Atrial Flutter
Definition
Atrial flutter is a supraventricular tachyarrhythmia characterized by atrial contractions at a regular rate, typically ranging between 240-340 bpm. Like atrial fibrillation (AFib), it arises from re-entry mechanisms within the atrium but follows a more organized and predictable pattern.
Risk Factors
Advanced Age
Diabetes Mellitus
Elevated Blood Pressure
Obstructive Sleep Apnoea
Alcohol abuse
Congenital or acquired structural heart abnormalities
Hyperthyroidism
Valvular Heart disease
Pathophysiology
Atrial flutter involves the circulation of electrical impulses within the atrial conductive system, leading to organized contractions. In contrast to AFib, atrial flutter follows a defined re-entry circuit in the atrium, resulting in a characteristic sawtooth pattern on an ECG.
Typical and Atypical flutter:
Typical Atrial Flutter: circuit in the right atrium, that typically revolves around the tricuspid valve.
Atypical Atrial Flutter: flutter that involves the left atrium, septum, or areas outside the tricuspid valve
Similar to AFib, atrial flutter heightens the risk of thrombus formation due to blood-stasis in the atria, resulting in a higher likelihood of embolic events.
Signs and Symptoms
Common signs and symptoms of atrial flutter include palpitations, shortness of breath, fatigue, and dizziness. Chest discomfort or pain may occur, necessitating the exclusion of myocardial infarction. However, asymptomatic patients are not rare, especially when they exhibit paroxysmal atrial flutter rather than persistent atrial flutter.
Diagnosis
The most important diagnostic tool in the diagnosis of atrial flutter is the ECG. The hallmark feature is the presence of a "sawtooth" pattern, characterized by atrial flutter waves (F-waves), typically occurring at a rate of approximately 300 beats per minute.
The clinical examination completes the ECG in the diagnostic process. Common findings include the manifestation of the aforementioned symptoms alongside a rapid and irregular pulse discernible through auscultation and palpation. This irregular pulse is due to the variable atrioventricular block, where not every atrial flutter wave is effectively conducted to the ventricles.
In instances where the characteristic sawtooth pattern is not detectable on standard ECG, a long-term ECG may be necessary to capture the paroxysmal atrial flutter episodes.
Management
The general treatment goals for symptomatic atrial flutter align with those for atrial fibrillation and include control of the ventricular rate, restoration of sinus rhythm, prevention of recurrent episodes and prevention of thromboembolic complications.
A notable distinction in the therapeutic approach between atrial fibrillation and atrial flutter lies in the notably higher success rates observed with catheter-based ablation in atrial flutter. This intervention method has an approximate acute success rate of 95%, with a recurrence rate of around 10%.
Following successful ablation, the necessity for anticoagulation can be re-evaluated in accordance with the individual's risk profile and as well with the CHA2DS2-VASc score in conjunction with the HAS-BLED score. In instances where the thromboembolic risk has been lowered enough, the discontinuation of anticoagulation may be considered.
In cases where catheter ablation was unsuccessful and a long-term rate control is necessary, beta blockers can be administered. Alternatively, calcium channel blockers such as verapamil or diltiazem are equally viable options, but only if the ejection fraction is ≥ 40.
In cases of haemodynamically unstable patients, prompt cardioversion should be undertaken.
References
Shah SR, Luu SW, Calestino M, David J, Christopher B. Management of atrial fibrillation-flutter: uptodate guideline paper on the current evidence. J Community Hosp Intern Med Perspect. 2018 Oct 15;8(5):269-275. doi: 10.1080/20009666.2018.1514932. PMID: 30357020; PMCID: PMC6197036.
Benedict M. Glover, Jian Chen, Kathryn L. Hong, Serge Boveda, Adrian Baranchuk, Kristina H. Haugaa, Paul Dorian, Tatjana S. Potpara, Eugene Crystal, Brent Mitchell, Roland Tilz, Peter Leong-Sit, Nikolaos Dagres, Catheter ablation for atrial flutter: a survey by the European Heart Rhythm Association and Canadian Heart Rhythm Society, EP Europace, Volume 18, Issue 12, December 2016, Pages 1880–1885, https://doi.org/10.1093/europace/euw402