###### Created: 2024-06-04 17:14 ###### Areas & Topics: #medicine #cardiovascular ###### Note Type: #permanent ###### Connected to: [[CHA2DS2VASc Score]] [[ORBIT Score]] - Atrial Fibrillation (AF) is the most common type of cardiac arrythmia. - It occurs due to abnormal electrical activity in the atria in the heart, causing the atria to fibrillate. ### Classification #### Paroxysmal AF - Episodes of AF which last longer than 30 seconds but less than 7 days, which are self-terminating and recurrent. - Patients will be in sinus rhythm at all other times. #### Persistent AF - Episodes of AF lasting longer than 7 days. OR - Episodes of AF lasting less than 7 days but requiring pharmacological or electrical cardioversion. N.B. After 7 days, spontaneous termination of the arrhythmia is unlikely to occur. #### Permanent AF - AF that fails to terminate using cardioversion. OR - AF that is terminated but relapses within 24 hours. OR - Longstanding AF (usually longer than 1 year) in which cardioversion has not been indicated or attempted (sometimes known as accepted permanent AF). ### Aetiology - Any condition that leads to inflammation, stress, damage, or ischemia affecting the anatomy of the heart can result in the development of atrial fibrillation. - In some cases, the cause is iatrogenic. - Essentially, any condition which affects the heart or autonomic nervous system can lead to AF development. The most common associations leading to AF include: - Advancing Age - Male Sex - [[Hypertension]] - Coronary Artery Disease (see [[Coronary Heart Disease]]) - Myocardial Infarction (see [[Acute Coronary Syndrome (ACS)]]) The main dietary and lifestyle factors associated with AF include: - Excessive Caffeine Intake - Alcohol Abuse - Obesity - Smoking ### Pathophysiology - The electrical system of the heart is controlled by the myocytes and various nodes within the heart. - The main node involved in controlling the synchronous contraction of the atria is the sinoatrial node (SAN). - Depolarisation and repolarisation starting in the SAN spreads throughout myocytes in the atria, leading to synchronised contraction throughout both atria. - However, all myocytes in the heart are able to contract independently and pace themselves. - In AF, some type of abnormality causes the myocytes to contract out of sync with one another. - Due to this disordered electrical activity and contraction, this then leads to the atria fibrillating. - However, because the atrioventricular (AV) node acts as the junction between the electrical activity of the atria and the ventricles, and has a long delay between depolarisations, this disordered electrical activity does not affect the contraction of the ventricles. - This is why patients with AF may be asymptomatic or have minimal symptoms, as the activity of their atria may not impact the overall ability of their heart when compensated by the ventricles. ### Epidemiology - Has a prevalence of around 2.5% in England. - Is more common in men than woman (2.9% vs. 2.0%) ### Clinical Features - AF can present in a wide variety of ways. - AF can present asymptomatically, as well as with various symptoms, signs, complications and haemodynamic instability. - AF should be considered or suspected in any patients who present with any of the following: #### Common Symptoms - Palpitations - Breathlessness - Syncope or Dizziness - Chest Discomfort - [[Stroke]] or TIA (due to an embolic event as a complication of AF) #### Common Signs - Irregularly irregular pulse - Tachycardia (typically around 160 to 180bpm bpm, but can be lower) - Hypotension - Absent 'a' wave on JVP inspection (the 'a' wave of the JVP signifies right atrial contraction, so in AF it would be absent as pressure from the right atria would not be high enough to produce the wave) ### Differentials The main signs indicating AF will include an irregularly irregular pulse found on manual palpation. Other causes of an irregularly irregular pulse include: - Premature beats (e.g. ectopics) - Atrial Flutter - Other Atrial Tachyarrhythmias (e.g. multi-focal atrial tachycardia) See the [[Tachycardias]] page for further