The CTO medical abbreviation, in cardiology, stands for chronic total occlusion, a heart artery that has been completely blocked for a long time, usually defined as at least three months. Blood still reaches the heart muscle beyond the blockage through small natural detour vessels called collaterals.
Most people meet CTO on a heart catheterization report or a cardiology note, often paired with the name of the artery, as in RCA CTO or LAD CTO. In mental health law, the same letters mean a community treatment order. This page focuses on the heart meaning, explains how cath report lines read and notes the other uses.
At a glance
Stands for
Chronic total occlusion (cardiology)Other meanings
Community treatment order (mental health law, outside the US mainly)Usual definition
A 100 percent blockage present for about 3 months or moreWhere you see it
Cardiac cath reports, cardiology notes, vascular reportsMost common artery
The right coronary artery (RCA)Do not confuse with
Acute occlusion, a sudden blockage during a heart attackSpecialty
Interventional cardiology, vascular medicine
CTO medical abbreviation in cardiology
Coronary arteries carry blood to the heart muscle. Over years, plaque can narrow an artery as part of coronary artery disease. When the narrowing closes off the vessel completely and stays closed, it becomes a chronic total occlusion.
Because the blockage forms slowly, the heart often grows collateral vessels that carry some blood around it. Some people have chest pain or shortness of breath with exertion, called angina, while others have few symptoms. A CTO is often found during a heart catheterization done for other reasons.
RCA CTO, LAD CTO and other artery labels
Cath reports name the artery and the segment. The location matters because each artery supplies a different part of the heart. In the phrase RCA CTO, each medical abbreviation names one piece, first the vessel and then the type of blockage, and LAD CTO follows the same order, with the artery medical abbreviation written before the occlusion.
| Label | Artery | Area supplied |
|---|---|---|
| RCA CTO | Right coronary artery | Lower wall of the heart, often the heart's rhythm centers |
| LAD CTO | Left anterior descending artery | Front wall and much of the septum |
| LCx CTO | Left circumflex artery | Side and back wall of the left ventricle |
Of these, the RCA is the most common site of a chronic total occlusion. A proximal CTO sits near the start of the artery, a mid CTO in the middle and a distal CTO near the end.
Reading a cath report line
| Piece | Meaning |
|---|---|
| Cath | Cardiac catheterization, an X-ray dye study of the heart arteries |
| mid RCA CTO | Complete long-standing blockage in the middle of the right coronary artery |
| left to right collaterals | Detour vessels from the left system filling the right artery |
| LAD 70% | A separate 70 percent narrowing in the left anterior descending artery |
In a cardiology plan: "Symptomatic RCA CTO despite medical therapy, refer for CTO PCI." PCI is a catheter procedure to open the artery with a balloon and stent. Opening a CTO is technically harder than opening a partial blockage, so it is often done by specialized teams.
How a CTO may be managed
Treatment depends on symptoms, how much heart muscle is at risk and the person's other health problems. Options written in notes include medicines alone, a CTO PCI to reopen the vessel, or bypass surgery, written CABG, especially when several arteries are involved. Tests such as stress imaging may be used to see whether the heart muscle beyond the blockage is still alive and getting too little blood.
Not every CTO needs to be opened. The decision is made by the cardiology team with the patient.
Other meanings of CTO
In mental health law in places such as the United Kingdom, Canada and Australia, CTO stands for community treatment order, a legal order allowing a person to live in the community while following a treatment plan. In the United States, similar arrangements usually go by other names, such as assisted outpatient treatment. A note from a psychiatric service using CTO almost certainly means the legal order, not an artery.
The condition abbreviation list gathers many more terms like this one.
After a blockage is found: points to raise
- Which artery is blocked, and how much heart muscle does it supply?
- Are my symptoms likely coming from this blockage?
- Would opening it help, or are medicines enough for now?
- Is there other narrowing that also needs attention?
A chronic total occlusion is assessed alongside your symptoms and other test results. Your cardiologist can explain what your own cath report shows and which approach makes sense for you.
Frequently asked questions
What does CTO mean in cardiology?
CTO means chronic total occlusion, an artery, most often a coronary artery, that has been completely blocked for about three months or longer. Collateral vessels often supply some blood around it.
What is an RCA CTO?
An RCA CTO is a chronic total occlusion of the right coronary artery. The RCA is the artery where chronic total occlusions are found most often.
What is an LAD CTO?
It is a long-standing complete blockage of the left anterior descending artery, which supplies the front wall of the heart. Because that area is large, an LAD CTO often gets close attention.
Does CTO mean I had a heart attack?
Not by itself. A heart attack usually comes from a sudden blockage. A CTO is a blockage that has been present for months, and the heart has often adapted with collateral vessels, though a past heart attack may have happened in the same artery.
Can CTO mean something outside cardiology?
Yes. In mental health law in some countries, CTO means community treatment order. Who wrote the note, and where, settles which one applies.