CW: What’s better for predicting heart disease: A CT-scanner or a Timex?

Good morning all. Cycling Wednesday fell prey to the Springtime weather in Kentucky. Right before post time last evening, our power (which means internet) went down when a large thunderstorm rolled through.

Here’s what I have for you this week:

It is hardly news to say that we need better means to predict who will die of heart disease. No matter how much you may hear about medical errors, hospital acquired infections, or even distracted driving, it’s still heart disease that kills the most of us.

The inflammation that begins narrowing our arteries starts when we are young. It percolates quietly, stealth-like for years. The young usually skate by unscathed. But all the cookies, beers, chips, inactivity and work stress adds up. The tension of life squeezes our arteries, daring them to crack or fissure. This cataclysm is one of the ways that middle age may introduce herself.

A friend, or colleague, or sibling dies suddenly of heart problems. Those of us that our “masters-aged” have likely felt these sensations of sadness, and then the reality that they may be next.

“I should probably come in and get a check-up,” is something I hear frequently in the doctor’s lounge after such a tragedy.

I agree. When you are old enough to use reading glasses it is time to think about what lurks inside your heart’s blood vessels.

But herein lies the catch.

  • What’s the best way to evaluate people without  symptoms?
  • Is it with simple tests or complex imaging procedures?
  • If we find partial blockages, should they be treated with medicines, or a procedure?
  • And…does treating non-symptomatic blockages make any difference in outcomes?

These are the tough questions that keep preventive cardiologists coming to work.

As an illustration of how tough it is to predict heart disease, let me briefly mention two recent studies that highlight opposite spectrums of complexity. One study looked at using complex imaging of the heart with modern CT scanners, and the other used a stop-watch and a treadmill.

Let’s start with the fancy new test. You have all heard about coronary CT angiography. The notion behind CT-Angio is that a CT-scan of the chest (often with the IV injection of contrast) can detect coronary artery disease. At a minimum, CT-scanners can detect calcium deposits in the heart, and at a maximum, these same machines can create beautiful 3D-images of the arteries surrounding the heart. They are indeed stunning images.

In this recent study published in the Archives of Internal Medicine, (summarized nicely here at Cardiobrief), researchers looked at the impact of using CT-scans for screening low-risk individuals. They compared 1000 South Korean patients that got a CT scan to a 1000 who did not.

There were interesting findings.

  • CT scans found more than 200 (of 1000) patients with heart blockages.
  • Many more patients in the CT scan group were treated with aspirin and statins.
  • More patients in the CT group underwent other heart tests or procedures.

All this sounds good, right? CT scans enhanced detection of disease, and more patients got treated.

But their final, and most telling finding was that none of this mattered.

  • At 18 months follow-up, there was one heart-related event in each group. In other words, the enhanced detection of CT-angiography had no impact on real outcomes!

(Now…I know it was a small study with short term follow-up. Larger trials are needed to be more conclusive. Plus, these were low-risk patients; the results may have been different in moderate-risk patients.)

The point is that detecting heart disease, starting medicines, and even doing procedures, in patients without symptoms, may not make much difference in real outcomes.

So are their any other tests that could be done to better predict heart outcomes?

You bet…check this out:

In a recent study published in the Journal of the American College of Cardiology, researchers studied the long-term predictive value of a single measurement of fitness at age 45, 55 and 65. Their metric did not involve radiating the patient, nor did it require injecting any potentially kidney-damaging dye. Rather they simply measured how long it would take a person to run a mile. They used a Timex.

The Cooper Institute in Dallas followed 11,000 patients for 23 years. They found that differences in fitness (as measured by mile times) were associated with marked differences in the chance for heart-related death. Listen to these numbers: A 55 year-old man who measured to be low fitness (>15 min/mile) had a 34% lifetime risk, while a high fitness (<10min/mile) 55 year-old had only a 15% risk.

They also found one other striking result

“the combination of high fitness with a high traditional risk factor burden was associated with a lifetime risk for CVD death that was comparable to that of a person with low risk burden.”

At least in their cohort, being fit counterbalanced having many of the traditional risk factors. That’s a strong statement.

Folks, I am still suffering a little withdrawal symptoms from Europe. All that pragmatism and mastery of the obvious was very infectious. But even so, I still love telling you about simple, inexpensive tests that speak strongly to our cardiovascular risk.

A simple measurement like the time it takes one to run a mile cannot make beautiful images of  the heart’s blood vessels. It just tell us about the end result–it measures function. And how things function aren’t always predicted by how they look.

When will it be that the message of fitness gets broadcasted as loud as the next new drug, bio-absorbable stent, or million dollar x-ray machine?

Taking care of the heart isn’t always complicated.

If it were, I’d only be a blogger, not a doctor.

JMM

5 comments

  1. I would imagine writing a blog must be an odd experience; you invest effort, and yet have little idea if people are reading it, and whether your comments are of value.

    I wanted to take a minute to tell you that this reader values your insights — particularly since you are able to explain complicated material in terms those of us in the lay audience can understand.

    Kudos…………..

  2. I love this stuff, John.

    Too many doctors( and patients!) ignore the lifestyle approaches to heart disease, preferring “squishing” (PTCA) and drugs instead.

    -Steve

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