Medical Oncologist
HER2-positive breast cancer
Ejection fraction monitoring on HER2 therapy: the numbers that matter
HER2-targeted drugs such as trastuzumab can occasionally weaken how well the heart pumps. Heart scans measure the ejection fraction before and during treatment so changes are caught early, when they usually recover. This page explains, in general terms, the tests, how results are read and what happens next.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
On this page
- Why is heart function checked during HER2 treatment?
- How heart function is measured
- What results generally lead to, in broad terms
- A typical monitoring schedule
- The vocabulary, in plain language
- What the numbers can and cannot tell you
- Keeping track of your own heart results
- Everyday ways to support your heart during treatment
- What people assume about heart monitoring
- Common questions about heart monitoring
The short answer
Why is heart function checked during HER2 treatment?
HER2-targeted drugs such as trastuzumab can occasionally weaken how well the heart pumps. The measure used to track this is the ejection fraction, the share of blood pushed out of the main pumping chamber with each beat. It is checked before treatment starts and every few months during it, so any change is caught early, when it usually recovers.
Why the heart is affected
HER2 plays a part in keeping heart muscle cells healthy. Blocking it can reduce pumping in some people. Unlike the damage from some chemotherapy drugs, this effect is usually reversible.
What the checks look for
Your team compares each result with your starting value. A drop below the normal range, or a large fall from your own baseline, is what leads to a pause or further tests.
Who needs closer monitoring
People with previous anthracycline chemotherapy, high blood pressure, diabetes, existing heart disease, or older age. Tell your team about any heart history before starting.
This page gives general information only. What your own results mean is for your oncology and cardiology team to explain.The tests
How heart function is measured
Different centres use different tests. Using the same test each time gives the most reliable comparison.
Echocardiogram
An ultrasound scan of the heart. It is painless, uses no radiation and is the most common test in India.
MUGA scan
A scan using a small amount of radioactive tracer to measure pumping. It gives very consistent results between tests.
Less widely available than echo.Strain imaging
An advanced echo measurement that can show subtle changes before the ejection fraction itself falls. Not available everywhere.
Blood tests and ECG
Sometimes used alongside scans to look for heart strain or rhythm changes.
For consistent results
- Use the same centre when possible
- Keep copies of every report
- Bring your baseline report to each scan
Reading the result
What results generally lead to, in broad terms
Result
Usual response
Within the normal range and stable
Treatment continues as planned
Small fall, still within normal range
Treatment usually continues, sometimes with an earlier repeat scan
Larger fall from your baseline
Treatment may be paused and the scan repeated
Below the normal range
Pause, heart medicines and cardiology review
Symptoms of heart failure
Prompt assessment, whatever the last scan showed
Through treatment
A typical monitoring schedule
A baseline scan
Before the first dose, to know your starting point. All later results are compared with it.
Repeat scans every few months
Usually about every three months during the year of treatment.
Extra scans if needed
If a result changes or symptoms appear, a scan may be repeated sooner.
Review before continuing
Your oncologist checks the result before the next doses, and may involve a cardiologist.
A scan at the end
Many centres check again when treatment finishes, and sometimes later for people at higher risk.
Words you will hear
The vocabulary, in plain language
- Ejection fraction
- The share of blood pumped out of the main heart chamber with each beat.
- LVEF
- Left ventricular ejection fraction, the full name on most reports.
- Baseline
- Your result before treatment, used for comparison.
- Cardio-oncology
- A specialty focused on heart health during cancer treatment.
- Heart failure
- When the heart does not pump well enough for the body's needs, causing breathlessness or swelling.
- ACE inhibitors and beta blockers
- Heart medicines sometimes used to help heart function recover.
Talk to our team
Have a question about your situation?
Call the helpline or leave your details, and someone will help you arrange a consultation at the CION centre nearest you. One helpline serves every CION centre.
Call 1800 202 8726
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Being straight with you
What the numbers can and cannot tell you
Serious heart problems on trastuzumab are uncommon. Most people finish treatment with no meaningful change. Among those whose heart function does fall, most recover once treatment is paused, often with the help of heart medicines.
