Atrial Fibrillation To Cardiovert or not to Cardiovert?

Transcription

1 Atrial Fibrillation To Cardiovert or not to Cardiovert? Brian Clarke. Bones Brains & Blood vessels

2 Atrial Fibrillation To Cardiovert or not to Cardiovert? AF Guidelines Definition & Classification Incidence / Prevalence Pathophysiological Mechanisms Causes & Clinical Manifestations Management Pharmacological (Rate, Rhythm, Stroke Prevention) Maintaining NSR DCCV

3 Atrial Fibrillation Common Arrhythmia characterised by Chaotic supraventricular activity P-waves replaced with fibrillatory waves of varying amplitude, shape & timing Deterioration of atrial mechanical function & loss of the atrial contribution to LV filling Varying Ventricluar response rates Classification Several clinical classification schemes, but none fully account for all aspects of AF Various labels: Acute, Chronic, Paroxysmal, Intermittent, constant, persistent, permanent

4 Atrial Fibrillation categories not mutually exclusive

5 Epidemiology 4.5 million in EU 30% of Arrhythmia hospitalizations Hospital admissions due to AF have increased 66% over the past 20 years due to an aging population Estimated cost burden per patient 3000/yr Overall burden 13.5 billion (EU)

6 Atrial Fibrillation(esc 2006) Prevalence 0.4 1% of general population 8% of those over 80 Median age is 75 yrs Higher in men. Incidence 0.1% per year in <40yrs 2% per year males >80 Pathological changes are characterised by fibrosis and loss of muscle mass in the left atrium. Atrial stretch and dilatation occurs.

7 AF Causes/Associations Obesity IHD Valve disease BP Cardiomyopathy Congen HD, ASD, VSD Haemochromatosis Amyloid Acute/Temporary Alcohol, Holiday Heart Surgery MI Pericarditis PE Hyperthyroid Pneumonia, sepsis Symptoms: Palpitations, Fatigue, Light Headedness, SOB, Pre-syncope

8 Management 1. Prevent Embolism n Rate control n n bpm at rest bpm during moderate exercise n Rhythm control n n Cardioversion Drugs or Electrical Ablation techniques (Pulmonary Vein Isolation)

9 Thromboembolism Thrombotic material most often arises in the Left Atrial Appendage the site of 95% of detected thrombus Begins with virchows triad of stasis, endothelial dysfunction & hypercoagulability Decreased LAA flow is assoc with Spont ECHO contrast However upto 25% of CVA in pts with AF may be due to intrinsic cerebrovascular disease and other cardiac sources or atheromatous pathology in the proximal aorta

10 Thromboembolism - Stroke 1/6 strokes are AF related 35% in the over 80 s 5% stroke rate per year in non-valvular AF 2-7 fold inc risk (compared to nsr stroke rate) 7% per year rate of brain ischemia (including silent strokes/tia) Upto a 17 fold stroke risk with Rheumatic heart disease AF related strokes are more disabling than non-af strokes Estimated that only 67% of pts eligible for warfarin are prescribed it

11 Warfarin & Stroke risk Reduction Warfarin reduces AF related stroke risk by 61% AHA/ESC/ACA Major bleeding: % (1.2% per yr over 5 RCT) ICH rate: % Aspirin offers modest protection Meta-analysis 1999: 19% reduction Evidence based on 300mg dose, higher GI risk (x2 75mg dose risk) but limited evidence at the lower doses Combining with clopidogrel is still inferior to warfarin alone

12 12 Stroke Risk Classification Schemes (Non-Valvular AF) Atrial Fibrillation Investigators: 1994 SPAF: 1995 European AF Trial Study Group: 1995 AFI: 1998 SPAF: 1999 CHADS 2 : 2001 American College Chest Physicians: 2001 Framigham Heart Study: core features Independently predict stroke 1. BP 2. Advanced Age 3. Prior CVA/TIA 4. DM Van Walraven et al: 2003 ACCP: 2004 BAFTA (Birmingham AF Treament of the Aged): 2006 ACC/AHA/ESC Guidelines: 2006

13 CHADS 2 Scoring System JAMA 2001? To Warfarinise CHADS 2 - score total of 6 CHF 1 Hypertension (>160) 1 Age (>75) 1 Diabetes 1 Stroke (TIA / CVA) 2 Consider if CHADS 2 >1 Note CHADS 2 does not take into account valve disease, which clearly, if present, further increases the risk of Stroke

14 Stroke Risk CHADS 2 Annual Stroke Risk %

15 Is it Safe to Anticoagulate Older patients? BAFTA 2007 in 234 GP practices in UK Midlands Trial of 973 pts aged > 75yrs (mean age 81) All with Af randomised to Aspirin 75mg or Warfarin Followed for average of 2.7 yrs Warfarin reduced risk of fatal or disabling stroke in this age group (9.9% vs 4.4%, RRR 50%) Extra-cranial Haemorrhage risk: Aspirin gp (1.6%) Warfarin (1.4%)

