Holter (24hr)
Order - Duration
- 24 hours
- Frequency
- Daily
Palpitations occurring daily; AF burden quantification; medication effect; post-ablation review
Which Cardiac Test to Order?
A quick reference for GPs and referring clinicians
Use this guide in two ways: choose a rhythm monitor based on symptom frequency, or start with a clinical scenario and select the investigation most likely to answer the question.
Which Monitor to Consider
The right monitor depends primarily on how often your patient has symptoms. More frequent symptoms are captured by shorter recordings; infrequent or unpredictable symptoms require longer monitoring windows.
| Monitor | Duration | Symptom Frequency | Key Indications | Action |
|---|---|---|---|---|
| Holter (24hr) | 24 hours | Daily | Palpitations occurring daily; AF burden quantification; medication effect; post-ablation review | Order |
| Holter (48hr) | 48 hours | Every 1-2 days | As above when 24hr recording is non-diagnostic; slightly infrequent symptoms | Order |
| Event Monitor (7d) | 7 days | Weekly | Palpitations or pre-syncope occurring a few times per week; paroxysmal AF detection | Order |
| Heart Bug (28d) | 28 days | Monthly | Infrequent palpitations or pre-syncope; AF screening; symptoms occurring a few times per month | Order |
| Loop Recorder | Up to 5 years | Very infrequent or unpredictable | Unexplained syncope; cryptogenic stroke (AF detection); symptoms occurring less than monthly or unpredictably | Refer |
Holter (48hr)
Order - Duration
- 48 hours
- Frequency
- Every 1-2 days
As above when 24hr recording is non-diagnostic; slightly infrequent symptoms
Event Monitor (7d)
Order - Duration
- 7 days
- Frequency
- Weekly
Palpitations or pre-syncope occurring a few times per week; paroxysmal AF detection
Heart Bug (28d)
Order - Duration
- 28 days
- Frequency
- Monthly
Infrequent palpitations or pre-syncope; AF screening; symptoms occurring a few times per month
Loop Recorder
Refer - Duration
- Up to 5 years
- Frequency
- Very infrequent or unpredictable
Unexplained syncope; cryptogenic stroke (AF detection); symptoms occurring less than monthly or unpredictably
Clinical Scenarios
Unexplained Syncope
If syncope is infrequent and the 12-lead ECG is non-diagnostic, a Loop Recorder is the investigation of choice. If syncope is exertional, consider an Exercise Stress Test first; if frequent or undiagnosed, a referral to a cardiac electrophysiologist is recommended.
Note: Loop Recorder implantation requires a cardiology consultation and is performed as a brief in-hospital procedure under local anaesthesia.
Refer for assessmentCryptogenic Stroke
Paroxysmal AF is a common hidden cause. A Heart Bug (28d) is a reasonable first step; if negative, a Loop Recorder provides long-term monitoring and significantly increases AF detection rates.
Known AF — Assessing Burden
A 24hr or 48hr Holter is appropriate for quantifying AF burden, assessing rate control, or evaluating response to antiarrhythmic medication or ablation.
Order HolterPalpitations — No Diagnosis Yet
Match the monitor to symptom frequency. If symptoms are daily, start with a Holter. For less frequent symptoms, a prolonged monitor is required — the 7-day Event Monitor for weekly symptoms, the 28-day Heart Bug for monthly symptoms, or a Loop Recorder for very infrequent or unpredictable episodes.
Suspected Ischaemia / Chest Pain
For exertional chest pain, exertional dyspnoea, or possible inducible ischaemia, consider an Exercise Stress Test if the patient can exercise and the resting ECG is interpretable. A Stress Echocardiogram may be more useful when imaging is required, baseline ECG changes limit interpretation, or higher diagnostic confidence is needed.
Order ischaemia testingShortness of Breath
For unexplained dyspnoea, an Echocardiogram is useful to assess ventricular function, valves, pulmonary pressures, and structural heart disease. If symptoms are episodic or paroxysmal, a Holter can help identify an arrhythmic cause. If symptoms are exertional or ischaemia is a concern, consider an Exercise Stress Test or Stress Echocardiogram. Refer to cardiology when symptoms are progressive, unexplained, or associated with abnormal ECG, murmur, heart failure signs, syncope, or chest pain.
High Blood Pressure Confirmation
A 24hr Blood Pressure Monitor is indicated to confirm hypertension, exclude white coat hypertension, or detect nocturnal non-dipping — particularly before committing a patient to lifelong antihypertensive therapy.
Order BP monitor