information. ### Investigations #### Manual Pulse Palpation - Use the radial pulse to check for an irregularly irregular rhythm, but if uncertain other pulses or chest auscultation can be used). - Perform other observations as well, especially blood pressure. #### ECG - Irregularly irregular pulse. - Absence of P-Waves. - Chaotic baseline. ![[af.jpg]] ![[Pasted image 20240604170939.png]] #### Ambulatory ECG - If paroxysmal AF is suspected but cannot be detected on initial use of ECG, use a 24-Hour Ambulatory ECG to detect AF - If episodes occur more than 24 hours apart then any appropriate ECG technology can be used. #### Bloods - FBC - U&E's - TFTs (thyrotoxicosis and overuse of thyroxines can cause AF due to the effect of excess thyroid hormones on the ion currents of atrial myocytes) - Cholesterol - Bone Profile (high serum calcium can cause paroxysmal AF via effects on the sarcoplasmic reticulum) - Magnesium (low serum magnesium has been shown to link to the development of AF) - Troponin (if a myocardial infarction is suspected) - CRP (if an aute infection is suspected) #### CHA2DS2VASc Score - Any patient with symptomatic or asymptomatic AF of any type should be evaluated for stroke risk using the [[CHA2DS2VASc Score]] N.B. Any patient with atrial flutter or who are at risk of arrhythmia recurring after cardioversion or catheter ablation should also be screened using CHA2DS2VASc. #### ORBIT SCORE - Patients with AF who are considering starting anticoagulation or who are already taking anticoagulation should be screened for risk of bleeding using the [[ORBIT Score]]. #### Echocardiography Transthoracic Echocardiography (TTE) should be offered to patients with AF mainly where: - Cardioversion for rhythm-control is being considered. - Heart Disease is suspected or likely as the underlying cause of AF and may influence future management. N.B. offer transoesophageal echocardiography (TOE) when TTE finds an abnormality or cannot be performed. #### Specialist Referral Referral to a specialist should be done within 4 weeks if: - Treatment fails to control AF at any stage. - AF recurs after cardioversion. ### Management #### Rate-Control Rate control is the first-line strategy for treating AF unless AF is: - Reversible - Caused by heart failure - New-Onset - With Atrial Flutter and suitable for ablation - Rhythm-Control seems more suitable Options for rate-control in order include: 1. Beta-Blocker Monotherapy (other than sotalol) OR Rate-Limiting CCB Monotherapy (Diltiazem or Verapamil) 2. Digoxin Monotherapy (if the person does very little physical exercise or is contraindicated for other options) 3. If AF is still not controlled by the above and thought to be due to poor ventricular rate control, consider combination therapy with any 2 of a beta-blocker, diltiazem or digoxin. #### Rhythm-Control - Rhythm control is a strategy for managing AF in patients who continue to have symptoms despite adequate rate control, in the hopes of improving their quality of life. Rhythm control for AF is indicated if the AF in question is: - Reversible - Caused by heart failure - New-Onset - With Atrial Flutter and suitable for ablation - Seems more suitable for Rhythm-Control **Pharmacological Rhythm-Control** - Beta Blockers (if long-term rhythm control is needed, beta blockers are 1st-line unless contraindicated) - Flecainide or Propafenone (Class 1c Antiarrhythmics are recommended for patients with no ischaemic or structural heart disease) - Amiodarone (Class III Antiarrhythmic recommended for patients with left ventricular impairment or heart failure) - Dronedarone (Class III Antiarrhythmic indicated after successful cardioversion if AF is not controlled by first-line therapies and if patients meet certain criteria) Pill-in-the-Pocket Strategy: - If patients present infrequently or after a clear trigger (e.g. alcohol, caffeine) with episodes of paroxysmal AF, a "pill-in-the-pocket" or no-drug treatment strategy can be offered. - This can be offered to patients who do not have structural or ischaemic heart disease, have normal blood pressure and are able to understand how, and when, to take treatment. - This