16 Pharmacological Management AFFIRM NEJM 2002 No difference in Stroke rates in those assigned to rate v rhythm control More of the rhythym controlled gp were hospitalized or gad ADR s RACE NEJM 2002 rate was not inferior to rhythm control in preventing of death/morbidity ACE-i/ARB have been shown to decrease incidence of AF LIFE, Losartan Decision to cardiovert someone should be based on: Severity of the associated symptoms Inability to rate control Patient preference

17 AHA/ESC Rate Control Recommendations Class 1 Recc: Persistent or permanent AF: bblockers or CaChB to control rate In AFFIRM bb (70%) were better than CaChB (54%) in achieving target Rates Acutely: IV bb or CaChB with normal LV Acutely: IV Dig or Amiodarone in those with HF Adequacy of rate control should be measured during exercise Digoxin is effective orally only in sedentary pts with HF or LV dysfunction Class 2a Recc: Combination of Dig & bb can be used Reasonable to consider ablation procedure if drugs fail or significant s/e

18 Rate Control: Drug Recommendations Class 2b Recc: Addition of amiodarone to other drugs to control rate is reasonable where above fail to rate control Class 3 Recc: Dig should not be used to control rate in parox AF Catheter Ablation should not be attempted without trial of drugs In decompensated HF CaChB should not be used

19 Cardioversion: Drug Recommendations Drugs are simpler but often less effective than electrical cardioversion. Drugs most effective if AF <7days duration Spontaneous Cardioversion occurs in proportion of pts with short duration AF Drugs much less effective if AF is persistent Proven CV Efficacy: Amiodarone Flecainide: Useful PO/IV in pts with AF < 7days, Without evidence of sinus/av node disease, BBB, QT prolongation Brugada or structural heart disease. Digoxin and sotalol should not be used to CV Digoxin no better than placebo in cardioverting

20 Maintain NSR: Drug Recommendations Amiodarone: more effective than Sotalol (69%v 39% over 16 months) off set by long term s/e profile Median time to AF recurrence: amiod (487d) v sotalol (74 d) Sotalol: A non-selective β-blocking drug with class III activity Not effective in CV of AF. May be used to prevent AF recurrences QT interval <450ms. Little or no Heart disease & normal electrolytes Beta-blockers: Not primary therapy to maintain NSR Controls ventricular rate in recurrences of AF

21 Maintenance of NSR - Drugs Treat the precipitating cause Define goals of treatment: AF is a chronic life-long disorder that is likely to recur at some point in most patients. Maintain NSR will in some patients: suppress s/s, improve exercise tolerance or prevent tachy induced CM Because RF for recurrence of AF are RF for stroke (age, BP, LA enlargement, LV dysfunction) correction to NSR may not reduce that patients inherent stroke risk Well tolerated recurrences of AF is reasonable as a successful outcome of AAR drug therapy

22 Electrical Cardioversion Synchronised ECV j biphasic, up to 200j Higher Initial energies significantly more effective Higher energies: in larger people and AF of long duration Success enhanced by preloading with Amiodarone or Sotalol (AHA, ESC) Risk Embolic event (1-7%) cluster in the first 10 days post ECV Bradycardia, Heart Block, Temporary Sinus arrest VF, VT if not synchronised Arrhythmia risk increased by Hypo-kalemia, Dig toxicity Relatively low associated Anaesthetic risk

23 Conclusions Success rates for ECV in maintaining NSR: ultimately poor But procedure can still be offered once mindful of the likellihood of reverting to AF Longer Surveillance period post CV (more than the usual 6 weeks)? 6months to capture those reverting to AF When selecting patients for ECV Symptomatic AF probably only real reason to CV Think of cause & Estimate length of time in AF (<1yr) CHADS 2 ECHO parameters, LA size up to 4.5cm Consider Amiodarone/sotalol pre-cv : especially if second attempt Use ACE/ARB to reduce LA stretch Consider ablation if repeated attempts fail and pt still symptomatic Asymptomatic AF & CHADS 2 >1: rate control and anti-coagulate

24 References Lane DA, Lip GY. Barriers to anticoagulation in patients with atrial fibrillation: changing physician-related factors. Stroke Jan;39(1):7-9. Fuster V, Ryden LE, Cannom DS, Crijns HJ, Curtis AB, Ellenbogen KA, et al. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society. Circulation Aug 15;114(7):e Mant J, Hobbs FD, Fletcher K, Roalfe A, Fitzmaurice D, Lip GY, et al. Warfarin versus aspirin for stroke prevention in an elderly community population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged Study, BAFTA): a randomised controlled trial. Lancet Aug 11;370(9586): Wyse DG, Waldo AL, DiMarco JP, Domanski MJ, Rosenberg Y, Schron EB, et al. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med Dec 5;347(23): Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA Jun 13;285(22):