When your “significant EKG changes” are missed

30 Mar

by Carolyn Thomas  @HeartSisters

A new cardiac study out of Montréal tells us yet again what women heart patients have already known for years: women receive poorer care during a heart attack than our male counterparts do. Quelle surprise . . .  But one specific finding caught my eye: one of the cardiac procedures that these researchers compared in this study was the use of the diagnostic electrocardiogram test (ECG or EKG) in male and female heart attack patients.(1)

They found that women were less likely than men to receive an electrocardiogram within the recommended 10 minutes of arriving in hospital with suspected cardiac symptoms.

It turns out, however, that even when we do finally get hooked up to a 12-lead EKG in a hospital’s Emergency Department, the doctors there may not be able to correctly interpret the “significant EKG changes” that identify heart disease.

Previous research has reported a disturbing reality about diagnostic EKGs, which is the likelihood that high-risk EKG abnormalities may NOT be detected by physicians working in Emergency Medicine.

stemiFor example, a 2006 study published in the journal Circulation monitored five hospital Emergency Departments in California and Colorado over a two-year period to determine how often the treating Emergency physicians failed to identify “significant EKG changes” during a cardiac event.(2)

The researchers concluded:

“Twelve per cent of patients studied had a high-risk EKG abnormality that was NOT detected by the Emergency Department provider.

“Rates of missed EKG findings from hospital to hospital ranged from 5.6% to 15.1%. Patients with missed EKG abnormalities tended to be older;  more commonly had a history of heart failure or other cardiac history; and less frequently had chest pain as a presenting symptom”

That last factor is particularly disturbing, given that up to 40% of women experience no chest pain during heart attack.  Yet chest pain is still the primary cardiac red flag docs seem to be looking for. If chest pain is absent, are they then more likely to interpret EKG findings through the pre-judged lens of “not a cardiac event”?  

In other words, if I show up to Emerg presenting with vague, atypical cardiac symptoms that many women experience during heart attack (like nausea, crushing exhaustion, shortness of breath or upper back/jaw pain) but no chest symptoms, I may face a greater risk of having my EKG misinterpreted compared to my male counterparts – even if it contains “significant high-risk EKG abnormalities”. 

Here’s how that looks in real life. A reader named Lori described her own experience with “normal” EKG tests in her response to my post, How Does It Really Feel to Have a Heart Attack?  She wrote:

“I know this from experience. A ‘normal’ EKG does not mean you don’t have heart problems.  I had a heart attack at age 46. My main artery was 99% blocked. I now have two stents. My dad and my brother also had heart attacks at age 46. Their EKGs were always ‘normal’. My grandfather on my mom’s side died of a heart attack at 52. His EKGs were ‘normal’. My mom was short of breath and went to the doctor: her EKG was ‘normal’. She now has two stents.

“Please don’t let a doctor tell you that you don’t have heart problems just because your EKGs are ‘normal’.”

Also disturbing is the conclusion of the Circulation paper:

“The failure to identify high-risk findings was independently associated with a higher odds of not receiving ideal treatment.”

This makes perfect sense. Any physician who misinterprets “significant EKG changes” as being ‘normal’ is unlikely to recommend further appropriate cardiac treatment for the patient.

Any diagnostic test is only as good as the interpretation of that test by the physician reading the test results. Consider, for example, a study on the performance of radiologists done at Michigan State University by Dr. E. James Potchen.(3)  When radiologists were shown a chest x-ray of a patient with a missing clavicle (collarbone), 60% of them failed to identify the missing clavicle. And when this group of radiologists were shown a series of chest x-rays that included duplicate films, their interpretations disagreed among each other an average of 20% of the time. 

But even more interesting, when researchers showed them x-rays they had already interpreted, they disagreed with their own previous interpretations 10% of the time.

One of the most troubling aspects of Dr. Potchen’s study was the degree of certainty that the most accurate doctors had compared to the least accurate.

For example, he compared the top 20 radiologists studied (95% diagnostic accuracy) with the bottom 20 (75% accuracy) and found that the specialists who performed poorly were not only inaccurate, they were also very confident that they were right when they were, in fact, quite wrong.

