What to note in a diary while you wear a Holter or event monitor for palpitations, and where to record the days around it
What to record in a Holter or event monitor diary for palpitations: symptom, time, what came before, and when to call emergency services.
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You are wearing a Holter monitor or an event monitor, and the clinic says: write down when something happens. The device records your heart, and your diary records what you felt and when. You can do that on paper or, for the days around it, in the symptom diary in Sam. Palpitations, skipped beats and dizziness each get a day with their strength there. Your monthly report as a PDF shows the days you had symptoms. For each episode, write the date, when it started and ended, what you felt, and what you were doing just before. One line per episode is enough, and the clinic matches your times to the recording. Your clinic's own diary form comes first.
Why does the clinic need a diary with the monitor?
Palpitations often come and go in short bursts. A quick ECG in the clinic can miss them. That is why a longer recording helps. The British Heart Foundation says your GP may arrange an ECG, and if it shows something unusual or your symptoms continue, you may need longer monitoring.
The monitor runs the whole time, even when you feel nothing. Your diary tells the clinic when you felt something and how it felt, so they can match those moments to the recording. Without your times, a symptom on the trace is hard to place.
What do you write for each episode?
One line per episode is enough. These fields are a suggestion, and the diary your clinic gives you comes first:
- Date and time it started and ended.
- What you felt: racing, pounding, fluttering, skipped or extra beats, chest pressure, breathlessness, dizziness, nausea.
- What you were doing in the time before: rest, exertion, stress, eating, sleeping.
- Whether you had caffeine, alcohol or nicotine that day, as a note without judgement.
- Whether your pulse felt regular or irregular, and the beats per minute if you counted them.
- Whether it began and ended suddenly or gradually.
- Whether it stopped on its own or something helped.
- Whether you pressed the event button, if your device has one.
- Whether you felt faint or actually fainted. If you fainted, read the emergency section below.
A line can look like this (invented example): "Wednesday, 21:40 to 21:52, racing heart, before that the stairs and a coffee, pulse felt regular, ended suddenly, no dizziness." Write what you felt, not what you guess.
The British Heart Foundation lists common triggers for palpitations: stress and anxiety, caffeine, alcohol, smoking, intense exercise, and some medicines. In healthy people these can cause extra beats. Which cause applies to you is for the clinic to work out. A filled-in record makes that conversation sharper.
How long does the monitor run, and what are the living rules?
A Holter monitor is a small recording device you wear. An NHS cardiology leaflet describes three electrodes on your chest connected by wires to a small recorder, worn for 24, 48 or 72 hours. You carry on with your normal activities.
An event monitor works differently. You switch it on when symptoms appear, or it records all the time depending on the model. Ask your clinic before you go home when and how to press the button, and note each time you did.
Living rules for the monitor, from an NHS hospital leaflet:
- Do not use body lotion, oil or cream on the morning you are fitted.
- Do not shower, bathe or swim until the device is returned. Ask your clinic how to wash.
- Continue your usual activities, including work, and take your medicines as normal unless told otherwise.
- Wear the device while you sleep.
If your device has its own rules, the clinic's instructions win.
What if nothing happens in the 24 hours?
Write exactly that: a day without symptoms. It shows you kept the diary and the day was calm. An empty diary does not mean the recording was empty, because the device records even what you do not feel.
If symptoms come back days later, tell your clinic. Whether you need another recording or an event monitor is their decision. An event monitor is often used for symptoms that happen only occasionally.
Which questions should you be ready to answer?
Your lines should let you answer the classic palpitation questions:
- When did it first happen, when last, and how often?
- Does it start suddenly or gradually?
- Is it linked to a situation, like stress or exercise, or does it come later, in sleep?
- How high was your pulse, and was it regular or irregular?
- How long does it last, what do you feel, and how does it end?
- Have you ever fainted, and did palpitations come before it?
- Does anyone in your family have a heart rhythm problem?
The American Heart Association diary uses the same idea: time of day for every activity and symptom. Preparing for the review appointment is covered in our checklist for a chronic-condition doctor visit, and if your symptoms are being dismissed, what to do when a doctor is not taking your symptoms seriously explains how records help.
When is it no longer a diary topic, but a call for help?
