1. Zoll Firm Lecture Series
Atrial Fibrillation
2008
Zoll Firm Lecture Series

2. Zoll Firm Lecture Series
Atrial fibrillation is associated with a wide variety of clinical situations:
Hypertension
CAD
CHF
Advanced age
Valvular heart disease (especially MS)
Post-operative (especially after cardiac surgery)
Physiologic stress (infection, SIRS…etc).
Pulmonary embolism
Chronic lung disease
Hyperthyroidism
WPW
“lone atrial fibrillation”
2008
Zoll Firm Lecture Series

3. Atrial fibrillation nonmenclature
Lone atrial fibrillation
Patients with a-fib without clinical or echocardiographic evidence of heart disease.
New onset atrial fibrillation
First recognized episode
Recurrent atrial fibrillation
More than 1 episode has occured
Paroxysmal atrial fibrillation
Recurrent atrial fibrilation that has returned to sinus rhythm
Permanent atrial fibrillation
2008
Zoll Firm Lecture Series

4. Morbidity of atrial fibrillation
Symptoms associated with fast ventricular rate, lost of AV synchrony, and loss of RR-regularity
Embolic event/Stroke
“conversion pauses”
Patient with atrial fibrillation often have sick sinus syndrome and experiences a prolonged pause when they convert back to sinus rhythm which can lead to syncope.
2008
Zoll Firm Lecture Series

5. Zoll Firm Lecture Series
Symptoms
When the ventricular rate is very fast,
does not have enough time to fill- lower output
congestion backs to the lungs
Loss of AV-synchrony leads to loss of “atrial kick”
Symptoms often includes palpitations, dypsnea, fatigue, dizziness, chest discomfort.
Worst in patient with a thick, non-compliant ventricle
Needs time to fill
Needs the atrial kick to fill
Includes pt with AS, HOCM, massive LVH…etc.
2008
Zoll Firm Lecture Series

6. Zoll Firm Lecture Series
Treatment
If the patient is unstable, needs to cardiovert immediately
Understand that there is a risk of stroke in patient who are not therapeutically anticoagulated.
Otherwise, it is not clear whether rhythm control or rate control is better.
5 clinical trials randomized patients to a strategy of rate control vs rhythm control (AFFIRM, RACE, PIAF, STAF, and HOT-CAFÉ).
AFFIRM and RACE were the largest of the 5 trials.
All found no major difference in the primary end-point between the two strategies.
The primary reason to attempt rhythm control for patients who are highly symptomatic with atrial fibrillation and/or who cannot be well rate controlled.
2008
Zoll Firm Lecture Series

7. “Rhythm control”- Cardioversion
For a-fib>48 or of unknown duration, cardioversion should be delayed until pts have been therapeutically anticoagulated for 4 weeks or if TEE shows no thrombus
Electrical-
effective (70-90%), pre-treatment with antiarrhythmic agents may increase likelihood of success.
often requires sedation (pt preferably fasted), can be complicated by pulmonary edema due to transient stunning
Pharmacologic
Not as effective (40-70%)
Dofetilide, flecainide, ibutilide, propafeone > amiodarone if <7 days duration; dofetilide> amiodarone + ibutilide if >7 days duration.
Can be proarrythmic- some agents can induce torsades
Many people thinks that most patients deserves one trial of cardioversion if the a-fib is diagnosed for the 1st time.
2008
Zoll Firm Lecture Series

8. “Rhythm control”- maintanance of sinus rhythm
Class Ia (quinidine, disopyramide, procainamide), class Ic (flecainide, propafenone), and class III (amiodarone, sotalol, dofetilide), class I associated with increase mortality.
Amiodarone is the most effective agent and can be used in the setting of LV dysfunction, CAD, LVH…etc. However, it has a lot of side effects (pulmonary, thyroid…etc).
Sotalol less effective but safe in pts with CAD.
Dofetilide safe in patients with heart failure but can induce torsades and require an in-patient load.
In patients without structural heart disease, class Ic agents such as flecainide and propafenone are a reasonable choice.
2008
Zoll Firm Lecture Series

9. Zoll Firm Lecture Series
Rate control
Urgent treatment in very symptomatic but not overtly unstable patients often requires IV medication. Long term maintenance is with oral medication.
B-blocker, non-dihydropyridine Ca channel blockers (verapamil, diltiazem), digoxin, and to some degree amiodarone are effective.
In general, beta blockers are more effective during exercise compared to at rest. Digoxin is more effective at rest compared to exercise. Ca channel blockers maybe effective in both situations
Co-existing conditions often dictate use- i.e. pts with systolic heart failure gets beta blockers, pts with low BP gets digoxin…etc.
Needs to assess response to treatment at rest and with exertion using Holters, exercise test…etc.
2008
Zoll Firm Lecture Series

10. Thromboembolic risk/Anticoagulation
C- congestive heart failure (1), H- hypertension (1), A- age >=75 (1), D- diabetis mellitus (1), S- previous history of Stroke (2)
Event per 100 person/years
CHADS2
Warfarin
no warfarin
NNT
0.25
0.49
417 1
0.72
1.52
125 2
1.27
2.5 81 3
2.2
5.27 33 4
2.35
6.02 27
5/6
4.6
6.88 44
Patients with CHADS score >1 needs to be anticoagulated with coumadin. However, they don’t need to be bridged with heparin for surgery unless they have rheumatic mitral stenosis.
2008
Zoll Firm Lecture Series

11. Zoll Firm Lecture Series
Catheter ablation
Most of the focus of initiation of atrial fibrillation occurs around the pulmonary veins.
Radiofrequency catheter ablation techniques to “electrically isolate” the pulmonary veins is effective in reducing future episodes of atrial fibrillation with an efficacy of approximately 50-70% in one year.
Probably most effective in patients with structurally normal hearts, paroxysmal atrial fibrillation who has a shorter duration of symptoms
The procedures can be complicated by cardiac tamponde, pulmnary vein stenosis…etc.
2008
Zoll Firm Lecture Series

12. Suggested algorithm for management of atrial fibrillation
2008
Zoll Firm Lecture Series