A Better Way to Assess Heart Disease Risk

Risk factors only go so far in assessing one's chances of something happening.  The traditional Framingham Risk Calculator divides heart disease risk into low (<10%), moderate (10-20%) & high (>20%) over the next 10 years.  However, the downfall is that its data is based upon Caucasians in the Northeast.

Does this really matter? Well, we know that the population distribution of strokes varies with an increase risk in the Stroke Belt in the South.  Racially speaking, there does appear to a subtle but real difference in prevalence of prostate cancer based upon ethnicity.  Which is why it's so important to look at the participants in any given study to determine whether the data can be generalized to you.

For heart disease, if we're suspicious, we can order a stress test.  But not everyone can get active enough on a treadmill and not everyone wants an IV stuck in their arm for a chemical stress test or nuclear imaging, especially not for screening asymptomatic patients in order to catch someone early enough in the disease process when we can make a difference and prevent a negative clinical outcome.

That's where the not-so-new kid on the block, coronary artery calcium scoring or CAC, comes in as it does a great job of predicting heart disease but at the risk of radiation exposure.  We like to claim that the radiation is minimal but the truth is that human errors have led to excessive radiation exposure during radiologic imaging.

One solution is the new darling, carotid artery intima media thickness (CIMT) assessment, which involves a very quick ultrasound of (both sides of) one's neck.  In a study published yesterday in the New England Journal of Medicine, the authors concluded that CIMT of the internal carotid artery (ICA) improved heart disease risk stratification beyond that achieved by the Framingham risk calculator alone.  The authors arrived at their conclusion after following 2,965 members of the Framingham Offspring Study cohort for over 7 years. 

Since no physical exertion, ionizing radiation or IV is involved, perhaps we should consider using CIMT as an intermediate step between pure risk calculation and CAC scans prior to stress testing & imaging in asymptomatic patients?  For now, that makes sense if you're a Caucasian from the Northeast.

One last thought: let's say you'd like to see if your coronary arteries have improved from lifestyle modifications after your initial CAC scan.  That means undergoing another scan and thus accepting more radiation exposure.  On the other hand, let's say you'd like to see if your CIMT has improved from lifestyle modifications after your initial ultrasound scan.  No ionizing radiation was required the first time and none will ever be required to repeat your CIMT scan!  Just something else to think about.

Disclaimer:  I serve as a medical consultant to HeartSmart Technologies EyeCare Division which markets CIMT to optometrists (whereas HeartSmart IMTplus focuses on the MD/DO segment).