Atrial Fibrillation (AF)-an introduction

Sara Dando

Introduction

Atrial Fibrillation- an overview

Mechanisms of AF

Risk factors

ECG

Management

Anticoagulation and stroke risk

Atrial Fibrillation

1-2% of the population are affected by AF and it's

prevelance increases with age

Men are more frequently affected than women

Increased incidences of death, thrombo-embolic events,

stroke, decreased exercise tolerance, reduced quality of life,

heart failure and left ventricular dysfunction

AF may remain undiagnosed for significant periods (silent

AF)

Mechanisms

Atrial cells fire at 400-600 times per minute.

The AV node acts as a frequency filter preventing

excessive ventricular rates

Cardiac output can be reduced by 5-15% due to acute loss

of coordinated atrial mechanical function

Risk Factors

Systolic and diastolic heart failure

Valvular heart disease

Myocardial infarction

Hypertension

Diabetes

Obesity

Cigarette smoking

Clinical manifestations

(May or may not include)

Palpatations

Decreased exercise tolerance

Fatigue

Shortness of breath

Chest discomfort

Types of Atrial Fibrillation

First diagnosed AF

Paroxysmal AF

Persistent AF

Long-standing persistent AF

Permanent AF

Silent AF

Detection

12 lead ECG

Holter monitoring

Event monitoring

Definition

ECG has'absolutely' irregular RR intervals

No distinct P waves seen on the ECG

ECG

Atrial Flutter

Atrial flutter is unlike AF, it results from a circuit usually in

the right atrium.

The management is different from atrial fibrillation and

ablation is often a good treatment option

Figure 2. Atrial flutter results from a rapid circuit that occurs most commonly in the right atrium.

Boyer M , and Koplan B A Circulation 2005;112:e334-e336

Copyright © American Heart Association

ECG

Long term management of Atrial Fibrillation

Prevention of thromboembolism

Symptom relief

Optimal management of contributing cardiovascular

disease

Protect the LV from the effects of tachycardia

Correction of rhythm disturbance.

Rhythm versus rate control

Rhythm control - restore and maintain sinus rhythm

Rate control - leaves the patient in AF while targeting ventricular rate response

Pharmacological rate control

Conventional beta blockers such as Metoprolol

Calcium channel antagonists such as diltiazem

Digoxin

Rhythm control

Antiarrhythmic drugs such as sotalol, flecanide, amiodorone

Direct current cardioversion

Assessing Stroke Risk

5% /year is the average risk of stroke in patients with AF

this increases to 20% with mitral stenosis and AF

The risk of AF complications is not different between short

episodes versus sustained episodes

The dominant source of embolism, >90% in non valvular

AF, is the left atrial appendage

Risk factor-based point-based scoring system - CHA2DS2-VASc

*Prior myocardial infarction, peripheral artery disease, aortic plaque.

Actual rates of stroke in contemporary cohorts may vary from these estimates

European Heart Journal (2010) 31, 2369-2429

The HAS-BLED bleeding risk score

*Hypertension is defined as systolic blood pressure > 160 mmHg

INR = international normalized ratio

European Heart Journal (2010) 31, 2369-2429

Anticoagulation

Dabigatran (Pradaxa)

(Exclude patients with severe renal impairement,Createnine clearence

<30ml/min)

Dose- Adults 150 mg twice daily

80 years and above 110 mg twice daily

Warfain

Once daily dose according to INR

Maintain INR between 2-3 with a target of 2.5

Take Home Message

If you have an irregular pulse

Think about AF

Take an ECG

Then assess for stroke risk.

ReferencesCamm, A., Kirchhof, P., Lip, G., Schotten, U., Savelieva, I., Ernst, S., Van Gelder, I., Al-Attar, N., Hindricks, G., Prendergast, B., Heidbuchel, H., Alfieri, O., Angelini, A., Atar, D., Colonna, P., De Caterina, R., De Sutter, J., Goette, A., Gorenek, B.,Heldal, M., Hohloser, S., Kolh, P., Le Heuzey, J-Y., Ponikowski, P., Rutten, F.(2010).Guidelines for the management of atrial fibrillation. European Heart Journal, 31, 2369-2429.doi:10.1093/eurheartj/ehq278

Connolly, S., Ezekowitz,M., Yusef,S., Eikelboom, J., Oldgren,J., Parekh, A., Pogue,J., Reilly, P., Themeles, E., Varrone, J., Wang, S., Ailings, M., Xavier, D., Zhu, J.,Diaz, R.,Lewis, B., Darius, H.,Diener, H-C., Joyner, C., Wallentin, L., and the RE-LY Sterring committee and Investigators, (2009). Dabigatran versus warfarin in patients with Atrial Fibrillation. N Engl J Med , 361:1139-1151 DOI: 10.1056/NEJMoa0905561

Mims New Ethicals

New Zealand Datasheet- Dabigatran etexilate

Wadke, R.(2013). Atrial fibrillation. Disease-a-Month, 59, 67-73. http://dx.doi.org/10.1016/j.disamonth.2012.12.002

New Zealand Guidelines Group (2005). The Management of People with Atrial Fibrillation and Flutter. www.nzgg.org.nz