Atrial Fibrillation (AF)

HOW COMMON IS AF
AF is the most common arrhythmia in clinical practice and predicted to increase over time

AF Incidence

The above figure shows the prevalence (the proportion of a population) with atrial fibrillation. AF is more common in men than women. AF rates in the population increases with increasing age. Overall, the lifetime risk of atrial fibrillation has been estimated to be 1 in 5 of the population

Incidencewtime

Prevalence of Diagnosed Atrial Fibrillation in Adults: National Implications for Rhythm Management and Stroke Prevention: the AnTicoagulation and Risk Factors In Atrial Fibrillation JAMA. 2001;285(18):2370-2375. doi:10.1001/jama.285.18.2370
TYPES OF AF
Broadly Atrial Fibrillation can be classified in 3 types depending on the duration of symptoms

(1) Paroxysmal AF is self-terminating, usually within 48 h

 

(2) Persistent AF: defined if AF episode either lasts longer than 7 days or requires termination by cardioversion, either with drugs or by direct current cardioversion (DCC)

(3) Long-standing persistent AF : if AF is present for ≥1 year

NATURAL HISTORY OF AF:
Usually people progress from paroxysmal to persistent to long standing persistent. The time frames can vary. This is shown in the diagram below ( adapted from the European Heart Rhythm Association (EHRA) guidelines)

AFprogression

AF and STROKE

  • The risk of stroke varies from less than 1% per year to as high as 20% a year. Therefore, it is important to determine the risk of stroke in each individual and therefore tailor therapy accordingly.
  • How do we therefore determine the risk of stroke in each individual?

    chadsvasc

    chadsvasc

    The risk of stroke is based on a simple calculation, depending on age, gender and other conditions. Guidelines in the USA use the CHADS2 score whereas in Europe we use the CHADS-VAsc Score.

    It is easy to remember

    C: Congestive Heart Failure

    H: Hypertension

    A: Age

    D: Diabetes

    S: History of stroke or mini stroke

    VAsc: Presence of Vascular disease: hardening of the arteries of the leg, neck or heart.

    What blood thinning is required?

    If the risk is high (CHADS Vasc ≥2), then we usually recommend Warfarin or one of the newer drugs.

    Warfarin will thin the blood and decrease the risk of stroke by up to 80%! However, it is important to check how thin the blood is from time to time. This is because Warfarin interacts with a lot of medications, food, alcohol etc. Initially, you may need more frequent tests, but over time- once you are stable these tests will be less frequent.

    New Oral Anticoagulants

    Treatment of AF
    There are 2 very important aspects to this:

    1. Stroke Prevention
    2. Treatment of Heart Rhythm

    Ablation vs Drugs
    There are now a number of New antocoagulants in the market. They have been licensed after extensive research in a large number of people world wide.

    heparin

     

    Dabigatran or Pradaxa

    Rivioraxaban or Xorelto

    Apixiban or Elquis

    Edoxaban ( Lixiana)

     

    These are the four NOACS available at the moment.

     

    They have been compared to Warfarin and found to safe and at least as effective as Warfarin. Major bleeding risk is also less with the NOACS. However, it depends, if INR is well controlled, then there probably not much to gain by changing to one of the NOACS as they are more expensive.

    Ablation vs Drugs
    A number of studies have looked at ablation vs medications. Some of them are showm below. These show that ablation is better than drugs.

    Radiofrequency Ablation vs Antiarrhythmic Drugs as First-line Treatment of Symptomatic Atrial Fibrillation: : A Randomized Trial. June 1, 2005, Vol 293, No. 21

    A multicenter prospective randomized study conducted from December 31, 2001, to July 1, 2002, of 70 patients aged 18 to 75 years who experienced monthly symptomatic AF episodes for at least 3 months and had not been treated with antiarrhythmic drugs.

    Patients were randomized to receive either radiofrequency ablation or antiarrhythmic drug treatment with a 1-year follow-up.

    RAAFT 12

    Radiofrequency Ablation vs Antiarrhythmic Drugs as First-Line Treatment of Paroxysmal Atrial Fibrillation (RAAFT-2: February 19, 2014, Vol 311, No. 7

    A randomized clinical trial involving 127 treatment-naive patients with paroxysmal AF were randomized to received either antiarrhythmic therapy or ablation.raaft

    “Among patients with paroxysmal AF without previous antiarrhythmic drug treatment, radiofrequency ablation compared with antiarrhythmic drugs resulted in a lower rate of recurrent atrial tachyarrhythmias at 2 years. However, recurrence was frequent in both groups.”

    Radiofrequency Ablation as Initial Therapy in Paroxysmal Atrial Fibrillation (N Engl J Med 2012; 367:1587-1595October 25, 2012)

     

    This study randomly assigned 294 patients with paroxysmal atrial fibrillation and no history of antiarrhythmic drug use to an initial treatment strategy of either radiofrequency catheter ablation or drugs. After 2 years of follow up, the AF burden was assessed with Holter monitoring.

    There was no significant difference between the ablation and drug-therapy groups in the cumulative burden of AF at 3, 6, 12, or 18 months. At 24 months, the burden of atrial fibrillation was significantly lower in the ablation group than in the drug-therapy group (90th percentile, 9% vs. 18%; P=0.007), and more patients in the ablation group were free from any atrial fibrillation (85% vs. 71%, P=0.004) and from symptomatic atrial fibrillation (93% vs. 84%, P=0.01).

     

    The crossover rate from antiarrhythmics to ablation was 36%, he noted.

    A Randomized Trial. Catheter ablation vs. antiarrhythmic drug treatment of persistent atrial fibrillation: a multicentre, randomized, controlled trial (SARA study)June 1, 2005, Vol 293, No. 21. Eur Heart J. 2014 Feb;35(8):501-7

    SARA1SARA REs

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    Ablation Results
    Atrial Fibrillation Ablation has emerged as an alternative to pharmacological therpy for the treatment of atrial fibrillation over the past 2 decades. Pioneered by Prof Michel Haïssaguerre and his group, the technique of atrial fibrillation ablation has improved over time. 3D mapping system is commonly and smarter technologies includinng contact force that allow doctors to know how much force is being exerted on the tissues. Increased understanding of arrythmia has increased the success rates over time.

    The success rates vary from depending on the type, duration, and heart size. REsults also vary from centre to centre and among operators within a centre.

    A recent pooled results of studies was publised by Ganesan et al (J Am Heart Assoc. 2013 Mar 18;2(2):e004549. doi: 10.1161/JAHA.112.004549) The scientific literature was scanned for studies describing outcomes at ≥3 years after AF ablation, with a mean follow-up of ≥24 months after the index procedure.

    (1) single-procedure success, (2) multiple-procedure success, and (3) requirement for repeat procedures.

    19 studies, including 6167 patients undergoing AF ablation were included in the analysis.

    The results below show the graphical representation of results.

    Single procedure success
    Single procedure success
    Results after multiple ablations
    Results after multiple ablations

    Late Success