By Billy Candra 
Deciding whether to start hormone therapy during the menopause transition, the life phase that’s the bookend to puberty and when a woman’s menstrual cycle stops, is a hotly debated topic. While hormone therapy (HT), or replacing the hormones that were previously produced by the body with synthetic medication, is recommended to manage bothersome symptoms like hot flashes and night sweats, Matthew Nudy, an assistant professor of medicine at the Penn State College of Medicine, has noted persistent confusion regarding the long-term effects of hormone therapy, particularly on cardiovascular health. However, a significant new study, spearheaded by Nudy and published in the journal Obstetrics & Gynecology, offers compelling evidence suggesting that long-term use of estrogen-based hormone therapies may, in fact, exert beneficial effects on heart health. A multi-institutional research team analyzed extensive data from hormone therapy clinical trials that were part of the landmark Women’s Health Initiative (WHI) and discovered that estrogen-based hormone therapy demonstrably improved several biomarkers associated with cardiovascular health over time. Crucially, the study indicates that hormone therapy may substantially lower levels of lipoprotein(a), a largely genetic risk factor independently associated with a significantly higher risk of heart attack and stroke.
The Shifting Sands of Menopause Hormone Therapy
The conversation surrounding menopause hormone therapy has seen a dramatic pendulum swing over the past few decades. Prior to the early 2000s, HT was widely prescribed, often with the belief that it offered broad protective benefits, including for the heart. This perspective was largely challenged in 2002 with the initial release of findings from the Women’s Health Initiative (WHI), a massive, long-term national study focused on postmenopausal women. The WHI’s initial report on combined estrogen-progestin therapy indicated an increased risk of breast cancer, heart disease, stroke, and blood clots, leading to a precipitous drop in HT prescriptions and widespread concern among both patients and physicians.
Subsequent re-analyses of the WHI data and other studies began to refine this understanding, giving rise to what is now known as the "timing hypothesis." This hypothesis posits that the benefits and risks of HT are highly dependent on a woman’s age and the time elapsed since her last menstrual period (time since menopause onset). It suggested that HT might be safer and more beneficial for younger women (typically under 60) or those within 10 years of menopause onset, particularly if they are generally healthy and without pre-existing cardiovascular disease. For women in this "early window," HT has been shown to be effective in managing severe menopausal symptoms and may offer other health benefits, while risks appear to be lower than initially feared for older women or those starting HT many years post-menopause.
Matthew Nudy echoes this evolving understanding: "The pendulum has been swinging back and forth as to whether hormone therapy is safe for menopausal women, especially from a cardiovascular disease perspective. More recently, we’re recognizing that hormone therapy is safe in younger menopausal women within 10 years of menopause onset, who are generally healthy and who have no known cardiovascular disease." This nuanced view underpins the significance of the latest research, which seeks to further clarify the long-term cardiovascular implications within this carefully defined population.
Menopause and the Heightened Risk of Cardiovascular Disease
Beyond the well-known vasomotor symptoms like hot flashes and night sweats, the hormonal changes that accompany menopause usher in another critical shift: an increased risk of cardiovascular disease (CVD). Cardiovascular disease remains the leading cause of death for women, and the decline in estrogen, a hormone known to have cardioprotective effects, contributes significantly to this accelerated risk. Estrogen influences various aspects of cardiovascular health, including lipid profiles, blood pressure regulation, and endothelial function. With its decline, women often experience adverse changes in cholesterol levels (e.g., increased LDL, decreased HDL), a rise in blood pressure, and an increase in plaque buildup within blood vessels, all of which elevate the risk of heart attack and stroke. The incidence of CVD in women has been observed to increase by two to three times post-menopause compared to pre-menopause. This makes understanding interventions that could mitigate this risk a critical area of research.
Despite the growing recognition of HT’s potential benefits for younger, healthy menopausal women, the long-term effect of hormone therapy on cardiovascular biomarkers had not been extensively evaluated over an extended period. Prior research in the field primarily focused on short-term effects, leaving a gap in understanding how these therapies might influence heart health over many years. This latest study directly addresses that knowledge gap.
