Download Atrial Fibrillation

Atrial Fibrillation
BGSMC Cardiology Study Group
January 6, 2011
Mohamad Lazkani, MD
Tomas Rivera-Bonilla, MD
Nick Sparacino, DO
Introduction
• History
William Harvey *1628
Robert Adams reported *1827
Etienne Marey *1863
Sir Thomas Lewis *1909
Bootsma and coworkers *1970
William Kannell and colleagues *1982
Epidemiology
• Most common dysrrhythmia
• Overall lifetime risk ~25%
• 416,000 hospital discharges
in 2001
• Avg medicare cost of
hospitalization 6k, not
including followup,
procedures (echo, etc),
meds
• 50-90% increase in mortality
from Framingham study
Recognizing A Fib
• Classic irregularly irregular pulse
– Remember to take pulse at carotids, not peripherally
• EKG WITHOUT P WAVES
– Note all that is irregular is not a fib…
Classification of Atrial
Fibrillation
• Presence of other cardiac disease
– Lone atrial fibrillation
– Valvular atrial fibrillation
• Type of presentation
– “First detected episode”
– Recurrent
• “Persistence”
– Paroxysmal – self converts within 7 days
– Persistent – requires pharmacologic or electrical
cardioversion, but does convert
– Permanent – refractory to attempts
Causes
• Valvular disease
– MS is classic, but any state that can cause dilation of the atria…
aka any valvular issue
• Hypertension
– Most common in US
• Alcohol – “holiday heart”
• MI
• Familial
– Mutation in slow K channel causes increased inward K flux and
decreased refractory period
• Hyperthyroid
• Hypersympathetic states
• Post-operative
Pathophysiology - Initiation
Pulmonary vein muscle sleeves
1)Increased automaticity
2)Epicardially contiguous
with myocardium of atria
3)Less commonly in the
similarly arranged muscular
sleeves of the proximal SVC
Pathophysiology Perpetuation
• 2 Preconditions for reentry
– Heterogeneous conduction
• Allows preferential
unidirectional conduction
• Allows impulse to still be
traveling down slow path while
fast path is repolarizing
– Short refractory period
• Allows fast path to be “primed”
for depolarization by the time
the slow pathway reaches
previously depolarized “fast”
tissue
Mechanism of Conduction
• The AV node limits
conduction during AF.
• There appear to be 2
distinct atrial inputs to the
AV node, posteriorly via the
crista terminalis and
anteriorly via the interatrial
septum.
Remodeling – “A fib
begets A fib”
• 2 Mechanisms
– Decrease in fast Na channel
and L-type Ca channel
expression = Short Refractory
Period
– Increased metabolic and
mechanical stress leads to
reparative and reactive
fibrosis = Heterogenous
Conduction
• Hmm… Short refractory period
and heterogeneous conduction,
that sounds familiar…
Consequences…
• Decrease in Cardiac
Output
• Thromboembolism
• Tachycardic
Cardiomyopathy
Why treat Atrial Fibrillation?
•
•
•
One of every 6 strokes occurs
in patients with AF. The
overall risk of
thromboembolism is
approximately 5% per year
In the Framingham cohort,
(OR) for total mortality was
1.5 for men and 1.9 for
women with AF after the
analysis was adjusted for
age, overt heart disease, and
other risk factors
Rheumatic heart disease and
AF had a 17-fold increased
risk of stroke. The AR* on
rheumatic heart disease was
5 times greater than in those
with nonrheumatic AF
•Loss of synchronous atrial
mechanical activity
•Irregularity of ventricular response
•Inappropriately rapid heart rate
Management of
Atrial Fibrillation
 The dilemma as to whether to try rhythm control, or to accept
the arrhythmia and control the ventricular rate
Rate control strategies : symptomatic improvement is
achieved solely because of better control of the ventricular rate
Rhythm control strategies: It has been demonstrated that
restoration of sinus rhythm is associated with improvements in
exercise capacity and peak oxygen consumption, both in
patients with structural heart disease and in those with normal
hearts. However, drugs used for rhythm control may cause
serious proarrhythmia.
Dilemma of Rate vs Rhythm
Pharmacological Agents for
Rate and Rhythm Control
Nonpharmacological
Approach for AFIB
•
•
•
•
Surgical Ablation
Catheter Ablation
Suppression of AF by Pacing
Internal Atrial Cardioverter/
Defibrillators
• The Radiofrequency Ablation for
Atrial Fibrillation Trial (RAAFT), will
better assess the late recurrence
rates of AF. The effect of ablation
on mortality rates, quality of life,
and health care costs will probably
be better established during the
coming years.
