Transmyocardial revascularization (TMR) is a therapeutic procedure that uses a laser beam to create small holes in the heart muscle (myocardium) of the left ventricle. TMR may be recommended for patients with chest pain (angina) that does not respond to medication or who are ineligible for other treatments such as coronary artery bypass graft (CABG) surgery. It may also be used as an adjunct to minimally invasive CABG surgery to increase the procedure's effectiveness. Studies have shown that TMR reduces the severity of symptoms and increases a patient’s capacity for exercise. However, TMR is not a cure for coronary artery disease, and there is no evidence that it can offer people a longer life.

There are a number of reasons patients may be referred for TMR instead of bypass surgery or balloon angioplasty. They include:

• There are too many individual blockages in the coronary arteries for either balloon angioplasty or bypass surgery to treat effectively.
  
  
• The patient’s arteries are too small to accommodate a catheter, which is necessary in order to perform a balloon angioplasty.
  
  
• The existing coronary artery disease is too advanced and the arteries cannot be repaired.

In some cases, TMR is also recommended as an adjunct therapy to bypass surgery. This often happens when the coronary artery disease is widespread and one area of the heart cannot be bypassed for a variety of reasons.

It is not completely clear how TMR helps relieve angina.  The channels created by the procedure close, but TMR may stimulate angiogenesis, a natural process in which the body creates new blood vessels to improve blood flow. In addition, the procedure may destroy some nerve cells in heart tissue, which reduces the angina pain. Finally, the success of TMR may be due to a placebo effect – patients feel better simply because they received treatment.