ECG Report Words Explained: Sinus Rhythm, Borderline, ST-T Changes
Stop. If you’re reading an ECG report because of chest pain, pressure, sweating or breathlessness right now, close this page and go to an emergency department, whatever the printout says. For everyone else: the words printed at the top of an ECG sheet are a computer’s first guess, and it over-calls. The report that counts is the one a doctor has read and signed. Here’s what each line and phrase means, in plain English.
Quick facts
- What an ECG records: the heart’s electrical signal, from 10 stickers giving 12 “views” (leads).
- What it can’t do: see the heart’s pumping strength or valves (that’s an echo) or rule out blocked arteries at rest.
- Machine text: an automatic reading, often marked “unconfirmed”.
- Best habit: bring old ECGs to every visit; “new or old?” is the doctor’s first question.
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How to read an ECG report: the numbers at the top
Most machines print a row of measurements. Here’s what they are, with the ranges widely used for adults. Small differences between machines are normal.
| Line | What it is | Usual adult range |
|---|---|---|
| HR / Vent rate | Heartbeats per minute | 60 to 100 bpm |
| PR interval | Time for the signal to travel from top chambers to bottom | 120 to 200 ms |
| QRS duration | Time for the bottom chambers to fire | Under 120 ms |
| QT / QTc | Firing plus recharging, corrected for heart rate | QTc roughly under 450 ms (men), 460 ms (women) |
| Axis | The overall direction of the signal | About minus 30 to plus 90 degrees |
A number just outside a band is common and often means nothing on its own. A fit young person’s resting heart rate of 55 is “bradycardia” to the machine and perfectly ordinary for them. A walk up two flights of clinic stairs can give you 104 and the word “tachycardia”.
The machine’s phrases, decoded
Normal sinus rhythm
Good news in two words. “Sinus” means each beat starts from the heart’s natural pacemaker, a small patch of tissue in the upper right chamber called the sinus node, exactly as it should, and “normal” means the rate is somewhere between 60 and 100 beats a minute.
Sinus tachycardia / sinus bradycardia
Normal starting point, but faster than 100 or slower than 60. Fever, anxiety, dehydration, chai and a rush to the clinic speed it up; fitness and sleepiness slow it down. The doctor decides whether it matters in you.
Borderline ECG
The machine found something just outside its limits but not clearly abnormal, and in a well, young person with no symptoms this is very often nothing at all. It’s a prompt, not a finding.
Non-specific ST-T changes
The ST segment and T wave are the recharging part of each beat. “Non-specific” means small shape changes that could come from many ordinary things: posture, a big meal, a low potassium, anxiety, breathing fast, some medicines. They need a doctor to compare with symptoms and older ECGs.
Possible LVH
Left ventricular hypertrophy means a thicker main pumping wall, often from years of high BP. The ECG guesses this from tall waves, and it guesses wrong often, especially in thin people and young men. An echo is the test that actually measures wall thickness.
Low voltage
The waves are smaller than expected. Common reasons are simply body build (extra fat or air in the chest, as in long-term lung disease) or loose stickers. Less often, fluid around the heart. Your doctor decides if an echo is needed.
Poor R-wave progression
A pattern across the chest leads that very often comes from stickers placed a little too high or too low on the chest, or simply from body shape and breast tissue. Sometimes it hints at an old heart muscle injury, which is why doctors compare with earlier tracings.
Incomplete RBBB (right bundle branch block)
A small delay in the wiring to the right side of the heart, and a common finding in healthy people, including many fit young adults who never have a heart problem in their lives. A “complete” block, or a new one, is something your doctor will want to look at more closely.
Unconfirmed report
Literally: no doctor has confirmed this yet. Draft.
The standard ECG paper runs at 25 mm per second, so each small square is 0.04 seconds and each big square is 0.2 seconds. That’s how a doctor can work out your heart rate with a ruler and no computer at all.
Why the same heart gives a different ECG
- Stickers placed on the wrong spot, or arm leads swapped (a classic cause of a “weird axis”).
- Shivering in a cold room, talking, or moving, which adds fuzz.
- A heavy meal, strong chai or coffee, or a cigarette just before.
