Atrial flutter and atypical flutter — structured written assessment

SAQ 1 (10 marks)

Practice scenario. A 64-year-old man presents with palpitations for two days. The ECG shows a regular tachycardia at 150 beats per minute with negative saw-tooth flutter waves in the inferior leads and positive flutter waves in V1.^[1] His blood pressure is 126/80 mm Hg and he is alert. He has no implanted device, his QTc interval is normal and his LV function is normal.^[1]

1. Name the circuit and describe its activation sequence, citing ESC 2019. (2)^[1]
2. Give four ESC 2019 acute-therapy rows that apply to a haemodynamically stable patient like him, with class and level. (4)^[1]
3. Why does ESC 2019 warn against a class IC drug without AV-nodal blockade in flutter? (1)^[1]
4. After successful cardioversion, what minimum duration of continued anticoagulation does the ACC/AHA 2023 row on typical (CTI-dependent) AFL give, with COR and LOE? (1)^[4]
5. This is his first episode of symptomatic typical flutter. What does ESC 2019 say about catheter ablation now, with class and level, and what does it say about AF after CTI ablation? (2)^[1]

Model answers — SAQ 1

1. Counter-clockwise typical (common) flutter: a macro-re-entry circuit around the tricuspid annulus using the cavotricuspid isthmus (CTI) as a critical passage at the inferior boundary (1 mark).^[1] Activation goes down the right atrial free wall, through the CTI and up the right septum; left atrial activation is passive (1 mark).^[1]
2. i.v. ibutilide or i.v. or oral (in-hospital) dofetilide for conversion to sinus rhythm: Class I, Level B (1 mark).^[1] Low-energy (≤100 J biphasic) electrical cardioversion for conversion to sinus rhythm: Class I, Level B (1 mark).^[1] i.v. beta-blockers or i.v. verapamil or diltiazem should be considered for control of rapid ventricular rate: Class IIa, Level B (1 mark).^[1] Propafenone and flecainide are not recommended for conversion to sinus rhythm: Class III, Level B (1 mark).^[1] Also accept: i.v. amiodarone may be tried if the above are not available or desirable (Class IIb, Level C), or invasive and non-invasive high-rate atrial pacing may be considered (Class IIb, Level B); four rows earn the four marks.^[1]
3. ESC 2019 says class IC drugs should not be used in the absence of AV-blocking agents because of the risk of slowing the atrial rate, which may result in 1:1 AV conduction (1 mark).^[1]
4. ACC/AHA 2023: in typical (CTI-dependent) AFL, after successful cardioversion or ablation restoring sinus rhythm, anticoagulation should be continued for at least 4 weeks postprocedure: COR 1, LOE C-LD (1 mark).^[4]
5. ESC 2019: catheter ablation should be considered after the first episode of symptomatic typical atrial flutter: Class IIa, Level B (1 mark).^[1] ESC 2019 says CTI ablation with confirmed bidirectional block gives a <10% rate of recurrence, but the incidence of AF is high in the long term (1 mark).^[1]

SAQ 2 (10 marks)

Practice scenario. A 58-year-old woman had pulmonary vein isolation with additional left atrial linear lesions for persistent AF seven weeks ago.^[1] She now has a regular atrial tachycardia with flutter waves that do not look like typical counterclockwise flutter, including a dominantly positive deflection in V1. She is haemodynamically stable.^[2]

1. What does ESC 2019 say about the lesions that sustain re-entry after AF ablation? (2)^[1]
2. What ECG finding suggests atypical flutter, and how is the diagnosis confirmed, according to ACC/AHA/HRS 2015? (2)^[2]
3. When should ablation of this tachycardia be done, citing ESC 2019 and ACC/AHA/HRS 2015? (3)^[1][2]
4. How should she be anticoagulated, according to ACC/AHA 2023? (1)^[4]
5. Give the ESC 2019 row on ablation of symptomatic, recurrent non-CTI-dependent flutter, with class and level. (2)^[1]

Model answers — SAQ 2

1. ESC 2019 says that, owing to its widespread use, AF ablation is the procedure that frequently causes the lesions able to sustain re-entry circuits, usually after linear ablation or extensive defragmentation (1 mark).^[1] Circumferential antral ablation may also create MRAT due to gaps in the lines (1 mark).^[1]
2. A positive or biphasic (but dominantly positive) deflection in V1, with deflections in other leads inconsistent with typical counterclockwise flutter, suggests atypical flutter (1 mark).^[2] Definitive diagnosis requires EP study and intracardiac mapping (1 mark).^[2]
3. ESC 2019: intervention should be delayed, if possible, for ≥3 months; as part of the maturation of the lesions some tachycardias may be transient, and initial rate control and/or antiarrhythmic drugs are favoured (1 mark).^[1] ACC/AHA/HRS 2015: many flutters seen in the first 3 months after catheter ablation will not recur, so it advises that attempts at ablation of flutter after AF ablation be deferred until after the 3-month waiting period (1 mark).^[2] ACC/AHA/HRS 2015: if, rarely, drugs fail to control the flutter during those 3 months, early repeat ablation is warranted (1 mark).^[2] No mark: ESC 2024 AF notes that an early recurrence after pulmonary vein isolation (AT, AF or flutter) is conventionally considered potentially transitory, and reports the conclusion of recent trials that used continuous implantable loop recorders for peri-procedural monitoring: they have confirmed a link between early and later recurrence.^[3]
4. ACC/AHA 2023 says left-sided AFLs or ATs that develop after AF ablation should be anticoagulated and managed in a manner similar to AF (1 mark).^[4]
5. Catheter ablation in experienced centres is recommended for symptomatic, recurrent episodes of non-CTI-dependent flutter (1 mark).^[1] ESC 2019, Class I, Level B (1 mark).^[1]