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Ibutilide for cardioversion of atrial flutter: efficacy of a single dose in recent-onset arrhythmias.

AIM: Ibutilide is particularly effective in rapid termination of atrial flutter (AFL) with few adverse effects. Despite the recommendation of 2 infusions, cardioversion may occur up to 70 minutes after a single dose. We investigated the feasibility, efficacy and safety of a single dose ibutilide treatment of AFL in a single-center, observational study. METHODS: Fifty-nine consecutive patients (44 males, mean age 70 +/- 12), referred to our CCU for paroxysmal AFL (mean arrhythmia duration 10 +/- 18 days), were treated with 1 mg ibutilide. In case of inefficacy, a 2nd dose could be administered 10 to 60 minutes later on the basis of the ECG examination for QTc prolongation and AFL cycle variations. Successful cardioversion was defined as sinus rhythm (SR) restoration within 2 hours. RESULTS: Forty-four patients (75%) converted to SR after ibutilide, 31 with single dose (53%, Group 1), and 13 with double dose (22%, Group 2). AFL duration was shorter in Group 1 (4 +/- 5 vs 16 +/- 29 days). The mean time to the 2nd dose administration was 34 +/- 11 minutes in responders, 51 +/- 23 minutes in non-responders. Only 3 (5%) significant adverse events, all observed after a single dose, occurred. CONCLUSION: Ibutilide is highly effective and safe, in a monitored environment, for rapid termination of AFL. Recent onset AFL may be terminated with a single infusion in many cases; yet, cardioversion should be waited for no more than 30 minutes after the end of the 1st dose, before administering the 2nd one, in order not to reduce the possibility of SR restoration.

Adult↗

Ibutilide added to propafenone for the conversion of atrial fibrillation and atrial flutter.

OBJECTIVES: We evaluated the safety and efficacy of ibutilide when added to propafenone in treating both paroxysmal and chronic atrial fibrillation (AF) and atrial flutter (AFL). BACKGROUND: The effects of ibutilide in patients with paroxysmal or chronic AF/AFL who were pre-treated with propafenone have not been previously evaluated. METHODS: Oral propafenone was initially given in 202 patients with AF/AFL without left ventricular dysfunction. Intravenous ibutilide was administered in 104 patients in whom propafenone failed to convert the arrhythmia. Two different propafenone dosage regimens were used according to the duration of the presenting arrhythmia: patients with paroxysmal arrhythmia (n = 48) received 600 mg loading dose, and patients with chronic arrhythmia (n = 56) were receiving 150 mg three times a day as stable-dose pre-treatment. RESULTS: Ibutilide offered an overall conversion efficacy of 66.3% (69 of 104 patients), 70.8% for patients with paroxysmal AF/AFL and 62.5% for patients with chronic AF/AFL. Ibutilide significantly decreased the heart rate (HR) and further prolonged the QTc interval (p < 0.0001). The degree of HR reduction after ibutilide administration emerged as the sole predictor of successful arrhythmia termination (p < 0.001). After ibutilide, one patient (1%) developed two asymptomatic episodes of non-sustained torsade de pointes, and 10 patients (9.6%) manifested transient bradyarrhythmic events; however, all bradyarrhythmic effects were predictable, occurring mostly at the time of arrhythmia termination. None of 82 patients who decided to continue propafenone after successful cardioversion had immediate arrhythmia recurrence. CONCLUSIONS: Our graded approach using propafenone and ibutilide appears to be a relatively safe and effective alternative for the treatment of paroxysmal and chronic AF/AFL to both rapidly restore sinus rhythm in nonresponders to monotherapy with propafenone and prevent immediate recurrences of the arrhythmia.

Administration, Oral↗

LocaLisa catheter navigation reduces fluoroscopy time and dosage in ablation of atrial flutter: a prospective randomized study.

