Learning: Atrial Fibrillation some revision…

Modern Emergency Departments see a lot of patients with a current or new diagnosis of atrial fibrillation.  The vast majority of these patients have it as a longterm chronic illness.  There is a small minority who present as primary presentation.  This is a bit of quick revision about the options for those patients that have a new diagnosis of atrial fibrillation as their primary presentation.

Most patients with atrial fibrillation will present with similar set of symptoms;

  • Breathlessness
  • Syncope/Dizziness
  • Collapse
  • Chest pain
  • Palpitations
  • Stroke or TIA

Treatment options for atrial fibrillation typically fall into two categories rate or rhythm control, these are well described by NICE guidance. [1]

Things to consider are;

  1. is there haemodynamic instability? if the answer is yes and it is life threatening, consider emergency electrical cardioversion with no delay for anticoagulation.
  2. is it less than 48 hours from onset? if the answer is yes then there is a choice between rate or rhythm control as a management option, if the answer is no then rate control is the management of choice.

 

A good history is key, but importantly establishing clear onset time if at all possible will aid management decisions.  It is worth remembering that the definition of paroxysmal atrial fibrillation is when symptoms terminate within 7 days of onset, most of the time this is within 48 hours.

In patients with an onset less than 48 hours previously, there is a choice between rate and rhythm control. [1]

So rhythm or rate control?

A number of big trails have suggested answers to this question, but that answer is still not clear. AFFIRM Study and RACE Study both looked at this with large multi centre trials. [2,3] AFFIRM is the most recent and found there was a similar mortality between the rhythm and rate control groups 23.8% vs 21.3%.  A closer look at the groups within the AFFIRM study does suggest that patents in sinus rhythm or those that are warfarinised have a high survival than those treated with anti-arrthymic drugs, or those that have coronary artery disease or heart failure (the later two would be expected).  In fact the negative effect is of an anti-arhythmic drug is probably equal to the benefit of sinus rhythm. [4]

Rhythm control:

  • Achieved via either electrical or pharmacological cardioversion, the evidence for each of these suggest similar success rates. A BestBets article from 2008 summarised a lot the evidence nicely and found that there was similar efficacy between these two methods but individual advantages and disadvantages should be discussed with the patient. [1,5]
  • Electrical cardioversion – There is probably a slightly higher success rate with electrical cardioversion (approximately 90%).  There are inherent risks with this as well because it should involve an anaesthetic or sedation which carries a degree of risk individual to each patient.
  • Pharmacological cardioversion – NICE recommends either amiodarone or flecinide as the drug of choice and specifically suggest avoiding calcium channel blockers and magnesium. [1]
  • Amiodarone (300mg IV loading + 23hr infusion) – a class 3 antiarrythmic drug that works to prolong nodal action potential via sodium and potassium channel blockade.  It has a large number of adverse side effects.
  • Flecinide (2mg/kg IV) – a class 1c antiarrythmic drug, works via slowing sodium channels and reducing cardiac excitability. It should only be used in patients who have no structural heart disease or ischeamic heart disease.  Again it has some serious adverse side effects, one of the worst is probably prolonged electrical pauses or proarrythmic effects.

Flecindide or Amiodarone?

  • NICE recommends the use of either drug but caveats the use of flecinide if there is no evidence of structural or ischaemic heart disease. [1]
  • A number of studies have compared these drugs and the efficacy of either is not dissimilar.  A quick summary of the evidence can be found from a BestBets article which summarised that in patients with no evidence of LV dysfunction flecinide was the more effiicous choice, but it also highlighted that 60% of people reverted spontaneously without intervention. [6]
  • It is considered that Amiodarone is weakly effective as drug for use in cardioversion.  Galve et al found that it had a cardioverison rate of approximately 68% but 12% of this group returned to atrial fibrillation within 15 days. It also found that those that didn’t convert to sinus rhythm they had a decreased heart rate. [7]
  • Felcinide as a comparison has a conversion rate of approximately 85%. [8] It is not recommended in patients with structural heart disease, myocardial infarction or coronary artery diesease base on the findings of the CAST study which showed increased mortality associated with these patient groups due to the proarrythmic effects. [9] This is probably where its important to understand that there is no definition for minimal structural heart disease and it is not clear if patients with non-q wave MI are included in the available evidence.  Given the increasing prevalence of undiagnosed heart failure and coronary artery disease in our population the use of flecinide is understandably low and its use probably needs studied in a broader population. It is possibly reasonable to consider its use in fit patients with minimal risk factors and an unrestricted exercise tolerance e.g. age <50 years, able to walk a flight of stairs without breathlessness and no history of angina or MI.

Rate Control:

  • If there is underlying illness then this probably going to be the best option as there is limited benefit to cardioversion if the cause is untreated.
  • There are a number of options that work here, short acting beta blockade or rate limiting calcium channel anatagonism are the most commonly used.
  • Beta blockade can be achieved by giving IV Metoprolol (up to 15mg IV in 5mg IV bolus) and then an oral dose once the desired effect is achieved. But what about asthma and chronic obstructive airways disease? It has long been thought that observationally these patients may benefit beta blockers and certainly the evidence suggests that there is minimal impact on FEV1 in mild to moderate asthma when using cardioselective beta blockers that improves with longer term use. [10,11] In COPD there ongoing trials due to the suggestion cardioselective beta blockers actually reduce mortality independently of cardiac disease in this patient population. [12,13]
  • Calcium channel antagonism with Diltizem. There was a study done in 2015 that showed Diltiazem had a higher success rate in reducing rate when compared to Metorolpol in the Emergency Department – 96% vs 46% within 30 minutes.  As such it is defiantly worthwhile considering as an option. [14]
  • Digoxin is often mentioned as a rate control option but in the acute setting probably has only a small role.  Where it has a benefit is in those patients with heart failure as it has a positive inotropic effect, so maybe a good option for slightly older patients.

