The mystery element shrouding cardiac syndrome X or its less dynamic nomenclature – microvascular angina – is mainly due to the fact that the cause of this particular type of chest pain or angina cannot be detected in an angiogram. Microvascular angina doesn’t show up on regular angiogram reports as the coronary arteries (major blood vessels supplying blood to the heart) of the affected individuals will be normal without any blockage or problems.
“That’s because the main problem is in the microvasculature comprising small vessels like arterioles, capillaries and venules as part of the heart muscle,” explains Gurugram-based Dr Sanjay Chugh, director of cardiology and interventional cardiology, Aarvy Health Care Super Speciality Hospital. These blood vessels are small and hence, cannot be detected during a regular angiogram.
He further explains that in this condition, people will feel chest pain during exertion or mental stress and it could present itself as an acute coronary syndrome with a sudden reduction in the flow of blood to the heart.
“But even then, the epicardial arteries or the coronary arteries would be normal and hence it was named cardiac syndrome X,” he adds.
The only way of confirming this cardiac condition is to establish that there is myocardial ischemia which is a reduction in the flow of blood test during a heart stress test.
“That’s when you realise that there is a cardiac issue at the microvascular level,” explains Dr Chugh.
The causes of cardiac syndrome X
According to Dr Chugh, there is an overlap between metabolic syndrome X (a cluster of conditions like obesity, diabetes, high blood pressure and cholesterol leading to heart disease risk) and cardiac syndrome X.
Experts explain the smaller capillaries and blood vessels (microvasculature) also could get constricted due to endothelial dysfunction. Endothelial dysfunction is a non-obstructive coronary artery disease where the blood vessels get affected eventually leading to disruption in blood circulation to the heart. According to American Heart Association, endothelial dysfunction could be regarded as a marker for inherent atherosclerotic (blockage in arteries) risk in an individual.
Dr Keshava R, senior director, interventional cardiology, Fortis Hospital, Cunningham Road Bengaluru, says that due to these conditions, the overall blood circulation to the heart gets affected and causes vascular angina.
“The blood supply to the muscle is affected and angina comes from the microvasculature and not from any blockages,” adds Dr Chugh.
Diagnosis of microvascular angina
To diagnose the main issue regarding the chest pain, first, an ECG at rest is done to check any irregularities. Sometimes even the ECG test may be normal, so next, an angina stress test is conducted.
An angina-stress test may include a treadmill test combined with a perfusion scan, a nuclear imaging test to check blood circulation to the heart muscles or a treadmill test combined with an echocardiogram to check for abnormalities in the heart’s structure.
Another test done to check for myocardial infractions is a troponin test which measures the levels of troponin T or troponin I proteins in the blood. “These proteins are released when the heart muscles are damaged,” explains Dr Keshava R.
Cardiac syndrome X common in women
According to Dr Chugh, some studies have shown this condition is more common among women than men and it could be a result of hormonal imbalance.
“It could be because of the lack of estrogen in women who are post-menopausal; that could affect the functionality of the blood vessels,” reasons Dr Chugh. Estrogen in women is known to have a protective effect on the cardiovascular system. Lack of estrogen after menopause could cause changes in the walls of the blood vessels, which may enable plaque and blood clot formation. It may increase fibrinogen in the blood which is a substance that makes blood clot.
Hormonal changes can also affect the autonomic functions (the body’s automatic processes such as breathing, heart rate, blood pressure, sweating etc) of the body.
“If the androgenic drive due to lack of female hormone estrogen (estrogen levels reduce post menopause) is more, it can affect the vascular reactivity to a certain stimulus like vasodilation (widening of blood vessels) or vasoconstriction ( narrowing of blood vessels),” reasons Dr Chugh.
Treatment
People with this condition can be given anti-anginal medications like alpha blockers, calcium channel blockers, beta-blockers or nitrates.
Doctors explain that alpha-blockers (blood pressure medication) improve microvascular angina by restoring vascular activity.
People with these conditions are often given medications to lower their blood pressure and improve blood circulation.
“These allow the vessels to relax and dilate so the perfusion (passing of blood through blood vessels or blood flow) to the vessel improves,” explains Dr Chugh.
In postmenopausal or menopausal women who have angina, estrogen helps with dyslipidaemia (imbalance of lipids) as well.
A C-reactive protein test may also reflect the coronary inflammation and the person can be treated with statins.
Sometimes for better accuracy, a nuclear angiogram or MUGA scan is also done. In this, a nuclear medicine test scan shows the heart’s chambers in motion and can also show how much blood is pumped with each heartbeat.
However, experts explain cardiac syndrome X is nothing to be alarmed about if you have identified the background issues leading to it.
“Timely lifestyle intervention followed by medication is helpful in managing the syndrome well,” explains Dr Keshav R.
Takeaways
Cardiac syndrome X now known as microvascular angina is caused when small blood vessels and arteries start to narrow, affecting blood circulation to specific parts of the heart. The main coronary artery remains free of any plaque or blockage. As a result, this condition cannot be detected through an angiogram. Doctors point out that with some lifestyle changes, this could be managed without any major complications.
