Best for “right now”
Repeat ECG (12-lead)
Useful if the first recording had artefact, symptoms have changed, or a clinician wants to compare patterns.
What an “abnormal ECG” actually means
An ECG (electrocardiogram) is a snapshot of your heart’s electrical activity at one moment in time. Software (and sometimes clinicians) use the word abnormal when the pattern falls outside a standard range — but that range doesn’t perfectly fit every person.
Why an ECG gets flagged when you might be fine
- Normal variants exist — athletic training, age, and body shape can shift the ECG baseline.
- Electrode placement matters — small changes can alter wave heights and axis readings.
- Artefact (movement, poor contact, sweating) can create misleading spikes or baseline wander.
- Computer interpretation is conservative — it often flags “possible” findings that need a human review.
One line that helps patients most
If you feel well and the ECG was done as a routine check, an “abnormal” label usually means: “Let’s confirm what this is” rather than “Something is definitely wrong.”
If symptoms brought you to the ECG (palpitations, chest pain, breathlessness, fainting), the same “abnormal” word carries more weight — because symptoms change the risk picture.
Common “abnormal ECG” findings and what they can mean
Below are the patterns that most often trigger an “abnormal” report. The key word is can — the same finding can be harmless in one person and significant in another.
| ECG wording you might see | What it often points to | What usually happens next |
|---|---|---|
| Sinus bradycardia Slow rhythm from the normal pacemaker |
Common in fit people; can also relate to medications or conduction changes. | Review symptoms (dizziness/fainting). Consider Holter if symptoms come and go. |
| Sinus tachycardia Fast rhythm from the normal pacemaker |
Stress, pain, fever, dehydration, anaemia, thyroid overactivity — not always a heart problem. | Check triggers, basic observations, and sometimes blood tests. Repeat ECG if needed. |
| Premature beats (ectopics) PACs/PVCs |
Extra beats; often benign. More important if frequent, symptomatic, or with dizziness/fainting. | Holter monitoring is usually the best next test to measure “how many” and link to symptoms. |
| Atrial fibrillation / flutter | Irregular rhythm; may increase stroke risk and cause breathlessness or fatigue. | Clinical review. Often needs medication discussion and sometimes an echo to assess structure. |
| Prolonged QT | Can be medication-related, electrolyte-related, inherited, or transient. | Review meds, electrolytes, and family history. Repeat ECG may be recommended. |
| Bundle branch block RBBB/LBBB |
Electrical delay in a heart “wire”. RBBB is often incidental; LBBB may be more significant. | Often prompts an echo to assess heart structure and pumping function. |
| ST-T changes “non-specific” or “ischaemic changes” |
Can be benign/non-specific, but in the right context can suggest reduced blood supply. | Symptoms decide urgency. Chest pain with ST changes needs urgent assessment. |
| Left ventricular hypertrophy | Thicker heart muscle; sometimes from high blood pressure, athletic training, or valve issues. | Echo is often used to confirm thickness and check valves. |
| Axis deviation | Can be normal; can also reflect body habitus, lung disease, or conduction patterns. | Usually interpreted alongside other findings rather than alone. |
If your report mentions “possible old infarct” or “septal infarct — age undetermined”, don’t panic. These phrases are commonly generated by ECG software and are a classic example of why correlation (symptoms + history + sometimes echo) matters.
What to do next (based on your symptoms)
This is the part most people actually need. The ECG is data — your symptoms tell us how urgent it is and which test is most useful next.
Seek urgent care now if you have
- Chest pain/pressure (especially with sweating, nausea, or pain to jaw/arm).
- Fainting (or near-fainting) that’s new or unexplained.
- Severe breathlessness at rest, or sudden worsening.
- New neurological symptoms (face droop, weakness, speech changes).
If in doubt, treat symptoms as the priority
An ECG result can be reviewed later. If you feel seriously unwell right now, urgent assessment comes first.
If you’re stable, here’s the usual clinical logic
- Palpitations that come and go → Holter monitoring usually gives the clearest answer.
- Shortness of breath, swelling, fatigue → consider an echo pathway (structure + pumping).
- No symptoms and a routine ECG flag → compare with an old ECG or repeat with good electrode placement.
- Chest discomfort → the best test depends on the story. Use Echo vs ECG as a decision page.
If you’re trying to decide whether you need echo imaging, see: Symptoms that require an echo. If you want the basics first, start with: What is an ultrasound echo?
Tests that clarify an abnormal ECG
Different tests answer different questions. A short ECG is great for “what is happening right now”. Monitoring and ultrasound add context when symptoms are intermittent or when structure matters.
Best for intermittent symptoms
Holter monitoring
Captures rhythm over time — ideal for palpitations that come and go, dizziness episodes, or suspected ectopics.
Best for structure + pumping
Ultrasound Echo (Echocardiogram)
If the ECG suggests hypertrophy, conduction problems, or you have breathlessness/swelling, echo can assess valves, chamber size, and heart function.
Contextual border: when does an abnormal ECG need echo imaging?
If you’re seeing terms like “LVH”, “bundle branch block”, “possible cardiomyopathy”, or you have symptoms like breathlessness, ankle swelling, or reduced exercise tolerance, an echo often becomes the “next best question” — because it tells you whether the heart’s structure and pumping match the ECG story.
Use the triage page: Symptoms that require an echo .
FAQs
These are the questions patients usually ask right after reading their ECG report.
Is an abnormal ECG always serious?
No. “Abnormal” is a prompt to interpret the pattern in context. Many ECG flags are normal variants, artefact,
or conservative computer interpretations — especially if you have no symptoms.
Should I get a Holter monitor after an abnormal ECG?
If your symptoms are intermittent (palpitations, dizziness episodes, “flutters”), Holter monitoring is often
the most informative next step because it links rhythm to real-life symptoms.
My ECG says “possible old infarct”. Is that a heart attack?
Not necessarily. ECG software can over-call these patterns. The next steps are usually a clinician review,
comparison with older ECGs, and sometimes an echo (or other investigations) depending on symptoms and risk factors.
Do I need an echo because my ECG is abnormal?
Sometimes. Echo is most useful when the ECG suggests structural issues (e.g., LVH, bundle branch block) or when
symptoms suggest the heart’s pumping/valves might be involved. Use:
Echo vs ECG
and
Symptoms that require an echo
.
