Managing Atrial Fibrillation
Atrial Fibrillation (AF) is defined as a cardiac arrhythmia with the following characteristics:
* The surface ECG shows absolute irregular R-R intervals;
* There are no distinct P waves on the surface ECG. Some apparently regular atrial electrical activity may be seen in some ECG leads, most often lead V1;
• The atrial cycle length (when visible), ie; the interval between two atrial activations, is usually variable and <200ms ( >300 bpm).1
Types of AF
The European Society of Cardiology distinguishes five different types of AF:
1) First Diagnosed AF - Every patient who presents with AF for the first time irrespective of the duration of AF, or the presence/severity of symptoms.
2) Paroxysmal AF - Self-terminating usually within 48 hours.
3) Persistent AF- AF episode lasts longer than 7 days or requires termination with cardioversion (CV).
4) Long-standing persistent AF- AF has lasted ≥ 1 year when decision is made to adopt rhythm control strategy.
5) Permanent AF - when the presence of AF is accepted by the patient and physician, and rhythm control is not pursued.1
Long Term Management of AF
Clinical management of patients with AF involves the following objectives:
• Prevention of thrombo-embolism
• Symptom relief
• Optimal management of concomitant CVD
• Rate control
• Correction of rhythm disturbance.1
Risk Stratification for stroke and thrombo-embolism
AF is a major contributor to stroke and thromboembolism. The simplest risk assessment is the CHADS2 [cardiac failure, hypertension, age, diabetes, stroke (doubled)] risk index based on a point system in which:
• 2 points are assigned for a history of stroke or TIA; and
• 1 point is assigned for age >75 years, a history of hypertension, diabetes or recent cardiac failure.2
For patients with CHADS2 score of 0 or 1 consider further risk stratification using the CHA2DS2VASc [congestive heart failure, hypertension, age ≥ 75 (doubled), diabetes, stroke (doubled), vascular disease, age 65-74 and sex category (female)]3
Initial therapy for AF should always include adequate antithrombotic therapy and ventricular rate control.
Rate and Rhythm Management
Choice of rate and rhythm control strategies require individual tailoring dependent on clinical evaluation once appropriate antithrombotic therapy has been initiated.
• Permanent AF is managed by rate control unless it is possible to restore sinus rhythm when the AF is 'long standing persistent'
• Paroxysmal AF is more often managed with a rhythm control strategy, especially if it is symptomatic and there is little or no associated underlying heart disease.1
Long-Term Rhythm Control
The 2010 ESC Guidelines illustrate principles of antiarrhythmic therapy to maintain sinus rhythm in AF:
• Treatment is aimed at reducing AF-related symptoms
• Efficacy of antiarrhythmic drugs to maintain sinus rhythm is modest
• Successful antiarrhythmic drug therapy may reduce rather than eliminate recurrence of AF
• Safety rather than efficacy considerations should primarily guide the choice of antiarrhythmic agent.1
Figure 2. Choice of antiarrhythmic drug according to underlying pathology
ACEI = angiotensin converting enzyme inhibitor; ARB = angiotensin receptor blocker; CAD = coronary artery disease; CHF = congestive heart failure; LVH = left ventricular hypertrophy; NYHA = New York Heart Association; ? = evidence for 'upstream' therapy for prevention of atrial remodeling remains controversial.1
European Society of Cardiology (ESC) Guidelineswww.escardio.org/guidelines
CHADS2 Score Calculator www.qxmd.com/calculate-online/cardiology/chads2-stroke-risk-in-atrial-fi...
CHA2DS2VASc Score Calculator www.qxmd.com/calculate-online/cardiology/cha2ds2-vasc-stroke-risk-in-atr...