Testosterone Therapy and Heart Health in NYC: What the Evidence Actually Shows About Cardiovascular Risk

For two decades, men considering testosterone therapy have heard conflicting messages about their hearts. Some headlines warned that testosterone causes heart attacks and strokes. Others claimed it protects the heart. Both oversimplified a nuanced body of research. At Regen Health Physicians, Dr. Ajit Dhaliwal and our team in New York City and Salt Lake City evaluate cardiovascular health before, during, and after any hormone protocol, because the question isn't simply "is testosterone safe?" It is "is testosterone safe for you, at this dose, with this monitoring plan?"

This guide walks through what the evidence actually shows, including the large TRAVERSE trial published in 2023, the specific cardiovascular signals that do matter (hematocrit, blood pressure, atrial fibrillation, and blood clots), and how a well-run hormone optimization program keeps those risks in check.

Why the Heart Question Became So Confusing

The early alarm: 2010–2014

Concern began with a handful of studies. In 2010, the TOM trial (Testosterone in Older Men with Mobility Limitations) was stopped early after more cardiovascular events occurred in the testosterone group. The participants were frail men in their mid-70s with high rates of heart disease, and they used relatively high doses of topical gel. In 2013 and 2014, two observational studies (one in veterans, one using insurance claims data) reported more heart attacks and strokes among testosterone users.

These studies had real limitations. Observational data cannot separate the effect of a drug from the reasons someone was prescribed it, and the veterans study faced corrections to its data after publication. Still, in 2015 the FDA added a cardiovascular warning to testosterone labels and required manufacturers to conduct a proper randomized trial.

The counter-evidence

At the same time, a large body of epidemiology showed the reverse association: men with low testosterone have higher rates of cardiovascular disease, type 2 diabetes, metabolic syndrome, and all-cause mortality. Low testosterone is strongly linked to visceral fat, insulin resistance, and inflammation. The problem is that association runs both ways — poor metabolic health suppresses testosterone, and low testosterone worsens metabolic health — so these observations could not prove that treatment would help the heart.

The TRAVERSE Trial: The Best Evidence We Have

The FDA-mandated study, TRAVERSE, was published in the New England Journal of Medicine in 2023. It is the largest randomized, placebo-controlled trial of testosterone and cardiovascular safety ever conducted.

Who was studied

• About 5,200 men aged 45 to 80
• All had confirmed low testosterone (below 300 ng/dL on two morning tests) plus symptoms of hypogonadism
• All had either established cardiovascular disease or multiple high-risk factors (diabetes, hypertension, high cholesterol, smoking)
• Treatment was daily 1.62% testosterone gel versus placebo, with dose adjustments to keep levels in a normal range
• Mean follow-up was about 22 months, with some participants treated for up to 5 years

What it found

Testosterone was non-inferior to placebo for major adverse cardiac events — the combined measure of cardiovascular death, non-fatal heart attack, and non-fatal stroke. Events occurred in roughly 7.0% of the testosterone group and 7.3% of the placebo group. In a high-risk population, restoring testosterone to normal levels did not increase heart attacks or strokes.

What it also found (and this matters)

TRAVERSE was not a clean bill of health on every measure. The testosterone group had higher rates of:

• Atrial fibrillation (an irregular heart rhythm)
• Acute kidney injury
• Pulmonary embolism (blood clot in the lung)

These differences were small in absolute terms, but they were real enough that the FDA updated testosterone labeling in 2025 — removing language suggesting a general increase in heart attack and stroke risk, while retaining and adding warnings about blood pressure increases.

What TRAVERSE did not answer

It is equally important to understand the trial's limits:

• It used transdermal gel at physiologic doses — not injections, pellets, or supraphysiologic "optimization" levels.
• Many participants stopped treatment early, which can dilute differences between groups.
• It did not test whether testosterone reduces cardiovascular risk. Non-inferiority means "not worse," not "protective."
• It did not include men under 45 or men with normal testosterone.

The practical takeaway: for men with genuinely low testosterone and symptoms, physiologic replacement under supervision does not appear to raise the risk of heart attack or stroke. That conclusion does not extend to high-dose or unmonitored protocols.

