Arrhythmias and Conduction Disease — DCE Clinical Case

The station frame

This is a short case with a long case hiding inside it. The examination takes five minutes; the examiner's real interest is whether you can move from a physical sign — the irregularly irregular pulse — to a complete management framework: confirm the rhythm, find the cause, assess the stroke risk, and decide rate, rhythm and anticoagulation [1].

Focused history — what you must establish

• Symptoms of the rhythm: palpitations, exertional breathlessness, chest discomfort, presyncope, fatigue — and how long they have been present, because "recently diagnosed" changes the rhythm-strategy evidence [4].
• Thromboembolic and bleeding history: prior stroke or TIA, systemic embolism; bleeding episodes, falls, and the medication list including NSAIDs and antiplatelets [1] [2].
• Drivers to correct: hypertension, thyroid symptoms, alcohol, sleep apnoea, valvular disease, recent illness or surgery.
• The patient's frame: what she has been told, what she fears — anticoagulation counselling lands much better when you know her starting point [3].

Examination priorities

Take the radial pulse for a full minute: rate, rhythm, character. An irregularly irregular pulse with variable volume is atrial fibrillation until proven otherwise — then demonstrate the apex-radial deficit (apical rate exceeds the palpated radial rate because some weak beats do not transmit) [1]. Then work outward: blood pressure in both arms; JVP; signs of thyrotoxicosis; mitral valve auscultation (rheumatic disease changes the anticoagulant choice to warfarin territory); heart failure signs; and the evidence around the edges — bruising from anticoagulants, a pacemaker scar, tremor [1].

Presentation template (deliver this to the examiner)

"Mrs Bell is a 76-year-old woman with an irregularly irregular pulse at about 90 beats per minute with an apex-radial deficit, consistent with atrial fibrillation. She is haemodynamically stable with a blood pressure of 138/78, no signs of heart failure, and no murmur to suggest mitral valve disease. She has hypertension as a stroke risk factor. My plan is to confirm the rhythm on a 12-lead ECG, screen for reversible drivers — thyroid function, electrolytes, echocardiography — and then make the two AF decisions: rate control targeting a resting rate under 110, and anticoagulation, where her CHA₂DS₂-VASc of at least 3 mandates a direct oral anticoagulant unless contraindicated." [1] [3] [5]

Management — what you will actually do

1. Confirm and characterise: 12-lead ECG now; an ambulatory monitor if the rate profile or paroxysmal pattern needs defining [1].
2. Screen the substrate: thyroid function, potassium and magnesium, full blood count, renal function (which will later drive anticoagulant dosing), and an echocardiogram for ventricular function and valve disease [3].
3. Rate control: start a beta-blocker or rate-limiting calcium channel blocker appropriate to her ventricular function; target a resting rate under 110 — RACE II showed lenient control is non-inferior to strict control, with less drug burden [5].
4. Rhythm strategy: if she is symptomatic or the AF is recently diagnosed with cardiovascular comorbidity, discuss early rhythm control — EAST-AFNET 4 showed cardiovascular outcome benefit from early rhythm-control therapy in that group [4].
5. Anticoagulate on the score, not the symptoms: CHA₂DS₂-VASc at least 3 here (age 75 or older scores 2, hypertension 1) — commence a DOAC, apixaban being a well-evidenced choice from ARISTOTLE; use HAS-BLED as a checklist of modifiable bleeding risks rather than a reason to withhold [1] [2] [3].
6. Review interval and safety-netting: when to return, what bleeding or syncope should trigger earlier review, and who follows up the echo result.

Probing questions

"The pulse is irregular. What are your differentials before you call it AF?" — "Frequent ectopics, atrial flutter with variable block, and multifocal atrial tachycardia can all feel irregularly irregular at the wrist. The ECG separates them — absent P waves with a chaotic baseline and no pattern to the irregularity is AF. I would still say 'consistent with AF' at the bedside and 'confirmed' after the tracing." [1]

"She tells you her neighbour had a stroke on a blood thinner and she does not want one. How do you respond?" — "I would separate the two risks and quantify hers: her CHA₂DS₂-VASc means several strokes per hundred untreated patients per year, and the DOAC trials — ARISTOTLE for apixaban — showed stroke prevention with less intracranial bleeding than warfarin. I would treat her fears as modifiable items on the HAS-BLED list — blood pressure, interacting drugs, falls — rather than as a veto, and make the decision with her, not for her." [2] [3]

"Would you offer her cardioversion or ablation?" — "It depends on two findings: how symptomatic she is, and how new the AF is. For recently diagnosed AF with cardiovascular risk factors, EAST-AFNET 4 supports early rhythm control; for long-standing minimally symptomatic AF in a 76-year-old, rate control with a lenient target is a legitimate default. The echo result and her preferences settle it." [4] [5]

"What if her pulse had been slow and regular instead?" — "Then the case pivots to conduction disease: I would look for cannon A waves of complete heart block, drug causes, and hypothyroid signs, check an ECG for the level of block, and remember that Mobitz II and complete heart block are pacing indications rather than atropine indications." [6]