Seven ways to misdiagnose a heart attack

by Carolyn Thomas  @HeartSisters

I’ve had a keen – some might say obsessive – interest in the subject of medical misdiagnosis ever since a man with the letters M.D. after his name sent me home from the Emergency Department in mid-heart attack. I had just been misdiagnosed with acid reflux – despite presenting with textbook cardiac symptoms.

These included crushing central chest pain, nausea, sweating, and pain radiating down my left arm. How can modern medicine still be making such potentially deadly misdiagnoses like this?

Dr. Charles Pilcher is a Washington State physician who’s also spent a great deal of time thinking about this very question. A veteran emergency medicine doc, Dr. Pilcher knows a lot about the potential devastation of a clinical  misdiagnosis.

In one of his essays, Dr. Pilcher cites some scary factoids.  For example:

  • about 5% of autopsies find clinically significant conditions that were missed and could have affected the patient’s survival
  • 40% of medical malpractice suits are for something called “failure to diagnose”
  • nearly one in three reported adverse events involve diagnostic errors, and more than 10% of these mistakes result in death

According to Dr. Pilcher, these errors are rarely system errors (e.g. mis-filing a pathology report that shows a tumour is malignant) – but are more often thinking errors.

He believes that there are several reasons why we make mistakes in our thought processes even when we have the knowledge and ability to think correctly. He points to a report(1) in the journal Academic Medicine that lists seven examples of these recognized thinking errors,  including:

  • Anchoring bias – locking on to a diagnosis too early and failing to adjust to new information
  • Availability bias – thinking that a similar recent presentation is happening in the present situation
  • Confirmation bias – looking for evidence to support a pre-conceived opinion, rather than looking for information to prove oneself wrong
  • Diagnosis momentum – accepting a previous diagnosis without sufficient skepticism
  • Overconfidence bias – over-reliance on one’s own ability, intuition, and judgment
  • Premature closure – similar to confirmation bias, but more “jumping to a conclusion”
  • Search-satisfying bias – the “Eureka!” moment that stops all further thought

In Dr. Pilcher’s opinion, the most fascinating and most common of these is “anchoring bias”, which means “locking on to a diagnosis too early and failing to adjust to new information”.

This seems precisely what happened to me during that first trip to the Emergency Department. When the first of two standard cardiac enzyme blood test results came back “normal”, my white-coated M.D. told me with an air of profound certainty:

”  Your first cardiac enzyme blood test is normal. We’ll do one more blood test – but that one will be normal, too.”

So even before that second blood test was done, he had looked me up and down and pronounced that I appeared to be in “the right demographic” for an acid reflux diagnosis. He never wavered from that misdiagnosis after almost immediately “locking on” to it.

In fact, this physician was so sure that my problem was NOT heart-related that he sent me home from Emergency within five hours of the onset of my symptoms – a far shorter period of observation than clinical practice guidelines dictate for any patient presenting for help with classic cardiac symptoms.

Worse, after I’d asked him: But what about this pain down my left arm?” (which even I knew was not a symptom of heartburn), the nurse returned to my bed and sternly scolded me to stop asking questions of the doctor.

“He is a very good doctor. And he does NOT like to be questioned!”

It turns out that I was not alone in being misdiagnosed and sent home from hospital due to such examples of anchoring bias.  According to a study reported in the New England Journal of Medicine, women like me in their 50s and younger are seven times more likely to be misdiagnosed during a cardiac event and sent home from Emergency compared to our male counterparts.(2)   See also: How  Can We Get heart Patients Past the E.R. Gatekeepers?

As thinking errors move to the forefront of patient safety debates, Dr. Pilcher explains that many medical schools are now beginning to teach something called metacognition.

This is described as a reflective approach to problem-solving that involves stepping back from the immediate problem to examine and reflect on the thinking process.

In other words, it’s “thinking about thinking.”

  • Some medical schools are already onboard with a shift in how med students are trained. For example, Dr. Pat Croskerry is an Emergency Medicine physician, a patient safety expert and director of the critical thinking program at Dalhousie University Medical School in Halifax. He implemented at Dal the first undergraduate course in Canada about medical error in clinical decision-making, specifically around why and how physicians make diagnostic errors.

Meanwhile, Dr. Pilcher maintains that the busier the Emergency Department gets, the more critical thinking skills become vitally important to making accurate diagnoses.

(1)  Acad Med. 2003 Aug;78(8):775-80.
(2) Pope JH, Aufderheide TP, Ruthazer R, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med. 2000; 342:1163-1170.


NOTE FROM CAROLYN:  I wrote much more about the cardiac diagnostic gender gap in my book, A Woman’s Guide to Living with Heart Disease (Johns Hopkins University Press). You can ask for this book at your local bookshop (please support your neighbourhood independent booksellers!)  or order it online (paperback, hardcover or e-book) at Amazon – or order it directly from Johns Hopkins University Press (use their code HTWN to save 30% off the list price when you order).

See also:

Diagnostic Uncertainty vs. Unwarranted Certainty: which is worse for patients?

Mandatory Reporting of Diagnostic Errors: “Not the Right Time?”

Cardiac Gender Bias: We Need Less TALK and More WALK

The Sad Reality of Women’s Heart Disease Hits Home

Misdiagnosis: the Perils of “Unwarranted Certainty”

How Can We Get Heart Patients Past the E.R. Gatekeepers?

Heart Attack Misdiagnosis in Women

The 18-Second Rule: How Doctors Missed Your Heart Attack Diagnosis

Experts: Why So Wrong, So Often?


6 thoughts on “Seven ways to misdiagnose a heart attack

  1. Went to E.R. for heart attack. One of the women to sign me in had to stop herself from laughing. Was told I had a previous diagnoses of arrhythmia which I was unaware of. Was told my EKG had a little blip, but it was nothing. Doctor said I was fine, and I said “something’s going on”, which upset him and he stormed out of the room. I was there probably two hours. I’ve been complaining about my heart for years.


    1. Hello Amber – not sure from your comment if you were actually diagnosed with a heart attack, or if you went to the ER because you were worried you might be having one. Please see your family doctor to review what happened. Good luck to you…


  2. I think Dr. Pilcher is right in delineating between “system” errors and “thinking” errors”. But what happens when BOTH kinds of errors are in play, based on the fact that one small system error (like losing the test results) can lead to a thinking error – insisting that the MD’s original diagnosis MUST be correct in spite of my wife’s worsening symptoms?

    Let’s face it — we all have personal bias of some sort, but few of our decisions mean life and death for other people.

    Liked by 1 person

    1. You’re right, Sid. These compounded errors can have tragic consequences that are unique to the health care professions.


Your opinion matters. What do you think?

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s