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Atrial Fibrillation: Key Concepts

Atrial Fibrillation: Key Concepts. Dr. Dave Dyck R3 April 10/2003. Today’s Objectives:. Review some of the landmark papers on rate vs rhythm control in detail. Review the literature on a few questions I had one day on atrial fibrillation: Why 48 hours? Use of TEE

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Atrial Fibrillation: Key Concepts

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  1. Atrial Fibrillation: Key Concepts Dr. Dave Dyck R3 April 10/2003

  2. Today’s Objectives: • Review some of the landmarkpapers onrate vs rhythm control in detail. • Review the literature on a few questions I had one day on atrial fibrillation: • Why 48 hours? • Use of TEE • “Lone” atrial fibrillation • Low Molecular Weight Heparin in atrial fibrillation • +++ Discussion/Questions at the end • (Will not discuss antiarrhythmics and no epidemiology, pathophysiology, etc.)

  3. Rate vs Rhythm • Historically goal of treatment has been maintenance of sinus rhythm. • Majority of trials in the literature are on anti-arrhythmics looking at conversion/maintenance of sinus rhythm as the primary outcome • Recent literature is providing good evidence that for most cases rate control is equal to, and possibly better than, rhythm control

  4. 3 papers to know: • PIAF • Recurrent Persistent Atrial Fibrillation • AFFIRM (landmark paper)

  5. “Hot Café” Study: • Initial randomized attempt to look at rate vs. rhyhm control in non-valvular chronic a fib. • Small prospective Polish study (plan to include 200 pts) • No final results published • Opolski et. al. in Polskie Archiwum Medycyny Wewnetrznej. 101(5):413-8, 1999, May

  6. Pharmacological Intervention in Atrial Fibrillation (PIAF) trial: • Hohnloser S.H, Kuck K.H., and Lilienthal J. Rhythm or rate control in atrial fibrillation-Pharmacological Intervention in Atrial Fibrillation (PIAF): a randomised trial. Lancet 2000; 356: 1789-94 • Open randomized trial at 21 German sites • Inclusion criteria: • Symptomatic persistent atrial fibrillation (7-360d) • Ages 18-75

  7. Exclusion Criteria: • CHF NYHA class IV • Unstable angina or acute MI within 30d • HR<50bpm • Sick sinus syndrome • Accessory pathway (WPW) • CABG/Valve repair within 3 months • Hypertrophic cardiomyopathy • Amiodarone tx within 6 months • Acute thyroid disease • Pacemaker • Pregnancy • CI to anticoagulants

  8. Methods: • Group A (Rate control) = diltiazem 90 mg bid or tid +/- additional rate control therapy at discretion of MD • Group B (Rhythm control) = amiodarone 600mg od x 3 weeks +/- electrical cardioversion + amiodarone 200mg od • All patients anticoagulated (INR 2-3)

  9. Primary Endpoints: Change from baseline in the 3 most reported a fib symptoms: - palpitations - dyspnea - dizziness

  10. Secondary Endpoints: • Ease of fatiguability (6min walking tests) • Change in mean HR • Stabilization of sinus rhythm • # hospital admissions • Quality of Life questionnaire. (SF-36)

  11. Trial Profile:

  12. Baseline Characteristics:

  13. Intention To Treat Analysis:* • Results:

  14. Secondary Endpoints:*

  15. Summary: • 1st good randomized trial showing no difference between improvement of symptoms due to a fib in a rate vs rhythm treatment strategy • (BUT – No Mortality End-points)

  16. Recurrent Persistent Atrial Fibrillation Trial (RACE): • Van Gelder et. Al. A Comparison of Rate Control and Rhythm Control in Patients with Recurrent Persistent Atrial Fibrillation. New England Journal of Medicine 347 (23): 1834-1840. December 5, 2002. • Multicentered Randomized Dutch Trial • N=522 • Inclusion Criteria: • Recurrent persistent A fib or flutter <1 year • 1 or 2 electrical cardioversions within 2 years

  17. Exclusion Criteria: • CHF NYHA class IV • Current/previous amiodarone treatment • pacemaker

  18. Rate control: • Use of digoxin, Ca channel blocker, and B-blocker alone or in combination • Target HR<100 • Cardioversion or AV node ablation + pacemaker if intolerable symptoms

  19. Rhythm Control • Electrical cardioversion without antiarrhythmic pretreatment then sotalol 160-320mg od • If recurrence within 6 months DC cardioversion + flecainide or propafenone  if recurrance  amiodarone + DC cardioversion • If recurrence after 6 months of any treatment above  no changes

  20. Methods Cont. • All anticoagulated 4 weeks prior and post cardioversion (goal INR 2.5-3.5) • If NSR at 1 month  ASA or no anticoag. • ASA allowed in rate control group if <65 and no cardiac disease (o/w anticoag.)

  21. Primary End Point* • Composite of death from cardiovascular causes, heart failure, thromboembolic complications, bleeding, pacemaker need, or severe adverse antiarrhythmic drug effects • Over 3 years of maximum follow-up

  22. Baseline characteristics: • Only statistically significant difference was more hypertension in rhythm control group (p.007)

  23. Outcome:*

  24. Summary: • No advantage to rhythm control vs rate control in recurrent persistent a fib. (trend in favor of rate control which was almost significant) • (esp. HT & women on POST-HOC analysis)* • (note – not applicable to 1st time a fib pts)

  25. AFFIRM trial: • Wyse DG et al, A Comparison of Rate Control and Rhythm Control in Patients with Atrial Fibrillation (AFFIRM investigators), New England Journal of Medicine, 347 (23), 1825-1833, December 5, 2002. • Multicentered Randomized North American Trial • N=4060