• The CABANA (Ablation vs Drug
Therapy for Atrial Fibrillation) pilot
study, will be followed by a 3000patient CABANA mortality trial, in
which 1500 patients older than 65
years or younger than 65 years but
with other risk factors for stroke will
be randomly assigned to drug
therapy, and an additional 1500
such patients will be randomly
assigned to ablative intervention.
Anticoagulation Therapy
•
•
CHADS score
– Gender (female sex)
– Mitral Stenosis
Dilemma: ACC/AHA/ESC AF
Guidelines.
– Six randomized trials have
compared adjusted-dose
warfarin to placebo reduction in
stroke averaged about 60%
– Six randomized trials
comparing aspirin to placebo
show a small effect of aspirin,
averaging about 20% for
reduction in all stroke
Anticoagulation Therapy
New Anticoagulation Option
•
Anticoagulation:
– RELY [Randomized
Evaluation of Long-term
anticoagulant therapY] trial
– Dabigatran is a competitive,
and reversible inhibitor of
thrombin, inhibiting both
thrombin activity and
generation
– peak plasma concentrations
of dabigatran are reached
approximately 2 hours after
oral administration.
– Dabigatran is not
metabolized by cytochrome
P450 isoenzymes, has no
interactions with food, and
also has a low potential for
drug–drug interactions
– The elimination half-life is
12 to 14 hours, with
clearance predominantly
occurring via renal excretion
of unchanged drug.
New medication for
rhythm control
•
•
ATHENA (A Trial With Dronedarone to
Prevent Hospitalization or Death in
Patients With Atrial Fibrillation) trial
Indirect meta-analysis by Piccini et al.
Compared amiodarone with
dronedarone in AF.
–
Patients treated with amiodarone,
compared with dronedarone, were
twice as likely to remain in sinus
rhythm
–
However, amiodarone was associated
with a trend toward greater all-cause
mortality and was associated with
greater rates of adverse events
requiring drug discontinuation.
–
Analytical approach to compare 2
drugs that have not been studied in a
head-to-head randomized controlled
trial
New medication for rhythm
control
Question 1
•
A previously healthy 47-year-old woman presented 6 days ago with a complaint
of palpitations of sudden onset. Her evaluation at that time included an
electrocardiogram, which revealed atrial fibrillation (AF) with a ventricular
response of 135 beats/min. She was late for an interview, and unfortunately she
left the office before you were able to evaluate her. Her symptoms persisted
without resolution until yesterday. She decided to return to your office out of fear
of this happening again. Repeat EKG shows normal sinus rhythm. Her cardiac
examination is unremarkable. She has no other medical problems and takes no
medications. A transthoracic echocardiogram (TTE) is normal. Which of the
following is the most likely classification of this patient's AF?
❏ A. Permanent
❏ B. Persistent
❏ C. Recurrent
❏ D. Isolated
❏ E. Paroxysmal
Question 1 Key Concept/Objective:
To understand the appropriate classification of AF
• Answer: E
•
The ACC/AHA/ESC guidelines include the following categories: recurrent—
more than one episode of AF has occurred; lone —AF occurring in a
patient younger than 60 years who has no clinical or echocardiographic
evidence of cardiopulmonary disease; valvular—AF occurring in a patient
with evidence or history of rheumatic mitral valve disease or prosthetic
heart valves is defined as valvular; paroxysmal—AF that typically lasts 7
days or less, with spontaneous conversion to sinus rhythm; persistent—AF
that typically lasts longer than 7 days or requires pharmacologic or direct
current (DC) cardioversion; permanent—AF that is refractory to
cardioversion or that has persisted for longer than 1 year. Paroxysmal,
persistent, and permanent AF categories do not apply to episodes of AF
lasting 30 seconds or less or to episodes precipitated by a reversible
medical condition. Reversible conditions include acute myocardial
infarction, cardiac surgery, pericarditis, myocarditis, hyperthyroidism,
pulmonary embolism, and acute pulmonary disease.
Question 2
•
A 75-year-old woman with a history of symptomatic, recurrent, persistent
nonvalvular AF comes to your office. She has been told that there are several
options for the treatment of her AF. Which of the following is true regarding
establishment and maintenance of normal sinus rhythm, as compared with
pharmacologic rate control?
