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Stem
A candidate is asked to manage a classic presentation of Atrial Fibrillation in an exam setting. Use precise definitions, scores, doses, and decision thresholds.
Core knowledge (model answer backbone)
Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia: irregularly irregular rhythm, absent P waves, fibrillatory f-waves. Care follows the ABC pathway: Avoid stroke (anticoagulate if CHA2DS2-VASc ≥2 in men, ≥3 in women, with a DOAC preferred), Better symptom control (rate vs rhythm control), Cardiovascular risk-factor optimisation. Unstable AF with rapid ventricular response needs emergency synchronised DC cardioversion.
Red flags
- Haemodynamically unstable AF (hypotension, heart failure, ischaemic chest pain, reduced GCS) = emergency synchronised DC cardioversion, not rate-control drugs
- Pre-excited AF (WPW) — broad irregular tachycardia with delta waves — NEVER give AV-nodal blockers (adenosine, calcium-channel blocker, beta-blocker, digoxin); use procainamide/amiodarone or cardiovert
- Mechanical heart valve or moderate-severe mitral stenosis = warfarin only — DOACs are contraindicated in valvular AF
- High HAS-BLED score is NOT a reason to withhold anticoagulation — it flags correctable bleeding risk factors
High-yield structure examiners expect
Cover: Overview & Definition, Classification, Epidemiology & Risk Factors, Pathophysiology, Clinical Presentation, Differential Diagnosis.
Key doses / thresholds (from topic teaching)
- and consider amiodarone 300 mg IV if first shock fails
- Reduce to 2.5 mg BD if TWO or more of: age 80+, weight 6
- Reduce to 15 mg OD if CrCl 15–50 mL/min; avoid if CrCl
- Reduce to 30 mg OD if any ONE of: CrCl 15–50 mL/min, we
- if CrCl over 95 mL/min"
- lvular AF randomised to dabigatran 110 or 150 mg BID vs warfarin",
Questions
a) Define the condition and give the most important classification or severity framework used in exams. (3 marks)
- Clear one-line definition matching standard teaching.
- Named classification / stages / types with discriminating features.
- One sentence on why classification changes management.
b) Outline pathophysiology in a mechanism chain that explains the main clinical features. (3 marks)
- Initiating insult → intermediate pathway → end-organ effect.
- Link at least two symptoms/signs to mechanism.
- Mention one complication pathway (e.g. shock, perforation, herniation, arrhythmia).
c) List discriminating clinical features and bedside assessment. (3 marks)
- Classic presentation plus one atypical group (elderly, pregnancy, child, immunocompromised).
- Named signs/manoeuvres if relevant.
- What must never be missed on exam/bedside (pregnancy test, airway, glucose, etc.).
d) Investigations with thresholds and one named score if applicable. (3 marks)
- First-line tests and what positive findings mean.
- Gold-standard or definitive investigation when needed.
- Score components reproduced exactly if a named score is standard for this topic.
e) Immediate resuscitation and definitive management with doses where standard. (3 marks)
- ABC / time-critical steps first.
- First-line drug(s) with agent + dose + route (or procedure steps).
- Escalation triggers (theatre, ICU, thrombolysis window, antidote, etc.).
- Disposition and safety-netting.
Marking tips
Full marks require specificity (numbers, names, doses) not generic "give antibiotics/fluids." Regional practice (ICMR / NICE / AHA) may be cited as alternative where relevant.