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.
For example, a 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, depending on the study being cited, between 10% and 40% of women experience no chest pain during heart attack.(3)
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.(4)
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 bias. (See 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.
For more on how doctors make critical thinking errors, consider what Dr. Pat Croskerry teaches about this subject. Dr. Croskerry is a trailblazer in teaching med students the skills of critical thinking. He implemented at Dalhousie University in Halifax the first undergraduate course in Canada teaching students about medical error in clinical decision-making, specifically around why and how physicians make diagnostic errors.
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, sweating 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.
NOTE FROM CAROLYN: I wrote more about diagnosis and misdiagnosis in women’s heart disease in my book “A Woman’s Guide to Living with Heart Disease“ published by Johns Hopkins University Press in 2017. You can ask for it at your local library or favourite bookshop, or order it online (paperback, hardcover or e-book) at Amazon, or order it directly from my publisher (use their code HTWN to save 20% off the list price).
(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) 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.
(4) 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
“The ECG told the whole story, but nobody listened: ECG interpretation skills are critical to patient outcomes” via Dr. Stephen Smith’s ECG Blog
Q: Have you had an EKG that missed your ultimate cardiac diagnosis?