With chest pain or tightness, severe shortness of breath, or fainting, no time is for notes. Call the emergency number. The NHS says to call 999 if you have palpitations with chest pain, shortness of breath, or feeling faint or fainting. The British Heart Foundation gives the same advice: call 999 with severe breathlessness, chest pain or tightness, dizziness, or fainting or blackouts. Use your local emergency number (112 in the EU, 999 in the UK, 911 in the US).
Palpitations are usually harmless, but a rhythm problem can occasionally be serious, and only a clinic can tell the difference. Palpitations that do not settle or that keep coming back are worth getting checked. Your diary does not replace that appointment.
How do Apple Watch recordings fit with your diary?
Apple says the ECG app on Apple Watch records about 30 seconds, similar to a single-lead ECG. It is not for people under 22, and it does not work on Apple Watch SE. A sinus rhythm result only applies to that one recording and does not mean you are healthy. The app cannot detect a heart attack, and Apple says to call emergency services if you have chest pain, pressure or tightness.
A wrist recording of 30 seconds does not replace a Holter monitor or your diary line. Note that you made a recording, with the time, and show it to the clinic. Whether a watch rhythm reading means anything for you is a question for a doctor, covered further in can an Apple Watch detect AFib.
Log palpitation days in Sam and take a report to the review
You arrive with your episodes in front of you instead of guessing from memory. The symptom diary in Sam holds the days you felt something.
- Instead of paper in your pocket: palpitations, skipped beats or dizziness each get a day with their strength in a few taps. The exact times stay on your paper protocol.
- Instead of remembering at the review: the monthly report as a PDF shows which days you had symptoms and your most common ones. You print it or show it on your phone.
- Instead of Apple Health alone: on a separate page Sam shows how your resting heart rate, heart rate variability and steps differ from your recent average, apart from the diary.
Sam shows no ECG or rhythm result. That stays with the device and the clinic.
Try Sam HealthSam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any condition or health state. Always consult qualified professionals for medical decisions.
Related reading
- Doctor visit checklist for a chronic condition
- Doctor not taking your symptoms seriously? What to document
- Can an Apple Watch detect AFib?
- Menopause: Palpitations, Anxiety and Blood Pressure
- Ramadan With a Chronic Illness: Plan Medications First
Sources
Updated: October 2026
- NHS: Heart palpitations (last reviewed 17 March 2026)
- British Heart Foundation: Heart palpitations (updated 6 October 2025)
- American Heart Association: Holter monitor diary
- Princess Alexandra Hospital NHS Trust: ECG monitor (24, 48 or 72 hour) patient leaflet (ratified February 2025)
- Apple Support: Take an ECG with the ECG app on Apple Watch
More on recording and taking it along
Frequently Asked Questions
How long do you wear a Holter monitor?+
A Holter monitor usually records your heart for 24 hours, and some services use 48 or 72 hours, as one NHS cardiology leaflet describes. Your clinic sets how long it runs for you, so ask before you leave.
What do I write in the monitor diary?+
Write the date, the time a symptom started and ended, what you felt, and roughly what you were doing. The American Heart Association diary asks for the time of day for every activity and symptom. The clinic matches your lines to the recording.
What if nothing happens during the recording?+
Then your diary honestly shows a day without symptoms, and the monitor still records your heart the whole time. If symptoms only come later, tell your clinic, which decides whether a longer recording or an event monitor follows.
Can I shower or bathe with a Holter monitor?+
Usually not. One NHS hospital leaflet asks you not to swim, shower or bathe until the device is returned. Ask your clinic for the rules for your device before you go home.
When do I get the results?+
That depends on your clinic and your follow-up. The recording has to be analysed first. Ask how and when you will hear your results, and what to do if you feel unwell before then.
Can the Apple Watch replace a Holter monitor?+
No. Apple says the ECG app on Apple Watch records about 30 seconds, similar to a single-lead ECG, and cannot detect a heart attack. That is not a longer monitor recording, so show your clinic what you recorded and keep your diary.
When do I call emergency services?+
If you have chest pain or tightness, severe shortness of breath, or you faint or black out, do not wait to write notes. The NHS says to call 999 for palpitations with these symptoms. Use your local emergency number (112 in the EU, 999 in the UK, 911 in the US).