Scan results vary a little
Echocardiograms have some natural variation between tests and operators. A small change may reflect that rather than a real fall, which is why trends matter more than a single result.
Symptoms matter as much as scans
Breathlessness, swollen ankles, a racing heart or waking up breathless should be reported even if your last scan was normal.
Protecting your heart helps
Controlling blood pressure, blood sugar and cholesterol, staying active and not smoking all support heart health during treatment.
What this page cannot tell you
It cannot interpret your own report. Ask your team to explain your baseline and each result in plain terms.
Your reports
Keeping track of your own heart results
Over a year you may have four or five heart scans, sometimes at different places. Keeping your own record makes each review easier and more accurate.
Keep every report together
File each scan report in date order with your treatment papers. If you change hospitals or see a cardiologist, the whole series tells the story better than one result.
Note the test type
Write down whether each result came from an echocardiogram or another scan, since results from different tests are not directly comparable.
Ask what changed
At each review, ask whether your result has moved from your baseline and whether anything needs to change. A short answer is usually enough to reassure you or explain the next step.
Looking after your heart
Everyday ways to support your heart during treatment
Heart scans catch changes, but everyday habits also help keep your heart strong through a year of treatment and beyond.
Keep blood pressure in check
High blood pressure makes the heart work harder. Have it checked regularly, take any prescribed medicines, and cut back on salty snacks and pickles.
Control blood sugar
If you have diabetes, keeping sugars steady protects the heart. Treatment can disturb appetite and routine, so check more often and tell your team about large swings.
Stay gently active
Regular walking or light exercise supports heart health and helps with tiredness. Build up slowly and rest on difficult days.
Sleep and stress
Poor sleep and constant worry raise the strain on the heart. Short rests during the day, a regular bedtime and talking to someone about your fears can all help, and your team can suggest further support if you are struggling.
Avoid tobacco
Smoking and chewing tobacco both strain the heart and blood vessels. Ask your team for help with stopping if you use either.
Commonly believed
What people assume about heart monitoring
Needing heart scans means the drug is dangerous for my heart.
Scans are routine for everyone on HER2 treatment. Serious heart problems are uncommon, and monitoring exists to catch changes early while they are easily reversible.
Any drop in the number means stopping treatment for good.
Small changes are common and often need no action. Larger drops usually lead to a pause, and many people restart once the heart recovers.
If I feel fine, my heart must be fine.
Early changes can occur without symptoms. That is why scans are done on schedule even when you feel well.
Heart damage from trastuzumab is permanent.
Unlike some other drugs, trastuzumab's effect on the heart is usually reversible once treatment is paused.
Questions we are asked
Common questions about heart monitoring
What is a normal ejection fraction?
Your report will usually state the normal range used by that centre. What matters most on HER2 treatment is whether your result stays within that range and how it compares with your own baseline.
Does the scan hurt?
An echocardiogram is painless. A probe with gel is moved over your chest. You may be asked to lie on your side and hold your breath briefly.
Can I get my scan done anywhere?
Using the same centre each time gives the most reliable comparison. If you must change, bring previous reports so trends can be judged.
What symptoms should I report?
Breathlessness, especially lying flat, swollen ankles, a racing or irregular heartbeat, or unusual tiredness. Report them even between scans.
Will I need to see a cardiologist?
Only if results change or you have existing heart problems. Many centres work closely with cardiologists for this.
Can exercise help my heart during treatment?
Regular moderate activity supports heart health for most people. Ask your team what level suits you.
Do I need scans after treatment ends?
Some people do, particularly those at higher risk. Your team will advise based on your results and history.
Where can I read about my own treatment?
Your oncology team will give you written information about your HER2 treatment, including heart monitoring. Use that as your main reference.
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Talk to our team
Speak to a breast cancer specialist
Call the helpline or leave your details, and someone will help you arrange a consultation at the CION centre nearest you. One helpline serves every CION centre.
Call 1800 202 8726
Helpline open 24/7
Sources
- American Society of Clinical Oncology — Prevention and monitoring of cardiac dysfunction in survivors of adult cancers
- European Society of Cardiology — Guidelines on cardio-oncology
- Cancer Research UK — Trastuzumab (Herceptin)
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.