ECG or Holter: what is the difference

Overview

Both tests record the electrical activity of the heart, but they answer different questions. The ECG is a “photograph” of the rhythm at one moment. The Holter is a “film” of the rhythm through day and night. They do not replace each other; they are often used together.

What the ECG is

• Small electrodes are placed on the chest, arms and legs; you lie still.
• It takes a few minutes, is painless and carries no risk; the machine only records and does not send electricity into the body.
• It shows the heart rate, the regularity of the rhythm and other changes in the electrical signal, which help to tell apart arrhythmias, signs of ischemia or enlargement of the chambers.
• Limitation: it captures only the rhythm of those few minutes. If palpitations do not occur during the recording, the ECG may be normal.

What the Holter is

• A small portable device with several electrodes on the chest, recording continuously for 24–48 hours during your usual life.
• Keep a diary: the time of symptoms (palpitations, dizziness, pain) so they can be matched to the recorded rhythm.
• The device must not get wet, so shower before it is fitted.
• The doctor analyzes the recording: number of beats, extrasystoles, fast or slow episodes and pauses.
• Limitation: if episodes are very rare, e.g. once every few weeks, 24–48 hours may not capture them; the cardiologist decides the next step.

Do not confuse it with the blood pressure Holter (24 hours), which measures blood pressure, not the heart rhythm.

Quick comparison

• Duration: ECG a few minutes; Holter 24–48 hours.
• What it captures: ECG the rhythm of the moment; Holter the rhythm through day and night, including passing episodes.
• When it is chosen: ECG for baseline assessment, chest pain or symptoms that are present; Holter when symptoms come and go.
• Preparation: ECG none; Holter a shower before fitting and a diary while wearing it.

Which one to choose

• Palpitations or dizziness that come and go — an ECG at the visit, often followed by a Holter (see palpitations).
• Persistent fast pulse — an ECG that captures the rhythm at that moment (see fast heart rate at rest).
• General check-up or before certain medicines — an ECG at the cardiology visit.
• Follow-up of a known arrhythmia (e.g. atrial fibrillation) — a Holter to see the burden and rhythm control.

The final choice belongs to the cardiologist after the conversation and examination. Related exams: Holter ECG, echocardiography.

Results

The result is interpreted by the cardiologist together with the symptoms and other tests. A normal recording is reassuring but does not rule out every problem; a single change on the ECG is not always significant.