5th May 2025

Diagnosis

Definitive diagnosis of an atrial arrhythmia will be based on ECG evidence, however as with all conditions a detailed history and examination should precede investigations (in a haemodynamically stable, alert patient).

Symptoms (history)

Palpitations
Chest pain
Shortness of breath
Orthopnoea/paroxysmal nocturnal dyspnoea (evidence of cardiac decompensation)
Loss of consciousness/blackouts (no warning)
Dizziness/light-headedness
Stroke symptoms

Signs (examination)

It is important to look for signs pertaining to possible underlying causes for the arrhythmia (based on history and presentation). Signs may include:

Fever
Hypotension
Loss of consciousness
Pallor
Cachexia
Tachypnoea
Irregular, fast pulse
Elevated JVP if in heart failure
Cardiac murmurs if associated structural disease
Evidence of thyroid disease – tremor, weight loss, exophthalmos, goitre, anxiety

Investigations

Investigations should be tailored to the suspected underlying cause. Below is a non-exhaustive table of immediate investigations to help ascertain the type of arrhythmia and possible underlying cause.

Investigation	Positive findings
Urine dip +/- culture	Evidence of infection Proteinuria/haematuria indicating renal/cardiac failure
Blood tests	ABG/VBG – acidosis, hypoxia, electrolyte abnormalities, lactate, hypercapnia FBC – infection, anaemia U&E – electrolyte derangement, renal failure CRP – infection LFTs – cholestasis, hepatitis, poor nutrition Mg – hypomagnesaemia TFTs – hyper/hypothyroidism Bone profile – hypo/hypercalcaemia, phosphate INR/coag – may determine treatment Troponin – evidence of strain/ischaemia
CXR	Evidence of infection/fluid overload
ECG	Characterise arrhythmia (see below)
Echocardiogram	View structural abnormalities, systolic function and assess for right heart strain (PE)

Table 3: Investigations in patients presenting with cardiac arrhythmias

ECGs

ECG_Atrial_Fibrillation_98_bpm

Image Source: Wikimedia Commons (2020). Atrial Fibrillation, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:ECG_Atrial_Fibrillation_98_bpm.jpg (Accessed 1 May 2025).

Image Source: Wikimedia Commons (2012). Cardio Networks ECGpedia, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:E234_(CardioNetworks_ECGpedia).jpg (Accessed 1 May 2025).

ECG 3: AV reentrant tachycardia

Image Source: Wikimedia Commons (2012). WPW 2012, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:WPW2012.jpg (Accessed 1 May 2025).

Junctional_Tachycardia

Image Source: Wikimedia Commons (2014). Junctional Tachycardia, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Junctional_Tachycardia.jpg (Accessed 1 May 2025)

Multifocal_atrial_tachycardia_