Who needs anticoagulation?

  • Use a CHADSVASC Score to assess the risk of thromboembolic events if its > or equal to one they shooed be considered for oral anticoagulation if it is two they need to be given the option of oral anticoagulation.
  • The recommendation is to also use a HAS BLED assessment of bleeding risk as well to rationalise the choice.
  • Aspirin is not sufficient to reduce the risk of thromboembolic disease or stroke.
  • Every centre has a different approach to this but it seems that the use of novel anticoagulants is gaining ground and NICE recommends either apixiban, dabigatran or rivaroxaban use depending on an individuals co-morbitiies. [1]

In conclusion how should we manage these patients, the answer to this is probably resource dependant and individual to each patient.  I wonder if there is more of a role for electrical or flecinide cardioversion in the new onset atrial fibrillation patient who is young and has no other medical problems, if successful it avoids admission and removes the need for patients to be on oral anticoagulation.  However the decision might depend on what the local cardiologist opinion is (I haven’t even mentioned ablation therapy which is considered much more successful than the other methods mentioned) and the resources within the emergency department on the day of presentation.  If you take financial impact of those patients admitted on antiarryhtmic agents its not insignificant, in the USA the it is about $23000 for patients admitted in AF vs $5500 for patients who are cardioverted. [15]

Toby Edmunds, ST4 Emergency Medicine, opinions are my own and do not represent those local organisation or department.

References:

1. Nice Clinical Guidance 180, June 2014, www.nice.org.uk

2. Olshansky B, Rosenfeld LE, Warner AL, et al. The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study: approaches to control rate in atrial fibrillation. J Am Coll Cardiol. 2004 Apr 7;43(7):1201-8.

3. Van Gelder IC, Hagens VE, Bosker HA, et al. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med. 2002;347:1834-1840.

4. Anter E, Callans DJ, Wyse DG. Pharmacological and electrical conversion of atrial fibrillation to sinus rhythm is worth the effort. Circulation. 2009 Oct 6;120(14):1436-43. doi: 10.1161/CIRCULATIONAHA.108.824847.

5. Hossack M. Pharmacological or electrical cardioversion for restoration of sinus rhythm of recent-onset atrial fibrillation. July 2008. http://bestbets.org/bets/bet.php?id=1657

6. Jon Argall. Amiodarone or flecainide for cardioversion in acute onset atrial fibrillation. March 2004. http://bestbets.org/bets/bet.php?id=423

7. Galve E, Rius T, Ballester R, Artaza MA, Arnau JM, García-Dorado D, Soler-Soler J. Intravenous amiodarone in treatment of recent-onset atrial fibrillation: results of a randomized, controlled study. J Am Coll Cardiol. 1996 Apr;27(5):1079-82.

8. Alboni  PBotto  GLBaldi  NLuzi  MRusso  VGianfranchi  LMarchi  PCalzolari  MSolano  ABaroffio RGagnoli  G. Outpatient treatment of recent-onset atrial fibrillation with the “pill-in-the-pocket” approachN Engl J Med2004351:23842391.

9. Echt DS, Liebson PR, Mitchell LB, Peters RW, Obias-Manno D, Barker AH, Arensberg D, Baker A, Friedman L, Greene HL, et al. Mortality and morbidity in patients receiving encainide, flecainide, or placebo. The Cardiac Arrhythmia Suppression Trial. N Engl J Med. 1991 Mar 21;324(12):781-8.

10. Short PM, Lipworth SI, Elder DH, Schembri S, Lipworth BJ. Effect of beta blockers in treatment of chronic obstructive pulmonary disease: a retrospectivecohort study. BMJ. 2011 May 10;342:d2549. doi: 10.1136/bmj.d2549.

11. Salpeter SR1, Ormiston TM, Salpeter EE. Cardioselective beta-blockers in patients with reactive airway disease: a meta-analysis. Ann Intern Med. 2002 Nov 5;137(9):715-25.

12. Trails listed for COPD and beta-blocker use. https://clinicaltrials.gov/ct2/show/NCT01656005?term=beta+blockers+asthma&rank=5

13. Salpeter SR, Ormiston TM, Salpeter EE. Cardioselective beta-blockers in patients with reactive airway disease: a meta-analysis. Ann Intern Med. 2002 Nov 5;137(9):715-25.

14. Fromm C et al. Diltiazem vs. metoprolol in the management of atrial fibrillation or flutter with rapid ventricular rate in the emergency department. J Emerg Med 2015.

15. Sacchetti A, Williams J, Levi S, Akula D. Impact of Emergency Department Management of Atrial Fibrillation on Hospital Charges West J Emerg Med. 2013 Feb; 14(1): 55–57.

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