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If Mary's heart scan score increases from 2 to 4 in one year, it represents a 100% increase in score.
If Jane's heart scan score increases from 1002 to 1004 over the same period, it represents <1% increase, even though the true growth is the same: 2 points.
This quirk of arithmetic needs to be factored in whenever you and your doctor try to puzzle out the meaning of an increasing CT heart scan score. Lower numbers, particularly those <100, can grow at seemingly much faster rates if viewed by percent per year increase. If no effort is taken to stop the growth in your coronary plaque, then scores of 10, 20, 30, or the like can easily grow 50-100% per year.
In contrast, scores of 1000, 1500, and 2000 tend to grow at "slower" rates of 20% or so per year without corrective efforts, even though the absolute growth may be substantial. (Obviously, this bit of confusion can be best eliminated by reducing your heart scan score, but it doesn't always work out that way.)
If we were all adept at advanced math, we should probably rely on logarithmic measures of plaque increase, rather than percent increase. Or, you can just keep in mind that the rate of plaque growth must always be viewed in the context of the absolute score.
Marathon star Alberto Salazar was just released from the hospital following a heart attack and a heart catheterization that led to a stent. The MSNBC version of the report can be viewed at http://www.msnbc.msn.com/id/19653682/.
At 48 years old and holder of several American records for marathon times, Salazar's story is eerily reminiscent of Jim Fixx, who died at age 52 after writing a bestselling book, The Complete Book of Running. Thankfully, Salazar's story has a happier ending.
Fixx died at a time when prevention of heart disease was quite primitive. Lipoprotein analysis was not broadly available to the public, CT heart scans had not yet been invented. Even statin drugs were just a gleam in the pharmaceutical industry's eye.
But not so with Salazar. This Cuban-born marathoner experienced his heart attack at at a time when enormously useful steps can be taken to 1) document the extent of disease with a CT heart scan (the presence of a stent just means that one artery can't be "scored"), and 2) identify the causes of his disease.
I suspect that the fact that yet another marathoner in the limelight will once again prompt the (likely non-sensical) conversation about long-distance running and the increased risk of heart disease. Unfortunately, I fear that the real cause will be left unidentfied and untreated: Lipoprotein(a), or Lp(a).
It's almost certain that Fixx had Lp(a), given the fact that his dad had a heart attack at age 35. Running simply postponed the untreated inevitable.
I hope Mr. Salazar is surrounded by doctors who have his true interests in mind (not just procedural excitement) and ask the crucial question: Why?