Trains, planes, and heart scans 4. September 2009 William Davis (10) A Heart Scan Blog reader posted the following question:It is not clear to me why getting a cardiac scan is the necessary first step, if in fact the next step would be to bring down small LDL particles which is revealed on a NMR lipoprofile or VAP test. Why isn't the NMR or VAP test the first thing?Good question. Think of it this way:Lipoproteins, as measured via VAP (Vertical Auto Profile) or NMR (Nuclear Magnetic Resonance), provide a snapshot of risk from a metabolic viewpoint at that moment. Lipoproteins shift with the tides of age, menopause, weight changes, even what you ate last evening for dinner (especially small LDL). There are also other factors that cause coronary plaque, as well, not revealed through lipoprotein testing, such as vitamin D deficiency, smoking, high blood pressure, phosopholipase A2, lipoprotein(a), inflammatory factors, thyroid dysfunction, omega-3 fatty acid deficiency, etc. A heart scan, providing a coronary calcium score, provides an indirect measure of coronary plaque that is the sum total of lipoprotein and other plaque-causing factors that have accumulated up to the time of your scan--regardless of the cause.It means that two females, each 60 years old, with 70% small LDL, HDL 42 mg/dl, triglycerides 150 mg/dl, and mild hypertension, have identical markers for potential coronary risk, but can have widely different heart scan scores. One might have a score of zero, while the other might have a score of 300. Why would the same panel of causes measured at one moment yield wildly different quantities of plaque? Several reasons:1) The lifestyles, eating habits, and weight of each woman differed during their earlier years, not currently reflected in this moment's lipid or lipoprotein patterns. Perhpaps one experienced several years of extraordinary stress from a failed marriage, or suffered through two years of depression that caused her to smoke and overeat. 2) There are hidden factors that affect coronary plaque growth that we are presently not able to detect, e.g., vitamin D receptor genotype, cholesteryl-ester transfer protein variants, variation in inflammatory factors. If we can't measure it, we won't know whether it might influence coronary plaque risk. With all the changes that occur over a person's life, with the uncertainties of yet-to-be-identified causes for coronary plaque, how can you possible know what your risk for heart disease truly is? Yup--a heart scan. Do it and you will know.