But how can this happen? How can trained, intelligent people with the letters M.D. after their names misinterpret diagnostic tests that clearly show abnormalities?

One theory behind such errors is what’s known as confirmation biasSee also Experts: Why So Wrong So Often?

Confirmation bias refers to a type of selective thinking in which we tend to notice and to look for what confirms our beliefs.

Not only that, but we then want to ignore, or undervalue, or not even look for the relevance of anything that contradicts those beliefs.

As a heart attack survivor who was misdiagnosed with acid reflux in the E.R. and sent home (despite presenting with textbook heart attack symptoms like debilitating central chest pain, nausea and pain radiating down my left arm), I’m no stranger to the damage caused by experts who are wrong.

My EKG that morning was ‘normal’. My cardiac enzymes were ‘normal’.  My treadmill stress test was ‘normal’.  And I was home within five hours of the onset of my symptoms – far earlier than most cardiac treatment guidelines recommend in order to correctly identify myocardial infarction. As cardiologist and founder of the Mayo Women’s Heart Clinic Dr. Sharonne Hayes explained:

“Treatment guidelines help women get the care that has been shown to improve survival and long term outcomes in large groups of patients.

“Part of the problem now is that the guidelines are less likely to be applied to women compared to men. We know that when hospitals have systems in place to ensure they provide care according to the guidelines, women’s outcomes improve, even more than men’s.”

Women under the age of 55 are in fact seven times more likely than men are to be misdiagnosed in mid-heart attack and sent home.(4) 

About 5% of autopsies find clinically significant conditions that were missed and could have affected the patient’s survival.

And over 40% of medical malpractice suits are for failure to diagnose.

The good news, as Erin Anderssen of The Globe and Mail wrote, is that most of the time our doctors do get their diagnoses right.

“But about one-fifth of the time, something is missed or conclusions are reached too quickly. Here’s how it can happen, and how a patient can help prevent it:

“Your doctor steps into the room, and already she has made a preliminary scan: your gender, your weight, your demeanor. She may have glanced at the chart with the nurse’s note and be considering two or three diagnoses, suggests Harvard medical professor Dr. Jerome Groopman, the author of ‘How Doctors Think’. It takes doctors, on average, 18 seconds before they interrupt a patient, which means facts in a patient’s history are often missed.

“Be as specific as you can about your symptoms. Write the details down if you need to keep them straight. Make sure you know your medications and the amounts you are taking, so the doctor doesn’t have to spend time figuring it out based on your ‘little white pill’ description.”

* Thanks to paramedic/fire captain Tom Bouthillet for telling me about the Circulation paper.

.

(1)  Roxanne Pelletier et al. Sex-related differences in access to care among patients with premature acute coronary syndrome. Canadian Medical Association Journal. March 17, 2014 cmaj.131450 10.1503/cmaj.131450 
( 2)  Frederick A. Masoudi et al. Implications of the failure to identify high-risk electrocardiogram findings for the quality of care of patients with acute myocardial infarction: results of the emergency department quality in myocardial infarction (EDQMI) study. Circulation. 2006; 114: 1565-1571
(3)  E. James Potchen. Measuring Observer Performance in Chest Radiology: Some Experiences. Journal of the American College of Radiology. Volume 3, Issue 6 , 423-432, June 2006
(4)  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.

See also:

Q: Have you had a serious condition that was originally misdiagnosed?

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7 Responses to “When your “significant EKG changes” are missed”

  1. Just Suze April 2, 2014 at 8:37 am #

    It was an interesting contrast between my husband’s physical exam and mine. I had a heart attack 12 years ago this summer; at my last visit to the doctor, I got one page (standard letter size) printed out for my EKG. It took longer to set up the machine, than to run the actual test.

    MY husband, who has never had any heart symptoms at all in his entire life, got six pages. We were having annual physicals with the same doctor, same staff, same date, same EKG machine. Granted I go to the women’s cardiology clinic at the state university, but that’s still quite a difference between an aging woman’s physical, and an aging man’s.

    My significant changes may not have even shown up in those couple of seconds. Oy vey!

