Did you know heart CT scans can identify narrowed coronary arteries better than a stress test?
For many years, the standard medical evaluation to look for heart disease has been a stress test. Walking on a treadmill, with continuous heart monitoring and periodic blood pressure checks, is still considered useful, and provides a functional heart evaluation.
The determination is based on stressing the heart with exercise and evaluating the cardiac response by electrical changes on the ECG. With patients suspected of having microvascular disease – when large coronary arteries may be normal but tiny arterioles are stiff and narrowed – the stress test is done with usual monitoring, followed by an immediate heart echocardiogram to further evaluate heart function under physical stress.
Nuclear Stress Tests
In addition to the treadmill evaluation, a nuclear dye may be injected into a vein and the heart is scanned to evaluate blood flow, comparing the heart at rest with blood flow through the heart muscle with exercise. These comparisons evaluate differences in blood flow and identify possible coronary artery narrowing.
Invasive Coronary Arteriogram – Coronary Angiogram
The gold standard for evaluating narrowed coronary arteries is the invasive coronary angiogram. In that procedure, a catheter is placed in an artery, threaded to the heart and dye visible under fluoroscopy X-rays is used to outline the inside of the arteries supplying the heart muscle with blood and oxygen. If an artery is dangerously narrowed, the blockage can be dilated and stented to keep it open and prevent a heart attack. So, this test can be both diagnostic and therapeutic.
CT Coronary Angiogram (CT = Computed Tomographic Angiogram of the coronary arteries of the heart)
Johns Hopkins researchers recently published their research comparing the noninvasive cardiac CT scan with stress tests and coronary angiograms. The CT angiograms showed a 91% accuracy in detecting or ruling out an artery blockage. Stress tests measured out at 69% accuracy.
Both heart CT scans and invasive angiograms are more expensive than stress tests. Stress tests provide information, but the CT scan is better. If the CT looks good, further medical follow-up will still be required, but you avoid complications, higher radiation exposure, and higher cost of the invasive procedure.
No evaluation carries 100% accuracy. The American Heart Association and the American College of Cardiology recommend stress tests as a first line screening tool. These guidelines may change because of this study showing the increased accuracy of the CT angiogram.
For more information on heart CT scans and the calcium score check out: https://www.nlm.nih.gov/medlineplus/ency/article/007344.htm
Betty Kuffel, MD