When Chest Pain Has No Clear Answer

By Asst Professor Keh Yann Shan, Consultant, Cardiology

For many people, chest pain is an unsettling symptom. Yet even after seeking medical help, some patients find that answers do not come easily. Despite repeated tests and specialist visits, standard investigations may not always reveal a clear cause, even as their symptoms persist and their quality of life suffers. A condition known as Angina with Non-Obstructive Coronary Arteries (ANOCA) may help explain why.

What is ANOCA

Angina is a heart condition characterised by chest discomfort or tightness, most commonly caused by narrowed heart arteries. That said, chest pain can also arise from non-cardiac causes such as gastric or muscular conditions, which can feel similar to angina.

When a patient presents with chest pain, doctors first look for heart artery blockages, which remain the most common cause of angina. However, not all patients with angina have severely narrowed heart arteries. Based on data from the Singapore Cardiac Data Bank, nearly one in five patients with stable angina did not have any severe narrowing of their heart arteries. Those whose cardiac tests do not reveal severe heart artery blockages are now recognised as having ANOCA, a condition also more commonly found in women than in men.

ANOCA can be caused by many different underlying conditions, including disorders of the heart arteries such as coronary microcirculatory dysfunction, where tiny blood vessels of the heart fail to work properly, spasm of the heart arteries, and myocardial bridging, a condition where the heart artery is compressed by the surrounding heart muscle. Because these causes affect different parts of the heart's blood vessels, identifying the specific cause in each patient is where the real challenge lies.

Standard coronary angiography, which looks for narrowing in the major heart arteries, is effective for most patients but cannot detect problems in smaller blood vessels or sudden spasms of the heart arteries. For patients with unexplained angina despite normal scan results, or whose symptoms persist despite treatment, further testing may be considered. These include nuclear stress tests, cardiac magnetic resonance imaging, and functional coronary angiography. Unlike standard angiography, functional coronary angiography measures how the heart's blood vessels behave, rather than how they look on scans. It uses specialised pressure wires and medications to assess blood flow and pressure within the coronary arteries, including the microscopic vessels invisible to standard imaging, giving doctors a much clearer picture of what is truly going on.

A Long Search for Answers

For three years, Ms Desker lived with recurring chest pain that standard tests could not fully explain. Although she had previously undergone a successful angioplasty to open blocked heart arteries, the tightness in her chest eventually returned. Repeated scans came back normal, yet the symptoms persisted. The frequent medical visits and consultations took their toll, not just physically and financially, but emotionally too, leaving her without a clear answer.

It was only after she was referred to NHCS in 2025 that functional coronary angiography finally provided the answers she had been searching for. She was diagnosed with coronary vasospasm, one of the underlying causes of ANOCA, in which the heart arteries suddenly tighten and restrict blood flow. With targeted medication, Ms Desker's symptoms have largely resolved, allowing her to return to her daily activities with greater confidence.

How Can ANOCA Be Treated

ANOCA is being increasingly recognised around the world, and with that comes a clearer path to diagnosis and treatment for patients like Ms Desker. When an underlying cause is known, doctors can prescribe targeted heart medications to help ease symptoms and improve quality of life.

To date, however, ANOCA treatment has not been proven to reduce the risk of heart attacks or other serious cardiac conditions. As such, ANOCA testing is currently recommended only for patients whose angina persists despite thorough specialist evaluation.

While research into ANOCA continues to evolve, one thing is clear: understanding the underlying cause of chest pain remains a vital first step in guiding treatment, easing anxiety, and restoring patients' quality of life.