Dr Avinash Haridas Pillai Atrial Fibrillation Dr Avinash Haridas Pillai

Background Most common sustained cardiac arrhythmia Prevalence 0.5-1% in general population It is characterised by an ECG:- Lacking any consistent p waves Irregular ventricular rate Atrial arrhythmia where uniform activation is replaced by chaos such that coordinated contractile function is lost and the atria dilate x10 fold greater in those over 65

Classification 1st detected vs.. Recurrent Self terminating vs.. Not self terminating Symptomatic vs... Asymptomatic Paroxysmal (self terminating within 7 days) Persistent (if cardioverted to SR by any means or last >7 days regardless of how it terminates) Permanent (does not terminate or relapses within 24 hrs of cardioversion) Lone (in the absence of structural heart disease) vs... Idiopathic (in the absence of any disease) All episodes of AF lasting greater than 30s should be described as

Common Causes Hypertension Left Ventricular Failure Coronary Artery Disease Mitral/Tricuspid Valve Disease HOCM AF is common end point for many forms of cardiac disease where atrial myocytes are damaged to stress of ischaemia, cyanosis, intracavaty + pericardial pressures = altered conduction of the myocardium Reversible – Alcohol/Hyperthyroid/MI/Pericarditis/Myocarditis/PE

Symptoms Palpitations Dyspnoea Fatigue Syncope Chest Pain 30% present with AF as incidental finding

Signs Irregular Pulse Variable intensity of 1st HS Faster at apex than at wrist Variable intensity of 1st HS Absent “a” wave in the JVP

Investigations ECG CXR Bloods Echo 24 hr tape/ETT/Angiogram FBC, UE, Cardiac Enzymes, TFT, LFT Mg, Ca2+ Echo 24 hr tape/ETT/Angiogram

Management Make a diagnosis Decide on rate or rhythm control strategy Stratify stroke risk and consider thromboprophylaxis

Rate vs. Rhythm control

Rate control Rate control first if:- Medication options:- over 65 with CHD (the vast majority) Medication options:- Beta-blocker or Calcium Antagonist (Verapamil/Diltiazem) If still no better then add in Digoxin Target heart rate of less than 90 bpm Digoxin is not initial monotherapy Rest – Beta blocker or Calcium Antagonist with Digoxin Exercise – Calcium Antagonist with Digoxin

Rhythm control Refer for rhythm control (cardioversion) if:- Symptomatic with congestive heart failure Younger Unable to achieve adequate An antiarrhythmic drug is not required to maintain sinus rhythm for those patients in whom a precipitant (such as chest infection, fever etc.) has been corrected and cardioversion has been performed successfully.

Bleeding risk with Warfarin Over 75 NSAIDs Past Hx of bleeding Polypharmacy Uncontrolled BP On other antiplatelets

Stroke risk stratification

Stroke risk stratification and thromboprophylaxis Low Under 65 and no risk factor Aspirin if no contraindications Moderate Over 65 and no risk factors Under 75 with risk factors Aspirin vs. Warfarin High Previous ischaemic event/TIA Over 75 with risk factors; valve disease or heart failure Warfarin if no contraindications Risk factors DM BP Vascular disease (CAD + PVD)

Annual Risk of Stroke Risk Group No Rx Aspirin Warfarin Very High (prev CVA/TIA) 12% 10% 5% High 5-8% 4-6% 2-3% Moderate 3-5% 2-4% 1-2% Low 1.2% 1% 0.5%

CHADS2 Condition Points C Congestive Heart Failure 1 H BP more than 160mmHg Or Treated BP A Age > 75 D Diabetes S2 Prior stroke/TIA 2 Data from 65 – 95 year old patients with AF not on Warfarin

CHADS2 Score Annual Stroke Risk % Risk Therapy Range 1.9% Low Aspirin 1.9% Low Aspirin 75- 300 mg 1 2.8% Moderate Aspirin/Warfarin 2/> 4.0% > High Warfarin INR 2-3

