Zero Cardiac Calcium Reduces Heart Attack Risk

Patients with a coronary artery calcium (CAC) score of zero have significantly lower risk of future heart attack or stroke, claims a new study.

Researchers at the University of Texas (UT) Southwestern Medical Centre (Dallas, TX, USA), Baptist Health South Florida (Miami, FL, USA), and other institutions examined the computerized tomography (CT) scans of the chest and heart of 6,184 patients (45-84 years of age) participating in the multi-ethnic study of atherosclerosis (MESA) study, with no prior history of heart attack or stroke. All participants underwent two CAC scans to establish CAC score; 3,415 participants had a CAC score of O and 508 had a score of 0-10.

The results showed that during median follow-up of 10.3 years, there were 123 cardiovascular disease (CVD) events. Patients with a CAC score of 1-10 experienced higher CVD event rates (5.5/1,000 person years), compared to 2.9/1,000 person years in those with a CAC score of 0. Age, current smoking, and hypertension significantly predicted CVD, but non HDL-cholesterol significantly predicted CVD only in those with a CAC score of 1-10. The study was published on August 7, 2017, in JACC: Cardiovascular Imaging.

“Our findings suggest that individuals with no calcium buildup in their blood vessels may not have to take statins, despite the presence of other risk factors that cause coronary disease,” concluded lead author cardiologist Parag Joshi, MD, of UT Southwestern. “New findings suggest that adding a CT scan for calcium may be worthwhile as doctors and patients discuss treatment options. A CT scan is a test that is easily done, costs about 100 bucks in most major cities, and can give a lot more information about the patient's 10-year risk.”

CAC is a noninvasive marker of plaque load in coronary arteries indicative of atherosclerotic plaque, but bears no relationship to plaque stability or instability. It is usually determined by conducting an electron beam computerized tomography scan (EBCT). Advantages of CAC scoring include variability on repeated testing and consistent thresholds of risk. Disadvantages include radiation exposure and lack of further information regarding a patient's functional capacity, which could be inferred from an exercise tolerance test.

Related Links:
University of Texas (UT) Southwestern Medical Centre
Baptist Health South Florida