B-QuiCK: Atrial fibrillation

B-QuiCK: Atrial fibrillation

Assessment and diagnosis

• Most cases of atrial fibrillation (AF) are asymptomatic. Opportunistically assess patients aged ≥ 65 years for cardiac arrhythmia via radial pulse palpation. Earlier assessment is warranted in patients with an increased risk of AF, e.g. Māori or Pacific peoples, previous TIA, hypertension. If AF is suspected after radial pulse palpation, chest auscultation to evaluate apical pulse can strengthen diagnostic accuracy.
• If present, AF symptoms may include palpitations, dizziness, shortness of breath (particularly on exertion), angina, fatigue
• AF can be confirmed via ECG. The typical pattern involves irregularly irregular RR intervals and no discernible, distinct P waves. For diagnostic purposes, AF is defined as lasting at least 30 seconds (observing this pattern for the duration of a standard 10 second 12-lead ECG tracing is sufficient for confirmation in primary care).
• Following ECG confirmation, perform a full cardiovascular evaluation and request bloods: FBC, creatinine and electrolytes, coagulation screening (if oral anticoagulants will likely be used), and LFTs and thyroid function tests (if not requested recently)
• Refer the patient for echocardiogram but do not delay treatment

Stroke prevention

• Assess need for anticoagulation by balancing stroke risk (CHA₂DS₂-VASc score) against bleeding risk (HAS-BLED score) – see below
  • Consider offering anticoagulation to males with a CHA₂DS₂-VASc score ≥ 1 of females with a score ≥ 2
  • There are no specific cut-offs to identify patients who should not be initiated on an anticoagulant based on their HAS-BLED score; manage any modifiable risk factors for bleeding where possible and consider more frequent follow-up if anticoagulation is prescribed to a patient at higher risk of bleeding
• In most cases, direct oral anticoagulants (DOACs) such as dabigatran or rivaroxaban are preferred over warfarin for stroke prevention in patients with AF (unless contraindicated). See the NZ Formulary for dosing recommendations and read here for more information about anticoagulants.

Stroke risk (CHA₂DS₂-VASc)

	Risk factor for stroke	Points
C	Congestive heart failure or left ventricular systolic dysfunction	1
H	Hypertension or current antihypertensive medicine use	1
A2	Aged 75 years or over	2
D	Diabetes mellitus	1
S2	Stroke, transient ischaemic attack or thromboembolism	2
V	Vascular disease (e.g. myocardial infarction)	1
A	Aged 65 – 75 years	1
Sc	Sex category – female	1
	Total (0 –9)

Bleeding risk (HAS-BLED)

	Risk factor for bleeding	Score
H	Hypertension (systolic blood pressure > 160 mmHg or uncontrolled blood pressure)	1
A	Abnormal renal and/or liver function, e.g. liver disease or aminotransferase levels > 3 times the upper limit of normal	1 point for each
S	Previous history of stroke	1
B	Bleeding (prior major bleeding or predisposition to bleeding, e.g. anaemia)	1
L	Labile INR (unstable/high or time in therapeutic range < 60%)	1
E	Elderly (aged > 65 years) or extreme frailty	1
D	Drugs or alcohol use (criteria includes patients who drink ≥ 8 standard drinks per week and/or medicine use predisposing to bleeding, e.g. antiplatelet medicines or NSAIDs)	1 point for each
	Total (0 – 9)

Symptom management

• The two main approaches for symptom management are rate control (medicines aiming to improve symptoms by reducing heart rate) and rhythm control (attempts to restore sinus rhythm using either electrical cardioversion or pharmacological cardioversion with antiarrhythmic medicines)
• In primary care, rate control is usually the best initial step. Beta blocker treatment is often preferred in the absence of echocardiology results – click here for medicine selection and dosing recommendations. Rate-limiting calcium channel blockers are also a first-line option but are not recommended in patients with LVEF < 40% or heart failure with reduced ejection fraction.
  • Most patients will benefit from targeting an initial resting heart rate of < 110 bpm (more intensive targets may be appropriate for patients with ongoing symptoms or known left ventricular dysfunction). Combination treatment may be required.
• Rhythm control strategies are usually initiated in secondary care (or under cardiology guidance) for patients with ongoing symptoms despite rate control. It is reasonable to trial rate control for a few months prior to rhythm control but the transition should not be excessively delayed as longer durations of persistent AF reduce the probability of successful subsequent rhythm control. Rhythm control may sometimes be considered as an initial treatment strategy, e.g. in younger or more symptomatic patients.
• Lifestyle modifications (e.g. weight loss, encouraging moderate intensity exercise, limiting alcohol intake, smoking cessation) and optimising the management of co-morbidities is always essential to help limit AF symptom burden and the risk of long-term complications

Follow-up and referral

• Within one to two weeks of initiating medicines: Most patients require early follow-up initially to check medicine tolerance and arrhythmia status. The monitoring schedule is can then be adjusted according to patient-specific factors, e.g. the underlying AF pattern, co-morbidities, the medicines selected.
• Three to six months after diagnosis and then annually: Low-risk patients with stable AF should have their stroke initially reassessed at these intervals at a minimum, but sooner if there are changes in symptoms
• More frequent review if high risk: Patients with AF considered to be at higher risk, or with co-morbidities, will require more frequent review, e.g. to regularly monitor renal function if reduced at baseline, to monitor INR if patient requires warfarin rather than a DOAC

Refer to cardiology: at any point if patients have ongoing symptoms or poorly controlled heart rate despite appropriate pharmacological treatment. See full article for more complete referral recommendations.