Thanks to Dr. Saya of Defy Medical for showing me a study that indicates that testosterone can, at least in some cases, play a role in reversing or halting arterial plaque. Now lifestyle is always going to be king in this area, but check out these interesting results:
"We showed that estradiol-induced nCAM sialylases are present in vascular endothelial cells and tested whether sex steroid pretreatment of human vascular endothelium could inhibit the capture of monocytes. Using in vitro techniques, pretreatment of human arterial endothelial cells with estradiol, testosterone, dehydroepiandrosterone and dihydrotestosterone all induced sialylation of endothelial cells and, in a dose response manner, reduced the capture of monocytes. Steroid hormones are protective against atherogenesis and its sequellae. Sex steroid depletion is associated with atherosclerosis."
Now I'd like to point out that the study actually looked at not just testosterone, but also DHT, estradiol and DHEA. However, in us men, DHT and estradiol are produced almost entirely from our testosterone. So, as you boost testosterone, you also get a parallel increase in these two hormones as well. Thus giving a low T man TRT will improve 3 out of 4 of the hormones in this study.
Although this study is in vitro, it showed something that is very promising: a dose dependent response. What this means is that the more T, DHT, E2 (estradiol) and DHEA were infused, the more blocking of the plaque-producing white blood cell process that occured. I should point out that monocytes (a type of white blood cell) are ground zero for plaque formation. So, if you can halt the monocytes from their inflammatory response, you can also likely go a long ways in stopping plaque from forming.
By the way, this complements nicely research done by Dr. Dzugan, who found that, if you correct all the "production hormones," including testosterone, DHT, estradiol, progesterone, cortisol and DHEA, then cholesterol plummeted. His theory was that the body increased cholesterol to compensate for low hormone levels, since all of the above hormones are made ultimately from cholesterol as their intial buidling block. Thus, his strategy was to find out where a man was low and then correct him to youthful levels and monitor lipids afterward.
The results were incredible, and I discuss them here: Hormones, HRT (In Men and Women) and Cholesterol. What this means is that correcting hormone deficiencies will likely not only stop the monocyte issue but actually significantly lower cholesterol and lipid levels as well. This also means that TRT physicians should not just be focused on testosterone and estradiol but look more at the big hormonal picture.
Now you may be thinking, "Well, if boosting a hypogonadal man with testosterone is so great, why don't we see a reduction in heart disease in men on TRT (testosterone replacement therapy?!" Well, we do! We now have three large, well done and recent studies that show very significant reductions in heart disease outcomes. Check out these studies here: Testosterone Therapy Cardiovascular Studies. Please read these and spread the word if you feel so inclined:, considering that heart disease is the #1 killer of men and a big percentage of men are low testosterone. (I also encourage men to read my links on Arterial Plaque Regression, because arterial plaque is not a simple thing and must be attacked from many angles. Doing so can really help your sex life as well!)
ESTRADIOL'S ROLE: One set of authors pointed to research that estradiol may play a key role in all of this:
"Testosterone retards atherosclerosis progression in animal models of atherosclerosis (33,34). In the LDL receptor-deficient mouse model of atherosclerosis, orchiectomy is associated with accelerated formation of early atherosclerotic lesions in the aorta. Testosterone supplementation retards the progression of atherosclerotic lesions, an effect that is blocked by concomitant administration of an aromatase inhibitor (34). Testosterone effects on atherosclerosis progression are independent of plasma lipids. Taken together, these data provide evidence that testosterone, through its conversion to estradiol, can retard the progression of atherosclerosis in these animal models." 
This is an important point, because some men on TRT take aromatase inhibitors, the most common being Arimidex (anastrozole) to control estradiol Some control of estradiol is a good thing if you are too high. However, driving estradiol too low could actually negate all of testosterone's benefits according to this line of research.
CONTROVERSY: It should be pointed out that one study on seniors actually looked to see if TRT effected atherosclerosis in seniors. However, the study was criticized for methodological flaws. Check out this commentary:
"The findings of the TEAAM trial appear to be consistent with previous studies that have demonstrated a lack of association between TST and cardiovascular morbidity in hypogonadal men  and . However, this is in contrast to other studies that have reached the opposite conclusion  and , including the Testosterone in Older Men (TOM) trial . Although these studies had potentially concerning findings, their credibility was limited by methodological flaws, such as exclusion of men with a history of myocardial infarction (MI) or stroke rather than being assigned to the no-testosterone arm , the use of men taking phosphodiesterase type 5 inhibitors as a purported benign control group , and recording of known side effects of testosterone (hypertension and lower extremity edema) as cardiovascular adverse events (AEs) ." 
That said, we have to admit that we are lacking a well done study in men that shows improvements in arterial plaque from TRT. However, I think these will come soon enough, as there are eight other critical cardiovascular factors that TRT improves according to the research. These are HUGE, including lowering arterial hardness - a little different than atherosclerosis - and insulin levels, decreasing inflammation and improving body composition and so on. Check out the details on this page: Testosterone and Heart Disease. CAUTION: Always discuss your medical situation with your doctor or naturopath. The research deals with certain subpopulations and your physician knows your individualized medical issues.
1) Reproductive Sciences, Dec 2016, 23(12):1620-1625, "Sex Steroids Block the Initiation of Atherosclerosis"
2) Diabetes Care, 2003 Jun, 26(6):1929-1931, "Testosterone and Atherosclerosis Progression in Men"
3) European Urology, April 2016, 69(2):371-2, "Effects of Testosterone Administration for 3 Years on Subclinical Atherosclerosis Progression in Older Men With Low or Low-Normal Testosterone Levels: A Randomized Clinical Trial"