Clearly fails
- FFR 0.75 or lower
- iFR 0.85 or lower
- Flow is limited
- Stent is usually advised
Names & Terms You Will Hear
Plain-language meanings for the terms your care team may use.
| Term | Meaning |
|---|---|
| FFR (Fractional Flow Reserve) | A pressure-wire test done during an angiogram. It measures how much a blockage limits blood flow. A medicine (adenosine) is given to open the small vessels first. |
| iFR (Instantaneous Wave-Free Ratio) | A newer pressure-wire test. It gives the same kind of answer as FFR but does not need the adenosine medicine. The reading is taken during one resting phase of the heartbeat. |
| Pressure wire | A very thin wire with a tiny sensor on the tip. The doctor passes it across the blockage to measure pressure on both sides. |
| Coronary physiology | The medical term for measuring blood flow in the heart's arteries, not just looking at the picture. |
| Hemodynamically significant | A blockage that is bad enough to actually starve the heart muscle of blood. This is what the wire is testing for. |
| Ischemia | When heart muscle does not get enough blood. A flow-limiting blockage causes ischemia and can cause chest pain. |
| RFR, DFR, dPR | Other resting wire scores, similar to iFR. They use the same idea and similar cutoffs. Your lab may use one of these. |
What Is FFR and iFR?
- FFR and iFR are tests done during a coronary angiogram (a dye picture of the heart's arteries). They are not separate appointments.
- An angiogram shows what a blockage looks like. But the picture can fool the eye. A blockage can look severe and still let plenty of blood through, or look mild and still cause trouble.
- The pressure wire settles the question. The doctor threads a thin wire with a sensor across the blockage and measures the pressure before and after it.
- FFR uses a medicine called adenosine to make the heart's small vessels open wide. This shows the worst-case flow. The brief medicine can cause a few seconds of chest tightness or flushing.
- iFR skips the medicine. It reads the pressure during a quiet part of each heartbeat instead. The result guides the same stent-or-not decision.
- The score is a ratio. A perfect artery scores 1.00. The lower the number, the more the blockage is choking off blood flow.
FFR vs iFR — Side by Side
| FFR | iFR | |
|---|---|---|
| Full name | Fractional Flow Reserve | Instantaneous Wave-Free Ratio |
| Needs adenosine medicine? | Yes | No |
| When the reading is taken | After medicine opens small vessels | During a quiet part of the heartbeat |
| Failing score (treat it) | At or below 0.80 | At or below 0.89 |
| Passing score (leave alone) | Above 0.80 | Above 0.89 |
| Key trials | FAME, FAME 2 | DEFINE-FLAIR, iFR-SWEDEHEART |
Lower is worse, not better. It feels backward, but a perfect artery scores 1.00. The lower the wire number, the more the blockage is choking off blood flow. So a low score fails and usually means a stent, while a high score passes and is safe to leave on medicine.
Why It Matters
- Stenting a blockage that is not limiting blood flow does not help, and it adds the small risks of the stent plus a lifetime of blood-thinner pills. The wire helps avoid stents you do not need.
- Missing a blockage that IS limiting flow leaves you at risk for chest pain and heart damage. The wire helps catch the ones that truly need treatment.
- Many blockages fall in a borderline range on the picture (about 40 to 70 percent narrowed). The eye cannot tell which of these matter. The wire can.
- In the FAME trial, using FFR to guide stenting led to fewer stents AND fewer heart attacks and deaths over the next year than relying on the picture alone.
- The chart below shows the two ideas behind these tests: fewer unnecessary stents, with the same safety whether your lab uses FFR or iFR.
Risk Factors
Knowing your personal risks helps your care team take extra precautions.
| Risk Factor | Why It Increases Risk |
|---|---|
| A borderline blockage on the angiogram | When a narrowing is in the 40 to 70 percent range, the picture alone cannot tell if it limits flow. The wire is most useful here. |
| More than one blockage | When several arteries have plaque, the wire helps pick which ones truly need a stent and which can wait on medicine. |
| Chest pain with unclear cause | If symptoms do not match what the picture shows, the wire helps confirm whether a blockage is the real culprit. |
| Deciding stent versus bypass | The wire helps the Heart Team count how many arteries are truly flow-limiting, which guides the choice between stents and bypass surgery. |
Treatment Options
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
- The wire test itself takes only a few extra minutes during your angiogram. You stay awake, and most people feel little or nothing from the wire.
- If FFR is at or below 0.80 (or iFR at or below 0.89), the blockage is limiting blood flow. Your doctor will usually treat it, often with a stent during the same procedure.
- If the score is above the cutoff, the blockage is not limiting flow. It is safer to leave it alone and treat with medicine, such as a statin, aspirin, and blood-pressure control.
