Why a ‘Normal’ Angiogram Can Still Miss a Silent, Dangerous Heart Attack

For

decades, the coronary angiogram has been considered the gold standard for detecting blocked arteries that cause a heart attack. When patients are told their angiogram is “normal”, it often brings relief – not just for them but also their doctors. However, experts say there is a crucial lesson learnt over the years - a normal angiogram does not always mean the heart is completely safe. A significant number of patients suffer from chest pain, heart attacks, or ongoing heart damage despite having no major blockages visible on angiography. Understanding why this happens is essential for early diagnosis and lifesaving care.

What are the limitations of a normal angiogram?

A standard coronary angiogram may help visualise large coronary arteries and identify major blockages. However, it cannot assess the entire coronary circulation. “One important reason is microvascular disease. Dysfunction of tiny vessels can significantly reduce blood flow, leading to ischemia and myocardial infarction, despite the absence of visible blockages on angiography,” said Dr Abhijit Khadtare, Cardiologist, Ruby Hall Clinic. According to Dr Khadtare, the condition is more commonly seen in women, diabetics, and patients with hypertension.

A heart attack without major blockages

Another important reason is the presence of unstable plaques that do not significantly narrow the artery. These may look harmless on angiography because they do not cause visible obstruction. However, they can suddenly rupture or erode, triggering clot formation and abruptly cutting off blood flow. “Atherosclerotic plaques may not significantly narrow the arterial lumen and therefore appear insignificant on angiography,” said Dr Khadtare. The phenomenon is now classified as myocardial infarction with non-obstructive coronary arteries, or MINOCA. Studies suggest that up to 5–10 per cent of heart attacks fall into this category, making it far from rare.

Temporary blockages with coronary artery spasms

Coronary artery spasm is another hidden culprit in which an artery suddenly constricts, sharply reducing blood supply to the heart muscle. These spasms can cause severe chest pain, abnormal heart rhythms, and even heart attacks. “Since spasms may resolve by the time angiography is performed, the arteries can appear entirely normal,” said Dr Kadtare. Also, spontaneous coronary artery dissection, or SCAD, is an under-recognised cause of heart attacks, especially in younger patients and women without traditional risk factors. It occurs when a tear forms in the artery wall, obstructing blood flow. SCAD can be subtle and sometimes missed on routine angiography, yet it can cause extensive heart muscle damage.Also read: “I’m Fit; I Don’t Smoke”: Why a 35-Year-Old CrossFit Athlete Still Had a Heart Attack

What patients must know?

According to Dr Kadtare, a “normal” angiogram must never override persistent symptoms. If you are having ongoing and recurrent chest pain, breathlessness, extreme fatigue, or unexplained sweating, you should seek further evaluation, even if angiography looks reassuring. Advanced imaging, functional tests, and careful clinical judgment are often needed to uncover hidden cardiac risk.