the attention on the electrophysiological properties of the atrial muscle in patients with atrial fibrillation: shortened and inhomogeneous refractoriness and local and regional conduction slowing, as well as prolonged intra- and interatrial conduction disturbances, are well described as electrophysiological parameters associated with the genesis of atrial fibrillation. Patients with sick sinus syndrome are variously included in these studies, but electrophysiological characteristics of patients with sick sinus syndrome alone appear less investigated, even if atrial fibrillation is part of its natural history. The aim of the present study was to define the electrophysiological characteristics of sick sinus syndrome patients with or without paroxysmal atrial fibrillation, compared to subjects without atrial fibrillation and sick sinus syndrome. METHODS: We reviewed the electrophysiological data of 39 patients with sick sinus syndrome (mean age 70 +/- 8 years), who underwent an electrophysiological study in sinus rhythm for the evaluation of the atrial substrate. In 12 patients an associated history of paroxysmal atrial fibrillation was documented. Twenty-seven patients were included in the study with a diagnosis of sinus node dysfunction alone. We also considered as control group 25 subjects (mean age 63 +/- 14 years), referred to our electrophysiological laboratory for unexplained syncope or atrioventricular disturbances. Following pharmacological wash-out and at a drive cycle of 600 ms, effective and functional refractory periods, S1-A1 and S2-A2 latency, A1 and A2 width, and the latent vulnerability index (effective refractory period/A2), were measured. In addition, the P-wave duration during spontaneous sinus rhythm on the surface ECG in D II/V1 leads was measured. RESULTS: Between sick sinus syndrome patients with or without atrial fibrillation, no significant statistical differences in electrophysiological parameters were found. When compared to the control group, sick sinus syndrome patients did not show any differences in effective refractory period (239 +/- 34 vs 250 +/- 29 ms), functional refractory period (276 +/- 28 vs 280 +/- 32 ms), S1-A1 (38 +/- 16 vs 33 +/- 11 ms), and S2-A2 latency (68 +/- 25 vs 63 +/- 25 ms). In contrast, we observed remarkable differences in terms of atriogram duration A1 (60 +/- 20 vs 39 +/- 13 ms, p < 0.001), A2 (95 +/- 34 vs 57 +/- 18 ms, p < 0.001), and effective refractory period/A2 (2.8 +/- 1.2 vs 4.8 +/- 1.7 cm, p < 0.001). Also the duration of the P wave was longer (103 +/- 17 vs 94 +/- 45 ms, p < 0.05). CONCLUSIONS: In sick sinus syndrome patients with or without atrial fibrillation, electrophysiological characteristics appear homogeneous. When compared to the control group, refractoriness was quite similar. In contrast, the most important abnormalities appear based on conduction slowing disturbances, responsible for a low latent vulnerability index. This could explain, at least in part, the tendency of sick sinus syndrome to develop atrial fibrillation as a part of its natural history. At present, the influence of an altered electrophysiological substrate on pharmacological or pacing therapy in patients with sick sinus syndrome is not yet known.

[The effects of the ablation of atrial flutter in patients with and without a clinical history of paroxysmal atrial fibrillation]. / Effetti dell'ablazione di flutter atriale in pazienti con e senza storia clinica di fibrillazione atriale parossistica.

BACKGROUND: Although the safety and effectiveness of radiofrequency (RF) transcatheter ablation in patients with atrial flutter (AFL) is well established, little attention is paid to previous history of associated paroxysmal atrial fibrillation (AF) and the recurrence of AFL after RF ablation. In addition, it is not known whether the elimination of AFL can modify the natural history of AF in patients who experience both of these arrhythmias. Accordingly, the aim of this study was to evaluate the effect of RF ablation of AFL in patients with or without a previous history of AF in terms of the incidence of both arrhythmias in the follow-up. METHODS: RF ablation of the atrial isthmus between tricuspid ring, coronary sinus os and inferior vena cava was performed in 27 patients (23 males, 4 females; mean age 61 +/- 9 years) according to the technique described by Cosio. Based on ECG pattern, twenty patients exhibited common or type 1 AFL (negative F waves in the inferior leads with a sawtooth morphology), while seven patients had both common and uncommon AFL (various surface F wave morphologies, generally positive F waves in the inferior leads). A history of association between AFL and paroxysmal AF was documented in 48% of patients, but AFL was the major arrhythmia. After ablation, the patients were followed up and the clinically documented occurrence of arrhythmias was determined. RESULTS: Based on clinical history before ablation, we compared patients with an association between AFL and AF (Gr AFL + AF; n = 13) vs patients with only AFL (Gr AFL; n = 14). The characteristics of the two groups were similar regarding age, sex, duration of symptom, structural heart disease, left atrial size, P-wave duration, AFL interruption during RF procedure, antiarrhythmic treatment before and after RF procedure, and duration of follow-up. During a follow-up of 12 +/- 6 months, AFL recurred in 10 patients (37%), 4 from Gr AFL + AF, and 6 from Gr AFL (p = NS). Episodes of paroxysmal AF occurred in 6 patients (22%), 5 from Gr AFL + AF and 1 from Gr AFL (p < 0.05). In Gr AFL + AF, the incidence of AF after ablation was significantly lower (1.8 +/- 0.6 vs. 0.7 +/- 1 episodes/year; p < 0.02). Characteristics of patients with or without AFL recurrence in the follow-up were similar. The percentage of patients with the occurrence of AFL or AF, associated or unassociated in the follow-up, was 55%. CONCLUSIONS: A history of paroxysmal AF before RF ablation of AFL is not predictive of long-term success or failure of the procedure when considering the recurrence of AFL alone. Nevertheless, the general results are disappointing because the majority of patients have arrhythmias, AFL or AF, associated or unassociated in the follow-up. A clinical history of AF before ablation is correlated with a higher incidence of AF in the follow-up. In any event, the incidence of AF episodes is lower in the follow-up, indicating a possible beneficial effect of AFL ablation on AF mechanisms.

