One of the most dangerous places to have a coronary blockage is in the left main coronary artery. Why is a blockage there so precarious?

To answer that, let’s start with some basic cardiac anatomy. The two major coronary arteries — the blood vessels that supply blood to the heart — are the left and right coronary arteries. The left main coronary artery (LMCA) is the very first portion of the left coronary artery. It provides oxygenated blood to most of the left ventricle, which is the main pumping chamber of the heart.

Any amount of blockage in the LMCA, such as from plaque buildup or a clot, is referred to as “LMCA disease.” However, treatment is only needed when there is a blockage of 50% or more. At that level, there is an increased risk of death, a major heart attack, or a life-threatening arrhythmia (irregular heartbeat). That’s why it needs to be treated quickly after a blockage is detected.

But what exactly is the best treatment of LMCA disease? This is the source of a lot of recent and ongoing controversy.

Treatment options for LMCA disease

Currently, there are three options for treating LMCA disease:

—Coronary artery bypass grafting, also known as bypass surgery or CABG, in which a blood vessel taken from a person’s leg, arm, or chest is moved and used to reroute blood around a clogged coronary artery.

—Percutaneous coronary intervention, also known as angioplasty and stenting. In this procedure, a catheter with a deflated balloon and stent (a wire mesh device) at the tip is threaded into the heart through a blood vessel in the leg or wrist. The balloon inflates along with the stent, clearing the blockage. The stent is left in place to prop open the blood vessel.

—Medical (drug) therapy.

Medical therapy is used in combination with both bypass surgery and stenting to help improve long-term outcomes. However, medical therapy alone has been shown to have worse outcomes in managing LMCA disease.

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