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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