lecture 25 - pharmaceutical care in patients with atrial fibrillation of stroke Flashcards
what is the definition of atrial fibrillation?
supraventricular tachycardia characterised by disorganised atrial electrical activity, results in absence of significant atrial depolarisation
what is shown on an ECG of atrial fibrillation ?
no p waves on the ecg. The ventricular Arte is rapid and irregular
what are symptoms of atrial fibrillation?
feeling breathlessness, dizzy, palpitations, tiredness, chest discomfort and difficulty exercising
what is used to diagnose atrial fibrillation? x5
ECG
Holter monitor
loop recorder
blood results
echo
what are blood results used for?
to rule out any underlying condition such as
diabetes
hyperthyroidism
anaemia
renal function
infections
high cholesterol
how is an echocardiogram used for atrial fibrillation diagnosis?
does not diagnose atrial fibrillation but shows damage to the heart muscle and looks for left ventricular dysfunction
what are 2 reasons to treat atrial fibrillation?
alleviate symtoms
management of the complications to irregular heart rate - to reduce risk of stroke and developing heart failure
what is a thromboembolic risk assessment ?
CHa2DS2-VASc score
thromboembolic risk assessment a condition when a blot clot forms in the vein ie it risk assessment for stoke ONLY when a patient has atrial fibrillation
explain the CHA2DS2-VASc score
C - chronic heart failure - 1 point
H - hypertension - 1 point
A - Age (>65 or > 75 years) - 1 or 2 points
D - diabetes - 1 point
S - stroke/ transient isachemaic attack - 2 points
VA - vascular disease - 1 point
S - sex (female) - 1 point
if score is 2 or over it is a high risk group
what are the treatment options for atrial fibrillation?
warfarin - vitamin K antagonists
or DOAC - direct orla anticoagulant such as direct thrombin inhibitor and factor Xa inhibitor - apixaban and edoxaban
describe the apixaban dose for treatment of af
standard dose is 5mg twice a day. reduced to 2.5mg if patient is over 80 years, weight 60kg or less or serum creatinine 133 micro moles/l
describe the edoxaban dose for treatment of af
standard dose is 60mg once daily
dose reduction to 30mg once daily id creatinine serum is 15-50ml/min
do not require INR checked for edoxaban
why is anticoagulant given for life?
to reduce risk of stroke
what drugs are used of rventriucalr ate control in patients with AF?
AV blocking drugs
what av blocking drugs are licensed for af?
beta blockers eg atenolol
calcium channel blocker - verapamil
digoxin
what patients is digoxin used in?
heart failure and asthmatic who cannot take beta blocker,
heart failure but only for short term use as has no nbenenfits longe term - switch to a beta blocker if possible
sedative, immobilised or elderly patients
what is the first line treatment in AF and describe its mechanism of action
beta blocker - atenolol
antagonise beta-receptors, resulting in decreased conduction through the AV node, which reduces the heart rate in patients with atrial fibrillation
what is the next line treatment in AF and what patients is it contraindicated in?
Non-dihydropyridine calcium channel blockers (verapamil)
reduce AV conduction by antagonising voltage gated calcium channels, decreasing intracellular calcium.
reduce left ventricular contractility via the same mechanism, and therefore contraindicated in patients with left ventricular systolic dysfunction (LVSD).
what is digoxin used for and describe its mechanism of action
rate control
blocks the sodium/potassium ATPase pump.
The mechanism by which this decreases AV conduction is not clear, but is perhaps due to increased vagal tone.
Effective to reduce ventricular rates at rest but not effective during physical activity.
what is digoxin recommended to be used in combination with and when may it be prescribed on its own?
Therefore, it is recommended to use digoxin in combination with a beta-blocker or non-dihydropyridine calcium channel blocker.
If prescribed on its own => only in patients not mobilising
when is digoxin used as first line treatment in patients?
Digoxin is 1st line treatment in patients with acute heart failure symptoms and AF.
what drugs are used for rhythm control - alleviate symptoms?
class II amiodarone and class IC flecainide
describe how class III amiodarone works
act by blocking potassium channels.
effective but toxicity is a concern
The half-life is 42 days.
Inhibition of T4 and T3 entry into the peripheral tissues.
preferred in patients with LVSD
Chemical cardioversion
describe how class IC flecainide works
maintain sinus rhythm or chemical cardioversion
Significant coronary artery disease is a contraindication
Flecainide can be used with a “pill-in-the-pocket” approach