What is AF?
Rapid uncoordinated atrial contractions w. variable ventricular response
Cardiac risk factors (4 + 3)
HTN
CAD
CCF
valvular heart diseease (esp. mitral)
arrhythmias
cardiothoracic surgery
alcohol abuse (chronic > acute)
Non-cardiac risk factors (4 + 3)
Age
DM
electrolyte imbalance
hyperthyroidism
infx (esp. pnuemonia)
PE
post-op
How is AF classified (according to chronicity)?
Acute 7 days OR requiring cardioversion (pharm/electrical)
Permanent = refractory to Rx OR accepted as final rhythm
AF pathophysiology + progression to chronic AF
Chaotic rhythm arises from unstable zone @ the junction of the pulmonary veins where they enter the RA (or from diseased atrial tissue). Multiple re-entry circuits within the atria result in re-entry loops –> sustained AF (more likely w. large atria/poor atrial conduction).
Ventricular rhythm determined by AV node conduction (autonomic / pharm control)
Progression to persistent/chronic AF due to:
- atrial remodeling (fibrosis, dilation)
- electrophysiological changes
Clinical Px
Hx:
- SOB
- palpitations
- chest pain
- fatigue
- (light headed, dizzy, syncope)
Ex:
- irregularly irregular pulse
- high JVP
- low BP
- added heart sounds
+/- evidence of stroke
Important Ix to ordr
ECG: irregularly irregular rhythm, absent P waves w. normal irregular QRS
Tests to rule out cause:
- UEC = electrolytes
- Troponins = AMI
- TFTs = thyroid fx
- CXR = cardiomegaly, HF signs, pnuemonia
- TTE = LV dilation, valvular disease, reduced EF%
Test for Cx:
- TOE = thrombus in atria
3 important short term Cx
1) Stroke = blood stasis in atria
2) AMI = increased myocardial demand, reduced diastolic filling time
3) CCF
How do you assess stroke risk?
CHADS2
CCF (1) - because at this stage normally have an element of LV systolic failure --> more prone to irregular rhythm HTN (1) Age > 65 (1) diabetes (1) Stroke Hx (2)
3 important elements of AF Rx?
1) Rate control
2) Rhythm control
3) TE prevention
Is it more important to control rate or rhythm in AF? Why?
Rate if young
Rhythm if older - b/c less likely to respond to cardioversion
Describe meds used for rate + rhythm control
RATE
- metoproplol OR digoxin
- diltiazem/verapamil OR amiodarone OR flecanide
- DC shock under GA (in R wave - or may cause VF)
RHYTHM
- sotalol (class III anti-arrhythmic - K+ channel blocker w. b-blocker properties)
- amiodarone
- flecanide
- DC cardioversion
- ablation (may require PPM if AV node ablated)
Which 2 drug classes can never be given together? Why?
b-blockers + Ca-channel blockers: bradycardia
What criteria is used to anti-coagulate someone on AF? When would you do so based on this criteria?
CHADS2
Anticoagulants at > 2 (may consider aspirin @1)
CCF (1) - because at this stage normally have an element of LV systolic failure --> more prone to irregular rhythm HTN (1) Age > 65 (1) diabetes (1) Stroke Hx (2)
When are the various anti-platelets / anti-coags used?
ANTI-P
- LD aspirin
- clopidogrel
ANTI-C
- Warfarin - already on it, renal failure, poor renal fx, NOAC allergy
- NOACs - better dose response curve, less risk of IC hemorrhage, no monitoring needed, no antidote, renally excreted
- Heparin/LMWH = short term in hospital
What preparation is required before (+ after) ablation? When will you know if ablation is successful?
Anti-coagulation 3w before + after due to risk of dislodging thrombus + continued increased TE risk.
Will known success after 1mo due to inflammation –> can cause AF again
When is cardioversion unhelpful?
Permanent AF
Rate of recurrence 1y after cardioversion in elderly people?
70%
What are the causes of most long term Cx?
Rx
Cx β-bocker use
- hypotension
- bradycardia
- asthma attacks
- heart failure
Cx amiodarone (+ digoxin)?
- thyroid dysfx
- arrhythmias (+ digoxin)
- lung toxicity (interstitial fibrosis)