The Cardiovascular Signals That Actually Matter on TRT

Rather than a vague fear of "heart problems," we focus on specific, measurable mechanisms.

1. Hematocrit and blood thickness (erythrocytosis)

Testosterone stimulates red blood cell production, partly by increasing erythropoietin and suppressing hepcidin (which frees more iron for new red cells). This is the most common lab change on TRT.

• When hematocrit climbs above roughly 54%, blood becomes more viscous, which may raise the risk of clots and strain the heart.
• Injections — especially large, infrequent doses — cause the biggest rises, because they produce high peak levels. Gels and more frequent, smaller injections tend to cause less.
• Smoking, sleep apnea, high altitude (relevant for our Salt Lake City patients), and dehydration all push hematocrit higher.

How we manage it: baseline and follow-up complete blood counts; adjusting dose or switching to more frequent dosing; screening for and treating sleep apnea; and therapeutic phlebotomy or blood donation when appropriate.

2. Blood pressure

Testosterone can modestly raise blood pressure through fluid retention and effects on the kidneys and blood vessels. Ambulatory blood pressure studies submitted to the FDA, particularly for oral testosterone undecanoate, showed average increases of a few points systolic — enough to matter at a population level.

How we manage it: baseline blood pressure, home monitoring after starting therapy, and treating hypertension aggressively. In many men, the weight loss and improved insulin sensitivity that come with appropriate therapy partially offset this effect, but we never assume it.

3. Atrial fibrillation

The AFib signal in TRAVERSE was unexpected and has not yet been fully explained. Possible mechanisms include effects on cardiac electrical remodeling and fluid balance. For men with a history of AFib, palpitations, or structural heart disease, this shifts the risk-benefit discussion and may warrant cardiology input before starting.

4. Venous blood clots

Data on deep vein thrombosis and pulmonary embolism are mixed, but TRAVERSE and some observational studies show a small increase, especially in the first months of therapy. Men with a personal or family history of clots, known clotting disorders, or recent surgery need careful evaluation.

5. Lipids

Physiologic transdermal or injectable testosterone has modest, usually neutral effects on cholesterol, sometimes slightly lowering HDL. Oral anabolic steroids and supraphysiologic doses, by contrast, can dramatically lower HDL and raise LDL — one of many reasons we do not use performance-enhancement doses.

Potential Cardiometabolic Benefits

The evidence for benefit is not about the heart directly, but about the metabolic factors that drive heart disease. In randomized trials and meta-analyses of hypogonadal men, testosterone therapy has been associated with:

• Reduced fat mass and increased lean muscle mass
• Improved insulin sensitivity; the T4DM trial found that testosterone plus a lifestyle program reduced progression from prediabetes to type 2 diabetes compared with lifestyle alone
• Improvements in anemia (the TRAVERSE anemia sub-study showed correction of unexplained anemia in some men)
• Better exercise capacity and energy, which support the lifestyle changes that genuinely lower cardiovascular risk

These benefits are meaningful, but they are best understood as part of a broader longevity and metabolic health strategy, not as a substitute for exercise, nutrition, sleep, and lipid and blood pressure control.

Who Needs Extra Caution — or Shouldn't Start TRT

Based on guidelines from the Endocrine Society and American Urological Association and the newer trial data, we are especially careful with men who have:

• A heart attack or stroke within the past 3–6 months
• Uncontrolled heart failure
• Uncontrolled hypertension
• Hematocrit already above 50% before treatment
• Untreated, moderate-to-severe obstructive sleep apnea
• A history of unprovoked blood clots or a known thrombophilia
• Active or recurrent atrial fibrillation
• Desire for near-term fertility (testosterone suppresses sperm production; alternatives exist)

Having one of these does not automatically rule out treatment, but it changes the plan — often meaning we address the underlying problem first, coordinate with a cardiologist, or choose a non-testosterone approach.

What a Heart-Conscious TRT Evaluation Looks Like

Confirming the diagnosis

A single low reading is not enough. We confirm low testosterone with at least two early-morning measurements, along with LH, FSH, SHBG, and free testosterone, and we look for reversible causes: obesity, sleep apnea, medications such as opioids, thyroid disease, and excess alcohol. Sometimes correcting those restores testosterone without any hormone therapy.

