Friday, July 6, 2018

A Stress Test.... Free Associations





I was just starting to breathe a little heavier.  The nurse running the test has been talking to me - continuously for the last nine minutes.  She was bright, pleasant, a great conversationalist but more to the point - everything she said seemed highly relevant. From time to time she would ask how I was doing, check my blood pressure and tell me what my heart rate was.  Some time at about the 9 minute mark she said that I might need to break into a jog for the next level.  It was a 16% grade at 4.1 mph.  The treadmill tilted up and it was a smooth transition.  I was still walking at a fast pace.  "Your heart rate is 160 are you OK?"  I was feeling very good.  Still talking in full sentences and not feeling stressed at all.  My left knee was sore and I said: "My knee is sore and I don't want to break into a jog.  I will complete this stage and call it a day."

I did have room at the end and am fairly confident I could have knocked off the next stage.  I have done it many times in the past starting with a test at about ago 42.  There were a number of considerations holding me back.  The knee.  It was nothing big.  When you exercise a lot as an adult - episodic knee pain is all part of it.  Secondly, a history of paroxysmal atrial fibrillation.  I probably got it in the first place from running heart rates too high for my age.  I did not want to flip into another episode of atrial fibrillation.  Third, the target rate.  Before starting, the supervising nurse told me that the target heart rate for a guy my age was 140 bpm and I was over that with no signs of ischemia or more importantly a widening QRS interval (I take flecainide).  Fourth, I was just happy to be there.  Even though I have had 5 exercise stress tests over the last 25 years, the last one was at the Mayo Clinic about 10 years ago.  These things are a lot less certain with age. As I was on the treadmill, I kept thinking of a review I read in the Medical Clinics of North America many years ago: "40% of 85 year olds have significant coronary artery disease".  Of course those are the 85 year olds who survived to that age.

I had other associations while I was walking and talking. I take a cardiac history on every person I talk with. Some are more detailed than others. I know a number of ways that stress tests can be failed. I know from talking with people what happens when your ECG suddenly shows signs of ischemia. Generally the next step is a Cardiologist spraying nitro into your mouth.  I also know that passing a stress test is a generally a good sign, but it is not a guarantee. Nothing in medicine is.  Too many people have told me about cardiac problems in the absence of a positive stress test, including an infarction in the absence of any occlusions.  Irrespective of the result, I would maintain humility and strive even more to avoid the trans fats that are quantitatively too low to make it on the food label.  And of course all of that bakery with thick frosting - the first display you encounter in any supermarket.           

I had the exercise stress test two weeks ago.  Four days earlier I was doing my usual dictation of an assessment in my office and as I stretched back - I experienced an intense sharp burning pain going down the left side of my sternum.  It lasted about 5- 10 seconds.  I have been having this pains for at least a year all over the chest, left shoulder and back.  At one point they were clearly musculoskeletal in origin and I could replicate them by certain movements or flexing certain muscles.  But then the discriminatory ability was gone.  All of the tricks I learned in medical school and residency about the  difference between musculoskeletal pain and true cardiac pain or angina did not apply.  One of the things they never teach you is that when you get old - all of the routine pains that you live with every day meld into vague pains all over your torso.  Was that chest pain or did it originate in my back, neck or shoulder?  Arthritic pain or pain from trying to do too many pull ups last night?  At some point I just decided to go in to see my internist to see if we could figure it out.

My internist has known me for 30 years.  Any chest pain in the early part of that period was immediately dismissed as musculoskeletal pain.  He knew I was a compulsive exercise fanatic and between the ages of 30 and 55 probably cycled 200 miles per week or the equivalent. In the winter, I would speedskate as much as possible.  My goal was to end the season by doing as many laps as possible in an hour on the John Rose Oval - one of the few refrigerated speedskating outdoor tracks in North America.  Doing that kind of exercise gets the heart rate up to very high levels.  During interval training up to 190+ beats per minute.  Whenever the subject came up during those years my internist would say: "You do a stress test every time you exercise".

That all changed at age 55.  I was out doing a warm up on the speed skating track.  I looked down at my heart rate monitor and it read 170 bpm.  One lap later it was chirping loudly and now it read 240 bpm.  I felt my carotid pulse and it was the irregularly irregular rhythm of atrial fibrillation.  That led to 2 hospital admissions, 2 cardioversions, 2 consultations with a sports cardiologist at the Mayo Clinic and 2 exercise stress tests on a bicycle at Mayo.  I ended up on flecainide  with the advice to consider an ablation procedure at some point in the future as long as the flecainide continued to work and "if the technology improves".  That is a direct quote from one of my electrophysiologists.

During the bicycle stress tests, I ran my heart rate up to 170 bpm and could have gone higher, but was concerned about triggering another episode of atrial fibrillation that would no longer respond to flecainide.  On echocardiography, I have features that are seen in some series of cyclists who do high levels of dynamic exercise - primarily an large left atrium and a slightly enlarged aortic root.  During dynamic exercise, there is a steady increase in blood pressure despite the fact that stroke volume peaks at about 120 bpm and main contributor after that point is heart rate and sympathetic nervous system output.  My adaptation was to try to keep my heart rate at 140 bpm or lower when exercising and lately 130 bpm.  It is good to know I can go higher even for brief periods of time.