Unpacking the Penn State Study: Methodology and Key Findings
To investigate the long-term effects, Nudy and his multi-institutional team undertook a comprehensive analysis of data from a subset of women who had participated in an oral hormone therapy clinical trial, specifically within the framework of the WHI. The study focused on postmenopausal women, ranging in age from 50 to 79 at the time of their assignment to a treatment group. Participants were randomly assigned to one of two oral hormone therapy groups: an estrogen-only group or an estrogen-plus-progesterone group. Blood samples were meticulously collected at baseline and then at one, three, and six-year intervals, allowing for a robust longitudinal assessment of cardiovascular biomarkers. In total, the researchers analyzed samples from 2,696 women, representing approximately 10% of the total participants in the original WHI oral hormone therapy trial. This substantial sample size provided ample statistical power to detect meaningful changes.
The research team observed a broadly beneficial effect of hormone therapy on most cardiovascular biomarkers across both the estrogen-only and the estrogen-plus-progesterone groups over the six-year period. Key positive findings included:
- LDL Cholesterol Reduction: Levels of low-density lipoprotein (LDL) cholesterol, often referred to as the "bad" cholesterol due to its role in arterial plaque formation, were significantly reduced by approximately 11% in both treatment groups.
- Total Cholesterol and Insulin Resistance Decrease: Overall total cholesterol levels also decreased, alongside a reduction in insulin resistance, a metabolic condition linked to increased risk of type 2 diabetes and cardiovascular disease.
- HDL Cholesterol Increase: High-density lipoprotein (HDL) cholesterol, known as the "good" cholesterol for its role in transporting excess cholesterol away from arteries, showed a notable increase. It rose by 13% in the estrogen-only group and 7% in the estrogen-plus-progesterone group.
While these improvements in conventional lipid markers and insulin sensitivity are significant, the study also noted some less favorable changes. Specifically, levels of triglycerides, another type of fat in the blood, and coagulation factors, proteins essential for blood clot formation, were found to increase. These increases, while requiring careful consideration, align with some previously observed effects of oral estrogen therapy.
The Lipoprotein(a) Breakthrough: Addressing a Genetic Risk Factor
Perhaps the most surprising and clinically impactful finding of the study centered on lipoprotein(a) [Lp(a)]. Lp(a) is a unique, cholesterol-like molecule that is considered an independent and largely genetic risk factor for cardiovascular disease. Unlike other types of cholesterol, whose concentrations can be significantly influenced by lifestyle factors such such as diet, exercise, and smoking, Lp(a) levels are primarily determined by an individual’s genetic makeup, with about 80-90% of its variability attributed to inherited factors. Elevated Lp(a) concentrations are associated with a substantially increased risk of heart attack and stroke, often at a younger age, and also contribute to the risk of aortic stenosis, a condition where calcium buildup narrows the heart valve. It is estimated that Lp(a) affects approximately 1 in 5 people globally.
The research team reported a significant decrease in Lp(a) levels: 15% in the estrogen-only group and an even more pronounced 20% in the estrogen-plus-progesterone group. This finding holds immense potential clinical significance, as Matthew Nudy, a practicing cardiologist, highlighted: "As a cardiologist, this finding is the most interesting aspect of this research. Currently, there are no medications approved by the Food and Drug Administration (FDA) to lower lipoprotein(a). Here, we essentially found that oral hormone therapy significantly reduced lipoprotein(a) concentrations over the long-term." The lack of FDA-approved pharmacological interventions specifically targeting Lp(a) makes any agent capable of lowering its levels particularly noteworthy. While ongoing research is exploring novel therapies to reduce Lp(a), the demonstration of its reduction through an existing therapy, even one with specific indications and caveats, represents a major step forward in understanding potential management strategies.
Disparities in Response: Racial and Ethnic Considerations
Adding another layer of complexity and an important avenue for future research, the study also examined the findings by self-reported racial and ethnic group. The researchers observed that the decrease in lipoprotein(a) concentration was notably more pronounced among participants with American Indian or Alaska Native ancestry or Asian or Pacific Islander ancestry. In these groups, Lp(a) levels decreased by 41% and 38%, respectively, which are substantially steeper reductions than observed in the overall cohort.
Nudy acknowledged that the precise reasons for these more significant reductions among specific racial and ethnic groups are not yet clear. However, the research team has expressed a strong interest in investigating this phenomenon further in future research studies. Understanding these differences could be crucial for developing more personalized and equitable approaches to menopause management and cardiovascular risk reduction, particularly for populations that may carry a higher genetic burden of elevated Lp(a).
