In just a minute we'll get to the topic of today what you can and cannot learn from a stress test
when someone we know has a heart attack we worry about the possibility of having a heart attack
ourselves so we rushed to the doctor and we asked how about a stress test a stress
test is a procedure used to measure the heart how the heart works while exercising
on a treadmill an exercise bite you can do it with drug induction as well you give a drug and it
causes the heart to beat fast there are four basic types of stress tests drug-induced stress tests
they bypass exercise as I mentioned it uses a drug usually adenosine to stress the heart and cause
the arteries to dilate stress EKG or stress ECG that is the original stress test the patient walks
for about 10 minutes on a treadmill and you get an EKG you don't have the nuclear studies now we'll
talk about the nuclear studies in just a minute but we show a clip I think it's NBC News video
about this topic a little bit later you'll see a couple of numbers in there which indicate they're
talking about stress EKG the first is that it says there's only 3.5 million being done per year the
reality is in 2018 there were 8 million nuclear stress tests done and a little bit less than a
million stress EKGs done in the US alone again in 2019 I haven't seen the data yet 2020 that number
plummeted the other difference if you go to that link and you watch the whole video you'll see it
listed as two to three hundred dollars that's the other tip off that's a stress EKG not a stress
nuclear test we'll talk about those a little bit further and we can talk about them in the Q&A
as well stress echo is also done it's the same as a stress EKG or nuclear stress test except
that it uses a cardiac ultrasound or echo nuclear stress test is now by far the most common there
are 10M nuclear stress tests done for every one of the other types that we're talking about again as
I said over 8 million were done per year up until 2020 with COVID instead of using echo they do have
EKGs as well but they also use radioactive thallium tracers so what can a stress test actually tell
you well according to the Mayo Clinic and I have some issues with the Mayo Clinic but we're going
to go ahead and quote them on this topic it shows how your heart works during physical activity well
that's true it can reveal problems with blood flow within your heart well that's true too
it may also guide treatment decisions measure the effectiveness of treatment or determine the
severity if you've already been diagnosed with a heart condition that's true as well diagnosis
coronary artery disease well if it's a positive test it can help it can help indicate the need for
other tests but there are a lot of false positives over 25 percent of positive stress tests are false
positives and as we'll show later on it depends on how you define false positive and false negative
clearly at least 25 percent of negatives are false negatives as well again back to what Mayo Clinic
says it diagnoses heart rhythm problems and guides treatment of heart disorders again you
start seeing me going a little bit like that from Harvard Health expert guidelines now discourage
just in case stress testing it's not a hundred percent accurate if stress testing were 100%
accurate everyone would have them regularly and that's not recommended but it's quite often done
it cannot absolutely rule out coronary artery disease or diagnose it a quote normal stress
test can't rule out the chance that a plaque will later rupture and block an artery the US
Preventive Services Task Force urges physicians to stop routinely offering exercise stress
testing the tide is turned against exercise stress testing for otherwise healthy men even men with
risk factors there are better tests an exercise stress test is designed to find out if coronary
arteries contain fatty deposits or plaque and here's the key that block a vessel 70% or more you
can still have a heart attack in fact most heart attacks occur in people with blockage less than 50%
which we'll get to here stress tests are the go-to measurement for arterial plaque
unfortunately and ironically stress tests don't measure plaque they only measure blood flow they
can't detect plaque unless there is greater than 50 to 70 percent blockage of the blood flow 86%
of heart attacks occur in people with less than 70 percent occlusion and 68%
of heart attacks occur in people with less than 50% so it's no wonder that the Tim Russert story
happened and all of us know stories of people that had a negative stress test were greatly
relieved and then had an event so heart attacks could happen even though a stress test won't show
anything increased blockage does not correlate with the plaque's susceptibility to rupture
and that's what the problem is a lot of this assumption about stress tests is based on
the incorrect assumption that it's the amount of plaque that you have and it's not the amount it's
the status of the plaque whether it's inflamed or not so if you look up accuracy of stress tests
you'll see a bunch of numbers you'll see between 60 and 80 percent you'll see nuclear stress tests
is eight quote 80 to 90 accurate but then start digging a little bit deeper and find out what they
mean by accurate and then ask the question well actually you can look it up you can google it
you'll see the snippet coming from I think one of the NIH references saying 1.5 million of those 8
million stress tests are known false positive or false negative so again you got to ask yourself if
you're feeling lucky stress tests like humans make mistakes or errors too and doctors label
such errors as false positive or false negative in tim russert's case his stress test result was
negative which should mean he's negative for heart disease which they knew was not the case and again
unfortunately was most likely interpreted as that he wasn't going to have a heart attack however we
knew that he had come to a heart attack six weeks later succumbed to a heart attack so therefore
if you're talking about prediction of heart attack clearly it was a false negative and when
you go back and you read about false negatives false positives and quote accuracy this 80 to 90%
accuracy of a nuclear stress test again dig a little bit deeper and find out exactly
what they mean by accuracy so again as I've said maybe too many times and you see it in
general places for lay people like Harvard Health a true positive does not automatically
equate to a heart attack and it doesn't necessarily mean that you need to have a stent
which doesn't prevent a heart attack either they just indicate the presence of cardiac pathology
so I'd like to talk with you a minute about the webinar people don't understand what the webinar
is it's actually a great way to get some access to healthcare that you're just not going to get
any other way you actually get the lab tests yourself for at a local lab a Quest lab near you
for the inflammation panel and the OGTT and the insulin survey these are things inflammation and
prediabetes that your doctor just does not know about and here's the thing Harvard Health and many
others have said look sudden death is not always so sudden the Hollywood picture that it's a bolt
out of the blue is not realistic it's more like real lightning preceded by clouds wind and rain
stop that metabolic storm before the lightning strikes and here's where that metabolic storm
comes from it's inflammation and it has to do usually with prediabetes so again we actually
get labs we go over them in the webinar and then you can start finding out how you can
prevent that heart attack others said that you couldn't even predict we can show you how thanks