When I showed up in the Emergency Department with textbook heart attack symptoms – central chest pain, nausea, sweating and pain radiating down my left arm – the hospital staff snapped to work and immediately ordered a flurry of diagnostic tests. These included an EKG (ECG, or electrocardiogram), blood tests, chest x-ray and a treadmill stress test. But all test results came back “normal”. I was then told that I was in the “right demographic” for acid reflux before being sent home – less than five hours after the onset of symptoms.
I left hospital that morning feeling terribly embarrassed for having made such a fuss over just a little case of indigestion. It was only much later – after finally being correctly diagnosed, taken directly from the E.R. to O.R. and admitted to the cardiac intensive care unit for a myocardial infarction (MI, or heart attack) caused by a fully occluded Left Anterior Descending coronary artery – when I learned that my first “normal” blood tests may have been far less “normal” than I was told. This is the part of my story where I like to insert a quick story – this one told to me by a woman in one of my Heart Smart Women presentation audiences. She described being an E.R. patient one day, and overhearing a conversation between the E.R. physician and the (male) patient lying in the bed next to her, behind the cubicle curtain. She heard the doctor telling the (male) patient:
“Your EKG is fine, and your blood tests are fine, too. But we’re going to admit you for observation just to make sure it isn’t your heart.”
Thus yet another male patient with symptoms but inconclusive cardiac test results is kept in hospital for observation, while I and countless other females with symptoms but inconclusive cardiac test results are misdiagnosed, patted on the head, and sent right home.
Turns out we’re not alone. A study published in The New England Journal of Medicine found that women in their 50s or younger presenting with cardiac symptoms were seven times more likely to be misdiagnosed and sent home from Emergency compared to their male counterparts.(1)
Here’s why that’s an important issue. The blood tests I mentioned look for specific cardiac enzymes in the bloodstream. This test will usually be ordered when a person like me with a suspected heart attack first comes into the Emergency Department. The blood test is usually repeated two more times over the next 12 hours.
One of these tests is for a specific cardiac biomarker called Troponin – particularly one called Troponin I that’s used to detect heart muscle damage that occurs during a heart attack. Ma Carolyn’s NOTE: although some consider the presence of this biomarker to be uniquely heart attack-related, increased blood concentrations of troponin are may also be detected in non-cardiac conditions (e.g. sepsis, hypovolemia, pulmonary embolism, or renal failure).
Patients who receive CPR, external defibrillation or shocks from an implantable cardioverter defibrillator may also have elevated troponin levels due to damage to the heart’s ventricular muscle. Medications and chemicals called “cardiotoxic” may also elevate troponins. Such agents include some chemotherapy drugs and chemicals such as carbon monoxide.
And some extreme endurance athletes – triathletes, for example – are even known to have temporarily detectable troponin levels in their blood. As Dr. Malissa Wood explained in a Runner’s World interview, this is because their cell membranes may leak troponin, which is what cardiac muscle does when under extreme stress. Dr. Wood (who is the co-director of the Women’s Health Heart Center at Massachusetts General Hospital, teaches at Harvard, and has run many marathons herself), cites studies showing that the healthy heart (unlike the unhealthy heart in the throes of myocardial infarction – heart attack) can almost always quickly repair these cell membranes, stem the troponin leakage, and suffer no permanent damage.
Many patients who experience a heart attack have increased troponin levels within six hours following the onset of symptoms.
This means that after 12 hours, almost everyone who has had a heart attack will exhibit raised troponin levels. Troponin levels may remain high for up to two weeks after a heart attack strikes. Many, but not all, Emergency Departments currently use a newer high-sensitivity diagnostic test for Troponins.
Cardiac troponin levels are normally so low they cannot be detected with most blood tests, so when they are detected, it’s usually significant in showing that heart muscle damage due to a myocardial infarction has occurred. Normal Troponin test results at 12 hours after the onset of symptoms typically mean that a heart attack is unlikely.
But I was already back home from the Emergency Department within five hours. No wonder it was “normal”.
Dr. Karin Humphries is a cardiac researcher in Vancouver whose studies include one of unique interest to women – especially women like me who were told in Emergency that their early diagnostic Troponin blood tests were “normal” – despite having a heart attack. As the Centre for Health Evaluation and Outcome Sciences described Dr. Humphries’ research:
“Cardiac Troponin is a protein that’s released into the blood by the heart muscle during a cardiac event, but the diagnostic threshold for this test is based on data from men.
“In fact, healthy women produce about half as much cardiac troponin as men, and many women who have had a heart attack show values below the diagnostic threshold of the current blood test. This has meant that women’s heart attacks have historically been underdiagnosed when it comes to heart attack, which can have serious implications for treatment and overall health. The CODE-MI Study, led by Dr. Karin Humphries, is addressing the diagnostic issue in heart attack by testing sex-specific thresholds for the cardiac troponin blood test, rather than one standard threshold.”
This difference is important for women to know. Being told your cardiac enzyme blood tests are “normal” – especially in the absence of chest pain – will likely mean you can kiss a cardiac diagnosis goodbye.
(1) 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.
(2) Fesmire et al. “Clinical Policy: Critical Issues in the Evaluation and Management of Adult Patients with Non–ST-Segment Elevation Acute Coronary Syndromes.” Annals of Emergency Medicine. Volume 48, No. 3. September 2006.
♥ See also:
- Heart attack Misdiagnosis in Women
- When Your “Significant EKG Changes” are Missed
- Stress Test vs Flipping a Coin: Which is More Accurate?
- Misdiagnosis: the Perils of “Unwarranted Certainty”
- Seven Ways to Misdiagnose a Heart Attack
- The ’18 Second Rule’: Why Your Doctor Missed Your Heart Disease Diagnosis
- How Women Can Have Heart Attacks Without Having Any Blocked Arteries