His treadmill test result was normal. 6 weeks later he had a heart attack. CMC Vellore doctor shares what went wrong

A clean treadmill test often brings a sense of relief. For many, it feels like a green signal that the heart is functioning well and there is nothing to worry about. But doctors say this reassurance can sometimes be misleading. A recent case shared by a CMC Vellore-trained neurologist has sparked concern, showing how a normal report can still miss bigger, silent risks that may only surface when it is too late.

Dr Sudhir Kumar, a neurologist trained at CMC Vellore and currently associated with Apollo Hospital, recently highlighted this issue on social media, challenging the widely held belief that a normal treadmill stress test guarantees a healthy heart. According to him, this assumption is not just incorrect but potentially dangerous.

To explain, he shared the case of a 55-year-old man who experienced intermittent chest discomfort. The patient consulted a local physician and underwent a treadmill stress test. The results came back normal, and he was reassured that his heart was fine. No additional tests or evaluations were advised at that stage, and the symptoms were not investigated further.

What happened 6 weeks later?

However, the situation took a serious turn just six weeks later. The same patient was rushed with an acute myocardial infarction, commonly known as a heart attack. Further investigation through coronary angiography revealed significant multivessel coronary artery disease, indicating that the underlying problem had been present but undetected.



Dr Kumar pointed out that nothing technically went wrong with the treadmill test itself. The issue lies in how the test is understood and relied upon. A treadmill stress test is designed to detect flow-limiting blockages in the coronary arteries. These are typically seen in more advanced stages of heart disease when the narrowing is severe enough to affect blood flow during exertion.

What does the treadmill test not reveal?

What the test does not reveal is equally important. It cannot measure the overall plaque burden within the arteries, nor can it identify so-called vulnerable plaques. These are unstable deposits that may not significantly block blood flow but can rupture suddenly, triggering a heart attack.

This distinction is crucial because many heart attacks do not occur due to large, obvious blockages. Instead, they are often caused by the rupture of smaller, non-obstructive plaques that go unnoticed in standard stress testing. As a result, a person may pass a treadmill test and still carry a significant underlying risk.

The case underscores a broader concern in cardiac care: the over-reliance on a single diagnostic tool. While treadmill tests are valuable, they offer only one piece of the puzzle. Heart disease is complex, involving not just visible blockages but also the biological behaviour of plaques within the arteries.

Dr Kumar’s message is clear. A normal stress test can rule out ischemia, meaning it shows that blood flow is adequate during exertion. But it does not rule out atherosclerosis, the underlying disease process that causes plaque buildup in the arteries. Understanding this difference can be critical in preventing delayed diagnosis and avoiding life-threatening events.