A normal cardiac stress test is reassuring. But it does not necessarily mean that your coronary arteries are free from atherosclerosis.
A cardiac stress test, often performed while walking on a treadmill, shows how the heart responds to exercise.
It can help detect myocardial ischemia. This means that the heart muscle is not receiving enough blood during exercise.
But coronary atherosclerosis can exist without causing ischemia.
Plaque may already be present without narrowing the coronary arteries enough to restrict blood flow during exercise. This is often called non-obstructive coronary artery disease.
A cardiac stress test can therefore be normal even when coronary plaque is present.
What Does Coronary CT Angiography Show?
Coronary CT angiography looks directly at the coronary arteries.
It can detect atherosclerotic plaque and show whether the arteries are narrowed. It can identify both non-obstructive and obstructive coronary artery disease.
The two tests answer different questions.
A cardiac stress test asks:
Is blood flow to the heart reduced during exercise?
Coronary CT angiography asks:
Is atherosclerotic plaque present in the coronary arteries?
This difference matters for cardiovascular prevention.
Finding coronary plaque can identify atherosclerosis before it causes significant narrowing or ischemia. It can also provide information that helps guide cardiovascular risk assessment and preventive treatment.
The long-term SCOT-HEART trial studied 4,146 patients with stable chest pain. Patients received standard care either with or without coronary CT angiography.
After 10 years, coronary heart disease death or non-fatal heart attack occurred in 6.6% of patients in the CCTA group and 8.2% in the standard-care group. Preventive treatment was also prescribed more often after CCTA-guided assessment.
A normal cardiac stress test can provide valuable information about ischemia. It does not exclude coronary atherosclerosis.
