Fractional flow reserve (FFR) assessment
A test done during a heart angiogram that uses a fine pressure-sensing wire to measure whether a narrowing in a heart artery is actually limiting blood flow.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- FFR is a quick measurement during an angiogram that shows whether a borderline narrowing is genuinely limiting blood flow.
- Its main value is avoiding unnecessary stents: if flow is not significantly reduced, medicines may be as safe as a stent.
- It adds only a few minutes and a fine wire to the angiogram you are already having; results are known straight away.
- It is an information test, not a treatment — it does not itself open the artery, and it cannot rule out future heart problems.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Shows whether a borderline narrowing is actually limiting blood flow, beyond what the picture alone reveals
When the angiogram already clearly shows a severe narrowing or a complete blockage — the result would not change the decision.
The flow-boosting medicine may make you feel briefly flushed or breathless. This settles within a minute or two once it stops.
A clear explanation of the FFR number and exactly what it means for your treatment.
The flow-boosting medicine may make you feel briefly flushed or breathless. This settles within a minute or two...
You rest while the wrist or groin puncture site is watched, just as after any angiogram. A groin approach means...
Most people go home the same day. You will be told the result and what it means for your treatment.
Mild tiredness and bruising at the access site are normal. Avoid heavy lifting and follow the advice you are given...
What is a fractional flow reserve (FFR) assessment?
Fractional flow reserve, or FFR, is a measurement taken during a coronary angiogram (the X-ray test that pictures the heart arteries). A very fine wire with a pressure sensor on its tip is passed across a narrowing to measure the blood pressure on each side of it.
An angiogram shows what a narrowing looks like, but a picture alone does not always tell the cardiologist whether that narrowing is actually starving the heart muscle of blood. FFR answers that 'does it matter?' question by measuring flow, usually after giving a medicine that makes the heart arteries work at full demand. A closely related measurement, iFR (instantaneous wave-free ratio), does a similar job without that medicine.
The purpose is to help decide whether a borderline narrowing needs a stent or bypass, or whether it can safely be managed with medicines. If flow is not significantly reduced, treating with tablets is often as safe as fitting a stent — and avoids an unnecessary procedure.
FFR is a decision-making tool, not a treatment. It does not open the artery; it gives the cardiologist information to plan what, if anything, to do next.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Angiogram picture compared with FFR
| Approach | What it shows | Limitation |
|---|---|---|
| Angiogram alone | What the narrowing looks like | A picture may over- or under-estimate how much flow is affected |
| FFR / pressure wire | Whether flow is actually reduced | Adds a wire and, for FFR, a short-acting medicine |
| FFR-guided decision | Helps avoid unneeded stents | It informs the decision; it is not itself a treatment |
FFR is used to add functional information to the angiogram picture. Your cardiologist decides when it is helpful. This is a guide, not advice.
Preparing for your test
- This is usually done as part of a planned coronary angiogram, so follow all the angiogram preparation instructions you are given.
- Bring a full list of your medicines; you will be told which to continue and whether any need adjusting.
- Tell the team about asthma or severe breathing problems, as the flow-boosting medicine (adenosine) may not be suitable and an alternative can be used.
- Mention any allergy to X-ray contrast dye and any kidney problems.
- You may be asked to avoid caffeine for a period beforehand, as it can interfere with the flow-boosting medicine.
- Arrange a lift home, as you should not drive straight after the angiogram.
- Ask whether FFR is likely to be needed, so you understand what the reading will be used to decide.
What happens
FFR is done during a coronary angiogram, so the set-up is the same: local anaesthetic at the wrist or groin, sometimes with light sedation, and a fine tube guided to the heart arteries using X-ray.
When the cardiologist finds a narrowing that needs assessing, they pass a thin pressure-sensing wire across it. To measure FFR they usually give a short-acting medicine (often adenosine) that makes the arteries work at full demand for a minute or two. You may briefly feel flushed, breathless or notice chest tightness — this is expected and passes quickly once the medicine wears off.
The reading appears on a screen immediately. A low number suggests the narrowing is significantly limiting flow and may benefit from a stent or surgery; a higher number suggests medicines may be just as safe. The whole assessment usually adds only a few minutes to the angiogram, and the cardiologist can often act on the result in the same sitting.
Is this test right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- When the angiogram already clearly shows a severe narrowing or a complete blockage — the result would not change the decision.
- When the artery anatomy makes a reliable reading difficult, so the number could mislead.
- When significant asthma makes the usual flow-boosting medicine unsafe — a resting measurement or alternative is used instead.
- When the patient is not a candidate for any treatment that the result would inform.
Delay or rearrange if…
- Active infection or another acute illness that should be treated before a planned angiogram.
- Poor kidney function that needs reviewing before contrast dye is used.