[The role of an electropharmacological transesophageal test in the prevention of paroxysmal atrial fibrillation. Experience with flecainide]. / Ruolo del test elettrofarmacologico transesofageo nella profilassi della fibrillazione atriale parossistica. Esperienza con flecainide.

BACKGROUND: The management of patients with paroxysmal atrial fibrillation (AF) is unsuccessful, because AF recurs in about 50% of patients despite an antiarrhythmic treatment. Usefulness of non-pharmacological strategies is available in a limited subset of patients and it does not present a global solution to the problem. At present, treatment with antiarrhythmic agents is the only available tool in patients with AF recurrence. The aim of this study was to assess the predictive value of the electropharmacological transesophageal (TE) test in the management of patients with paroxysmal AF treated by flecainide. METHODS: In 32 patients, ranging in age from 38 to 70 years (mean: 59 +/- 12 years), with documented episodes of paroxysmal AF (mean: 5.6 +/- 3.7 episodes/last year), we performed an electrophysiological transesophageal (TE) test following pharmacological wash-out. An aggressive protocol was used: step A: 10 sec atrial burst at Wenckebach point + 10 bpm, 200 and 250 bpm; step B: 10 sec atrial bursts at 300, 400, 500 and 600 bpm; step C: 8 sec increasing rate burst from 200 to 800 bpm. Induction of sustained AF (> 1 min) was considered the end-point. Patients were treated with flecainide 100 mg bid and a second TE test was performed at the steady-state, with an identical induction protocol and end-point. Based on the response of the second test, patients were divided into responders (R Group: non-inducible AF) and non-responders (NR Group: inducible, sustained AF). Patients were followed-up by periodical controls and contacted by telephone to confirm their clinical status. RESULTS: Sustained AF was induced in 30 patients (94%) at the first TE study. Eight of them dropped-out at the time of the second TE test (6 patients for lack of consent, 1 patient for side-effects and another one for proarrhythmic effects). In the mean follow-up of 15 +/- 6 months, among patients who underwent a second TE test, AF recurrence was documented in 2 out of 14 patients from the R Group and in 7 out of 10 patients from the NR Group (p < 0.01). There were 4 AF episodes in the R Group and 19 in the NR Group (p < 0.001). We did not find significant statistical differences between the two groups in terms of age, sex, body weight, AF episodes/past year, P-wave duration, left atrial dimension, structural heart disease, AF duration at the first TE test and follow-up duration. In five patients from the NR Group with induced AF lasting > 5 min, the percentage of recurrence was 100% and there were 16 AF episodes. Global percentage of patients with recurrence was 37%. CONCLUSIONS: Flecainide is effective in reducing the incidence of AF and results are similar to other antiarrhythmic agents generally used. The electropharmacological TE test might be a useful tool to predict the response to an antiarrhythmic treatment.

[Idiopathic atrial fibrillation of recent onset and atrial stunning: the echocardiographic evidence after pharmacological cardioversion]. / Fibrillazione atriale idiopatica di recente insorgenza e stunning atriale: evidenza ecocardiografica dopo cardioversione farmacologica.

Successful cardioversion of atrial fibrillation may result in prolonged recovery of normal atrial mechanical function. This prolonged recovery of atrial contraction (so-called atrial stunning) might depend on: the amount of energy delivered during direct current cardioversion; the time course between the onset of atrial fibrillation and the conversion to sinus rhythm; the size of the left atrium; the underlying cardiac disease. The aim of this study was to evaluate, in subjects with normal atrial size and without heart disease, the phenomenon of atrial stunning soon after pharmacological cardioversion of an episode of atrial fibrillation of recent onset. Twenty-five patients with an acute episode of atrial fibrillation, without evidence of heart disease and M-mode left atrial dimension (< or = 40 mm received i.v. propafenone or flecainide 2 mg/kg/10 min in order to restore sinus rhythm. Atrial fibrillation lasted < 48 hours in all patients. Doppler echocardiography was used to assess atrial function, by recording the peak velocity of atrial contraction (A wave). An echocardiographic study was performed within 12 hours of successful cardioversion and was repeated on day 3, 12 and 30. The size of the left atrium (37 +/- 3.9; 37.57 +/- 2.9; 37.4 +/- 4; 37.82 +/- 3.7 mm) and peak E velocity (57.97 +/- 18.3; 59.4 +/- 18.3; 59.0 +/- 16; 59.07 +/- 16.7 cm/s) did not show any significant differences over the time, as demonstrated by the serial echocardiographic evaluations. In contrast, both peak A velocity (cm/s) and E/A ratio evaluated within 12 hours of cardioversion (60.29 +/- 12.3 and 1.0 +/- 0.37) and on day 3 (73.71 +/- 10.7 and 0.82 +/- 0.27) were statistically different (p < 0.000001 and p < 0.00001). No further statistically significant increase was found in subsequent examinations (respectively 76.31 +/- 12 and 0.78 +/- 0.24 on day 12, and 76.91 +/- 14.8 and 0.78 +/- 0.21 on day 30). In conclusion, this study suggests that patients with alone atrial fibrillation of recent onset have a delayed recovery of normal atrial systolic function even after pharmacological cardioversion.