What is the current approach to treating a 100% blocked coronary artery, in the absence of angina or other obvious symptoms? Can a stent safely be placed? Is the risk worth the benefit?

A long standing, 100% blocked coronary artery is called a CTO (Chronic Total Occlusion). I am a CTO Specialist and I perform about 120 - 150 CTO procedures every year. To give you an idea of the CTO world, any Interventional Cardiologist who performs more than 50 CTO Angioplasties every year can be termed as a “Dedicated CTO Operator”.

CTOs can develop after an untreated or incompletely treated heart attack that leads to a 100% blocked artery or they develop gradually over a period of years. This process provides an opportunity for the heart to develop collaterals (small channels that develop connecting the blocked segment to the other arteries of the heart that have good flow). These collaterals can keep the heart muscle alive and functioning near normally at rest. The best of collaterals can provide about 10–15% of the blood flow needed by the heart muscle in the blocked area. This translates to a 85–90% block.

With this background, if you look at the symptoms that patients have, 90% of patients have chest discomfort or breathlessness during exertion. Most patients have gradually adjusted their life style to avoid the symptoms. Invariably, when questioned skilfully, patients realise that they have been having symptoms. A more scientific way of dealing with this is to do a myocardial perfusion study which can show either reversible ischaemia or good viable heart muscle in the blocked artery’s territory.

If the patient has NO symptoms and if the perfusion studies show NO ischaemia and if the CTO is in a small artery not supplying significant heart muscle (myocardium), then it may not be worth a procedure. In most cases, patients who come to the hospital for a cardiac problem are usually symptomatic and have an important artery blocked with a large area of heart muscle supplied by it. These patients will benefit from the procedure.

Coming to the procedure itself, we need to go back a few decades to see why ‘traditionally’ people with one 100% blocked artery were treated medically. At a time (Early 1980 to 1990) when the only option available for a blocked artery was CABG (Bypass Surgery) and the risk of the surgery was >5%, it was not beneficial to do such a major surgery for one blocked artery. This was simply because the risk of dying from one 100% blocked artery was less than the risk of dying during surgery. Since angioplasty was not so well advanced in many fronts (Hardware, understanding, skills and expertise), these 100% blocks were not managed with angioplasty. Whenever it was attempted, the success rates were low. This led to the traditional management for a CTO with oral medications.

Fast forward 2 decades, we are in a world today where the angioplasty techniques, hardware, skills and understanding of CTOs have come a long way and have rapidly evolved. For the last 10 years, the success rates of CTO angioplasty has increased from around 50% to 95%. This increased success rate is because of the dedicated segment of cardiologists who perform CTO procedures. CTO angioplasty is NOT like the regular angioplasty and is a completely different animal. One needs to have at least a decade of experience and expertise to perform these procedures successfully. A 95% success rate for a minimally invasive procedure for a CTO is definitely worth it.

There is a major downside to the traditional view of medical management. The reason why anyone develops a CTO is because he or she has atherosclerotic obstructive coronary artery disease. Now, this 100% blocked major artery is supplied by collaterals (insufficiently) through another major artery of the heart. Remember that the patient is NOT free of the primary problem (atherosclerotic coronary artery disease) and the disease usually continues to progress inspite of treatment. If this patient has an Acute Coronary Event (A heart attack - which is a sudden occlusion of a coronary artery) involving the artery that supplies the collaterals, there is complete loss of blood flow in 2 major arteries. This usually leads to death in minutes and does not give the patient an opportunity to reach hospital. This to me is the most important reason for opening a CTO.

Almost all patients report immediate feeling of wellbeing after the CTO angioplasty and long term relief from symptoms. Doing a CTO angioplasty does not close the collaterals. The collaterals become non functional, but anatomically present and can open up if needed at a later date.

The risk of a CTO procedure to open a 100% blocked artery is minimally more than a regular angioplasty (0.5%), but still less than half the risk of a Bypass surgery for a similar problem. In todays world, the risk of dying from the 100% block is more than the risk of the procedure itself. So, it is definitely worth it.