strategy involves the patient only taking antiarrhythmics when an AF episode starts, rather than using long-term treatment (since their episodes are so infrequent and they are at reduced risk of embolic events and complications, long term treatment is not as necessary). **Electrical Rhythm-Control (Cardioversion)** - Cardioversion is a main-stay of AF treatment for restoring normal rhythm. - It involves delivering a DC electrical shock to the heart, in order to stop the atria fibrillating and restore sinus rhythm. For electrical cardioversion, NICE recommends that: - For AF that has persisted for longer than 48 hours, electrical cardioversion should be offered over pharmacological cardioversion (as there is a higher risk of a thromboembolic event for patients who have been in AF longer than 48 hours, so using electrical cardioversion to immediately achieve sinus rhythm is better to reduce future risk). - Amiodarone therapy should be offered for 4 weeks before and continuing up to 12 months after electrical cardioversion. - Transoesophageal echocardiography (TOE)-guided cardioversion and regular cardioversion are considered equally effective, but TOE-guided cardioversion is preferred if possible and patient has had minimal anticoagulation beforehand. #### Ablation - Ablation involves using some form of energy to destroy tissue, causing it to necrose. - This necrosis can help reduce AF by destroying myocytes or parts of the electrical circuitry of the heart which are overactive in AF, thereby providing relief to patients. - Patients who receive ablation should have antiarrhythmic drug therapy for three months following to reduce the risk of AF recurring. Left-atrial ablation for AF is indicated when: - AF drug treatment is unsuccessful, unsuitable or not tolerated. - A patient with symptomatic AF is already receiving other cardiothoracic surgery. N.B. Radiofrequency point-by-point ablation is the first-line form of ablation in these cases, but if this is unsuitable, cryoballoon or laser balloon ablation should be considered instead. Pacing and AV Node Ablation is indicated for : - permanent symptomatic AF. - Patients with left ventricular dysfunction thought to be caused by high ventricular rates. N.B. patients can receive left-atrial ablation before pacing and AV node ablation for patients with paroxysmal AF or heart failure caused by non-permanent AF. #### Stroke Prevention (Anticoagulation) - Anticoagulation is a cornerstone of AF management, and reduces the chance of stroke by around 66%. - It is important to note that you should not ever withhold anticoagulation solely because of a person's age or their risk of falls. **New-Onset AF:** - Heparin is first-line (if not already on anticoagulants). - Heparin should be continued until a full assessment, including risk stratification, is done and appropriate oral anticoagulation is recommended. **Diagnosed AF presenting within 48 Hours:** Oral anticoagulation (e.g. DOAC) is first line if: - Stable sinus rhythm is not successfully restored within the same 48‑hour period after onset of AF OR - Factors indicate a high risk of AF recurrence (including history of failed cardioversion, structural heart disease, prolonged atrial fibrillation (more than 12 months), or previous recurrences) OR - Oral anticoagulation is recommended after risk stratification with [[CHA2DS2VASc Score]] and [[ORBIT Score]] **All patients with CHA2DS2VASc >=2:** - Offer DOAC - If contraindicated, offer warfarin (or other suitable vitamin K antagonist) **Male patients with CHA2DS2VASc >=1:** - Consider DOAC - If contraindicated, consider warfarin (or other suitable vitamin K antagonist) **DOAC Options include:** - Apixaban - Dabigatran Etexilate - Edoxaban - Rivaroxaban **Anticoagulation following Stroke or TIA** In cases where a patient has had a [[Stroke]] or TIA alongside AF, and scans have excluded haemorrhagic causes: - Following a TIA, patients should immediately be put on anticoagulation (in line with AF guidance). - Following an acute ischaemic stroke, patients should be started on anticoagulation 2 weeks after onset (with antiplatelets given in the interim). N.B. if