Palpitations, syncope, unexplained arrhythmias: which cardiac monitor should you choose?
A short guide to the most commonly used ambulatory ECG monitoring devices and when to use them. 🧵
1/ Holter Monitor
A portable ECG device that records continuously for 24–72 hours (up to ~2 weeks in newer models).
Patients can mark symptoms using an event button or diary to correlate symptoms with rhythm.
Best for frequent symptoms expected to occur within a few days.
2/ Event Monitor
Records ECG only when the pt activates it during Sx and sends the recording to a monitoring center via telephone.
Useful when Sx occur intermittently within 2–6 weeks.
Limitation: not ideal for sudden syncope, since the pts may not be able to activate the device.
3/ External Loop Recorder
Continuously records ECG for wks to months, storing rhythm before, during, and after an event.
Can be patient-triggered or automatically triggered for asymptomatic arrhythmias.
Often used when syncope or palpitations occur sporadically within several wks
4/ External Patch Recorder
A leadless adhesive patch placed on the chest.
🟢 Records continuously for 2–14 days
🟢 Comfortable and water resistant
🟢 Allows patient activation and automatic arrhythmia detection
Commonly used to evaluate AFib burden.
5/ Mobile Cardiac Outpatient Telemetry
A system that continuously records and transmits ECG data for up to 30 days.
When significant arrhythmias occur, the ECG is automatically sent to a 24/7 monitoring center.
Provides near real-time alerts to clinicians.
6/ Implantable Cardiac Monitor
A small device implanted subcutaneously, with a battery life of 2–3 years.
Automatically detects arrhythmias and allows remote transmission.
Best for recurrent, unexplained syncope or suspected arrhythmias that occur very infrequently.
7/ Quick clinical takeaway
◼️Symptoms within days → Holter
◼️Symptoms within weeks → Event monitor / loop recorder
◼️Need real-time monitoring → MCOT
◼️Symptoms rare (ms–yrs) → Implantable monitor
Choosing the right monitor often depends on how frequently the symptoms occur.
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