Borderline Coronary Narrowing | Prof. Dr. Umuttan Doğan

It is one of the sentences that causes the most worry after a coronary angiogram: borderline coronary narrowing. Written in your report, or said to you by your doctor, it means a narrowing was seen in your artery but that what the narrowing actually does cannot be told from the picture alone. This is not indecision. It means the decision needs one more step.

What Does Borderline Coronary Narrowing Mean?

A borderline narrowing is one that is too marked to be called mild and not large enough to be called severe. It is seen on the angiogram and its percentage is estimated, but whether it is really reducing the blood flow to the heart muscle stays uncertain.

The phrase comes from the method itself. A coronary angiogram is an imaging test: the dye given into the artery shows the artery’s shadow in two dimensions. Where the shadow narrows there is an atherosclerotic plaque, a mass of fat and calcium built up in the artery wall.

The picture tells you where the plaque is and roughly how big it is. It does not tell you how much the plaque is restricting flow. That gap is what the word “borderline” honestly records in the report.

What Is an Intermediate Narrowing?

An intermediate narrowing is the medical term for the same thing. Narrowings of roughly 40 to 70 per cent are assessed under this heading, and in the literature they are called intermediate lesions.

Narrowings below the lower limit usually do not affect flow. Above the upper limit it is often clear that flow is restricted. The range in between is the range where the picture does not settle the decision.

It helps to know that these percentages are not sharp boundaries. The percentage on an angiogram is an estimate made from an image, and the same image can be read differently. That is why in intermediate narrowings the percentage is not the only thing the decision rests on.

Does the Narrowing Percentage Tell You Everything?

No. The narrowing percentage is important information, but on its own it does not make the decision. Two narrowings that look the same to the eye can affect the blood flow to the heart muscle very differently.

What changes the outcome:

The length of the narrowing: A short narrowing and one that runs over a long distance resist flow differently, even at the same percentage.
The diameter of the artery: A 60 per cent narrowing does not mean the same thing in a small side branch as it does in a main artery supplying a large part of the heart.
The muscle mass it supplies: The more heart muscle there is beyond the narrowing, the more a restriction in flow matters.
The state of the side branches: Collateral circulation from neighbouring arteries can reduce the effect of a narrowing.
Procedures you have already had: A narrowing around a stent that is already in place is not assessed in the same way as one seen for the first time.

Your symptoms say more than the percentage

The first thing your doctor will ask about is your symptoms. Chest pain or a feeling of pressure brought on by exertion, breathlessness that increases when you climb stairs, a tightness that eases with rest: these suggest that the muscle the artery supplies is not getting enough blood, which is to say ischaemia.

A narrowing that looks borderline in someone with no symptoms is assessed differently from the same narrowing in someone whose chest tightens as they walk.

Which Tests Are Used for a Borderline Narrowing?

There is one aim: to show that the narrowing is restricting flow, or to establish that it is not. Tests that do not need a catheter can be used first.

Exercise test: The ECG (electrocardiogram) and your symptoms are followed while the heart is loaded on a treadmill.
Myocardial perfusion scan: A labelled substance given into a vein shows how the heart muscle is supplied at rest and under load, and can show which area is not supplied well enough.
Stress echocardiography: Changes in the contraction of the heart muscle under load are followed with ultrasound.

If these tests give a clear result, the decision becomes clear. If the result stays uncertain, or contradicts what the angiogram showed, the measurement is made inside the artery itself.

The Measurement That Settles It: FFR

FFR measurement (fractional flow reserve) compares the blood pressure before and after the narrowing. A very fine wire with a pressure sensor at its tip is passed beyond the narrowing, and the ratio of the two pressures is worked out.

In a healthy artery, blood travels from one end to the other losing almost no pressure. If the narrowing is restricting flow, the pressure beyond it drops noticeably. For the measurement to be accurate the artery has to be opened to its widest; a drug called adenosine is given for this and the artery widens for a short time. This state is called hyperaemia.

FFR is not a separate procedure. It is done in the same session as the coronary angiogram, in the catheter laboratory, through the same access at the wrist or the groin. You will not need to be taken in a second time.

The result is a number:

0.80 or below: The narrowing is restricting the blood flow to a meaningful degree, and a procedure is considered.
Above 0.80: The narrowing is not affecting flow noticeably, and treatment usually continues with medicines.
Between 0.75 and 0.80: This is a grey zone. The decision is not made on the number alone; your symptoms, which artery is involved, the muscle area it supplies and your other tests are assessed together.