    Like

    • Carolyn Thomas April 2, 2014 at 5:42 pm #

      Hi Suze – that’s a pretty compelling difference within exactly the same family and within the same facility – and particularly questionable given that one of you already has a history of cardiovascular disease (which is of course a known risk factor for future cardiac events). If anything, you’d expect they’d be especially diligent in doing more careful testing with YOU, the actual heart patient. “Oy vey!” is right!

      Like

      • Just Suze April 3, 2014 at 5:10 am #

        Thank you, Carolyn, for all that you do.

        To make a long story short, my husband was so upset that he called the cardiologist at the university clinic. She asked for the name and address of the PCP, and was going to send off a letter about the neglect of female patients. She also said that with all of the articles and research appearing in medical journals, there is no reason at all for ANY physician in practice today to be ignorant of women’s cardiac issues.

        (She sometimes says that if she were in charge, every doctor on earth would have a week long seminar on heart disease in women with a difficult test at the end.)

        Like

        • Carolyn Thomas April 3, 2014 at 5:47 am #

          Well, you just made my day. I love that reaction from your cardiologist, and I hope that letter was a smack upside the head for that PCP and all other docs who hear this story. Thanks for that part of the story!

          Like

  2. Kathleen March 30, 2014 at 12:37 pm #

    I don’t think results of that study of radiologists can be told too many times. Especially the part about how the worst were the most confident and the best were the most uncertain.

    Aside from confirmation bias, my own cardiac story points to yet another point of Dr. Groopman’s.

    My EKG was abnormal on 3 of 4 indices. Along with my episodes of exhaustion and shortness of breath (extraordinary in anyone who works out as much as I do) it alarmed them enough to send me to the ER and give me an angiogram the next morning, which was 90% clear. So far, so good. Chalk one up for the HMO.

    But at that point the cardiologist lost all interest in my symptoms (which still popped up out of nowhere). Some triathletes have similar EKGs, and he insisted that the EKG was just my Normal, like my very low heart rate, due to years as a runner, even though that was some time ago.

    When I did more research and pointed out that Apical Hypertrophic Cardiomyopathy would explain the EKG as well as my symptoms, he smiled tolerantly. For several years the cardiologist and one PCP after another smiled tolerantly and told me how very rare that would be. When I reminded them that I have already survived a cancer that is far more rare, the smiles became rigid. They reassured me that “Dr. X” or “Dr. W” is an excellent doc and that was that. Among the list of indicators for AHCM is Sudden Death.

    Then I changed PCP yet another time (see “Anxious Female”) and decided to revisit the heart issues.

    My new doc asked a cardiologist she really respected to read my echocardiogram, and he determined that I do have Apical Hypertrophic Cardiomyopathy, consistent with previous echo and all previous EKGs. In fact, a pretty textbook case (my new cardiologist tells me) missed by all previous docs at the HMO.

    Dr. Groopman tells us that docs are trained: “When you hear the sound of hooves, look for horses, not zebras.” And too many docs behave as though rare means impossible in that person before them.

    But some of us really are zebras, even again and again.

    Like

    • Carolyn Thomas March 30, 2014 at 12:59 pm #

      Hello Kathleen,
      It’s usually a bad sign when a cardiologist loses all interest in your symptoms on the basis of a “normal” diagnostic test. “Normal” does not mean one’s disease politely goes away.

      Right now, a dear friend is in ICU on life support with brain swelling of sudden onset and unknown cause while neurologists, radiologists and other specialists report that they are “mystified” as test after “normal” test reveals little to solve the mystery. Yet they’re continuing to aggressively pursue a diagnosis. SOMETHING is causing this and they’re trying desperately to figure out what that is.

      Yet in cardiology, a “normal” diagnostic test can make some physicians forgetful – as in, they seem to forget about the symptoms that were distressing enough to bring us to seek medical care in the first place.

      And as if that weren’t bad enough, they “smile tolerantly”. Arrrrgh….

      Like

      • Kathleen March 31, 2014 at 12:08 am #

        So sorry about your friend, Carolyn, and good to hear that the team looking after her (or him) has not thrown in the towel but is aggressively pursuing a diagnosis. So often real life conditions take a different form from “type”. We hope for the best.

        Like

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