A catheter-based imaging technology called optical coherence tomography (OCT) can successfully identify the characteristics of coronary plaques in patients with various cardiac symptoms, according to a study by researchers at Massachusetts General Hospital (MGH).

"More than 1.2 million people die from coronary artery disease every year, a quarter of them before or soon after arriving at the hospital," Ik-Kyung Jang, director of cardiovascular clinical research in the MGH Cardiology Division and lead author of the current study says adding, "The ability to identify dangerous plaques before they rupture and produce a heart attack or sudden cardiac death will be crucial to innovative preventive therapies."

Plaques are deposits of fats, cholesterol and other materials that collect in major arteries, restricting or sometimes blocking blood flow. While some plaques are relatively stable, others are vulnerable to rupture and release their contents into the bloodstream, causing a blood clot to form. Heart attacks and other acute coronary events usually result from the rupture of high-risk, vulnerable plaques in coronary arteries, and the characteristics of those plaques have been determined primarily by autopsy studies.

OCT uses infrared light delivered via fiberoptic catheter to produce high-resolution, cross-sectional images of blood vessels. Researchers developed the use of OCT to visualize coronary arteries, including vulnerable plaques. The technology developed in their laboratory was used for this first study to examine the structure of plaques in patients with cardiac disease.

Vulnerable plaques are believed to have three major characteristics - a deposit of lipids (fats), a thin cap of fibrous material covering the lipid pool, and infiltration of the immune cells called macrophages. The OCT images showed that the heart attack and ACS patients had more lipid in their plaques and significantly thinner fibrous caps than did the stable angina patients. Overall, vulnerable plaques were identified in 72 per cent of the heart attack patients, 50 per cent of those with ACS and only 20 per cent of stable angina patients.