Vulnerable plaque (VP) has been identified as a possible cause of sudden cardiac death, most of which occurs in patients with no history of heart disease.
VP has an underlying lipid-rich core covered by a thin fibrous cap, which is very difficult to visualize, and is considered to be a major step in detecting and treating the condition.
Researchers at Ajou University School of Medicine in Suwon, Korea, have now claimed that OCT provides superior contrast and resolution in imaging the components of plaque in coronary arteries, in comparison to other methods including intravascular ultrasound (IVUS) and virtual histology (VH-IVUS).
"OCT may answer longstanding questions about the relationship between vulnerable plaque and the risk of heart attack," said lead investigator Dr. So-Yeon Choi.
The researchers aimed at examining the ability of each imaging modality to detect the specific characteristics of vulnerable plaque. They performed IVUS, VH-IVUS and OCT in 48 patients who were categorized as having stable angina pectoris (15) or acute coronary syndromes (33).
With the help of OCT, the detection of vulnerable plaque turned out to be quite easy.
"OCT detected most of the major and minor characteristics of vulnerable plaque, including the thin cap with large lipid core, and it has the ability to detect thrombus and fissured plaque at a level that is four to five times better than that of other modalities. Because of OCT's high resolution capabilities, which is almost 10 times greater than with IVUS and related modalities, it can assess this tissue more accurately than other imaging methods," said Choi.
The researchers believe that OCT may provide a better understanding of the natural progression of coronary artery disease. For example, stenosis or erosion of endothelial cells with plaque could be detected even in patients with stable angina.
"That finding is something that we had never experienced before; we should study more the clinical implication of these findings. New evolving OCT imaging is moving closer to becoming a powerful diagnostic tool that will provide new insights into the etiology and treatment of coronary artery disease," said Choi.
The investigators admit that the current OCT technology has some limitations-it needs a blood-clear zone and a low penetrating depth to be most effective. They, however, insist that the procedure is safe and can be performed in a cath lab.
Their findings are summarized in the abstract titled "Comparison of Intravascular Modalities for Detecting Vulnerable Plaque: Conventional Ultrasound vs. Virtual Histology vs. Optical Coherence Tomography."