Download atrial fibrillation

ATRIAL FIBRILLATION
PHCP 403
Samirah Abdu-Aguye
INTRODUCTION
• Atrial fibrillation is the most common
sustained cardiac arrhythmia
• Occurs in 1-2% of the population in the
developed world
• Prevalence increases with age
• It may occur in isolation or secondary to
structural heart disease, hypertension,
myocardial ischemia and infarction,
hyperthyroidism, obesity and sleep apnea
INTRO CONT’D
• AF can be asymptomatic or symptomatic
• Signs & Symptoms may include palpitations,
dizziness, dyspnea, angina and worsening
heart failure
INTRO CONT’D
• Its management depends on the assessment
of thromboembolic risk and control of
symptoms
• In general, a decision is made to pursue either
a rhythm or rate control strategy.
• With rhythm control the aim is to maintain
the patient in sinus rhythm, while with rate
control the aim is to control the ventricular
rate with medication
TYPES
Atrial fibrillation may be categorized according
to its presentation and duration (paroxysmal,
persistent and permanent/chronic )
• Paroxysmal: sudden onset, reverts in 24-48hrs
• Persistent: abrupt onset and persists for > 7
days
• Permanent/ chronic: patient is unable to
return to sinus rhythm
ASSESSING STROKE RISK
• Systemic thromboembolism, leading to stroke,
transient ischemic attacks or embolization to
other sites, is the most dreaded complication
of AF.
• AF is believed to be responsible for up to 40%
of all strokes
• Anticoagulant therapy reduces this risk.
CONT’D
• The decision to use anticoagulant or
antiplatelet therapy is dictated by the
patient's risk of these events
• The CHADS2 and CHA2DS2-VASc scores have
been commonly used to stratify risk
• A score of 1 or more is generally taken to
indicate a risk of thromboembolism which
may warrant anticoagulant therapy
CHADS2 SCORE
CHADS2 score: stratifying risk of stroke in patients
with atrial fibrillation
• Congestive heart failure
1 point
• Hypertension
1 point
• Age ≥ 75 years
1 point
• Diabetes
1 point
• Systemic embolism, including Stroke, 2 points
(previous episode)
CHA2DS2 VaSC SCORE
Risk factor
Score
• Congestive heart failure or left ventricular dysfunction 1
• Hypertension
1
• Age 75 years or older
2
• Diabetes mellitus
1
• Stroke or transient ischemic attack history
2
• Vascular disease
(prior myocardial infarction, peripheral artery disease, aortic
plaque)
1
• Age 65–74
1
• Sex category (female gender)
1
CHADS2 SCORE
0
Use CHA2DS
VaSC SCORE
≥1
Monitor
regularly
Use
anticoagulants
TREATMENT OF AF
1. Rhythm control(Conversion to sinus rhythm)
-DC shock/ cardioversion
-Medication
2. Rate control(Control ventricular rate)
-Medication
3. Prevent thromboembolism
-Use of anticoagulants
Proposed management of nonvalvular AF
Anticoagulants
• Warfarin used to be the drug of choice for
anticoagulation
• MOA?
• Requires regular INR monitoring, has
unpredictable rxkinetics, various interactions
and carries a risk of bleeding especially ICH
• Newer agents that can be used instead are
dabigatran, apixaban and rivaroxaban
HASBLED TOOL
•
•
•
•
•
•
•
HASBLED score
Hypertension
Abnormal liver or kidney function,
Stroke
Bleeding
Labile INRs
Elderly (e.g. >65 years)
Drugs or alcohol
1 point
1 point each
1 point
1 point
1 point
1 points
1 point each
*Hypertension = systolic blood pressure >160 mmHg
*Abnormal renal function = dialysis/renal
transplantation/serum creatinine ≥200 mmol/L
*Abnormal liver function = chronic hepatic dysfunction
(e.g. cirrhosis) or biochemical evidence of significant
hepatic derangement (e.g. bilirubin 2 x upper limit of
normal in association with aspartate
aminotransferase/alanine aminotransferase/alkaline
phosphatase 3 x upper limit normal etc.)