- Leaving a non-flow-limiting blockage alone is not 'doing nothing.' Good medicine plus healthy habits is the proven treatment for these blockages.
- If a stent is placed, you will take a blood thinner for a set time to keep the stent open. Your doctor will tell you exactly how long.
- See our guides on coronary artery disease, the coronary angiogram, and angioplasty and stents for the bigger picture.
If Your Score Fails — A Stent Is Likely
- A failing score means the blockage is starving the heart muscle of blood.
- Your doctor will usually place a stent during the same procedure, so you avoid a second trip.
- You will take a blood thinner for a set time to keep the stent open. Do not stop it without asking.
- Treating a flow-limiting blockage can ease chest pain and lower the risk from that lesion.
If Your Score Is Borderline — The Gray Zone
- Scores just around the cutoff are a close call. The wire is one piece of the picture.
- Your doctor also weighs your symptoms, which artery it is, and how much muscle it feeds.
- Sometimes a repeat reading or a second test helps settle a borderline result.
- Shared decision-making matters most here. Ask what tips the balance in your case.
If Your Score Passes — Medicine Is the Plan
- A passing score means the blockage is not limiting blood flow right now.
- The proven treatment is medicine and healthy habits, not a stent.
- This is backed by trials: stenting these blockages does not lower risk and adds the stent's downsides.
- Your team will recheck if your symptoms change. A passing score today can be re-tested later.
What Your Score Means — At a Glance
Gray zone
- FFR 0.76 to 0.80
- iFR 0.86 to 0.89
- Borderline result
- Decision weighs symptoms
Clearly passes
- FFR above 0.80
- iFR above 0.89
- Flow is fine
- Leave it on medicine
Comfort Measures at Home (No Medication Needed)
These simple steps support healing and ease symptoms. Use them alongside any medication your doctor prescribes.
- Tell the team if you feel short of breath, flushed, or chest tightness during the adenosine. It passes within seconds once the medicine stops.
- Hold still during the few seconds the reading is taken. Staying relaxed gives a cleaner number.
- Keep the wrist or groin access site still and flat afterward, as the team instructs, to prevent bruising.
- Drink fluids after the procedure to help your kidneys clear the dye, unless you are told to limit fluids.
- Bring a written list of your questions. Ask what your score was and what it means for your plan.
Risks, Benefits, and Alternatives
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
Every choice has trade-offs. Use this table to start the shared decision conversation with your care team.
| Option | Risks | Benefits | Alternatives |
|---|---|---|---|
| Pressure wire (FFR or iFR) to guide the decision | A few extra minutes. With FFR, brief chest tightness or flushing from adenosine. Very rare wire injury to the artery. | Avoids stents you do not need. Catches the blockages that truly need treatment. Backed by large trials (FAME, DEFINE-FLAIR). | Judge by the picture alone (less accurate for borderline blockages). A non-invasive stress test before the cath. |
| Stent a flow-limiting blockage (score at or below cutoff) | Small procedure risks. A lifetime of at least one blood-thinner pill for a time. Rare re-narrowing. | Relieves flow-limiting blockages. Eases angina. Lowers heart-attack risk for the worst lesions. | Medicine-first trial (for milder symptoms). Bypass surgery (for complex multi-vessel disease). |
| Leave a non-flow-limiting blockage on medicine (score above cutoff) | Requires sticking with pills and habits. Small chance the blockage progresses and is rechecked later. | Avoids an unneeded stent and its risks. Just as safe as stenting for these blockages in the trials. | Stent anyway (not shown to help these lesions). Repeat the wire later if symptoms change. |
Common Misconceptions
| Myth | Reality |
|---|---|
| A blockage that looks bad on the picture always needs a stent. | Not true. The picture can mislead. Many blockages that look severe are not actually limiting blood flow. The wire score tells the difference, and leaving a non-flow-limiting blockage alone is safe. |
| The pressure wire is a separate, scary procedure. | It is done during the same angiogram you are already having. It adds only a few minutes. Most people feel little or nothing from the wire itself. |
| iFR is less accurate than FFR because it skips the medicine. | Two large trials (DEFINE-FLAIR and iFR-SWEDEHEART) showed iFR guided stent decisions just as safely as FFR over the first year. The labs pick the test that fits the patient. |
| If they don't stent my blockage, they are ignoring it. | Leaving a non-flow-limiting blockage alone is a proven treatment, not neglect. You still get statins, blood-pressure control, and follow-up. A stent there would add risk without adding benefit. |
| A higher wire score is worse. | It is the opposite. A perfect artery scores 1.00. The LOWER the number, the more the blockage is choking off blood flow. Low scores fail; high scores pass. |
| The wire can fix the blockage. | The wire only measures. It does not treat anything. It helps your doctor decide whether a stent, medicine, or surgery is the right next step. |
Possible Complications
Knowing what can go wrong helps you spot problems early. Most complications are uncommon, especially with treatment.