Oral vs. Transdermal: Nuances in Estrogen Delivery
It is important to contextualize the study’s findings within the broader landscape of hormone therapy formulations. Nudy noted that the estrogen therapy administered to women in the clinical trial was conjugated equine estrogens (CEE), a commonly prescribed form of oral estrogen therapy. A key characteristic of oral hormone therapy is its "first-pass metabolism," a process where the medication is absorbed from the digestive tract and directly processed by the liver before entering the general circulation. This hepatic processing can sometimes lead to increased production of certain proteins, including inflammatory markers, triglycerides, and coagulation factors. This physiological mechanism may explain the observed rise in triglycerides and coagulation factors in the study.
However, the field of hormone therapy has evolved, and newer formulations offer different delivery methods. "There are now other common formulations of estrogen hormone therapy like transdermal estrogen, which is administered through the skin," Nudy explained. Transdermal estrogen, delivered via patches, gels, or sprays, bypasses the liver’s first-pass metabolism, directly entering the bloodstream. This difference in pharmacokinetics has significant clinical implications. As Nudy pointed out, "Newer studies have found that transdermal estrogen doesn’t increase triglycerides, coagulation factors or inflammatory markers." This distinction is vital for clinicians and patients, as it suggests that the potential negative impacts on triglycerides and coagulation factors observed with oral CEE might be mitigated or avoided entirely with transdermal preparations, while still potentially delivering the beneficial effects on other cardiovascular biomarkers like Lp(a). Further research specifically on transdermal estrogen’s long-term effects on Lp(a) would be highly valuable.
Broader Implications for Clinical Practice and Future Directions
The findings from this study significantly add to the understanding of the complex interaction between hormone therapy and heart health, providing additional guidance to patients and doctors. For individuals considering menopause hormone therapy, Nudy strongly recommended undergoing a comprehensive cardiovascular disease risk assessment. This assessment is crucial even if the person has not had a previous heart attack or stroke or has not been diagnosed with cardiovascular disease. Such an evaluation provides health care providers with more complete information, enabling them to make the most informed decision when considering the best option to treat menopause symptoms, weighing potential benefits against individual risks.
It is critical to reiterate that, as Nudy noted, "Currently, hormone therapy is not FDA-approved to reduce the risk of coronary artery disease or stroke." The primary FDA-approved indications for menopause hormone therapy remain the treatment of moderate to severe vasomotor symptoms (hot flashes and night sweats) and the prevention of postmenopausal osteoporosis. While this study reveals promising long-term effects on cardiovascular biomarkers, including the novel finding regarding Lp(a), it does not alter the official FDA indications. Nevertheless, these findings contribute to a growing body of evidence that helps shape clinical guidelines and inform shared decision-making between patients and their healthcare providers.
The study’s insights into Lp(a) are particularly groundbreaking. The absence of FDA-approved drugs to lower Lp(a) makes any intervention demonstrating this effect a subject of intense scientific and clinical interest. While more research is needed to understand the mechanisms behind these reductions, especially the observed racial and ethnic disparities, this study opens new avenues for exploring HT’s potential role in managing a difficult-to-treat cardiovascular risk factor. Future research should aim to confirm these findings in diverse populations, explore the effects of transdermal estrogen on Lp(a), and further elucidate the mechanisms of action.
In conclusion, this comprehensive study led by Matthew Nudy and his team offers a more nuanced and encouraging perspective on the long-term cardiovascular effects of estrogen-based hormone therapy for specific populations of menopausal women. By demonstrating improvements in key lipid profiles, insulin resistance, and, most notably, a significant reduction in lipoprotein(a), the research provides valuable data for clinicians navigating the complexities of menopause management. It reinforces the importance of individualized care, risk stratification, and ongoing research to unlock the full potential and understand the precise applications of hormone therapy in promoting women’s health.
This extensive work was supported by funding from the National Center for Advancing Translational Sciences. Other notable authors on the paper include Aaron Aragaki, Fred Hutchinson Cancer Center; Peter Schnatz and Xuezhi Jiang, Drexel University College of Medicine; JoAnn Manson, Brigham and Women’s Hospital, Harvard Medical School and Harvard T.H. Chan School of Public Health; Aladdin Shadyab, University of California San Diego; Su Yong Jung, University of California Los Angeles; Lisa Martin, The George Washington University; Robert Wild, University of Oklahoma Health Sciences Center; Catherine Womack, University of Tennessee Health Science Center; Charles Mouton, University of Texas Medical Branch; and Jacques Rossouw, formerly of the National Heart, Lung, and Blood Institute at the National Institutes of Health.
