AF Flashcards
def AF
characterized by rapid, chaotic and ineffective atrial electrical conduction. Often subdivided into: ‘permanent’, ‘persistent’ and ‘paroxysmal’. 300-600bpm
aetiology AF
may be no identifiable cause (lone AF)
secondary causes lead to abnormal atrial electric pathways = AF
systemic causes - thyrotoxicosis, hypertension, pneumonia, alcohol, caffeine, post-op, hypokalemia, low Mg, haemochromatosis, sarcoid
The AV node responds intermittently to the atrial rhythm = irregular ventricular rhythm
CO drops by 10-20% as ventricles arent primed reliably
in pre-excited AF accessory pathways capable of conducting rapid rates pass erratic electrical activity from the atria to the ventricles, unfiltered by AVN
ECG - irregular, broad QRS at >200bpm
ventricles cant sustain this for long - pt is at high risk of VT and VF
heart causes AF
- mitral valve disease
- ischemic heart disease
- rheumatic heart disease
- cardiomyopathy
- pericarditis
- sick sinus syndrome
- atrial myxoma
- HF
lung causes AF
bronchial carcinoma
PE
pneumonia
epi AF
common in elderly <=9%
may be paroxysmal
sx af
often asymptomatic
palpitations/syncope
chest paun
dyspnoea
symptoms of the cause other than the AF
signs af
- irregularly irregular pulse
- difference in apex beat and radial pulse (apical greater than radial)
- thyroid disease
- valvular heart disease
- 1st heart sound of varying intensity
- signs of LVF
- examine the whole pt - AF is often associated with non-cardiac disease
Ix AF
FBP
CRP see if they have an infection
thyroid check - see if hyperthyroid
troponin - in case MI
imaging - ask for echo in anyone with palpitations - see the structure of the heart, see if thrombus in L atria that can become embolic = stroke
X ray - see if lung problem
ECG
Blood
echo
ecg af
Uneven baseline (fibrillations) withabsent P waves, irregular QRS complexes. If there is asaw-tooth baseline, consider if there is atrial flutter
blood af
cardiac enzymes
TFT
lipid profile
UE
Mg, Ca (risk of digoxin toxicity increased with hypokalaemia, hypomagnesaemia or hypercalcaemia)
echo af
assess for mitral valve disease, LAD, L ventricular dysfunction, or structural abnormalities, L atrial enlargement
mx af
a-e
dont need pacemaker
irreg irreg rhythm
see if stable or not - SBP <90, chest pain, drowsy/unconscious, crackles in lungs (PE) = unstable
if unstable need to shock them - chemically or electrically
- stable need to do rate or rhythm control
- rate = b blocker if ejection fraction is normal. If EF is low = digoxin, if in COPD - Ca channel blocker LOOK UP NORMAL EF VALUES
- rhythm - if had past AF
af rhythm control
If the AF is>48 h from onset, anticoagulate (at least 3–4 weeks) before attempting cardioversion.
DC cardioversion: Synchronized DC shock (2x100 J, 1x200 J).
Chemical cardioversion: Flecainide (contraindicated if there is history of ischaemic heart disease) or amiodarone.
Prophylaxis against AF: Sotalol, amiodarone or flecainide. Also consider providing ‘pill-in-the-pocket’ strategy for suitable patients.
af rate control
Chronic ‘permanent’ AF: Ventricular rate control with digoxin, verapamil and/or b-blockers. Aim for rate of 90/min.
af stroke risk prevention
low risk pts managed with aspirin
high risk warfarin
- previous thromboembolic event,
- >75yrs with HTN, dm or vascular disease
- clinical evidence of valve disease, HF or impaired l ventricular function
mx acute af
if showing adverse signs (shock, myocardial ischemia - chest pain/ECG changes), syncope, HF
- ABCDE
- senior input
- DC cardioversion (synchronized shock, start at 120–150J) ± amiodarone if unsuccessful
- dont delay treatment to start anti-coagulation
if stable and started <48hr ago
- rate/rhythm control
- start heparin in case cardioversion is delayed
if stable and >48hrs or unclear time of onset
- rate control eg with bisoprolol or diltiazem
- If rhythm control is chosen, the patient must be anticoagulated for >3wks first.
correct electrolyte imbalance (K, Mg, Ca), treat associated illnesses, and consider anti-coagulation
chronic af mx
main goals are rate control and anti-coag
rate control is at least as good as rhythm, but rhythm may be appropriate if
- symptomatic/CCF
- younger
- presenting for 1st time with lone AF
- AF from corrected precipitant
anticoag
rate control - chronic af
B blcoker or rate limiting CCB 1st choice
if fails, add digoxin, then consider amiodarone
Digoxin as monotherapy in chronic AF is only acceptable in sedentary patients.
do not give B-blockers with verapamil.
Aim for heart rate <90bpm at rest and 200 minus age (yrs) bpm on exertion. Avoid getting fi xated on a target heart rate.
rhythm control chronic af
elective DC cardioversion
- echo 1st to check for intracardiac thrombi
- If there is increased risk of cardioversion failure (past failure, or past recurrence) give amiodarone for 4wks before the procedure and 12 months after
elective pharmacological cardioversion
- flecainide is 1st choice (CI if structural heart disease, eg scar tissue from MI: use IV amiodarone instead)
- In refractory cases, AVN ablation with pacing, pulmonary vein ablation, or the maze procedure may be considered.
paroxysmal af mx
Pill in the pocket’ (eg sotalol or flecainide PRN) may be tried if: infrequent AF, BP >100mmHg systolic, no past LV dysfunction.
Anticoagulate
Consider ablation if symptomatic or frequent episodes
anticaog acute af
heparin until full risk assessment for emboli made
trans-oesophageal-guided cardioversion is an option if urgent cardioversion is required (ie cant wait for the 3weeks of anticoag if AF >48hrs ago)
Use a DOAC (eg apixaban) or warfarin (target INR2–3) if high risk of emboli (past ischaemic stroke, TIA, or emboli; >75yrs with high BP, DM; coronary or peripheral arterial disease; evidence of valve disease or low LV function/CCF—only do echo if unsure).
no anticoagulation if stable sinus rhythm has been restored, no risk factors for emboli, andAF recurrence unlikely (ie no failed cardioversions, no structural heart disease, no previous recurrences, no sustained AF for >1yr)
anticoag chronic af
Chronic AF may be paroxysmal (terminates in <7d but may recur), persistent (lasts >7d), or permanent (long-term, continuous AF, sinus rhythm not achievable despite treatment).
the need for anticoagulation should be assessed using the CHA2DS2-VASc score to assess embolic stroke risk - consider anti-coag if score men >0, women >1
and balancing this against the risks of anticoagulation to the patient, assessed with the HAS-BLED score.
Long-term anticoagulation should be with a DOAC or warfarin.
a flutter mx
similar to AF - rate and rhythm control and anticoag
DC cardioversion preferred to pharmacological - start with 70-120J
IV amiodarone may be needed if rate control is proving difficult.
Recurrence rates are high so radiofrequency ablation is often recommended for long-term management.
complications af
Thromboembolism (e.g. embolic stroke 4% risk per year, increase risk with left atrial enlargement or left ventricular dysfunction).
Worsens any existing heart failure.
px af
Chronic AF in a diseased heart does not usually return to sinus rhythm.
