Sunday, July 05, 2015

The American Heart Associations "911" heart attack campaign is not evidence based

My friend Jim Levin died a couple of years ago; he had an MI running for a plane. Shortly after his death I visited the American Hearth Association's warning signs of a “heart attack”. I wasn’t impressed. What active 55yo doesn’t have chest discomfort 20 minutes into a killer CrossFit workout? Short of breath? Yeah, a bit.

So I made my own list, based on nothing but my native ignorance ...

  • If these things occur together it's more likely to be heart disease. So shortness of breath AND "cold sweat" [2] AND jaw discomfort all together means more than one of them by itself.
  • It's one thing to feel short of breath when you're a healthy person running a 5 mile race, another if you are short of breath doing stuff that is normally easy (like watching TV).
  • If symptoms like "arm discomfort" and " nausea" come on with exercise and get better with rest -- that's ominous. (Exercise means the heart needs more oxygen, so it can expose an underlying problem.)
  • If your parents died of heart disease in their 40s and your LDL cholesterol is 250 and you smoke and you're male ... Ok. You get the point. Most of us have some heart disease by age 50, but some people have a lot. Weird pains at rest may not mean too much in a low risk 30 yo woman but in a "high risk" person they might be bad news.

Today I again thought of the AHA’s non-specific warning sign list. I thought maybe things had improved, so I went looking for a publication that describes the predictive value, or even sensitivity and specificity, of the AHA’s heart attack classification criteria. After all, we communicate the AHA list to hundreds of millions of people. There’s gotta be some science behind it … right ...

I found two interesting references, one predating my 2013 blog post

The 2014 study was limited to patients who were actually in the ED. The 2008 study was broader and concluded: "there were almost no included studies that investigated the diagnostic accuracy of combinations of signs and symptoms …it was not possible to define an important role for signs and symptoms in the diagnosis of acute myocardial infarction or acute coronary syndrome”.

Dear AHA — this is ridiculous. I suspect if everyone took your 911 signs seriously ERs would be overwhelmed with “rule out MI”. You need to come up with an evidence-based symptom list.

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