  26. Inclusion Criteria: • A fib which was likely to be recurrent and cause illness or death • Age >65 or other CVA/death risk factors • Expected long term treatment • Anticoagulation not contraindicated • Eligible to undergo trials of at least 2 drugs in both treatment strategies

  27. Rate Control: • Goal HR < 80 bpm at rest and < 110 bpm during 6 min walk test • Options: beta blockers, Ca channel blockers, digoxin (alone or in combination) • Anticoagulated INR=2.0-3.0

  28. Rhythm Control: • Antiarrhythmic chosen by treating physician (amiodarone, disopyramide, dofetilide, flecainide, moricizine, procainamide, propafenone, quinidine, sotalol, and combinations allowed) • Anticoagulation encouraged but could be dc’d if NSR at 4, or preferably, 12 weeks if the physician chose to

  29. Other considerations: • If 2 trials of either a rate or rhythm control drug failed, then non-pharmacologic therapies could be considered (ablation, maze procedure, pacing etc)

  30. Primary End Point: • Overall mortality

  31. Secondary End Points: • Composite of death, disabling stroke, disabling anoxic encephalopathy, major bleeding, and cardiac arrest. • Mean follow-up time of 3.5 years

  32. Of Note:* • More than 1/3 were enrolled after having had a first episode of a fib* • More than 2/3 had duration > 2 days • No significant differences in baseline characteristics • Only 12% had no associated cardiac disease (may not apply well to lone a fib) • 7401 patients were eligible and offered enrollment, but only 4060 were enrolled**

  33. Drugs Used:*

  34. Rate control f/u: • At 5 year visit: 34.6% in NSR, and over 80% in a fib had adequate HR control. 5% had radiofrequency ablation. • 248/2027 crossed over to rhythm control at some point with 86 of these returning to rate control by the end of the study. (uncontrolled a fib/CHF were most common reasons)

  35. Rhythm Control f/u: • At 5 year visit: 62.6% in NSR. Electrical cardioversion attempted x1 (18%), x2 (11%), x3 or more (9%) • 594/2033 crossed over to rate control at some point with 61 returning to rhythm control by the end (inability to maintain NSR and drug intolerance)

  36. Results:* • Intention to treat analysis

  37. No significant difference between rate control (21.3%) vs rhythm control (23.8%) and a trend towards benefit of rate control p=.08*

  38. Secondary End Points:*

  39. Summary: • LANDMARK PAPER! • There is no benefit to rhythm control over rate control in patients > 65 or with other stroke risk factors who have persistent/recurrent atrial fibrillation. In these patients there is even a trend towards benefit of rate control. • This is also one of the first trials to show that in first presentation a fib, if selected as likely to be recurrent/persistent and mandate treatment, then there is also a trend to benefit of rate control. • Does not apply to lone a fib; especially in the younger population*

  40. Question 2: Why 48 hrs?

  41. Risks of Thromboembolism with Cardioversion: Why 48 hrs? • Weigner et. Al. Risk for clinical thromboembolism associated with conversion to sinus rhythm in patients with atrial fibrillation lasting less than 48 hours. Annals of Internal Medicine Vol 126 (8); April 15,1997. • Prospective chart review of admitted patients with atrial fibrillation clinically estimated to be < 48 hrs in duration. • Outcome= thromboembolic events during hospitalization or within 30 days of conversion • (excluded those who were therapeutically anticoagulated on presentation)

  42. Results: • 375 patients (mean age 68 +/- 16 yrs)* • 357 (95.2%) patients converted to NSR (250 spontaneously and 107 actively converted) • 228 (61%) patients were anticoagulated or given ASA upon admission (IV heparin= 133; 35.5%, coumadin= 26; 6.9%, ASA= 69; 18.4%) • 3 patients (0.8%) (95% CI=.2-2.4%) had clinical thromboembolic events (This is the same rate as for patients >48 hrs treated with the conventional coumadin for 4 weeks pre/post conversion)**

  43. Affected patients: • 1. 86y female w HTN (on ASA) with 24 hrs a fib converted spontaneously to NSR with rate control and had a L parietal embolic stroke <12 hrs later (pt was not anticoagulated) • 2. 83y female w CAD and a fib < 24 hrs on presentation converted with rate control after 2 days and heparin was DC’d. The next day she had a brachial artery embolus. • 3. 89y female w HTN and a fib < 24 hrs converted to NSR with rate control the next day (<48hrs). 12 hrs post conversion the patient became aphasic which then resolved within hours. (pt was not anticoagulated until after her TIA) • (2 of these patients did not have anticoagulants started)*

  44. Summary: • This study provides fairly good evidence that the risk of thromboembolism after cardioversion of AF<48 hrs is low. • (This study also recommended that IV heparin be initiated on admission for all patients with AF < 48 hours, and continued for at least 24 hours post cardioversion.)

  45. More Evidence: • Gallagher MM et al. Embolic complications of direct current cardioversion of atrial arrhythmias: Association with low intensity of anticoagulation at the time of cardioversion. Journal of the American College of Cardiology. 40(5): 926-33, 2002 Sep 4. • DC cardioversion performed within 2 days of onset of AF/flutter in 443 episodes (352 pts not on prolonged anticoagulation) • 1 embolic event

  46. More evidence: • Mitchell et. al., Cardioversion related stroke rates in atrial fibrillation and atrial flutter, Circulation, 1997; 96:I-453. • Reviewed the Ibutilide database to review the cardioversion related (<7d) stroke rate in patients who were cardioverted at <48 hrs and not given prolonged anticoagulation • In 688 patients 1 stroke occurred.**

  47. Summary: • Reasonable evidence that there is a very low risk of thromboembolism if cardioversion occurs in atrial fibrillation < 48 hrs duration.*

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