Paroxysmal AF Thromboprophylaxis Rhythm drugs Just the same Standard B Blocker vs.. Pill in Pocket Sotolol vs.. Class 1c agents Amiodarone Referral to EPS specialist Consider a ’pill-in-the-pocket’ strategy for those who: i) have no history of LV dysfunction, or valvular or ischaemic heart disease ii) have a history of infrequent symptomatic episodes of paroxysmal AF iii) have a systolic blood pressure > 100 mmHg and a resting heart rate above 70 bpm, iv) are able to understand how and when to take the medication.

Atrial Flutter Same antithrombotic Rx as AF Re-establish SR Cardiovert (Medication/DCCV) Pacing

Papers Mixed comparison of stroke prevention treatments in patients with non- rheumatic AF – Arch Int Med 2006:166:1269 Warfarin more effective than Aspirin in reducing stroke in AF Warfarin: will prevent 28 strokes at the cost of 11 major bleeds Aspirin: will prevent 16 strokes at the cost of 6 major bleeds Update of previous Cochrane review on anticoagulants (warfarin/ximelagatran) + antiplatelet (aspirin) therapy for non-rheumatic AF 19 trials including 18000 patients

Papers Comparison of Warfarin vs. Aspirin- Clopidogrel in AF Lancet 2006:367:1903 Warfarin is superior to dual antiplatelet therapy The study compared these 2 strategies in patients with AF and one other RF for stroke Study was stopped early after a year CVA rate was 3.93% with Warfarin and 5.6% for Clopidogrel + Aspirin The bleeding rate with Aspirin + Clopidogrel was higher

Papers BAFTA study 2007: Warfarin vs. Aspirin in an elderly, community population. Lancet 2007:370:493 Support the use of Warfarin over Aspirin in patients over 75 unless there are contraindications 973 patients aged over 75 recruited from primary care with AF, randomised to Aspirin 75mg or Warfarin (INR 2-3) and followed up for a mean of 2.7 years Absolute annual event rates 1.8% Warfarin vs. 3.8% aspirin i.e. ARR2%, NNT=50

Papers ACTIVE A Trial NEJM 2009;360:2066 Neither regime as effective as Warfarin Warfarin 1.1-1.3% Aspirin 3.3% Aspirin + Clopidogrel 2.4% Conclusion: In patients with moderate to high risk of stroke in whom Warfarin is unsuitable, the combination of Clopidogrel + Aspirin will be most likely to provide NET clinical benefit Aspirin vs. Aspirin + Clopidogrel Looking at alternative for patient with high risk of stroke but not suitable for Warfarin 7554 patients; RCT; Primary outcome was stroke, MI, embolism, vascular death Major vascular event 7.6% vs. 6.8% (ARR 0.8%;NN 125) Stroke occured in 3.3% vs. 2.4% (ARR 0.9%;NNT 111) Major Bleeding increased from 1.3% to 2.0% (ARI 0.7% = NNH143)

Papers The ATHENA Study. NEJM 2009:360:668 Primary outcome occured in 32% of the Dranadone group vs. 39% of the placebo (ARR of 7% = NNT 14) Significant reduction in CV deaths (2.7% vs. 3.9%) Dronedarone is a new antiarrythmic agent similar to amiodarone but shorter half life and reduced side effects. RCT of 4600 high risk patients (over 70 + RF) and compared Dronedarone to placebo Primary outcome was hospitalisation or death due to CV events Critised for short f/u period 21 months + high drop out rate 30%

Papers Aspirin + Warfarin in patients with AF and vascular disease BMJ2008:336:614 If a patient taking Aspirin for a CVA develops AF stop Aspirin start Warfarin Combination does not prevent more strokes but increases bleeding risk These patients should just be on Warfarin

Questions

Summary Haemodynamically Stable Cause Rate vs. Rhythm Bleed risk Stroke risk stratification Thromboprophylaxis