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....................................................... clockwise flutter, ECG flutter waves in inferior leads look positive and broad, and are frequently bimodal negative in V1.220,221 Typical atrial flutter has a strong reproducible anatomical dependence,222

resulting in the morphological reproducibility of the ECG. However, this well-recognized ECG pattern may be significantly changed when atrial activation has been modified, as it is in cardiac surgery involving atrial tissue, after extensive radiofrequency ablation, or in advanced atrial disease.223,224 Antiarrhythmic drugs may also modify the typical ECG pattern.225 In these situations, an atypical ECG does not rule out a circuit of typical flutter using the CTI.226 Typical flutter is related to AF in clinical practice, with both being associated with similar clinical settings and coexisting in the same patients: AF may trigger atrial flutter, and after typical flutter ablation AF is frequent.23,227229 Typical flutter may also frequently occur in patients treated for AF with class IC drugs or amiodarone. In this case, flutter rate may be reduced to <200 b.p.m. facilitating 1:1 AV conduction. The action of antiarrhythmic drugs on ventricular activation may result in wide QRS tachycardia.230232 Beyond symptoms associated with high-rate and loss of atrial kick, reversible systolic dysfunction and subsequent TCM are not unusual.233,234

11.1.4.1.3 Acute therapy. Although the first step should be rate control when the ventricular rate is high, this may be difficult to achieve. AV nodal blocking drugs,235238 including amiodarone applied mostly in HF or critically ill patients,239,240 may be of help, but cardioversion may be necessary (Figure 11). In some cases, presenting with 2:1 AV block, the diagnosis of atrial flutter may not be obvious on the ECG. In these situations, i.v. adenosine may increase the degree of AV block and reveal the typical ECG pattern. However, adenosine can produce a rebound increase in AV conduction to 1:1 and may also precipitate AF.271,272 Thus, it should only be used if deemed necessary for diagnosis and resuscitation equipment is available. Rate control should be the first step in very symptomatic patients with rapid ventricular rates. This is a particularly difficult goal in atrial

Recommendations for the therapy of macro2re-entrant atrial arrhythmias

Recommendations Classa Levelb Anticoagulation, as in AF, is recommended for patients with atrial flutter and concomitant AF.4 I B Patients with atrial flutter without AF should be considered for anticoagulation, but the threshold for initiation has not been established.241247 IIa C Acute therapy Haemodynamically unstable patients Synchronized DC cardioversion is recommended for haemodynamically unstable patients.248,249 I B Haemodynamically stable patients i.v. ibutilide or i.v. or oral (in-hospital) dofetilide are recommended for conversion to sinus rhythm.250257 I B Low-energy (<_100 J biphasic) electrical cardioversion is recommended for conversion to sinus rhythm.248,249 I B High-rate atrial pacing is recommended for termination of atrial flutter in the presence of an implanted pacemaker or defibrillator.258260 I B i.v. beta-blockers or non-dihydropyridine calcium channel blockers (verapamil or diltiazem) (i.v.), should be considered for control of rapid ventricular rate.235238 IIa B Invasive and non-invasive high-rate atrial pacing may be considered for termination of atrial flutter.258,261 IIb B i.v. amiodarone may be tried if the above are not available or desirable.239,240 IIb C Propafenone and flecainide are not recommended for conversion to sinus rhythm.250 III B Chronic therapy Catheter ablation should be considered after the first episode of symptomatic typical atrial flutter.262,263 IIa B Catheter ablation is recommended for symptomatic, recurrent episodes of CTI-dependent flutter.262264 I A Catheter ablation in experienced centres is recommended for symptomatic, recurrent episodes of non-CTI-dependent flutter.224,265269 I B Catheter ablation is recommended in patients with persistent atrial flutter or in the presence of depressed LV systolic function due to TCM.233,234 I B Beta-blockers or non-dihydropyridine calcium channel blockers (verapamil or diltiazem, in the absence HFrEF) should be considered if ablation is not desirable or feasible.237,270 IIa C Amiodarone may be considered to maintain sinus rhythm if the above measures fail.263 IIb C AV nodal ablation with subsequent pacing (‘ablate and pace’), either biventricular or His-bundle pacing, should be considered if all the above fail and the patient has symptomatic persistent macro-re-entrant atrial arrhythmias with fast ventricular rates. IIa C

i.v. verapamil and diltiazem are contraindicated in the presence of hypotension or HFrEF. i.v. beta-blockers are contraindicated in the presence of decompensated heart failure. i.v. ibutilide, and i.v. and oral dofertilide are contraindicated in patients with prolonged QTc interval. i.v. amiodarone prolongs the QTc but torsades des pointes is rare. AF = atrial fibrillation; AV = atrioventricular; CTI = cavotricuspid isthmus; DC = direct current; HFrEF = heart failure with reduced ejection fraction; i.v. = intravenous; LV = left ventricular; TCM = tachycardiomyopathy. aClass of recommendation. bLevel of evidence. Downloaded from academic.oup.com/eurheartj/article/41/5/655/5556821 by guest on 07 October 2026