So the coronary arteries may be OK, but that leaves paroxysmal afib and the enlarged aortic root/aorta.  We have only recently discovered the role of the layered extracellular matrix in aortic anatomy. Like most of these structures disruption of those layers can result in permanent weakness.  It is also known that high levels of dynamic exercise results in aortic enlargement.  I have not seen any outcome studies of those individuals - but it would be useful to find an expert. 

My next step is to see a Sports Cardiologist about the afib and aorta.  I anticipate that he or she will wonder about why there is an old man in the examination room trying to get as much performance as possible out of an aging cardiovascular system.  If that question comes up, the response is simple:

"I don't want to die on the side of the road from a blown aorta because I tried to race a 40 year old up a hill.  I need your most conservative estimate on how I can prevent that."

And so it goes......


George Dawson, MD, DFAPA





         

10 comments:

  1. The prevalence of Afib in endurance athletes is underappreciated...I dialed it back and focused more on strength and flexibility. I know too many people who ran into problems when they thought they were doing something good for themselves.

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    1. Agree - I even got bad advice along the way from experts.

      Nobody should be told to "keep doing what your are doing" after a first episode of lone afib and a clean stress test and echocardiogram.

      It ignores all of the animal research showing that you can create afib just by consistently overpacing the heart.

      To say nothing about what is not known about the effect on the aorta.

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  2. I'm surprised that endurance events still have a strong following given what we've learned about HIIT, muscle confusion, flexibility, the need for strength (especially squats and lunges) to counter sarcopenia, not to mention the enormous time and cost involved in competing in marathons and triathlons.

    There have been a few ultra athletes who have had major medical problems and even fatalities and this is widely known in fitness circles.

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    1. The article on possible CAD associated with endurance running should have been an eye opener. I recall a physician who was an "Ultra-marathoner" who had an MI on day 5 or 6 and purportedly finished the last 2 days of marathons. If that is true - it reflects a serious problem with judgement in my estimation.

      The recent articles about resistance training and sarcopenia seem a little off to me. I always considered sarcopenia to be more of a serious endocrine condition rather than a lack of training. Deconditioning is widespread and major cause of chronic pain and further injury.

      I like the HIIT concept. I like all of the new toys that will help you measure it (but the accuracy of wrist monitors needs to go some before I trust them). Also a question of how much you can do on aging joints.

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  3. I was referring to age related sarcopenia, the natural loss of muscle mass with age which really is a type of deconditioning. As you pointed out, most of it is just disuse atrophy. This of course relates to future falls, hip fractures and lots of ugly problems later on in life. There was a really impressive twin study in Gerontology in 2016 by a researcher named Steves on lower body strength and cognition. I rarely make changes based on one study but the results were so impressive I have become a pistol squat and Bulgarian squat fanatic. Which is the chicken and which is the egg? Loss of mental vitality or loss of spring in the step? I don't really care, I'll work on one if it helps the other.

    It was always my impression that young guys need to stretch more and older women need to do more resistance training though we're finding out own body weight is just fine for most people. When I was young like most dumb young guys I worked on chest and biceps but now legs are the focus. It's next to impossible to put on muscle mass at my age (I'd rather not anyway since strength to weight is key) but functional strength gains are proportionally just as good.

    Some of what we're talking about with deconditioning isn't even that geriatric. I see it in millennial men. Men who haven't worked out since high school gym class struggle to do one pullup at 30. I don't know too many young men who can do five legitimate pullups. When you compare that to WW2 military fitness standards, it's kind of sad. Grandpa was in serious shape in his day when the analog world was the proving ground for manhood.

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  4. This is kind of where I am now on this issue:

    https://www.thehealthyhomeeconomist.com/wp-content/uploads/2011/08/marathon2.jpg

    I think if people want to run, they can get more out of fast miles and 400s than marathons in much less time.

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    1. Agree - also think that the type of HIIT you do can be optimized for genetics and lifestyle. For example many generic genetic tests this days will tell you if you have more fast twitch fibers than average and that may translate to sprinter genetics and musculature. To some extent I wonder if people aren't sorted into power/sprint versus endurance at an early age based on those genetics but I have never seen the studies done. Big confounders would be access to coaches who know how to train people. I think there is a serious deficiency at that level especially high school track and field.

      Would also like to see optimal HIIT routines per exercise (eg. bike versus sprint) for a number of exercises.

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  5. I agree...I'll never be the guy on the right or never could be because I'm a natural ectomorph but I sure as hell don't want to be the guy on the left. Probably the guy on the right may be glorious under 35 but run into problems later on so there's a middle ground as you get older (strength to weight more important than hypertrophy). BTW some of the data on the 99 dollar DNA test sites will give you that fast twitch info. Training for 100s might lead to the guy on the right but training for 400s or miles will lead to a much leaner body type but not the guy on the left.

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  6. I would go so far to say that the guy on the left has serious problems as evidenced by a lack of muscle bulk c/w being an endurance athlete. He is burning too much protein for calories. I tend to see it in people who either stop eating or get most of their calories from alcohol. In some of the literature on over training that I have read there are also inflammatory theories.

    I consider loss of medial thigh muscle to be a particularly bad sign

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  7. Agree totally about thigh strength and leg strength in general. The Gerontology article was a real pivot point for me in terms of the importance of leg strength for not only mental health but all cause mortality. The soleus/quad/hamstring is the second heart, without it and venous valves, basically we'd all have CHF with massive ankle edema and shunting of blood from the brain.

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