❏ A. Establishment and maintenance of sinus rhythm provides no survival advantage
❏ B. Establishment and maintenance of sinus rhythm reduces thromboembolic risk
❏ C. Establishment and maintenance of sinus rhythm improves the degree of symptomatic
impairment
❏ D. Conversion to normal sinus rhythm is rarely needed for patients with unstable angina, acute
myocardial infarction, heart failure, or pulmonary edema
❏ E. Answer choices B, C, and D are all true
Question 2 Key Concept/Objective:
To understand that establishment and maintenance of
sinus rhythm is not superior to ventricular rate control
in patients with AF
•
Answer: A
•
Several trials compared restoration of sinus rhythm with control of ventricular rate
in patients with AF. Evaluated outcomes included overall mortality, stroke,
symptoms, and quality of life. Contrary to the expectations of many experts,
maintenance of sinus rhythm provided no survival advantage and possibly a higher
mortality when compared with ventricular rate control. Maintenance of sinus rhythm
frequently requires the use of antiarrhythmic medications that may precipitate
ventricular arrhythmias, bradycardia, and depression of left ventricular function. It
was further theorized that maintenance of sinus rhythm would reduce rates of
thromboembolism and the need for anticoagulation; however, trial results
demonstrated no significant reduction in thromboembolic risk. Peak exercise
capacity may improve with maintenance of sinus rhythm, but the two treatment
strategies result in a similar degree of perceived symptomatic impairment.
Nevertheless, ventricular rate control frequently is not feasible because of the
complications that patients experience while in AF. AF often cannot be tolerated by
patients with unstable angina, acute myocardial infarction, heart failure, or
pulmonary edema.
Question 3
•
An 81-year-old man with a history of symptomatic permanent AF
presents to your office to discuss options for reestablishing sinus
rhythm. He hopes to decrease his symptoms of dyspnea. In addition
to AF, the patient has congestive heart failure and
echocardiographically documented significant mitral regurgitation.
Which of the following is a risk factor for cardioversion failure in this
patient?
❏ A. Duration of AF of longer than 1 year
❏ B. Older age
❏ C. Left atrial enlargement
❏ D. Rheumatic heart disease
❏ E. All of the above
Question 3 Key Concept/Objective:
To know the risk factors associated with failed synchronized
DC cardioversion
•
•
Answer: E
Although success rates are high with DC cardioversion, a number of
risk factors for cardioversion failure have been identified. These
include longer duration of AF (notably, longer than 1 year), older age,
left atrial enlargement, cardiomegaly, rheumatic heart disease, and
transthoracic impedance. Pretreatment with amiodarone, ibutilide,
sotalol, flecainide,propafenone, disopyramide, and quinidine have
been shown to increase DC cardioversion success rates.
Question 4
•
A 70 y/o AAF with DM type 2 is evaluated for dyspnea and fatigue. She has h/x
of AF that has resulted in these symptoms in the past. She has had a
successful cardioversion, most recently 2 years ago. She also has HTN,
controlled with medications and mild LVD related to CAD and myocardial
infarction. Her current medications include atenolol, lisinopril, ASA and insulin.
Physical examination demonstrates an irregular irregular rhythm with a HR of
78 beats per minute. Blood pressure is 130/80mm Hg. The cardiovascular and
pulmonary examinations are otherwise unremarkable. What medication should
this patient receive AFTER cardioversion?
❏ A. ASA for 3 weeks only
❏ B. Warfarin for at least 4 weeks
❏ C. Plavix for 6 months
❏ D. Metoprolol for 1 week
❏ E. No additional medications are needed
Question 4 Key Concept/Objective:
To know which anticoagulation is indicated with
synchronized DC cardioversion
•
Answer: B
• Patients with AF lasting more than 48 hrs or those with
intracardiac thrombus should receive anticoagulation with
warfarin, 3weeks before cardioversion and for at least 4
weeks afterwards. If the patient will get a TEE, they will
need 48hrs of heparin followed by 4 weeks of
amiodarone.
Question 5
•
A 67 year old woman is admitted to the emergency room because of sudden
onset of chest pain and rapid pulse. She has no history of similar occurrences.
Physical examination reveals a pale diaphoretic woman in moderate
respiratory distress. Her systolic blood pressure is palpable at 75mm Hg.
Lungs show bibasilar crackles. There is no JVD and heart sounds are distant
with a variable S1. An ECG showed AF with RVR.What is the most
appropriate immediate therapy?
❏ A. Digoxin, 0.5mg intravenously
❏ B. Dialtiazem, 20 mg intravenously, followed by 10mg/h infusion
❏ C. Rapid infusion of 500ml of normal saline
❏ D. Direct-Curent Cardioversion
❏ E. Procainamide, 500mg IV over 20 min.
Question 5 Key Concept/Objective:
To know the management of unstable patients with AF
•
Answer: D
• Unstable patients with Atrial Fibrillation
need cardioversion