Dr John M

cardiac electrophysiologist, cyclist, learner

Cycling Wed: Athletes with large atria and the effect of exercise on BP

By

Hi all,

I know; it’s Thursday morning and this is supposed to be Cycling Wednesday. My excuse is a good one. I bought an Iphone 5 yesterday and then became hypnotized by the inanimate object. Time flies with a new Apple product. Bedtime came and I said, “Crap…it’s Wednesday!.”

Anyways, I was scanning the recent AHA’s meeting abstract page and came upon two interesting exercise-related abstracts worth sharing.

The first one was on Left Atrial Size in Elite Athletes. (A side note is it comes from my Medical School–UConn). What the researchers did was perform a meta-analysis on 56 other studies that encompassed more than 6000 athletes. You can click on the abstract for the details but the short summary is that elite athletes have enlarged left atria. Endurance exercisers show the greatest LA sizes. These kinds of studies get accepted at meetings because it’s important for doctors who evaluate athletes to know about athletic variants.

The reason why this study caught my eye is that athletes are clearly at risk for heart rhythm problems, especially atrial fibrillation. We don’t understand exactly why this is, but one of the theories involves enlargement of the heart. It’s normal for the heart to adapt to exercise. We call this the athletic heart. What’s not known, and hard to sort on a patient-to-patient basis is the gray area between normal adaptation and abnormal enlargement of the chambers and muscle walls. The thinking goes that chronically enlarged chambers mixed in with years of excessive and unremitting inflammation (training) in genetically susceptible individuals leads to the athlete-arrhythmia syndrome. We are still learning a great deal about the upper-limit of exercise quantity.

The second abstract involves an issue I see every day in the office. It’s entitled Exercise Training for Blood Pressure: A Systematic Review and Meta-Analysis. 

When faced with high blood pressure readings in the office, it’s important to recommend treatment. High blood pressure is a serious problem. This is not news. The issue is what treatment? The overwhelming majority of the time, doctors prescribe a medicine. And medicines do lower blood pressure. You know my opinion: I think we don’t emphasize exercise and lifestyle enough. That’s why I like abstracts like this one. Again, in another meta-analysis of previously published studies, researchers show that exercise–as the sole intervention–lowers blood pressure. It works.

This is a contentious topic, isn’t it? If things that patients do–not doctors–like exercise and eat right, can control blood pressure than a question arises: What are the roles of patient and doctor in the treatment of high blood pressure? Right now, the consensus opinion is that it’s mostly the doctor’s job. Studies like this one should lead us to reconsider this skewed proportion.

JMM

CW: Put your arm in the machine

By

Hey Cyclists,

I know.

You ride a lot.

You eat well.

You stay thin.

So you rightfully call yourself athletic.

Congratulations.

Now, take the time in the off-season to go get your blood pressure checked.

Doing so is free in most grocery stores and pharmacies.  Plus, you get to grin at that funny voice that says:  “You must hold perfectly still…Do not move or talk during the test…I have to squeeze your arm a little.” (I can’t help myself; I always talk during the test.)

Don’t assume the red numbers will come up reassuring.

It’s surprising how many athletes can’t out-run or out-pedal their predisposition to inelastic blood vessels—high blood pressure.

Here are some basic steps to take for newly discovered high blood pressure:

  • Make an appointment with your primary care doctor. Don’t’ have a doctor?  Now you have a good reason to get one.
  • Go back and take a few more BP measurements at different times of the day. Write them down.  Check that, enter them in the smartphone.
  • Stop taking cold medicines that contain pseudofed.  These include common allergy medicines that have a “-D” at the end of their name.  (Allegra-D, Zyrtec-D)
  • Stop all arthritis drugs called NSAIDS (ibuprofen, Advil, naprosyn, Aleve).  These drugs can cause high blood pressure.
  • Be mindful of excessive salt intake.  Though salt restriction is more relevant to the non-athletic general population, there are clearly ‘salt-sensitive’ athletes.
  • Either discontinue, or cut back daily alcohol intake to less than 1.5 drinks per day.  Studies have shown that more than moderate daily drinking raises BP.  Sorry about that.

If all these conservative measures fail and the blood pressure remains high a medicine might be required.

The problem is that if your doctor treats your high blood pressure according to national guidelines this may mean taking the commonly used water pill, hydrochlorothiazide (HCTZ).  Ouch.  That’s a problem.

I suggest gently asking your doctor about the findings of this week’s important high blood pressure trial published in the Journal of the American College of Cardiology. In this meta-analysis (a review of previous studies), the researchers at Columbia University showed that—at the doses commonly used, and when used alone—HCTZ was the least effective blood pressure medicine.

The strength of this report stemmed from the inclusion of 24-hour BP monitors.  Interestingly, when single BP readings from doctor’s offices were considered, HCTZ looked reasonable, but on the more accurate 24-hour recordings it was significantly inferior to other commonly used BP medicines.

I’m glad to see this data because it supports my common-sense bias that water pills—when used alone—are lousy BP medicines.  They lower BP by increasing the elimination of fluids and electrolytes. That’s the paradox, their primary effect causes their most common side-effect: dehydration and electrolyte depletion—something most of us athletes try to avoid.

What’s more, heart rhythm doctors were brought up on the teachings from the famous 1982 MRFIT BP trial in which the highest mortality rates were found in the group of men with high blood pressure who were treated with HCTZ.  The presumption here was that low potassium levels from the diuretic increased the risk of sudden death from a rhythm problem.

For endurance athletes with high blood pressure, the most common problem is inflexible arteries, not excess salt and water. So it makes sense to use a medicine that acts on the primary problem; we call these blood-vessel relaxers, or vasodilators.  Examples include ACE-inhibitors, ARBs, and some Calcium channel blockers.

If you train hard, eat right, and still need a BP pill, it seems reasonable to ask your doctor to question the guidelines.

Maybe the guidelines are wrong?

Oops, can I say that?

JMM

Disclosure:

When my blood pressure warrants a medicine, I’ll start with a blood-vessel dilator, not a diuretic.  Unless of course there is a new wonder drug available, and I can afford it.

Just because thiazide diuretics aren’t very potent when used alone, they can be very useful as add-on agents when a single medicine fails to control BP.  That’s doctoring 201.