In people for whom adenosine is not suitable — with severe asthma or advanced chronic lung disease, for instance — pressure measurements that do not need the drug can be preferred. iFR (instantaneous wave-free ratio) measures over a particular part of the cardiac cycle and so does not require adenosine.

If information about the structure of the narrowing is needed, IVUS (intravascular ultrasound) can be used. IVUS is not a measurement but an imaging method: it shows the structure of the plaque, the true diameter of the artery and, where there is one, how a stent is sitting. In short, FFR shows what the artery is doing and IVUS shows what it looks like.

Does a Borderline Narrowing Need a Stent?

The answer is not in the percentage but in the measurement and in your symptoms. If you ask whether a narrowing that is not restricting flow needs a stent: it adds nothing to a well-arranged course of medicines.

Every stent, on the other hand, brings its own follow-up and the use of blood thinners with it. That is why the decision is not made as “there is a narrowing, let us close it”.

If the measurement shows that flow is restricted, a procedure comes into question. The site and length of the narrowing, how many arteries are involved and your general condition are then assessed together, and the choice between a coronary procedure and bypass surgery is made with that same assessment.

Which route is right for you is decided by assessing the tests and the symptoms you have.

If no stent is placed, am I left without treatment?

No. This is what worries patients most; the thought that “there is a narrowing but they are not touching it” causes anxiety.

If the measurement shows the narrowing is not restricting flow, continuing treatment with medicines is the appropriate approach. That does not mean nothing is being done. Medical treatment and daily routine include:

Cholesterol-lowering treatment (a statin) and, where needed, blood thinners
Control of blood pressure and blood sugar
Stopping smoking
Regular walking and a settled diet
Cardiology review at set intervals

To be honest about it: a narrowing does not disappear because it has been measured. If the risk factors are not brought under control it can progress over time. For that reason, if your symptoms change you should see your doctor without waiting.

What Should You Do If Your Report Says Borderline?

These help, in order:

Ask for a copy of the images. A digital copy of the angiogram images is the basis of any assessment; one line in the report is not enough.
Write your symptoms down. When the pain or the breathlessness starts, how long it lasts, what makes it ease. This says more than the percentage.
Gather your earlier tests. The exercise test, the perfusion scan, the echocardiogram and your blood results are assessed together.
Find out which artery it is. Which artery the narrowing is in, and where along it, changes the decision.
Ask whether a measurement was made. If FFR or iFR was measured during the angiogram, the number will be in the report.

An assessment made with this information is a different thing from a decision taken by looking only at the percentage in the report.

Borderline Coronary Narrowing in Antalya

Prof. Dr. Umuttan Doğan is a cardiologist working in interventional cardiology and complex coronary procedures. FFR is carried out in the catheter laboratory at Antalya American Hospital, in the same session as the coronary angiogram.

If you have already had an angiogram and were told the narrowing was borderline, you can be seen at the clinic in Konyaaltı with the images and results you already have. You will find his background and contact details on their own pages.

Frequently Asked Questions

My angiogram report says borderline narrowing — what does that mean?

It means a narrowing was seen in your artery, but whether it is reducing the blood flow to the heart muscle cannot be told from the picture alone. Your symptoms, tests that do not need a catheter, or a pressure measurement made inside the artery are used to reach a decision.

What is the difference between a 50 per cent and a 70 per cent narrowing?

Both can fall in the intermediate range, and in neither does the percentage tell you whether flow is restricted. The length of the narrowing, the diameter of the artery and the muscle mass it supplies change the outcome, so a higher percentage does not always mean a more serious situation.

Which tests are asked for in a borderline narrowing?

Depending on your symptoms and your earlier results, an exercise test, a myocardial perfusion scan or stress echocardiography may be asked for. If the result stays uncertain or contradicts the angiogram, FFR or iFR can be measured inside the artery in the same session.

Can I carry on with daily life and sport with a borderline narrowing?

This is decided for each person. Your symptoms, your measurement result, which artery is involved and your other tests are assessed together. If you have chest pain or breathlessness brought on by exertion, you should not increase your level of exertion without agreeing it with your doctor.

How often should I come for review with a borderline narrowing?

The interval is set by your doctor according to your risk factors, the medicines you take and how your symptoms are going. If the frequency or the severity of your chest pain increases in between, you should seek advice without waiting for your appointment.

The information on this page is for general guidance and does not replace a consultation. Decisions about diagnosis and treatment are made by your doctor after assessing your own situation.