INTRODUCTION: Catheter ablation has become a well-established therapy for isthmus-dependent right atrial flutter (AFL). Recently, mapping and ablation of AFL have been performed using sophisticated three-dimensional mapping systems, such as electroanatomic and noncontact mapping systems. The LocaLisa system enables nonfluoroscopic navigation of intracardiac electrode catheters based on impedance changes related to catheter movements in transthoracic current fields. The aim of this randomized prospective study was to compare the efficacy of the LocaLisa system with the conventional mapping/ablation approach for radiofrequency ablation of AFL. METHODS AND RESULTS: Fifty consecutive patients with AFL (39 men and 11 women; age 65 +/- 10 years) were studied. The patients were randomly assigned to undergo radiofrequency ablation guided by a conventional fluoroscopy-based approach (24 patients) or by the LocaLisa system (26 patients). Ablation success rate and documentation of bidirectional isthmus block were 100% in both groups. Compared with fluoroscopy-guided approaches, LocaLisa-guided procedures demonstrated a reduction in total fluoroscopy time from 15.9 +/- 10.6 minutes to 7.5 +/- 6.5 minutes (P < 0.005). Total fluoroscopy dosage was reduced from 21.0 +/- 19.8 to 8.7 +/- 9.5 Gycm2 (P < 0.05). Fluoroscopy time required for ablation was significantly shortened in the LocaLisa group (2.6 +/- 2.6 min) compared with the conventional approach group (11 +/- 10 min, P < 0.0005). In 9 (35%) of 26 patients, the ablation could be performed with a fluoroscopy time < or = 1 minute. There were no significant differences with regard to the number of radiofrequency applications, fluoroscopy time needed for diagnostic reasons, total procedure time, or other ablation data. CONCLUSION: Compared with the conventional approach, the LocaLisa system significantly reduces the fluoroscopy times needed for ablation of typical AFL.

Aged↗

[Chronic atrial flutter: an infrequent manifestation of sick sinus syndrome. Clinical case].

We report a 41 years old female, previously operated of an atrial septal defect, presenting with a persisting atrial flutter. Sinus node dysfunction became evident during an electrophysiological study at the moment of interrupting the flutter with electrical stimulation. The patient was treated with his bundle ablation and implantation of a definitive pacemaker. After one year of follow up, she is devoid of symptoms.

Adult↗

Differential pacing for distinguishing slow conduction from complete conduction block of the tricuspid-inferior vena cava isthmus after radiofrequency ablation for atrial flutter--role of transverse conduction through the crista terminalis.

BACKGROUND: Partial conduction block has been suggested a predictor of recurrence of atrial flutter (AFL). AIM: The aim of this study was to assess transverse conduction by the crista terminalis (CT) as a problem in evaluating isthmus block and the usefulness of differential pacing for distinguishing slow conduction (SC) and complete conduction block (CB) across the ablation line. METHODS: We assessed 14 patients who underwent radiofrequency catheter ablation of the eustachian valve/ridge-tricuspid valve isthmus for typical AFL. Activation patterns along the tricuspid annulus (TA) suggested incomplete CB across the isthmus. In these patients, atrial pacing was performed from the low posteroseptal (PS) and anteroseptal (AS) right atrium (RA) while the ablation catheter was placed at the ablation line where double potentials (DPs) could be recorded. The pattern of activation of the RA free wall was assessed by a 20-pole catheter positioned along the CT during pacing from the coronary sinus (CS) ostium (CSos) and low lateral RA (LLRA). RESULTS: Faster transverse conduction across the CT resulted in simultaneous or earlier activation of the distal halo electrodes than of the more proximal electrodes, suggesting incomplete conduction block across the isthmus. CB (13) and SC (1) were detected as changes in the activation times of the first and second components of DPs (DP1, DP2) during PS RA pacing and AS RA. Similar changes in the activation times DP1 and DP2 during AS RA pacing as compared to PS RA reflected SC through the isthmus, whereas increased DP1 activation time and decreased of DP2 activation time reflected complete conduction block across the isthmus. CONCLUSIONS: Transverse conduction across the CT influences the sequence of activation along the TA after isthmus ablation. Differential pacing can distinguish SC from complete conduction block across the ablation line in the isthmus.

Adult↗

Inducibility of atrial flutter in patients with atrioventricular nodal reentrant tachycardia.

BACKGROUND: Previous studies have shown that both atrioventricular nodal reentrant tachycardia (AVNRT) and atrial flutter (AFL) have an area of slow conduction located in the low posterior right atrium near the ostium of the coronary sinus. The aim of this study was to evaluate the inducibility of AFL in patients with AVNRT. METHODS AND RESULTS: One hundred and seventy patients were prospectively evaluated for inducibility of tricuspid valve - inferior vena cava isthmus-dependent AFL. Two groups of patients were analyzed: 71 patients with inducible AVNRT and 99 control patients without a history of AFL. AFL was induced in a greater percentage of patients with AVNRT (53%) than of control patients (27%, p<0.02). In all 21 patients with AVNRT and inducible AFL before slow pathway ablation, AFL was also inducible after slow pathway ablation. There was no difference in the cycle length of induced AFL before and after ablation. CONCLUSIONS: AFL was induced in a greater percentage of patients with AVNRT, suggesting that there may be a common area of posteroseptal perinodal atrium participating in the two-tachycardia circuits. However, radiofrequency ablation of the slow pathway of the AVNRT circuit does not influence the inducibility of AFL.

