Heart scan: Standard of care?

If coronary disease is easy to detect by measuring coronary calcium, shouldn't this represent the standard of care?

In other words, if you've been seeing your doctor and he/she has been monitoring cholesterol levels and, inevitably, talks about statin drugs, then you have a heart attack, unstable angina, or die--yet never knew you had heart disease--isn't this negligence?

Coronary calcium, and thereby coronary atherosclerotic plaque, are markers for the disease itself. Unlike cholesterol, high blood pressure, etc., that represent risk factors for coronary atherosclerotic plaque, coronary calcium is a measure of total plaque: "soft" elements like lipid collections, necrotic tissue, fibrous tissue, as well as "hard" elements like calcium. Because calcium occupies 20% of total atherosclerotic plaque volume, it can be used as an indirect "dipstick" for total plaque.

So why isn't an unexpected heart attack, hospitalization for unstable heart symptions, emergency bypass, etc., not regarded as potential malpractice? These are not benign events, but potentially life-threatening.