- Anxiety, which raises the rate and can change the T waves.
- A rushed walk to the clinic. Five quiet minutes lying down first gives a cleaner trace.
- Low potassium or other blood salt changes after vomiting or diarrhoea.
Myth: a normal ECG means the heart is fine
A resting ECG is a 10-second snapshot of the electrical signal, taken while you’re lying still. Narrowed arteries often don’t show at rest, and many valve problems never show on an ECG at all. That’s why a doctor may still order an echo (a heart ultrasound) or a stress test when your symptoms fit. The reverse myth hurts too: a “borderline” printout in a fit 25-year-old sends many people into weeks of worry over what is usually a normal variant. People believe both because the printout looks so final.
The machine’s sentence is a first draft. The signature underneath is the report.
Questions to ask your doctor about an ECG report
- Has a doctor read this trace, or is it only the machine’s reading?
- Is anything on it new compared with my old ECGs? (Bring every old one, even crumpled.)
- Does this finding fit my symptoms, or is it a common variant?
- Do I need an echo, a stress test, a Holter (24-hour ECG) or blood tests such as potassium?
- Could my BP, sugar or a medicine be affecting it?
If dizziness and a pounding heart are why you had the test, our page on chakkar aana and dil ghabrana explains the common causes. For how chest symptoms can be quiet in some people, see heart attack signs in women and diabetics. More in Diabetes & Blood Pressure.
Go to an emergency department now, or call for an ambulance, if you have chest pain, pressure or tightness, pain spreading to the arm, jaw or back, sudden breathlessness, fainting, or cold sweats, whatever your ECG shows. A normal ECG doesn’t rule out a heart attack in the first hours. Also go now if a report mentions “acute”, “STEMI”, “infarct”, “injury”, “ischaemia” or “consider” alongside any of these symptoms, or if your heart rate stays above 150 or below 40 with dizziness. Don’t drive yourself, and don’t stop or change any heart or BP medicine because of a printout; talk to your doctor first.
ECG report questions people search
How do I read my ECG report?
Start with the numbers at the top (heart rate, PR, QRS, QTc, axis) and compare them with usual adult ranges. Then read the machine’s phrase, remembering it’s a draft until a doctor signs the report.
What is a borderline ECG report?
It means the computer found something just outside its limits but not clearly abnormal. In a healthy person with no symptoms this is often a normal variant. A doctor should look at the actual trace.
ECG report abnormal means what?
Only that the machine flagged something. Many “abnormal” readings are from sticker placement, movement or normal variants. A doctor compares the trace with your symptoms and older ECGs.
What does low voltage in an ECG mean?
The waves are smaller than expected. Body build, lung disease and loose stickers are common reasons; fluid around the heart is a less common one. Your doctor decides whether an echo is needed.
What does normal sinus rhythm mean?
The heartbeat starts from its natural pacemaker at a rate between 60 and 100. It’s the normal finding you want to see.
What does non-specific ST-T change mean?
Small shape changes in the recovery part of the beat that can come from many everyday causes. They’re not a diagnosis on their own and need a doctor’s review with your symptoms.
What is the normal heart rate on an ECG?
60 to 100 beats per minute at rest for adults. Fit people often sit lower, and anxiety or a fast walk pushes it higher.
Can an ECG be normal during a heart attack?
Yes, especially early on. That’s why chest pain goes to emergency no matter what an ECG shows, and doctors often repeat the ECG and do blood tests.
What is QTc in an ECG report?
The QT interval corrected for heart rate, a measure of how long the heart takes to recharge. Roughly under 450 ms in men and 460 ms in women is usual; some medicines and low salts lengthen it.
Is “possible LVH” on ECG serious?
It’s a guess from wave size, and the ECG often over-calls it. An echo measures wall thickness properly. Ask your doctor whether one is needed, especially if you have high BP.
Can anxiety change an ECG?
Yes. It can speed the heart and cause small ST-T changes. Resting quietly for a few minutes before the test helps.
Can I eat before an ECG?
Yes, no fasting is needed. A heavy meal, chai or a cigarette just before can slightly change the trace, so a light meal and a few minutes’ rest are sensible.