You Can Know Your Real Heart Attack Risk By CT Angiography and Coronary Calcium Scoring – An Interview with Cardiologist Warrick Bishop

An “Ah-Hah” Moment on “Real” Heart Attack Risk Assessment
Cardiologist Dr. Warrick Bishop had an enlightening experience of helping resuscitate an individual on the side of the road from a cardiac event only to find out later that this person had been a patient of his which he had cleared from significant cardiovascular risk two years prior with a stress EKG. This challenged him to look at what really needs to be done to evaluate someone’s true risk of a heart attack and intervene accordingly. He became aware of and began to utilize the three dimensional CT scan (xray) of the heart for coronary calcium accumulation (without contrast dye) and with contrast (CT angiography) as excellent low risk, low cost tests that could tell the practitioner and patient the status of the plaque in the coronary arteries and what specific treatment approaches to employ, and to what level of intensity, to reduce the patients heart attack risk. The analogy of the coronary artery calcium testing would be analogous to that of the routine mammogram for breast cancer. The difference is heart disease is the number one killer in men AND WOMEN and many more women’s lives are lost to heart disease than breast cancer so this raises the question of why not screening all women starting at 60 for heart disease with this technology (and men at age 50)?

Coronary Calcium Screening
It is Dr. Warrick’s belief that coronary calcium testing (noninvasive, without contrast dye) is the “gate keeper” in that if no coronary calcium is found in the coronary arteries (and if the patient has no cardiac symptoms i.e. chest pain, shortness of breath, or significant risk factors like elevated lipids, family history, diabetes, etc.) then no further study is needed, nor treatment for coronary arterial plaque accumulation. But if there is ANY calcification found then a CT angiogram is warranted because he has seen cases where the calcification is small but the non-calcified “soft” plaque is large, and/or the plaque is located in a dangerous place anatomically in the coronary artery, and/or there is significant stenosis (narrowing) of the coronary artery warranting more aggressive treatment.

Hard (Calcified) and Soft (Non-Calcified) Plaque
The coronary calcium test without dye is a 10 minute, three dimensional scan (xray) of the moving heart that measures the calcium buildup in the coronary arteries or the “calcified plaque”. This calcified plaque may be a protective response by the body to seal off small “microvascular” ruptures of plaque with calcium to prevent penetration of the inner artery wall. This is usually a smaller percentage of the total plaque burden (i.e. generalization 20% calcified plaque and 80% non-calcified plaque; % can vary). To “see” this soft, non-calcified plaque (amount, location), which is thought to be the more dangerous plaque because it can rupture leading to clot formation in a coronary artery (heart attack), artery in the brain (stroke), lung (pulmonary embolism/thrombosis) or leg (DVT – deep vein thrombosis) the CT angiogram with dye is needed. The soft plaque (generally 3 types – unstable necrotic core or low attenuation plaque of inflamed lipids more likely to rupture; a more stable fibro-fatty plaque, a mixture of lipids and fibrous material; and a fibrous plaque or fibrous cap that is more stable that might turn into more calcified plaque) is measured by the CT angiogram which requires dye to be injected prior to the exact same test and machine (scanner) that gave you the original calcium score.

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