- Important medicines (for example some blood-thinners) that need adjusting first.
- Recent caffeine intake when this would interfere with the flow-boosting medicine, if timing allows.
Alternatives to discuss
- Relying on the angiogram picture alone, where the narrowing is clearly severe or clearly mild.
- Non-invasive tests of blood flow, such as stress imaging or CT-based assessment, before going to an angiogram.
- iFR or another resting pressure measurement instead of standard FFR.
- Managing stable symptoms with medicines without invasive testing, where appropriate.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Shows whether a borderline narrowing is actually limiting blood flow, beyond what the picture alone reveals
- Helps avoid stents that are not needed, sparing you an unnecessary procedure and its risks
- Gives an answer immediately, so decisions can be made during the same procedure
- Can support a confident decision to manage with medicines instead of a stent
- Adds only a few minutes and a fine wire to the angiogram you are already having
Risks & complications
- A brief flushing, breathlessness or chest tightness from the flow-boosting medicine, which passes within minutes
- The usual angiogram effects: bruising or a tender lump at the wrist or groin
- Feeling tired for a day or so after the procedure
- A short-lived slow or irregular heartbeat from the flow-boosting medicine
- The wire irritating the artery, causing a temporary spasm
- The usual angiogram risks, such as a reaction to the contrast dye or a temporary effect on the kidneys
- Damage to the heart artery from the wire, very occasionally needing treatment
- Triggering a more serious heart-rhythm disturbance
- The serious but rare complications of any angiogram, such as heart attack or stroke
The extra risk from adding FFR to an angiogram is small, but the wire and the flow-boosting medicine each carry their own small risks. Tell the team about asthma or breathing problems before adenosine is used, as an alternative is available. Ask your cardiologist what the result will change — a test is most worthwhile when its answer will alter your treatment.
Published figures to discuss
FFR adds only a small amount of risk to an angiogram. The flow-boosting medicine commonly causes brief, harmless symptoms, while wire-related artery injury is rare. Robust separate complication percentages specifically for FFR are limited, so we describe these qualitatively rather than inventing figures.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| FFR threshold used for treatment decisions | FFR of 0.80 or below is commonly treated as functionally significant | The result is interpreted with symptoms, angiogram findings and overall risk. Borderline results need careful discussion rather than automatic stenting. | Fractional Flow Reserve — StatPearls (NCBI Bookshelf)ncbi.nlm.nih.govSource-linked context |
| Additional procedural risk beyond angiography | Small | FFR uses a pressure wire during angiography, so the main risks are those of coronary angiography plus rare wire-related vessel injury or spasm. | Fractional Flow Reserve — StatPearls (NCBI Bookshelf)ncbi.nlm.nih.govSource-linked context |
| Adenosine-related symptoms | Common but usually brief when adenosine is used | Flushing, chest tightness, breathlessness or a sense of impending faintness usually stops quickly when the infusion stops. | Guide sourcesClinical context |
| Misleading result in complex physiology | Recognised | Microvascular disease, diffuse disease, serial narrowings, acute coronary syndromes and technical factors can make interpretation harder. | Guide sourcesClinical context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no separate recovery from FFR itself — you recover from the angiogram it is part of. The flow-boosting medicine wears off within minutes, and any sensations it caused settle quickly.
- The flow-boosting medicine causing a brief, harmless flush or breathlessness during the test
- Bruising or a small tender lump at the wrist or groin afterwards
- Feeling a little tired for a day or so
- Knowing the FFR number on the day, even if the full plan is confirmed at follow-up
Aftercare
- Follow the standard aftercare for a coronary angiogram, including caring for the wrist or groin puncture site.
- Drink normally to help your kidneys clear the contrast dye, unless told otherwise.
- Avoid heavy lifting and strenuous activity for a short time, as advised.
- Do not drive until you are told it is safe.
- Make sure you understand the FFR result and what happens next — stent, surgery, or medicines.
- Keep any follow-up appointment where the plan is confirmed.
- Understand whether FFR is being done and what the result will be used to decide
- A lift home arranged, as for the angiogram
- A note of your FFR result and what it means
- Clear instructions on wound care for the wrist or groin
- A follow-up appointment to confirm the treatment plan, if needed
- The contact number for any concerns after you go home
Scars and how they heal
There is no surgical scar. FFR uses the same wrist or groin puncture as the angiogram, which usually heals to a tiny mark, sometimes with bruising that fades over a week or two.
