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Decision guide (rhythm testing)

ECG vs Holter Monitor: Which Heart Test Should You Book?

If you’re feeling palpitations, skipped beats, dizziness, or an “irregular heartbeat” sensation, the right test depends on one key thing: is it happening now, or does it come and go? This guide helps you choose the correct test first — and shows when an ultrasound echo is the better next step.

Choose the right test Book online Call 020 3633 4902

If you have severe chest pain, collapse, severe breathlessness at rest, or stroke symptoms, seek emergency care first. This page is for non-emergency diagnostic decision-making.

The simple rule that usually gets it right

Most “wrong bookings” happen because people choose a test name instead of choosing based on symptom timing. Use this:

Book an ECG if…

  • Symptoms are happening now (palpitations, fluttering, irregular beats) and you want a rhythm snapshot.
  • You want a baseline check for reassurance or a clear starting point.
  • Your question is: “What is my rhythm right now?”
ECG service page

Book a Holter monitor if…

  • Symptoms come and go (“I can’t catch it in clinic”).
  • You need rhythm data across normal life (sleep, walking, work stress).
  • Your question is: “What happens over time?”
Holter service page
When neither is the right first test

If your dominant concern is valves/pumping (murmur, suspected valve disease, reduced exercise tolerance, swelling, breathlessness with a structural concern), start with an ultrasound echo guide: What is an ultrasound echo? and triage page: Symptoms that require an echo.

ECG vs Holter: side-by-side comparison

This table is the “decision shortcut” — it reduces uncertainty and helps you book once, correctly.

Feature ECG Holter monitor
What it is A short clinic recording (“snapshot”) of the heart’s electrical activity. Longer ambulatory ECG recording during daily life (“timeline”).
Best for Symptoms happening now; baseline rhythm check. Intermittent episodes; symptoms that occur at home/work/sleep.
Core advantage Fast, simple, immediate rhythm view. Higher chance of capturing the episode you’re worried about.
Main limitation May be normal between episodes. Doesn’t image structure/valves; it’s still an electrical test.
Typical next step Holter if intermittent; echo if structural concern. Management plan based on captured rhythm; echo if structural concern appears.
Clinical ECG setup in a calm private clinic
ECG

When speed matters

If you’re currently symptomatic, an ECG can be the fastest first step to clarity.

ECG service page
Close-up of Holter monitor device and leads
Holter

When timing is the problem

Holter monitoring is built for “it happens later”, “it happens at night”, and “I can’t catch it”.

Holter service page
Patient wearing Holter monitor under clothing in everyday life
Goal

Match test to real life

The best test is the one that captures your symptom at the moment it happens.

See real scenarios

Real booking scenarios (so you don’t waste time)

These are the patterns we see most often. Choose the test based on the story — not just the symptom label.

“My heart races or flutters at night”

  • Best first test: Holter (captures sleep/night patterns).
  • Why: a clinic ECG may be normal by morning.

“I feel it right now and I’m worried”

  • Best first test: ECG (fast snapshot while symptomatic).
  • If ongoing: Holter to capture recurrence and frequency.

“My ECG was normal but symptoms keep happening”

  • Best next test: Holter (because the issue is intermittency).
  • Goal: match symptom times to rhythm data.

“I’m short of breath and worried about my heart”

When an ultrasound echo is the better next step

ECG and Holter answer rhythm questions. Echo answers structure/pumping questions. If your worry is “is my heart working properly?” echo is often the correct diagnostic move.

Use these internal guides

• What is an ultrasound echo?
• Symptoms that require an echo

If you’re weighing rhythm testing vs imaging, start with the symptom page and then book the test that matches the dominant question.

ECG vs Holter FAQs

Practical answers that reduce anxiety and prevent the wrong booking.

Can an ECG miss an arrhythmia?
Yes. An ECG is a snapshot. If the rhythm is normal between episodes, it may look normal during the test. If symptoms are intermittent, Holter monitoring is often the better first choice.
Is Holter monitoring uncomfortable?
Most people find it very manageable. Electrodes are stickers on the skin and the device is worn externally. Mild adhesive irritation can happen in sensitive skin.
Do I need both tests?
Not routinely. The goal is to choose the test most likely to capture the data that changes the clinical plan. Sometimes ECG is used as a baseline and Holter for intermittency.
What if my main worry is valves or pumping strength?
That’s an echo question. Start here: What is an ultrasound echo?.
Book the right heart test (without overbooking) Start with ECG if symptoms are happening now. Start with Holter if they come and go. Use echo guidance when the question is structure/pumping.
Book online ECG service page Holter service page

Helpful next reads: Symptoms that require an echo · What is an ultrasound echo?

Still unsure?

Call: 020 3633 4902
Email: info@sonoworld.co.uk

Quick rule:
Now = ECG · Intermittent = Holter · Structure = Echo

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