The combination of statin and the PCSK9 inhibitor evolocumab produces ‘favourable’ changes in coronary atherosclerosis, new research from the Monash Victorian Heart Institute shows.

In the HUYGENS study patients with non-ST elevation MI (NSTEMI) were treated with monthly evolocumab 420 mg (n=80) or placebo (n=81).

Patients underwent serial optical coherence tomography (OCT) and intravascular ultrasound imaging within a matched arterial segment of a non-culprit vessel.

At 12 month follow-up 135 patients had imaging that was able to be evaluated by the researchers.

Results showed the evolocumab group achieved lower LDL-C levels (28.1 vs 87.2 mg/dL, P<0.001).

The treatment group also had a greater increase in the study’s primary endpoint of minimum fibrous cap thickness (+42.7 vs. +21.5 μm, P=0.015).

A  decrease in maximum lipid arc (-57.5 vs. -31.4°, P=0.04) and macrophage index (-3.17 vs. -1.45 mm, P=0.04) was also observed throughout the arterial segment.

The trial, led by Director of Monash University’s VHI Professor Stephen Nicholls, also found a greater regression of percent atheroma volume with evolocumab compared with placebo (-2.29±0.47 vs. -0.61±0.46%, P=0.009).

However, there was no difference between the groups with regards to changes in microchannels or calcium.

According to the research team, the trial results demonstrate the ability to change the character of unstable plaques over time.

“By reducing the lipid core and thickening the fibrous cap – which helps stabilise and protect the plaque from rupture – the overall size of the atheroma also regressed. The degree to which this is possible is directly related to how much LDL cholesterol could be lowered,” they wrote in their paper published in the Journal of the American College of Cardiology: Cardiovascular Imaging.

“This demonstrates a potential mechanism for the improved clinical outcomes observed achieving very low LDL-C levels following an ACS,” they added.