Help reduce plaque size? I'd be interested to see those studies!
Some studies for plaque reduction: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3872716/ http://atvb.ahajournals.org/content/19/8/1956.short http://atvb.ahajournals.org/content/15/7/827.short
There were also studies that show better diet stabilizes the plaque, preventing it from causing problems.
If you want to find more studies: https://scholar.google.com/scholar?q=plaque+regression
You've changed your claim. First you said a healthy diet will reduce plaque volume, now you say it just helps reduce heart attack rates.
Even the studies you cited only show minimal plaque volume reduction (so small it's questionable if it helps at all) and only with intensive pharmacological therapy.
There are tons of studies that show that better lifestyle helps, it's just most people can't do it. Not eating trans fats is one small change that will help, that is also easily done.