Adult↗

[The clinical features and long-term follow-up of atrial fibrillation or atrial flutter complicating Wolff-Parkinson-White syndrome].

Twenty six patients (20 male, 6 female, aged 50 +/- 14) with recurrent episodes of atrial fibrillation or atrial flutter (Af/AF) associated with WPW syndrome were retrospectively studied and followed. During Af/AF, 17 patients showed ventricular preexcitation. Of them, 15 patients had hypotention, 8 syncope, 4 precipitating acute heart failure and 4 spontanous degenerated into ventricular fibrillation. Hypotention was found only in 2 of the 9 patients without pre-excited ventricular beats. The mean shortest prexcited R-R intervals of the former were shorter (247 +/- 47 ms) and the average ventricular rates (198 +/- 43 beat/min) were faster than those of the latter (393 +/- 80 ms & 144 +/- 22 beat/min) respectively (P < 0.01). When pre-excited Af/AF occurred, both cardioversion and antiarrhythmic agents of class I and II had marked effect in terminating the Af/AF or slowing pre-exicted ventricular responses. Digitalis and verapamil caused deterioration in the clinical condition of 6 patients (4 with hypotention, one syncope, and one ventricular fibrillation). Management of patients for WPW complicating Af/AF without pre-excited QRS was the same as for the ordinary Af/AF. Over a period of 53 +/- 44 months of follow-up, 5 died (3 of sudden death, one of heart failure, and one of noncardiac cause) in the group with preexcited Af/AF, but all of the patients without preexcited QRS during Af/AF were alive. Conclusion, clinical severity, response to the treatment, and long-term prognosis of patients of WPW with preexcited Af/AF are different from those without.

Anti-Arrhythmia Agents↗

Use of ibutilide in cardioversion of patients with atrial fibrillation or atrial flutter treated with class IC agents.

OBJECTIVES: We sought to assess the efficacy and safety of ibutilide cardioversion for those with atrial fibrillation (AF) or atrial flutter (AFL) receiving long-term treatmentwith class IC agents. BACKGROUND: Attenuation of ibutilide-induced QT prolongation has been observed in a small number of patients pretreated with class IC agents. The clinical significance of the interaction between ibutilide and class IC agents is unknown. METHODS: Seventy-one patients with AF (n = 48) or AFL (n = 23), receiving propafenone 300 to 900 mg/day (n = 46) or flecainide 100 to 300 mg/day (n = 25), presented for ibutilide (2.0 mg) cardioversion. RESULTS: The mean durations of arrhythmia episode and arrhythmia history were 25 +/- 48 days and 4.4 +/- 6.4 years, respectively. Sixty-five patients (91.5%) had normal left ventricular systolic function. Twenty-three of 48 patients (47.9%; 95% confidence interval, 33.3% to 62.8%) with AF and 17 of 23 patients (73.9%; 95% confidence interval, 51.6% to 89.8%) with AFL converted with mean conversion times of 25 +/- 14 min and 20 +/- 12 min, respectively. There was a small increase in corrected QT interval after ibutilide (from442 +/- 61 ms to 462 +/- 59 ms, p = 0.006). One patient developed non-sustained polymorphous ventricular tachycardia and responded to intravenous magnesium. Another developed sustained torsade de pointes and was treated effectively with direct-current shock and intravenous dopamine. CONCLUSIONS: Our observations suggest that the use of ibutilide in patients receiving class IC agents is as successful in restoring sinus rhythm and has a similar incidence of adverse effects as the use of ibutilide alone.

Aged↗

[Relation of parameters of frequent transesophageal electric stimulation of the atria during the treatment of atrial flutter and electrophysiologic characteristics of the myocardium].

After arresting paroxysms with frequent transesophageal cardiostimulation (TECS), 20 patients with coronary heart disease accompanied by episodes of Type 1 atrial flutter (AF) were studied by using a technique of intracardiac electrophysiological examination. The length of the atrial cycle in AF was found to correlate with that of successful TECS (r = 0.83). The correlation increases when a difference of atrial functional and effective refractory periods is subtracted from the length of the atrial cycle in tachycardia (r = 0.92). The equations of simple and multiple linear regression were derived, which defined the optimal frequency parameters of stimulation with a sufficient accuracy to stop Type I AF episodes. The efficacy of frequent TECS in arresting 324 spontaneous AF episodes was 92.9%.

Adult↗

Left atrial flutter after segmental ostial radiofrequency catheter ablation for pulmonary vein isolation.