*Bleeding = history of bleeding or a bleeding diathesis
*Drugs = concomitant use of antiplatelet or non-steroidal
anti-inflammatory drugs
Problems with anti-arrhythmic drugs
• Extensive side effects- Pro-arrhythmic,
increase mortality
• Drug and disease interactions
• Negative inotropes except amiodarone and
digoxin
Rate control Vs. Rhythm Control
• No difference, both treatments are equivalent
to each other
Rate control
• Most patients with atrial fibrillation are
managed by controlling the ventricular rate
• The ventricular rate may be controlled using
beta blockers( 1st line), non-dihydropyridine
calcium channel blockers (for example
verapamil) or digoxin.
• Target heart rate is less than 110 beats/min
• Anticoagulation should be continued in these
patients
Rhythm control
• In severely symptomatic patients it may be
reasonable to attempt to restore sinus
rhythm.
• Patients who present within 48 hours of the
onset of AF, immediate cardioversion
(electrical or drug) may be attempted.
RHYTHM CONTROL CONT’D
DC Cardioversion
- Requires anesthesia
- Maintainance of sinus rhythm is variable
• ≤ 48 hrs of onset best outcome
• Appropriate anti-coagulation
• Usually requires drug therapy to maintain
sinus rhythm e.g. beta blockers, flecainide and
amiodarone
RHYTHM CONTROL CONT’D
Pharmacological
Simpler, but less effective than DC cardioversion
• Acutely if < 48 hours
- 1st line: Flecainide
- 2nd line: Amiodarone
• Anticoagulation is needed
• May also require long term drug therapy for
maintenance
Practice Question
• Mr John Jones (61 years) is admitted to the
emergency assessment unit at his local hospital
complaining of palpitations, breathlessness and
dizziness.
• He has a 5-day history of some dizziness and
palpitations. In the last 24 hours he complained
additionally of shortness of breath. He collapsed
at home and was then admitted to hospital via
the emergency department.
• He experienced similar symptoms two months ago but did
not seek medical advice at that time and seemed to
recover quickly. On examination and review by the
admitting doctor the following information is obtained:
Previous medical history
• Hypertension (diagnosed 5 years ago), no previous history
of cardiovascular disease.
• The patient is a regular cigarette smoker (>20 per day) and
drinks approximately 20 units of alcohol per week.
Drug history
• No known allergies.
• Mr Jones had been prescribed lisinopril tablets 20 mg once
daily but was poorly compliant with treatment.
Signs and symptoms on examination
• Blood pressure 100/70 mmHg
• Heart rate 175 bpm, irregular
• Respiratory rate 25 breaths per minute
• No basal crackles in the lungs.
Diagnosis
• Atrial fibrillation.
Relevant test results
• Full blood counts, liver function tests, electrolytes and
renal function were all normal at admission and
throughout the admission to discharge
• Mr Jones is subsequently transferred to the
cardiology ward where his continuing atrial
fibrillation is later confirmed as persistent
atrial fibrillation.
Questions
1. What is this patients CHADS Score? What does it mean for him?
2. What are the most common signs and symptoms exhibited by patients with atrial
fibrillation? Indicate which of these signs and symptoms the patient is exhibiting
3 What are the two options in terms of treatment strategy that may be employed to
manage atrial fibrillation? Indicate what would be the most appropriate strategy that
you could recommend to the doctor managing this patient and why you think this is
the case.
4 Assuming a rate control strategy is to be used what class of drug should be the firstline treatment for this patient? If the first-line drug was contraindicated what class of
drug could be used as alternative treatment?
5 What patient parameters should be monitored to assess therapy with the usual firstline treatment and what is an appropriate treatment target for such parameters?
6 Suggest 2 drugs that can be used as anticoagulants in this patient
7 Assuming the patient is to be discharged on warfarin, what counselling does the
patient require?
REFERENCES
• Samardhi H, Santos M, Denman R, Walters D,
Bett N. Current management of atrial
fibrillation. Australian Prescriber [Internet].
2011 [cited 21 February 2015];(Volume 34,
Issue 4):100-103. Available from:
http://www.australianprescriber.com/magazin
e/34/4/article/1204.pdf
• Munns A. Atrial Fibrillation Introduction.
Lecture presented at; 2011; University of
Queensland.
• NPS Medicinewise. Good anti-coagulant
practice. Internet:
http://www.nps.org.au/publications/healthprofessional/medicinewise-news/2013/goodanticoagulant-practice#References; 2013.