Greyscale IVUS reframes plaque progression in atherosclerosis

A picture says so much, especially in treating patients. To clear up the picture of how atherosclerosis progresses in patients, a group of researchers set their sights on imaging with greyscale intravascular ultrasound (IVUS).

Yu Katoka MD, PhD, of South Australian Health and Medical Institute at the University of Adelaide, and colleagues used IVUS to determine how lesions are structured and progress over the course of two years. Their findings were published in the September issue of the European Heart Journal: Cardiovascular Imaging.

The analysis of eight clinical trials provided them with 4,477 patients, 4.5 percent of whom had high-risk plaque. Patients with and without high risk lesions were assessed.

Katoka et al found that percent atheroma volume, total atheroma volume, and external elastic membrane as seen on greyscale IVUS were larger, while lumen volume was smaller throughout the vessel scanned in high risk patients. The team also observed higher levels of remodeling, plaque and calcification in these patients.

Percentage of plaque in high risk lesions was more than 11 percent greater than those that were not high risk (83.6 percent vs 72.1 percent). Five percent more calcification was seen in high risk lesions (33.6 percent vs 28.6 percent). The difference in remodeling index between vessels in patients with high risk lesions and those without was 0.2 (1.1 vs 0.9).

Over the course of the two year follow-up, more than 90 percent of patients with and without high risk lesions were prescribed statins as part of their treatment regimen.

As the study progressed, statin use in patients with and without high risk lesions slowed disease advancement. In patients with high risk who did not take statins, however, progression of percent atheroma volume increased.

While remodeling was still greater in high risk patients, it did reduce to a degree. External elastic membrane and lumen volumes did not decrease, however improvements were seen in the reduction of percent atheroma volume and total atheroma volume between baseline and follow-up in high risk and not high risk lesions (approximately -0.26 percent vs -0.24 percent and approximately -8.25 mm3 vs -3.90 mm3).

Ultimately, mortality and incidents of MI were very low among the observed group and differences were insignificant.

Kataoka et al wrote “When medical therapies including a statin are used, they profoundly regress, emphasizing the relative modifiability of the patient with evidence of high-risk plaques.”

Other studies have used different technologies and techniques to a similar end, developing methods to determine how patient risk could be better identified by plaque composition, size and other defining characteristics. “Greyscale IVUS, despite its limited resolution to visualize plaque composition, enables us to illustrate a large plaque burden, positive remodeling, and spotty calcification that have been reported to associate with plaque vulnerability.”

Further, longer term studies were recommended by Kataoka et al to continue to better understand disease progression or regression at the lesion level.

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