Cardiovascular baseline

Before starting, a typical workup includes:

• Complete blood count (hematocrit and hemoglobin)
• Comprehensive metabolic panel, including kidney function
• Lipid panel, and often ApoB and lipoprotein(a)
• Fasting glucose, insulin, and HbA1c
• PSA (age-appropriate) and estradiol
• Blood pressure, and an ECG when history suggests rhythm issues
• Sleep apnea screening — symptoms, questionnaires, and home sleep testing when indicated
• For higher-risk patients, a coronary artery calcium score or cardiology referral

Choosing the formulation and dose

The goal is physiologic, steady levels — typically mid-normal range — rather than chasing a high number. Options include topical gels or creams, more frequent lower-dose injections (e.g., weekly or twice weekly), and other formulations depending on the patient. Steadier delivery generally means smaller hematocrit and estradiol swings. For men who want to preserve fertility or avoid testosterone altogether, options such as enclomiphene or hCG may be considered.

Ongoing monitoring

A typical schedule:

• 6–12 weeks after starting: testosterone level, hematocrit, blood pressure, symptoms
• 3–6 months: repeat labs, adjust dose
• Every 6–12 months thereafter: CBC, metabolic panel, lipids, PSA, and blood pressure review

We act early: if hematocrit rises above about 52%, we adjust before it reaches the 54% threshold where guidelines recommend pausing or reducing therapy.

Where Peptides and Other Therapies Fit

Some patients ask about peptide therapy as an alternative or complement — for example, growth hormone secretagogues for body composition or recovery. These carry their own considerations (including effects on glucose) and are not a replacement for treating true hypogonadism. Others are primarily interested in recovery and tissue health; our regenerative medicine services are a separate pathway. Hormone decisions are always made within the context of a full health picture.

Frequently Asked Questions

Does testosterone therapy cause heart attacks?

In the largest randomized trial to date (TRAVERSE), physiologic testosterone replacement in men with low testosterone and high cardiovascular risk did not increase heart attacks, strokes, or cardiovascular death compared with placebo over about two years of average follow-up.

Is TRT safe if I already have heart disease?

TRAVERSE specifically enrolled men with existing heart disease or high risk and found no increase in major cardiac events. However, men with recent heart attacks, uncontrolled heart failure, or atrial fibrillation need individualized evaluation and often cardiology coordination.

What hematocrit level is too high on TRT?

Most guidelines recommend pausing or adjusting therapy when hematocrit exceeds about 54%. We aim to intervene earlier, around 52%, through dose changes, more frequent dosing, treating sleep apnea, or blood donation.

Are injections riskier for the heart than gels?

Injections produce higher peaks and tend to raise hematocrit more than gels. TRAVERSE tested gel only, so its results apply most directly to transdermal therapy. Smaller, more frequent injections can reduce peaks.

Can testosterone lower my cardiovascular risk?

It may improve body composition, insulin sensitivity, and anemia in men with true deficiency, which are linked to heart health. But no trial has proven that testosterone therapy itself reduces heart attacks or strokes.

The Bottom Line

The evidence has matured. For men with confirmed low testosterone and symptoms, physiologic replacement does not appear to increase heart attack or stroke risk, but it does require monitoring for hematocrit, blood pressure, atrial fibrillation, and clotting. The danger lies less in testosterone itself than in high doses, poor diagnosis, and inadequate follow-up.

If you are considering testosterone therapy — or are already on it and unsure whether you're being monitored properly — Dr. Ajit Dhaliwal and the team at Regen Health Physicians offer comprehensive, cardiovascular-aware hormone evaluations in New York City and Salt Lake City. Learn more about our approach, or book a consultation to review your labs and options.

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Medical Disclaimer: This article is for educational purposes only and does not constitute medical advice. Testosterone therapy is a prescription treatment with risks and is not appropriate for everyone. Individual results vary. Consult a qualified physician before starting, stopping, or changing any hormone therapy, especially if you have a history of heart disease, blood clots, or abnormal heart rhythms.