TRT and Cardiovascular Safety: What the Current Evidence Actually Shows
TRAVERSE and other trials clarify TRT's cardiovascular risk profile. Here's what the data says, what remains uncertain, and how clinicians monitor heart risk on therapy.
Is testosterone replacement therapy something that could put your heart at risk down the line? It is one of the most common questions men raise before starting TRT, and for years the honest answer was "we're not sure." The evidence base has since matured, and the picture it paints is more specific, and more useful, than a simple yes or no.
Table of Contents
- Why Cardiovascular Safety Became the Central TRT Question
- The TRAVERSE Trial Changed the Evidence Base
- What Later Analyses and Reviews Confirm
- The Signals That Still Warrant Monitoring
- How This Should Change (or Not Change) a Candidacy Conversation
- What Ongoing Monitoring on TRT Typically Looks Like
- TRT Formulations and the Compounding Pathway
- FAQ
Why Cardiovascular Safety Became the Central TRT Question
For over a decade, testosterone replacement therapy carried an FDA label warning about possible cardiovascular risk. That warning was based largely on early observational studies with real methodological limitations, including small sample sizes and non-randomized designs that made it hard to separate testosterone's effect from the health status of the men who were prescribed it in the first place.
A 2013 study from the Department of Veterans Affairs on testosterone therapy and cardiovascular events raised alarm among clinicians and regulators, and it prompted the FDA to require label changes warning of possible cardiovascular risk, per research.va.gov. The study was influential, but it was observational, not a randomized trial, which limits how confidently it can establish cause and effect.
Hypogonadism, clinically low testosterone accompanied by symptoms like fatigue, low libido, or reduced muscle mass, is common enough that this question affects a large population of men weighing therapy. That combination, a widespread condition and an unresolved safety signal, is exactly why cardiology and endocrinology needed a definitive trial rather than another retrospective dataset.
The uncertainty of the 2010s shaped a decade of prescribing caution, particularly for men with existing heart disease or multiple cardiovascular risk factors.
The TRAVERSE Trial Changed the Evidence Base
The TRAVERSE trial, published by Lincoff and colleagues in the New England Journal of Medicine in 2023, was a large randomized, placebo-controlled trial designed specifically to answer the cardiovascular safety question that observational data could not settle, per nejm.org.
The headline finding: testosterone-replacement therapy was not associated with a higher incidence of major adverse cardiovascular events, a composite outcome that includes heart attack, stroke, and cardiovascular death, compared with placebo. This held in men with hypogonadism who also had existing or elevated cardiovascular risk, the exact population earlier warnings were most worried about, per nejm.org.
But TRAVERSE did not come back clean across the board. The trial also found a higher incidence of atrial fibrillation, acute kidney injury, and pulmonary embolism in the testosterone group compared with placebo, per nejm.org.
That combination, no increase in the "big" outcome but increases in three narrower ones, is why TRAVERSE reframed clinical guidance rather than simply closing the debate. It remains the largest and most rigorous randomized trial on this question to date.
What Later Analyses and Reviews Confirm
TRAVERSE has not stood alone. Subsequent reviews and studies in different populations have generally reinforced its central finding while adding nuance.
- A 2025 review published in PMC found that testosterone therapy does not significantly increase the risk of major adverse cardiovascular events, consistent with TRAVERSE's own conclusion, per Zitzmann and colleagues (2025), pmc.ncbi.nlm.nih.gov.
- Cleveland Clinic's clinical summary of TRAVERSE describes testosterone therapy as not associated with an increase in MACE when used as indicated, per Cleveland Clinic ConsultQD (2023), consultqd.clevelandclinic.org.
- A 2025 study in The Lancet Regional Health Europe, focused on men with Klinefelter syndrome, found TRT appears safe with respect to cardiovascular risk in that specific population, per Chang and colleagues (2025), thelancet.com.
None of these sources claims TRT eliminates cardiovascular risk or is universally safe. Each finding applies to the population studied, under monitored, trial-level conditions, not to every man in every context.
Table: How the Evidence Base Shifted
| Evidence source | Design | Key finding |
|---|---|---|
| 2013 VA study | Observational, retrospective | Associated TRT with increased cardiovascular events; prompted FDA label warning |
| TRAVERSE (NEJM, 2023) | Randomized, placebo-controlled | No increase in MACE; increased atrial fibrillation, acute kidney injury, pulmonary embolism |
| 2025 PMC review | Systematic review | Confirms no significant MACE increase, consistent with TRAVERSE |
| Cleveland Clinic summary (2023) | Clinical interpretation of TRAVERSE | No MACE increase when used as indicated |
| 2025 Lancet study (Klinefelter cohort) | Population-specific study | TRT appears safe on cardiovascular risk in this group |
The Signals That Still Warrant Monitoring
The three narrower findings from TRAVERSE deserve their own explanation, since "increased incidence" without context can sound scarier than it should, or be dismissed too quickly.
Atrial fibrillation is an irregular, often rapid heart rhythm that originates in the upper chambers of the heart. TRAVERSE found an elevated incidence of it in the testosterone arm compared with placebo, per nejm.org.
