Unprotected left main (ULM) percutaneous coronary intervention (PCI) less than 1 percent of all PCIs in clinical practice in the United States from 2009 through 2016, according to a study published online Jan. 2 in  JAMA Cardiology .

Percutaneous coronary intervention (PCI) is a non-surgical procedure used to treat narrowing (stenosis) of the coronary arteries of the heart found in coronary artery disease. After accessing the bloodstream through the femoral or radial artery, the procedure uses coronary catheterization to visualize the blood vessels on X-ray imaging.

After this, an interventional cardiologist can perform coronary angioplasty, using a balloon catheter in which a deflated balloon is advanced into the obstructed artery and inflated to relieve the narrowing; certain devices such as stents can be deployed to keep the blood vessel open. Various other procedures can also be performed.

Javier A. Valle, MD, from the Rocky Mountain Veterans Affairs Medical Center in Aurora, Colorado, and colleagues analyzed data from the National Cardiovascular Data Registry CathPCI Registry (1,662 institutions; 33,128 patients undergoing ULM PCI and 3,309,034 patients undergoing all other PCIs between April 2009 and July 2016).

Comorbid conditions and adverse events

The authors sought to assess the current practice of ULM PCI and its outcomes. These results were compared to the results reported in clinical trials. The researchers found that ULM PCI represented 1.0% of all procedures during the study period, with a modest increase from 0.7 to 1.3% over time.

Only 1,808 of 10,971 operators (16.5%) and 892 of 1,662 facilities (53.7%) performed an average of at least one ULM PCI annually, with a mean annualized ULM PCI volume of 0.5 procedures for operators and 3.2 procedures for facilities.

Major adverse clinical events occurred more frequently with ULM PCI versus all other PCIs (odds ratio, 1.46) after adjustment for other factors. Compared with clinical trial populations, real-world patients in the CathPCI Registry were older with more comorbid conditions and adverse events were more frequent.

"Trials of unprotected left main PCI do not reflect actual practice, although it is possible that case selection and procedural inexperience influence the observed discrepancies," the authors write. Several authors disclosed financial ties to the pharmaceutical and biotechnology industries.