All about microvascular angina

Jennifer Waller

Microvascular angina (sometimes called cardiac syndrome X) results from an abnormality of the tiny arteries within the heart muscle that play a crucial role in regulating blood supply to the heart. Juan Carlos Kaski, Professor of Cardiovascular Science, explains to Sarah Brealey.

Professor Kaski says: “Unfortunately, the coronary micro vessels are not visible with an angiogram and therefore cardiologists do not always think about them as a source of the patient’s chest pains”.

“It can be caused by essentially two mechanisms” says Professor Kaski. “Either the microvessels are unable to dilate (open up) in the normal way to allow increased blood flow, for example during exercise or at times of stress, or they go into spasm (severe constriction), reducing the blood flow to the heart muscle, even without obstructions in the large coronary arteries (coronary artery disease).” A patient can experience both.

“If the problem is lack of dilation, symptoms can mimic angina – chest pain when the heart is under increased workload, such as during exercise. If the issue is abnormal constriction (spasm), the patient may experience chest pain for no apparent reason, such as when resting.”

Women, particularly around or after the menopause, are more likely than men to get microvascular angina

Professor Juan Carlos Kaski

In some cases, the pain can be severe and may not respond to GTN spray in the same way as ‘normal’ angina.

Professor Kaski says there are biological reasons why it’s more common around the menopause. “There may be a connection between oestrogen reduction and development of abnormalities of the micro vessels. Oestrogen also affects how the brain reacts to pain: when oestrogen levels are low, the pain threshold falls.”

Microvascular angina is not always diagnosed, because, says Professor Kaski, “there is unfortunately a lack of awareness as to how common the condition is and the situation is not helped by the fact that abnormalities of the coronary microvessels are difficult to spot.

“As the angiogram is ‘clear’ in these individuals, the majority of patients are told that there is nothing wrong with their heart. It is therefore important to increase awareness as to the existence of this debilitating condition and to encourage patients to discuss with their GP or cardiologist the possibility of microvascular angina being responsible for their symptoms. Tests such as MRI, stress echocardiography and acetylcholine provocation during angiography can help diagnosis.”

Treatment will vary according to the mechanism causing the microvascular angina, but is effective in a large proportion of cases. Lifestyle changes such as improving your diet, doing regular exercise, not smoking, reducing obesity and controlling diabetes can often improve symptoms.

“With the right treatment, symptoms can improve significantly,” says Professor Kaski. “But it’s important that patients realise there may not be immediate relief.

“Understanding the mechanisms causing their symptoms, and knowing that effective treatment is available can help patients deal with the condition.”

Prinzmetal angina

Prinzmetal angina is also more common in women, especially younger women. It’s caused by spasms in the coronary arteries when at rest.

Smoking is a major risk factor. It is typically treated with medications such as nitrates and calcium channel blockers.

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