Palpitations on and off for three weeks, now persistent for two hours with mild breathlessness

2026-09-13

The case

55-year-old woman. Palpitations on and off for three weeks, now persistent for two hours with mild breathlessness

Non-smoker, no cardiac history. Takes no regular medication. She has lost three kilograms over six weeks without trying and reports feeling hot and restless. No syncope, no chest pain.

On arrival

HR: 72
SpO₂ (%): 98
Respiratory rate: 18
Temperature (°C): 36.8
Systolic BP (mmHg): 128
Diastolic BP (mmHg): 78

Stage 1 of 2

She looks well. There is a fine tremor of the outstretched hands but no goitre. Heart sounds are normal apart from the irregular rate. No murmur, no signs of heart failure. This twelve-lead is recorded in the department.

The tracing for the quiz “Palpitations on and off for three weeks, now persistent for two hours with mild breathlessness”. — Twelve-lead on arrival, 25 mm/s, 10 mm/mV. Open this tracing in the studio

What is the atrial rhythm?

AMultifocal atrial tachycardia Your answer
BEctopic atrial tachycardia with variable AV conduction Correct answer Your answer
CAtrial flutter with variable block Your answer
DSinus tachycardia with dropped beats Your answer

Stage 2 of 2

TSH comes back suppressed at 0.02 mU/L with a free T4 of 38 pmol/L. Potassium 4.1, magnesium 0.92, troponin T below the reporting threshold. She is haemodynamically stable and comfortable.

Bloods

TSH (m U/L): 0.02
Free T4 (pmol/L): 38
Troponin T (ng/L): <5
Magnesium (mmol/L): 0.92
Potassium (mmol/L): 4.1

Notes

Overt hyperthyroidism confirmed.

What is the most appropriate next step?

AUrgent referral for catheter ablation Your answer
BSynchronised DC cardioversion Your answer
CRate control with a beta-blocker and treat the thyrotoxicosis Correct answer Your answer
DIV flecainide to restore sinus rhythm Your answer

Diagnosis

Ectopic atrial tachycardia with variable AV conduction, driven by thyrotoxicosis

P wave morphology is often overlooked. Here it is clear that a sinus origin is highly unlikely. Closely scrutinizing lead III, there is regular atrial activity at 145/min with 2:1 AV conduction. Only in one beat there is brief 1:1 conduction.

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This tracing was generated, not recorded. It opens in the studio with every dial live.

Open the studio

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