While the mantra that menopause hormone therapy (MHT) must be stopped after a heart attack has prevailed since the 2002 Women’s Health Initiative study, change is in the wind, with studies suggesting a low dose of estrogen (plus a progestin if needed for endometrial protection) could actually be beneficial.

The British Menopause Society (BMS) recently issued new guidance for clinicians suggesting women who’ve had a myocardial infarction (MI) don’t necessarily need to stop taking MHT, and could even be started on it.

MHT safer for the heart than previously thought

The BMS guidance lists several studies which suggest MHT can be safe for women with established coronary heart disease, including two randomised, placebo-controlled trials which used estrogen for secondary prevention. Both found no significant differences in coronary events or cardiac death in treatment versus placebo groups.

The BMS makes the case that estrogen has several benefits for arterial health, adding that studies have shown that MHT reduces atherosclerosis progression and coronary events if it’s started before 60 or within 10 years of the last period.

They say there is no evidence to indicate MHT should be stopped after a myocardial infarction, citing a large 2001 study of women over 55 who were hospitalised with acute MI, which showed significantly lower mortality for those taking MHT at the time.

So what does all this mean for clinical practice?

Professor Rodney Baber, clinical professor of obstetrics and gynaecology at The University of Sydney and head of the Menopause and Menstrual disorders clinic at Sydney’s Royal North Shore Hospital, says the BMS puts up a compelling argument.

“The BMS data is not new, but it is put together very well and is persuasive,” he says.

However, he stresses this does not mean hormone therapy should be used to prevent heart disease.

“No major societies are yet suggesting MHT for primary or secondary protection against CHD or CVD,” Professor Baber says. “I think the BMS data says there is no harm in continuing transdermal MHT after an MI.”

The BMS does not make claims beyond that, even if some influencers and advocates online do.

Dr Sylvia Rosevear, President of the Australasian Menopause Society and a New Zealand based obstetrician and gynaecologist says the guidance provides clarity about the use and benefits of MHT in a climate rife with misgivings and controversy.

It is written by clinicians distinguished in their fields and takes over 20 years of research into consideration, she notes.

“The guideline will provide a much-needed confidence boost to prescribers of MHT, that it does not need to be stopped with an MI. It may be given with a history of an MI, transdermally and in low doses with micronised progesterone as necessary,” she says.

Proceed with care after acute myocardial infarction

However, prudence and clinical judgement are still required.

Dr Tim Hillard, BMS medical advisory board member and former president, says “the message is that women who are unlucky enough to have menopause symptoms and have had a heart attack should not be denied HRT.”

But speaking to the Menopause Research and Education Fund, he advised some caution, noting that MI puts the body into a hypercoagulable state, so there is a slightly increased risk of blood clots. “So one would be cautious about it. But certainly, introducing them back onto it on a low dose would be entirely appropriate.”

MHT type and delivery mode matter

Importantly, not all forms of MHT are equal. The BMS guidance document suggests:

• non-oral administration of estrogen is preferable in anyone with a perceived risk of thrombo-embolism
• using a non-androgenic progestogen when required for endometrial protection
• starting on a dose that is appropriate for the patient’s age.

It also recommends seeking help from a menopause specialist.

“The argument against oral MHT is that it can be pro inflammatory and is associated with a rise in matrix metalloproteinases which would not be good after acute MI” as they are associated with the progression of heart failure, Professor Baber explains.

When it comes to women with established CVD, Professor Baber recommends using an online risk calculator to assess their absolute CVD risk “and then evaluating the need for MHT based primarily on its role in relief of vasomotor symptoms and maybe bone health. At this stage I would not be giving consideration to a role for MHT in preventative cardiovascular health.”

MHT and statins

The BMS says adding a statin may be beneficial, citing a study which found a combination of statin therapy and MHT led to a 55% reduction in venous thrombo-embolism rates, among other studies.

Dr Rosevear says adjuvant treatment with statins enhances plaque stability through reduced lipids and inflammation.

Professor Baber says while the data suggests “MHT and statins are not contra-indicated together and that there may be some synergistic benefit,” the decision should be made by a cardiologist.

Key takeaways:

• MHT may be given/continued after myocardial infarction, starting at a low dose appropriate to the age of the patient
• Transdermal administration is recommended in anyone with a risk of thrombo-embolism.
• When needed, non-androgenic progestogens are preferable.