⚠ Get urgent help if…
- Chest pain that does not settle after you go home — seek urgent advice; call 999 if severe
- Severe breathlessness, collapse or a racing or very slow heartbeat
- Signs of a stroke: face drooping, arm weakness or slurred speech — call 999
- Heavy or uncontrolled bleeding from the wrist or groin site
- A rapidly swelling, very painful or cold, pale hand or leg on the side used
- Much less urine, or feeling very unwell, in the days after the procedure
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A good FFR study gives a clear number that the cardiologist can act on straight away. A reading below the usual threshold suggests the narrowing is significantly limiting blood flow and may benefit from a stent or surgery; a reading above it suggests medicines may be just as safe.
FFR tells you about the narrowing tested at that moment. It cannot promise you will never have heart trouble, and it does not assess arteries that were not measured. A reassuring result still means continuing your heart medicines and looking after risk factors such as blood pressure, cholesterol, weight and smoking.
An FFR reading reflects the artery at the time of the test. Coronary disease can progress, so a narrowing that does not need treating now may change over time, and new symptoms should always be reviewed. The result is best thought of as guiding today's decision rather than a permanent verdict.
Related tests, treatments or support
FFR is, by design, combined with coronary angiography. If the result shows a narrowing worth treating, a stent (PCI) can often be placed in the same sitting. If not, the focus shifts to medicines and risk-factor control. iFR or a pressure-wire pullback may be used alongside or instead of standard FFR.
Follow-up & long-term care
The cardiologist usually explains the FFR result on the day and confirms the plan — stent, surgery or medicines — at the procedure or a follow-up appointment. Ongoing management of symptoms and risk factors is often shared with your GP.
Repeat, follow-on and what comes next
- A borderline result may need repeating or interpreting alongside other tests if the picture is unclear.
- A narrowing left untreated now may progress, so repeat assessment can be needed if symptoms change.
- If the result shows treatment is needed, a stent or surgery follows, with its own repeat-procedure realities.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- A clear explanation of the FFR number and exactly what it means for your treatment.
- A confirmed plan: stent, surgery or medicines, with reasons.
- Standard angiogram aftercare and a contact number for concerns.
- Shared follow-up with your GP for symptoms and risk factors if no procedure is needed.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- Whether it is added to an NHS or private angiogram
- The cardiologist's (operator's) fee and the cath-lab/facility fee
- The pressure-wire and any flow-boosting medicine used
- How many arteries are assessed
- Whether a stent is then placed in the same sitting (a separate cost)
- Follow-up appointments to confirm the plan
- Whether FFR is included in the angiogram fee or charged separately
- The cardiologist's fee and the cath-lab/facility fee
- The cost of the pressure-wire and flow-boosting medicine
- What happens, and what it costs, if a stent is then needed in the same sitting
- Follow-up appointments to discuss the result
- The cancellation policy and what happens if the result is inconclusive
On the NHS? FFR is available on the NHS as part of coronary angiography when clinically indicated; private testing is usually chosen for speed or choice of cardiologist.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not being told what the result will actually change about your treatment.
- Not being warned about the brief flushing or breathlessness from the flow-boosting medicine.
- Assuming a reassuring FFR means no future heart risk, when it only assesses the artery tested today.
- Not discussing that asthma may affect which medicine is used.
Marketing red flags
- Promoting image-based 'virtual FFR' as proven when NICE has said the evidence is not yet strong enough for routine NHS use.
- Implying the test prevents future heart problems rather than guiding today's decision.
- Charging for FFR routinely where the angiogram result alone would settle the decision.
- Presenting a single number as a guarantee rather than one piece of the picture.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- Will this result change my treatment — and how?
- What happens if the reading is borderline or inconclusive?
- Will you use the flow-boosting medicine (FFR) or a resting measurement (iFR), and why?
- If the result shows the narrowing matters, will you treat it in the same sitting?
- If it shows the narrowing does not matter, what medicines and follow-up will I need?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my test, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this test not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is FFR a treatment or a test?
Why might I have FFR instead of just being given a stent?
Will the test hurt?
What does a normal FFR result mean?
Can I have this on the NHS?
What if I have asthma?
Find a verified specialist for fractional flow reserve (ffr) assessment
Every consultant is GMC-checked and independently reviewed. Search by postcode and distance, or switch to a map. Ordered by rating, relevance and recency — never by who pays.
No verified consultants list this procedure yet — browse the full directory.
How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NICE — QAngio XA 3D QFR and CAAS vFFR (HealthTech guidance, formerly DG43) Fractional Flow Reserve — StatPearls (NCBI Bookshelf) Performing and Interpreting FFR in Clinical Practice — Expert Consensus (PMC) British Heart Foundation — Coronary angioplasty and stents NHS — Coronary angioplasty (angiogram and procedure)
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
Related guides: Coronary angioplasty and stenting (PCI) · Ambulatory ECG (24-hour Holter monitor) · Echocardiogram (heart ultrasound) · Electrocardiogram (ECG) · Event recorder or implantable loop recorder