scans show a cerebral infarction to be very large then starting anticoagulation should be delayed. ### Step-By-Step of AF Acute Management - The most important parts of managing a patient presenting acutely with AF involve determining if they are haemodynamically stable and when the onset of their symptoms was. - Haemodynamic instability puts the patient at higher risk of serious issues and complications, and therefore needs to be treated more urgently. - Whether the patient's onset of symptoms are less than or more than 48 hours before presenting also changes their risk of complications and thereby the management needed. - If the time of onset is uncertain, it should be assumed to be more than 48 hours ago. - All patients with new-onset AF should always be offered heparin at their initial presentation. Signs of haemodynamic instability include: - HR > 150bpm - BP < 90mmHg systolic - Loss of Consciousness - Severe Dizziness/Syncope - Ongoing Chest Pain - Increasing Breathlessness #### Question Flowchart for Managing Acute AF 1. Is there life-threatening haemodynamic instability? **Life-Threatening Haemodynamic Instability** - Electrical Cardioversion (give electrical cardioversion immediately) **Non Life-Threatening Haemodynamic Instability** 1. Is the onset less than 48 hours, or more than 48 hours/uncertain? 2. Is the onset less than 48 hours, or more than 48 hours/uncertain? **Less than 48 Hour Onset** - Rate or Rhythm Control **More than 48 hour Onset or Uncertain Time of Onset** - Rate Control N.B. if long-term rhythm control is indicated instead, give anticoagulation for at least 3 weeks and appropriate rate-control before cardioversion 3. Is pharmacological cardioversion indicated? **Acute AF with Pharmacological AF Indicated** - Flecainide or Amiodarone (if there is no structural or ischaemic heart disease) - Amiodarone (if there is structural heart disease) ### Complications of AF - The main complications from AF are a result of the heart not functioning correctly and/or emboli forming and travelling to other areas of the body. - The most common complication of AF is [[Stroke]] and TIA The main complications include: - [[Stroke]] and TIA (the main complications of AF which result if an embolus is lodged in the brain) - [[Heart Failure]] (commonly associated with AF due to inefficient ventricular filling) - Tachycardia-Induced Cardiomyopathy - Acute Limb Ischaemia (if the embolus is lodged in a limb artery) - Mesenteric Ischaemia (if the embolus is lodged in a mesenteric artery) - Cardiac Arrest ### Resources NICE guideline NG196 Atrial fibrillation: diagnosis and management 2021 https://www.nice.org.uk/guidance/ng196/chapter/recommendations#management-for-people-presenting-acutely-with-atrial-fibrillation Atrial fibrillation NICE CKS https://cks.nice.org.uk/topics/atrial-fibrillation/ Scenario: Secondary prevention following stroke and TIA https://cks.nice.org.uk/topics/stroke-tia/management/secondary-prevention-following-stroke-tia/ Nesheiwat Z, Goyal A, Jagtap M. Atrial Fibrillation. [Updated 2023 Apr 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK526072/ Arrythmias NICE BNF https://bnf.nice.org.uk/treatment-summaries/arrhythmias/ Pulsenotes Atrial Fibrillation https://app.pulsenotes.com/medicine/cardiology/notes/atrial-fibrillation Denham, Nathan C et al. “Calcium in the Pathophysiology of Atrial Fibrillation and Heart Failure.” _Frontiers in physiology_ vol. 9 1380. 4 Oct. 2018, doi:10.3389/fphys.2018.01380 Goyal A, Sciammarella JC, Chhabra L, et al. Synchronized Electrical Cardioversion. [Updated 2023 Mar 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482173/ King GS, Goyal A, Grigorova Y, et al. Antiarrhythmic Medications. [Updated 2024 Feb 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482322/ Sucu, Murat et al. “Electrical cardioversion.” _Annals of Saudi medicine_ vol. 29,3 (2009): 201-6. doi:10.4103/0256-4947.51775 Ghzally Y, Ahmed I, Gerasimon G. Catheter Ablation. [Updated 2023 Jul 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470203/ Atrial fibrillation with rapid ventricular response ECG Library https://ecglibrary.com/af_fast.html