FFR (Fractional Flow Reserve) is an advanced diagnostic method that evaluates the functional significance of coronary artery stenosis.
What is FFR?#
FFR (Fractional Flow Reserve) is the ratio of maximum myocardial blood flow distal to a coronary stenosis to the maximum flow that should occur under normal conditions.
Calculation:
$$FFR = \frac{P_d}{P_a}$$
- Pd: Pressure distal to stenosis
- Pa: Aortic pressure
- Condition: Measured during maximal hyperemia
Normal value: FFR = 1.0 (no stenosis)
Importance of FFR#
Anatomical vs Functional Assessment#
Angiographic stenosis degree does not always reflect functional significance:
| Anatomical Stenosis | FFR ≤0.80 Frequency |
|---|---|
| 50-70% | ~35% |
| 70-90% | ~80% |
| >90% | ~95% |
Clinical Conclusion: Most moderate stenoses are not functionally significant.
FFR Indications#
Primary Indications#
1. Moderate Stenoses:
- Anatomically 40-70% stenosis
- Angiographic ambiguity
- Discordance with non-invasive tests
2. Multivessel Disease:
- Decision on which lesions to treat
- Complete vs Incomplete revascularization
- Treatment priority determination
3. Left Main Coronary Disease:
- Ostial/shaft lesions
- Ambiguous angiographic findings
4. Serial Lesions:
- Evaluation of multiple stenoses
- Determination of each lesion’s contribution
Special Situations#
- Diabetic patients
- Post-CABG patient evaluation
- Post myocardial infarction
- Recurrent symptoms
FFR Procedure Process#
Preparation#
- Standard coronary angiography access
- Anticoagulation
- 6Fr or 5Fr guide catheter
Equipment#
Pressure Wire:
- 0.014" diameter
- Distal sensor
- Optical or piezoelectric
Hyperemia Agents:
- Intravenous adenosine: 140 μg/kg/min
- Intracoronary adenosine: 100-200 μg
- Regadenoson: Single bolus
Procedure Steps#
- Calibration: Equalization of pressure wire with aortic pressure
- Wire advancement: 2-3 cm distal to stenosis
- Hyperemia induction: Adenosine administration
- Measurement: Stable Pd/Pa ratio recording
- Pullback: Optional, for serial lesions
FFR Value Interpretation#
| FFR Value | Interpretation | Recommended Treatment |
|---|---|---|
| >0.85 | Stenosis not significant | Medical therapy |
| 0.81-0.85 | Gray zone | Clinical decision |
| ≤0.80 | Significant stenosis | Revascularization |
| ≤0.75 | Definitely significant | Stent/CABG |
FFR Evidence Base#
Landmark Studies#
FAME Study (2009):
- FFR-guided vs Angiography-guided PCI
- 2-year MACE: 17.9% vs 22.4%
- Fewer stents, better outcomes
FAME 2 Study (2012):
- FFR ≤0.80: PCI vs Medical therapy
- Urgent revascularization: 1.6% vs 11.1%
- Study terminated early
DEFER Study (2007):
- FFR >0.75 → Stent deferral
- 15-year follow-up: Safety proven in deferred group
Guideline Recommendations#
ESC/EACTS 2018:
- Ischemia documentation with FFR: Class I, Level A
- In multivessel disease: Class I, Level A
ACC/AHA 2021:
- For moderate stenoses: Class IIa
FFR Alternatives#
iFR (Instantaneous Wave-Free Ratio)#
Does not require adenosine:
- Measurement during diastolic wave-free period
- Equivalent diagnostic accuracy
- Shorter procedure time
Decision threshold: iFR ≤0.89 → Revascularization
QFR (Quantitative Flow Ratio)#
- FFR calculated from angiography
- No wire required
- Estimated FFR value
RFR (Resting Full-Cycle Ratio)#
- Measurement at rest
- No adenosine required
- iFR-like results
FFR Limitations#
Technical Limitations#
- Presence of microcirculatory dysfunction
- High left ventricular pressure
- Severe tachycardia
- Diffuse disease
Clinical Limitations#
- Reliability decreases in acute MI
- No standardization in bypass grafts
- Presence of aortic stenosis
FFR vs IVUS#
| Feature | FFR | IVUS |
|---|---|---|
| Assessment | Functional | Anatomical |
| Hyperemia | Required | Not required |
| Plaque analysis | None | Detailed |
| Stent optimization | Indirect | Direct |
| Treatment decision | Clear threshold | Interpretation-dependent |
Optimal Approach: Treatment decision with FFR + Stent optimization with IVUS
FFR Complications#
Adenosine-Related (Temporary)#
- Chest tightness
- Dyspnea
- Flushing
- Bradycardia/AV block
Wire-Related (Rare)#
- Coronary spasm
- Dissection
- Wire fracture
Frequently Asked Questions#
What is FFR?
What does the FFR value mean?
How is the FFR procedure performed?
How is FFR different from angiography?
Is FFR safe?
Appointment and Contact#
To schedule an appointment for FFR measurement and functional coronary evaluation:
📍 Eurasia Hospital - Beştelsiz Mah. 101. Sokak No:107, Zeytinburnu, Istanbul
📞 Phone: +90 212 665 50 50 (Ext: 4012)
This content has been prepared by Assoc. Prof. Habib Çil for general informational purposes. Please consult a cardiology specialist for definitive diagnosis and treatment.
Related Coronary Evaluation Services#
Other services related to FFR:
- Coronary Angiography - Diagnostic coronary imaging
- IVUS - Intravascular ultrasound
- Coronary Stenting - Vessel opening procedure
- Bifurcation Intervention - Branching site treatment
- CTO Intervention - Chronic total occlusion opening