Pulmonary embolism is a blood clot that travels to and lodges in the lungs, a serious and potentially life-threatening event. This was also elevated in the testosterone group in the trial.
Acute kidney injury, a sudden decline in kidney function, was the third signal flagged. Its mechanism is not yet fully explained, which is itself a reason for ongoing research rather than dismissal.
This is precisely why ongoing clinical monitoring, not a one-time lab check at intake, is part of responsible TRT management.
How This Should Change (or Not Change) a Candidacy Conversation
The current evidence base supports a more measured framing than either extreme. TRT does not appear to broadly increase heart attack or stroke risk in the populations studied, but it is not risk-neutral across every cardiovascular outcome.
Men with a personal history of atrial fibrillation, clotting disorders, or kidney disease are exactly the group where a clinician should weigh these specific TRAVERSE signals carefully before starting therapy, per nejm.org.
The honest summary of TRAVERSE is not "testosterone is safe for the heart" or "testosterone is dangerous for the heart." It is that the major heart attack and stroke signal did not appear, while three narrower risks did, and both facts matter for individualized care.
Decisions about starting or continuing TRT should be made with a licensed clinician who reviews personal cardiovascular history in detail, not from a single headline about a study.
What Ongoing Monitoring on TRT Typically Looks Like
Monitoring on TRT is not a formality; it is how the TRAVERSE signals get translated into individual care.
- Hematocrit is tracked regularly, since testosterone can increase red blood cell production, and elevated hematocrit is linked to clotting risk.
- Blood pressure and rhythm symptoms, such as palpitations or a noticeably irregular heartbeat, are reasonable topics to raise at every follow-up visit given the atrial fibrillation signal from TRAVERSE.
- Baseline and follow-up bloodwork, reviewed against personal and family cardiovascular history, is how a clinician contextualizes whether continuing TRT still makes sense for a given patient over time.
LodeRx patients are evaluated and monitored by EliteCare, state-licensed clinicians, using a bloodwork-informed process throughout care. You can review what a baseline panel typically includes at the LodeRx bloodwork hub.
TRT Formulations and the Compounding Pathway
Testosterone prescribed through LodeRx is prescribed by a licensed clinician and compounded and dispensed by a 503A partner pharmacy, including RxAve among other partners. This is a distinct regulatory pathway from an FDA-approved brand-name product, and the difference matters for how the medication should be described.
Compounded testosterone formulations are not FDA-approved in themselves; only certain brand-name testosterone products carry that designation. Compounded medications should never be described as equivalent to, the same as, or identical to those FDA-approved brands, because the manufacturing pathway, oversight, and evidence base differ.
LodeRx is LegitScript Healthcare Merchant Certified, certification ID 50431222, effective July 30, 2026. LegitScript is a healthcare merchant compliance and accreditation certification; it is not FDA approval and not a medical endorsement.
Formulation choice, dosing schedule, and monitoring cadence are all part of the same clinical conversation. You can see how candidacy, labs, and formulation options connect at the LodeRx TRT hub, and read more about how compounded prescriptions move from evaluation to dispensing at how LodeRx works.
FAQ
Does TRT increase the risk of heart attack or stroke? The largest randomized trial to date, TRAVERSE, found testosterone therapy was not associated with a higher incidence of major adverse cardiovascular events, a composite that includes heart attack and stroke, compared with placebo, per NEJM (2023). This applies to the population studied, men with hypogonadism and elevated cardiovascular risk, under trial monitoring conditions.
What cardiovascular risks did the TRAVERSE trial actually find? TRAVERSE found a higher incidence of atrial fibrillation, acute kidney injury, and pulmonary embolism in the testosterone group compared with placebo, per NEJM (2023). Major adverse cardiovascular events overall were not increased. Both findings are part of the same trial and should be considered together.
Why did earlier studies suggest TRT was risky for the heart? Earlier concerns, including a 2013 VA study, were largely based on observational data with design limitations rather than large randomized trials. TRAVERSE was specifically designed to address those limitations with a placebo-controlled, randomized structure, which is why its findings carry more clinical weight, per NEJM (2023).
Is TRT safe for men who already have heart disease? TRAVERSE enrolled men with existing or elevated cardiovascular risk and did not find an increased MACE signal in that group, per NEJM (2023) and Cleveland Clinic (2023). Individual cardiovascular history, including clotting or arrhythmia history, should still be reviewed by a licensed clinician before starting therapy.
How is cardiovascular risk monitored while on TRT? Clinicians typically track hematocrit, blood pressure, and rhythm symptoms like palpitations at follow-up visits, given the atrial fibrillation and clotting signals identified in TRAVERSE. Monitoring frequency and specific labs are individualized based on a patient's baseline bloodwork and personal cardiovascular history.
If you are weighing TRT and want to understand how your own cardiovascular history factors into candidacy, the next step is a bloodwork-informed evaluation with a licensed clinician, not a decision based on a single study summary. You can start that conversation through EliteCare via the LodeRx TRT hub.