Segmental ostial ablation to electrically isolate pulmonary veins has been performed for atrial fibrillation. Left atrial flutter that utilized a critical isthmus adjacent to the ostium of the left superior pulmonary vein was diagnosed and successfully ablated in a patient 3 months after a successful pulmonary vein isolation procedure. Documenting the cause of symptoms after pulmonary vein isolation in patients with atrial fibrillation is critical in guiding therapy.

Atrial Fibrillation↗

Radiofrequency catheter ablation of atrial flutter. Further insights into the various types of isthmus block: application to ablation during sinus rhythm.

BACKGROUND: Radiofrequency ablation of type 1 atrial flutter (AF1) has recently evolved toward an anatomically guided procedure directed to isthmuses at the lower part of the right atrium (RA). However, different types of block at these isthmuses may be observed and potentially correlated with different late outcomes. In addition, because the ablation is anatomically guided, ablation should be possible during sinus rhythm. METHODS AND RESULTS: Forty-four patients underwent ablation of type 1 AF1 performed during ongoing tachycardia (33 patients) or sinus rhythm (11 patients). Evidence of inferior vena cava-tricuspid annulus isthmus block was assessed by changes in RA impulse propagation while pacing from both sides of the ablation site. Apparent complete isthmus block was achieved in 43 of 44 patients with 9 +/- 7 pulses. However, incomplete block mimicking complete block because of intra-atrial conduction delay but leading to a different low RA activation pattern was individualized. At the end of the procedure, isthmus block was complete in 35 patients and incomplete in 8, but since AF1 reinduction was no longer possible, patients were discharged. During a follow-up period of 12.1 +/- 5.5 months, 4 patients experienced AF1 recurrence; all had shown incomplete or no block. CONCLUSIONS: Detailed multiple-point low RA mapping is necessary to differentiate incomplete from complete isthmus block. Complete block is the best marker for long-term success of AF1 ablation, although incomplete block may be sufficient to prevent recurrence in a significant number of cases. Isthmus block is achievable during sinus rhythm, and AF1 induction is not mandatory.

Atrial Flutter↗

Antiarrhythmic actions of intravenous ibutilide compared with procainamide during human atrial flutter and fibrillation: electrophysiological determinants of enhanced conversion efficacy.

BACKGROUND: The selective class III antiarrhythmic agent ibutilide prolongs action potential duration and terminates atrial flutter (AFL) and fibrillation (AF), but the mechanism of its antiarrhythmic efficacy in humans has not been fully characterized. This study compared the antiarrhythmic effects of ibutilide with the class IA agent procainamide in humans during AFL and AF. Antiarrhythmic drug actions and electrophysiological characteristics of AFL and AF that enhanced pharmacological termination were investigated. METHODS AND RESULTS: Right atrial monophasic action potentials were recorded during 148 episodes of AFL (n=89) or AF (n=59) in 136 patients treated with intravenous ibutilide (n=73) or placebo (n=22) as participants in randomized, double-blinded comparative studies or intravenous procainamide (n=53) in a concurrent open-label study. The conversion rates in AFL with ibutilide, procainamide, and placebo were 64% (29 of 45 patients), 0% (0 of 33), and 0% (0 of 11), respectively, whereas in AF the rates were 32% (9 of 28), 5% (1 of 20), and 0% (0 of 11), respectively. In AFL, ibutilide increased atrial monophasic action potential duration (MAPD) more (30% versus 18%, P<.001) and prolonged atrial cycle length (CL) less (16% versus 26%, P<.001) than procainamide. Ibutilide shortened and procainamide prolonged action potential diastolic interval during AFL (-12% versus 51%, P<.001). Ibutilide increased MAPD/CL ratio, whereas procainamide tended to decrease this ratio (13% versus -6%, P<.01). In AF, ibutilide and procainamide induced similar increases in atrial CL (48% versus 45%), but ibutilide induced a greater increase in MAPD (52% versus 37%, P<.05). Independent electrophysiological predictors of pharmacological arrhythmia termination were increase in MAPD/CL ratio (P=.005) in AFL and longer baseline mean MAPD (P=.011) in AF. Termination of AFL with ibutilide was characterized by significant increases in beat-to-beat atrial CL, MAPD, and diastolic interval variability. Ibutilide was significantly more effective in converting AF when the mean atrial CL was > or = 160 ms (64% versus 0%, P<.001) or MAPD was > or = 125 ms (57% versus 0%, P=.002) at baseline. CONCLUSIONS: Enhanced conversion efficacy of ibutilide compared with procainamide in AFL is correlated with a relatively greater prolongation of atrial MAPD than atrial CL, and termination of AFL by ibutilide is characterized by oscillations in atrial CL and MAPD. Conversion of AF by ibutilide is enhanced by a longer baseline mean atrial CL or MAPD.

