Assessment of Coronary Artery Disease (CAD) – Dr Ramesh G

Assessment of coronary artery disease

When is a stent recommended for people with heart disease?

Heart disease can appear to us in 2 different ways-  one is in emergency and the other is in non-emergency. In an emergency, the patient usually presents with a heart attack, so these patients generally come into casualty. In patients with heart attacks, we usually do an angiogram once we confirm that the patient has got a heart attack. The confirmation is by doing an ECG or echo and a blood test called thrombin. Once the patient’s heart attack is confirmed we go ahead and take the patient for an angiogram. Most of the patients on angiogram have a very critical block, most of them will have a block of 80-90%. These patients generally would need stenting or if the patient has got multiple blocks, an emergency Bypass surgery. In a patient with an emergency, the diagnosis is generally more clear after angiogram if they would need further revascularisation in the form of stenting or bypass surgery. In a non-emergency patient where they come to the OPD with either two things- one, the patient has got some symptoms like chest pain while he walks, shortness of breath when he is walking. These are patients who come to us with existent symptoms and can be managed differently. We generally do a thread mill test if the patient’s symptoms are not very clear or sometimes the patient themselves do a thread mill test and come back. Suppose the patient’s TMT is positive and they are stable, then we do an angiogram. Once we do an angiogram, we decide what the patient needs based on the tightness of his block. If the patient’s block is more than 70%, most of the time they would need stenting, but if it is less than 70% we avoid stenting and manage medically.

What is the role of fractional flow reserve (FFR)?

FFR is called fraction flow reserve. In a patient where after an angiogram we find a block around 50-70% or basically to say patients borderline block when patients get symptoms and we do an angiogram and if angiogram shows any critical blockage which is more than 70-80% then they need a stent, suppose the patient has got a borderline block then we would do a test for FFR. This is done using a wire called a fractional flow reserve wire. The wire is passed through the block and then we see if it persists distal to the block or proximal to the block. So we assess the lesion or the block and decide if the patient needs stenting or not. So there’s a specific value of 0.8, if the patient’s FFR value is less than 0.8 we generally go ahead and stent the patient. That means an FFR value of less than 0.8 indicates the blood flow to that blood vessel is coming down and you need stenting for it. Suppose when we do an angiogram on a patient and find that the patient’s block is borderline, we do an FFR, and if FFR is more than 0.8, generally we can leave the patient for medical management without any need for stenting.

What is intravascular ultrasound (IVUS) and optical coherence tomography (OCT)?

There are two more methods of assessment of coronary artery disease, one is called Intravascular Ultrasound (IVUS) and the other is Optical Coherence Tomography (OCT)

Intravascular ultrasound is using ultrasonic waves. These two modalities can assist for 2 things, whenever we do an angiogram for a patient and find there’s a block we can further assist those blocks by using two things, Intravascular ultrasound (IVUS) and optical coherence tomography (OCT). Intravascular ultrasound uses sound waves, and optical coherence tomography uses light waves. So these are additional imaging modalities to assist the significance of the block, tightness of the block, and to assist the post result in case of stenting the patient. So whenever we do an angiogram on a patient and find a block we can directly put a stent but the better thing would be to assist the block properly whether the block has a lot of calcium or if the block is extended more than we thought and to know the exact diameter of the block. So for this, we use these methods, either intravascular ultrasound or optical coherence tomography. So once we pass the catheters inside the vessels we assist the size of the vessels, the diameter of the vessels, tightness of the block that is before stent. Once we stent the patient also again we can assist whether the stent is deployed properly and whether the expansion is proper and are there any further leaks or any extension of disease either proximally or distally. 

So to assist the pre stent and post stent results the IVUS or OCT is very useful. 

Recommendations:

Normally we do an angiogram in patients with severe chest pain or patient with heart-attack. For many of these patients after doing an angiogram where the blocks are borderline we can assist them with a fractional flow reserve (FFR). FFR will guide us to determine whether the patient needs stenting or we can manage medically based on a certain value.

Another point, if the patient is planned for a PTCA or stenting, we can do an intravascular ultrasound or optical coherence tomography to further elaborate the size of the vessels for us to see the significance of the block, the tightness of the block, and to see the post stenting result. So these are modalities in addition to angiogram to make us find the results. FFR can be used for a borderline lesion and IVUS and OCT can be used for a borderline lesion as well as significant lesions to assist the stenting and post stenting results.

 Book an appointment or Get a free second opinion from our experts at Yashoda Hospitals today.