| Where / What | What Can Happen |
|---|---|
| The artery being tested | Very rarely the wire can scratch or dissect the artery, or trigger a brief spasm. Interventional cardiologists handle this in the same setting. Serious wire injury is uncommon. |
| Reaction to adenosine (FFR only) | The medicine that opens the small vessels can cause a few seconds of chest tightness, flushing, shortness of breath, or a slow heartbeat. It wears off within seconds. iFR avoids this because it uses no medicine. |
| The angiogram itself | Because the wire is used during a cath, it shares the angiogram's small risks: bleeding or bruising at the wrist or groin, dye reaction, and rare kidney strain from the contrast dye. |
| A wrong-sounding number | Rarely the reading can be thrown off by a damped pressure, a kinked wire, or heavy disease in the smallest vessels. The team checks the signal and repeats the reading if it looks off. |
Points to Know
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you remember nothing else, remember these key points.
- FFR and iFR measure blood FLOW, not just how a blockage looks. The picture can fool the eye.
- A perfect artery scores 1.00. The lower the number, the worse the blood flow.
- FFR fails at or below 0.80. iFR fails at or below 0.89. A failing score usually means a stent.
- A passing score means the blockage is safe to leave on medicine. That is a real treatment, not neglect.
- The test adds only a few minutes to an angiogram you are already having.
- FFR uses a brief medicine (adenosine). iFR skips it. Both guide the decision just as safely in trials.
- Using the wire leads to fewer unneeded stents and, in FAME, fewer heart attacks and deaths.
- Ask your doctor what your score was and what it means for your plan.
When to Call Us — and When to Call 911
Shown in English for your safety — this section is not automatically translated. Confirm with your doctor or call the office.
If you are not sure, call. We would rather hear from you twice than miss a real problem.
- Chest pain or pressure that does not go away, or spreads to the arm, jaw, or back — call 911.
- Sudden severe shortness of breath, fainting, or a cold sweat — call 911.
- Bleeding at the wrist or groin site that soaks through a dressing or swells fast — call 911 or press firmly and call us.
- A growing lump, increasing pain, numbness, or a cold or blue hand or foot below the access site — call us today.
- Fever, chills, or spreading redness at the access site — call us today.
- New or worsening chest pain in the days after your procedure — call us today.
- Questions about your wire score, your stent, or your medicines — call us; we would rather hear from you.
Office: (727) 943-5200
Trusted Resources
Independent, evidence-based pages we recommend for deeper reading.
- Cleveland Clinic — Fractional Flow Reserve — Plain-language overview of the FFR pressure-wire test and what the numbers mean.
- Mayo Clinic — Coronary Angiogram — Background on the cath-lab angiogram during which the pressure wire is used.
- American Heart Association — Cardiac Catheterization — AHA patient page on heart catheterization, the setting for FFR and iFR.
- SCAI SecondsCount — Coronary Angiogram and Physiology — Patient education from the Society for Cardiovascular Angiography and Interventions.
Sources Used to Build This Guide
- Cleveland Clinic — Fractional Flow Reserve (FFR) [clinical] — Patient overview of the pressure-wire test that decides whether a blockage needs a stent.
- FAME — FFR vs Angiography for Guiding PCI (NEJM 2009) [clinical_trial] — Landmark RCT showing FFR-guided PCI improves outcomes and reduces unnecessary stents.
- FAME 2 — FFR-Guided PCI vs Medical Therapy in Stable CAD (NEJM 2012) [clinical_trial] — Pivotal RCT supporting FFR-guided revascularization of functionally significant lesions.
- DEFINE-FLAIR — iFR vs FFR-Guided PCI (NEJM 2017) [clinical_trial] — Pivotal RCT establishing iFR (adenosine-free) as non-inferior to FFR for guiding PCI.
- iFR-SWEDEHEART — iFR vs FFR-Guided PCI (NEJM 2017) [clinical_trial] — Companion pivotal RCT to DEFINE-FLAIR confirming iFR non-inferior to FFR for guiding stent decisions.
- 2021 ACC/AHA/SCAI Coronary Revascularization Guideline [guideline] — U.S. guideline supporting the use of FFR or iFR to guide treatment of intermediate (borderline) blockages.
- 2024 ESC Guidelines for Chronic Coronary Syndromes [guideline] — European guideline backing physiology-guided (FFR/iFR) decisions for borderline coronary lesions.
- Mayo Clinic — Coronary Angiogram [clinical] — Plain-language background on the cath-lab angiogram during which the pressure wire is used.