Adult↗

Evaluation of the cavotricuspid isthmus and right atrium by multidetector-row computed tomography in patients with common atrial flutter.

The sizes of the right atrium (RA), cavotricuspid isthmus, and Eustachian valve are predictors of success of radiofrequency catheter ablation for atrial flutter (AFL). We examined the relationship between the sizes of cavotricuspid isthmus as measured by multidetector-row computed tomography (MDCT) and fluoroscopy. We used eight-detector MDCT to measure the tricuspid isthmus of 23 patients prior to linear ablation for common AFL. One patient with a deep pouch in the RA was excluded. Parameters measured were (1) the length of the trace of isthmus (Ti), which was equivalent to the blocking line; (2) the size of the tricuspid isthmus (DTi); and (3) the distance from the tricuspid valve and inferior vena cava (IVC) (LDTi). DTi and LDTi indicate the size of the RA, reflecting the appropriately sized steerable ablation catheter, respectively. Of the 22 patients, 21 were ablated successfully without recurrence of AFL, and clinical success was achieved in one additional patient despite failure to obtain a bidirectional block. Ti, DTi, and LDTi were correlated with fluoroscopy time (r = 0.84, r = 0.88, and r = 0.88, respectively; P < 0.0001), total delivered energy (r = 0.81, r = 0.80, and r = 0.83, respectively; P < 0.0001), and application time (r = 0.84, r = 0.80, and r = 0.87, respectively; P < 0.0001). Measurement of the tricuspid isthmus by MDCT may noninvasively provide important information for successful linear ablation.

Atrial Fibrillation↗

Electrophysiologic and antiarrhythmic effects of the new class III antiarrhythmic drug KCB-328 in experimental canine atrial flutter.

BACKGROUND: The electrophysiologic and antiarrhythmic effects of a new class III antiarrhythmic drug (KCB-328), a delayed rectifier potassium current (IKr) blocker with minimal reverse use-dependent effect on atrial repolarization, were evaluated in the canine night atrial crush-injury model of atrial flutter (AFL). METHODS: Ten anesthetized, open-chest dogs, were studied after right atrial crush-injury. Atrial effective refractory period (ERP), conduction velocity (CV), wavelength, and dispersion of refractoriness were determined during programmed stimulation (S1S2 at S1S1 = 200, 300, 400, and 500 msec) at four sites via a mapping plaque sutured on the right atrial free wall. Right and left ventricular ERP were similarly measured at single sites. Electrophysiological parameters were determined at baseline and following sequential cumulative doses of KCB-328 (10, 30, 100, and 300 microg/kg). RESULTS: Sustained AFL was inducible in 7/10 dogs by rapid pacing following baseline electrophysiologic measurements. KCB-328 significantly prolonged sinus cycle length, but had no effect on PR interval, and prolonged QTc only at the highest dose level. KCB-328 significantly prolonged atrial ERP and wavelength and ventricular ERP, and significantly reduced dispersion of atrial refractoriness. KCB-328 significantly prolonged AFL cycle length, and increasing doses progressively terminated sustained AFL and prevented its reinduction by pacing. No adverse hemodynamic or ventricular proarrhythmic effects were observed. CONCLUSIONS: The electrophysiologic profile of KCB-328 in this canine model of AFL, particularly its lack of reverse use-dependent effect on atrial refractoriness, suggests that it may have significant antiarrhythmic potential in treatment of atrial arrhythmias.

Animals↗

The coincidence of fetal magnetocardiography and direct electrocardiography in a case of fetal atrial flutter due to intracardiac tumor.

OBJECTIVE: To demonstrate the coincidence of fetal magnetocardiography (FMCG) and fetal direct electrocardiography (FDECG) in a case of fetal atrial flutter (AF). METHODS: FMCG and FDECG using a fetal scalp electrode were recorded in the case of fetal AF at 41 weeks' gestation. RESULTS: FMCG revealed fetal AF with 2:1 atrioventricular block, which was also documented by FDECG using a fetal scalp electrode. The prenatal diagnosis was confirmed by postnatal electrocardiogram. Neonatal echocardiography revealed an intracardiac tumor on the left atrial septum. The tumor seemed to be the cause of AF. CONCLUSION: FMCG may provide the same information as a fetal electrocardiogram in the prenatal diagnosis of fetal AF.

Adult↗