• The medical community once believed that microvascular angina — chest pain caused by the tiny arteries in the heart — occurs predominantly in females and is harmless.
• However, a new study suggests that the condition increases the risk of heart attacks, stroke, and death.
• The study also found no significant differences in outcomes between males and females, or by ethnicity.
• Cardiologists often misdiagnose the condition and fail to treat it.

Maria George first experienced angina at the age of 42 years. The pain in her chest and between her shoulder blades became so intense that she ended up in her local emergency room (ER).

An electrocardiogram (ECG) suggested a possible heart attack, but an angiogram the next day found that her coronary arteries were free of any obstruction, so she was sent home.

She returned to the ER with chest pains several times over the next few weeks and months, but each time the doctors assured her there was nothing wrong.

“Indeed, I was even told by one of the cardiologists in my local hospital that if I ever had chest pain again, I should just breathe through it and not phone an ambulance,” she recalled. “Thankfully, my [physician] ignored that advice.”

The doctor referred her to a specialist, who diagnosed microvascular angina — a condition that cardiologists often fail to recognize and treat appropriately.

Like a heart attack, microvascular angina causes severe chest pain. However, standard diagnostic tests reveal the heart rhythm to be normal and find no blockages to the main coronary arteries that supply blood to the heart muscle.

Spasm or failure to dilate

The pain of microvascular angina is triggered either by a spasm in the tiny arteries within the heart muscle, by their failure to dilate and increase blood flow in response to stress, or a combination of both.

Even if cardiologists diagnose the condition correctly, they have often assumed that it is more likely to affect females than males, and that it is mostly benign.

However, a newly published study has found that almost 8% of patients with microvascular angina experience a major adverse cardiovascular event each year.

The research, which appears in the European Heart Journal, also found no significant difference in outcomes between males and females or between different ethnic groups.

The first author, Hiroaki Shimokawa, M.D., Ph.D., a professor from Tohoku University Graduate School of Medicine in Sendai, Japan, told MNT that there is a lack of awareness of the condition among cardiologists.

“Microvascular angina is somewhat difficult to diagnose, as it is not visible by simple coronary angiography,” he said. “As a result, many patients remain undiagnosed, suffering from chest pain and poor prognosis.”

International study

A total of 686 patients with microvascular angina enrolled in the study at hospitals in seven countries between July 2015 and December 2018.

Over a follow-up period of a median of 398 days until December 2019, 78 major cardiovascular events occurred.

These included 63 cases of unstable angina, nine cardiovascular deaths, and five heart attacks.

Overall, these events affected 7.7% of participants each year. Additionally, there was little difference in outlook between males and females or according to ethnicity.

However, females with the condition had significantly worse quality of life than males, possibly as a result of experiencing worse pain.

Prof. Shimokawa is part of the COVADIS (COronary VAsomotor Disorders International Study) Group. In 2018, the group proposed the criteria for diagnosing microvascular angina that they used to enroll patients in the new study.

Prof. Shimokawa and his colleagues believe the condition is much more prevalent than health experts generally assume.

Research suggests that up to half of patients who undergo coronary angiography for chest pain do not have blocked coronary arteries.

Prof. Shimokawa also notes that many patients with angina who have surgery to unblock their coronary arteries still experience chest pain afterward.

“Angina is usually thought to be caused mainly by narrowing of the large coronary arteries,” he says. “However, even after treatment of these arteries with stents or bypass surgery, approximately 40% of patients will still experience chest pains, suggesting problems with microvascular dysfunction are very common.”

Some study limitations

The authors of the new study note that the research was observational and lacked any comparison group.

The number of adverse cardiovascular events was also relatively small, limiting the statistical power of the study.

In addition, they say they have no information about changes in drug treatments, symptoms, or quality of life during follow-up.

Optimistic outlook

Prof. Shimokawa told MNT he is hopeful that drug treatments can improve the outlook for patients with these conditions.

“We can say that it is highly possible to reduce the incidence of major cardiovascular events if we are able to treat microvascular angina or coronary microvascular dysfunction,” he said. “Currently, several trials are ongoing to address this important issue.”

Maria, who is now 60 years old, said she considers herself to be “one of the fortunate ones” in being diagnosed and treated by an expert in the condition.

However, she added:

“Despite the excellent work of leading experts, even now, patients with microvascular angina are being turned away from local, regional, and even large tertiary centers with ongoing or recurring severe chest pain and being told there is nothing wrong with them, that it is all in their head or that they are just suffering from anxiety.”

Maria has founded INOCA — which stands for Ischemia with Nonobstructed Coronary Arteries — International, a partnership between patients and medical professionals that aims to raise awareness of heart conditions that do not involve blockage of the coronary arteries.

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