Testosterone Therapy Cardiovascular Studies
2014 through 2016 proved to be very good years for TRT (Testosterone Replacement Therapy) due to three back to back studies that showed incredibly positive results. In fact, one of the studies easily beat out statins at their own game and dropped heart attack and angina levels dramatically in men with existing heart disease. The results were astonishingly positive and come close to the results of the plaque reversers, i.e. the doctors that regress arterial plaque. Of course, keep in mind that this is just one study and the results are only applicable to men with low testosterone, whereas the plaque reversing doctors work with a broad set of patients.
Nevertheless, there is great reason for the TRT community to celebrate these findings, and I summarize the results and studies below for those who wish to dig into more detail.
CAUTION: Always consult with your doctor when it comes to any medical condition including heart disease. He or shoe knows your specific situation and medical background: the studies just deal with averages and can have their own issues.
1. Men with Severe Heart Disease. This study looked at 755 senior men between the ages of 58 and 78 with very advance arterial plaque levels - many were diabetics, smokers, etc. - and split them up into three groups: those who got no testosterone; those got a lower dose of testosterone; and those who got a higher dose of testosterone. The latter group end up with testosterone > 742 ng/dl. I highly suggest that you look up the study and read it for yourself, but a quick summary is that the researchers measured a quantiy called MACE, Major Adverse Cardiovascular Events. This will include things like a heart attack, stroke and probably angina. What they found was the "the men who did not receive testosterone as part of their treatment were 80 percent more likely to suffer an adverse event, such as a heart attack, than those taking T." 
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Again, this is just an incredible number and appears to achieve much superior results than that of statins. Again, keep in mind, though, that these results only apply to men with low testosterone in the first place.
2. Senior Men Receiving Injections. This study found that "older men who were treated with intramuscular testosterone did not appear to have an increased risk of MI [heart attack]. For men with high MI risk, testosterone use was modestly protective against MI."  Injections, in particular, have been criticized - more on that below - as posing some additonal cardiovascular risk but notice that testosterone actually lowered the risk of heart attack in those who need it most.
3. NORMALIZATION Greatly Improves Risk of Heart Attack, Stroke and Mortality. This recent study in The European Heart Journal pointed out that the major component missing from the two negative CVD studies were normalization of testosterone levels, i.e. proof that the patients actually had their testosterone boosted significantly. The authors of this study used a VERY large set of 83,000+ veterans data and found results that were so positive it has silenced virtually all TRT critics from what I have seen: 
a) A 47% reduction in all cause mortality!
b) An 18% reduction in heart attacks
c) A 30% reduction in strokes.
These are incredible numbers and, as I often point out, it is no wonder considering that testosterone lowers insulin levels and improves insulin sensitivity,
something that is a major issue for most 45+ men in modern societies. (See my pages on
Testosterone and Diabetes and Testosterone and Metabolic Syndrome for more information.)
Again, just because a man goes on TRT does not necessarily mean that anyone has proven that his testosterone has normalized. He may not have been compliant and some delivery systems just do not work in some circumstances.
In the early days of testosterone therapy (HRT) for men the big concern was prostate cancer. As time went on these concerns were largely allayed, something I cover in my page on
Does Testosterone Therapy Cause Prostate Cancer? In this environment testosterone therapy has grown exponentially in the last ten years, at least here in the U.S., as the door has been almost completely open for widespread use and adoption.
Recent studies now show that TRT appears to be very helpful in the battle against heart disease. Other hormones may help profoundly as well, something I discuss in my page on the Profound Lowering of Cholesterol in Men through HRT.
In my layman's opinion, the research overall shows that testosterone therapy significantly improves cardiovascular outcomes in the average hypogonadal man placed on standard TRT. This is actually remarkable considering that some rather lousy protocols are used out there, something that I highlight in my page on
Potential Testosterone Injection Dangers. In addition, some men with clotting disorders may be at risk and you
can read about this on my page called The Potential Risks of Testosterone Therapy.
So talk to your doctor and do your own research as I always say, but it would appear that testosterone therapy still has a bright future ahead of it.
NOTE: Before I go on, I want to be clear that I am not a doctor or a researcher but simply another guy out there enjoying the benefits of testosterone therapy. That said, I am probably more interested in the subject that the great majority of physicians out there, simply because testosterone therapy has been such a life changer for me and greatly improved my health from all I can tell. I also have a wife and three kids and certainly
do not want to do anything reckless, and so I want to know the strengths and weaknesses of what I am doing.
I HEARD THERE WERE STUDIES SHOWING TRT INCREASES CVD RISK?
Within just a few months (Oct 2013 to Jan 2014) testosterone replacement therapy appeared to be on the ropes with two back-to-back studies showing increased cardiovascular risk for men on TRT.  These studies were
controverisal and widely criticized in the TRT community however. And one of the reasons is that, in general, testosterone therapy has done very well in the cardiovascular research, and so this was quite a shock. In my opinion Dr. Morgentaler did an incredible job of showing the issues with these studies in two papers that you can read here and here.
Although his discussion is not exactly an easy read, I see no point in rehashing it here, and I highly encourage you to read what he wrote. Below is a quick recap by Dr. Morgentaler of the key problems:
"However, methodological flaws and data errors invalidate both studies as credible evidence of risk. One showed reduced adverse events by half in T-treated men but reversed this result using an unproven statistical approach. The authors subsequently acknowledged serious data errors including nearly 10% contamination of the dataset by women. The second study mistakenly used the rate of T prescriptions written by healthcare providers to men with recent myocardial infarction (MI) as a proxy for the naturally occurring rate of MI. Numerous studies suggest T is beneficial, including decreased mortality in association with TTh..." 
Although one of our posters pointed out that Dr. Morgentaler has disclosed considerable financial ties to the testosterone manufacturers,
Dr. Morgentaler's position seemed completely vindicated by the above three ensuing major studies showing that testosterone therapy actually IMPROVES cardiovascular risk.  
1) PLoS One. 2014 Jan 29;9(1):e85805, "Increased risk of non-fatal myocardial infarction following testosterone therapy prescription in men"
2) JAMA, 2013, November 6, 2013, 310(17), "Association of Testosterone Therapy With Mortality, Myocardial Infarction, and Stroke in Men With Low Testosterone Levels"
4) Ann Pharmacother, 2014 Jul 2;48(9):1138-1144, "Risk of Myocardial Infarction in Older Men Receiving Testosterone Therapy"
5) Asian J Androl, 2015 Jan-Feb, 17(1):26-31, "Testosterone deficiency and cardiovascular mortality"
6) European Heart Journal, published August 6, 2015, "Normalization of testosterone level is associated with reduced incidence of myocardial infarction and mortality in men"
7) JACC, Apr 5 2016, 67(13), "CLINICAL EFFECTS OF TESTOSTERONE SUPPLEMENTATION AMONG HYPO-ANDROGENIC MEN WITH PREEXISTING SEVERE CORONARY ARTERY DISEASE: THE INTERMOUNTAIN HEART COLLABORATIVE STUDY"