Why Look Beyond
the Angiogram?
OCT and FFR are two tests done through the same catheter during a coronary angiogram. FFR checks how much a blockage reduces blood flow, so cardiologists can decide whether a stent is really needed. OCT produces very detailed images from inside the artery so the right stent can be chosen, placed and fully expanded. Together they make angioplasty more precise.
A standard coronary angiogram shows the inside of the arteries as a two-dimensional X-ray silhouette. It is excellent for finding severe blockages, but two questions are often hard to answer from the picture alone: does this moderate narrowing actually reduce blood flow to the heart muscle? and exactly what size and length of stent is right?
FFR answers the first question with a pressure measurement. OCT answers the second with microscopic imaging. Using them can mean fewer unnecessary stents, better-placed stents, and fewer problems later.
At KG Heart Center, the interventional cardiology team uses OCT and FFR in two advanced cath labs that also have digital subtraction angiography (DSA).
- Done during the angiogram
- Same wrist or groin access
- Adds only minutes
- No extra incision
- FFR: function of a blockage
- OCT: detail inside the artery
What Is FFR
(Fractional Flow Reserve)?
FFR is a measurement of blood pressure beyond a narrowing in a heart artery compared with the pressure before it, taken with a very thin pressure wire while blood flow is increased with medicine. An FFR of 0.80 or less means the blockage significantly limits blood flow and a stent usually helps; above 0.80, medicines are often the better choice.
A narrowing that looks 50–70% on an angiogram may or may not starve the heart muscle of blood. FFR settles the question with a number. An FFR of 0.75, for example, means only 75% of the normal maximum flow can pass the blockage.
This matters because stenting a blockage that does not limit flow adds risk without benefit, while missing one that does can leave you with symptoms. FFR is especially useful when several arteries have moderate narrowings and the team needs to know which ones to treat.
What Is OCT
(Optical Coherence Tomography)?
OCT is an imaging test that uses near-infrared light from a tiny catheter inside the heart artery to create cross-sectional pictures at 10–20 micron resolution — about ten times finer than ultrasound. It shows the artery size, the type of plaque, calcium and, after stenting, whether the stent is fully expanded and sitting against the artery wall.
Before the Stent: Planning
Measures the true artery diameter and the length of disease so the cardiologist can choose the right stent size and landing zones.
SizingPlaque & Calcium
Shows soft, fibrous or calcified plaque. Heavy calcium can be treated first with rotablation or IVL so the stent can expand.
PlaqueAfter the Stent: Optimisation
Confirms the stent is fully expanded, well apposed to the wall and free of edge tears, so any problem is fixed on the table, not discovered later.
OptimisationFailed Stents & Unclear Cases
Finds why an old stent has narrowed again and helps clarify the cause of a heart attack when the angiogram is not conclusive.
DiagnosisOCT and IVUS: intravascular ultrasound (IVUS) is another way of imaging inside arteries. It sees deeper into the artery wall, while OCT gives much sharper surface detail. Both are recognised by international guidelines for guiding complex stenting.
OCT vs FFR
at a Glance
| Factor | FFR | OCT |
|---|---|---|
| Question answered | Does this blockage limit blood flow? | What does the artery look like, and is the stent right? |
| Type of test | Physiology (pressure) | Imaging (light) |
| Device | Thin pressure wire | Imaging catheter with brief contrast flush |
| Main use | Deciding whether to stent moderate blockages | Planning and optimising stents; complex lesions |
| Result | A number (0.80 cut-off) | Detailed cross-sectional images |
The two tests answer different questions, so some patients have both in the same procedure.
When Are OCT and
FFR Used?
How OCT and FFR
Are Done
Angiogram first
Under local anaesthesia, a catheter is placed through the wrist or groin and contrast dye shows the heart arteries on X-ray, as in any angiogram.
FFR measurement
A very thin pressure wire is passed beyond the narrowing. A medicine is given to increase blood flow briefly — you may feel warmth, flushing or mild chest tightness for a minute — and the FFR value appears on screen.
OCT imaging
A tiny imaging catheter is moved into the artery. A short flush of contrast clears the blood while the catheter takes a few seconds of high-resolution pictures along the vessel.
The decision
If FFR shows the blockage limits flow, the cardiologist proceeds to angioplasty, using OCT to plan the stent. If not, medicines are usually advised and no stent is placed.
Final check
After stenting, OCT confirms the stent is fully expanded and well positioned before the procedure ends. Recovery is the same as for a standard angiogram or angioplasty.
Are OCT and FFR safe?
Both are well-established and add only a small risk to the angiogram itself. OCT needs a little extra contrast, which matters for people with kidney disease. The flow-increasing medicine for FFR can cause brief flushing or breathlessness that passes within a minute or two. Rarely, any wire or catheter can injure the artery; your cardiologist explains your individual risk.
What the
Research Shows
FFR: in the landmark FAME trial of patients with blockages in several arteries, using FFR to decide which blockages to stent — instead of the angiogram alone — lowered the combined rate of death, heart attack and repeat procedures at one year (13.2% vs 18.3%) while using fewer stents.
Intravascular imaging: randomised trials in complex stenting have shown that imaging-guided PCI improves stent results and reduces later problems in the treated artery compared with angiography guidance alone.
Guidelines: the 2024 European Society of Cardiology guidelines on chronic coronary syndromes recommend pressure-wire assessment such as FFR for intermediate blockages and intravascular imaging (OCT or IVUS) to guide complex stenting.
Source: Tonino et al., New England Journal of Medicine, 2009 — see references below.
OCT & FFR Cost
in Coimbatore
OCT and FFR use single-use imaging catheters and pressure wires, so they add to the cost of an angiogram or angioplasty. On the other hand, FFR can show that a stent is not needed, and OCT helps get the stent right the first time. KG Hospital explains the expected cost before the procedure and gives a written estimate.
KG Hospital is empanelled with 50+ insurers and TPAs and with CMCHIS, PM-JAY, ESI, CGHS and ECHS. Cover for OCT and FFR depends on your policy or scheme, so the insurance desk checks eligibility and sends pre-authorisation, usually within 1–4 hours. Call 0422-4042121, Extn 205. Insurance & cashless details →
Interventional Cardiologists
at KG Heart Center
KG Heart Center is part of KG Hospital, founded in 1974 by Padma Shri awardee Dr G. Bakthavathsalam, and accredited by NABH.
About this page. Written by the KG Heart Center interventional cardiology team, KG Hospital, Coimbatore. Clinical information is consistent with the guidelines and studies listed below. Last updated: .
References
- Fractional flow reserve versus angiography for guiding percutaneous coronary intervention (FAME) — Tonino PA et al., New England Journal of Medicine, 2009.
- 2024 ESC Guidelines for the management of chronic coronary syndromes — European Society of Cardiology (key points summary).