Claims Case Study: Missed Myocardial Infarctions

One in five myocardial infarctions (MIs) occurs “silently” and can easily go undetected by both the affected patient and their physician. When patients present to the emergency department experiencing acute coronary symptoms, such as unstable angina, these may be the warning signs of impending MI and should be closely monitored.

When a patient is discharged from the ED and is later found to have sustained an acute MI in the next 48-72 hours, this is referred to as a “missed MI,” and is often the result of atypical presentation of symptoms. Missing an MI diagnosis can result in significant consequences, and lawsuits regarding undiagnosed MIs often account for some of the largest awards in medical malpractice suits.

In this study, we examine two patient cases involving a missed MI that resulted in an unfortunate outcome post-discharge, and we offer tips to help avoid a similar situation.

Case #1: 87-Year-Old-Male

An 87-year-old male nursing home resident with a significant history of coronary artery disease, hypertension, and congestive heart failure presented to the ED via EMS with complaints of severe right shoulder pain radiating to his back and neck. The insured emergency medicine physician examined him and ordered various lab tests, including a troponin level, CPKs, rapid strep test, and blood cultures, as well as an x-ray of his chest and right shoulder. No EKG was ordered. His cardiac lab results were within normal limits, but his white blood cell count was elevated at 10.2, and the rapid strep test was positive.

He was diagnosed with strep throat and right shoulder pain resulting from arthritis. He was prescribed amoxicillin and Robaxin to combat the strep bacteria and was discharged back to the nursing home. The following day, the patient was found unresponsive and resuscitation efforts were unsuccessful. The cause of death was determined to be MI.

Case #2: 55-Year-Old-Female

A 55-year-old female smoker with a history of hypertension, gastroesophageal reflux disease (GERD), and chronic back pain presented to the ED with a one-day history of sharp chest pain below her breast that radiated to her back and throat. She also noted a tingling sensation in her left arm but reported a prior negative stress test. Before arriving, she took antacids that did not relieve the pain, but the use of tramadol provided some relief. She was not experiencing nausea, vomiting, diaphoresis (abnormal sweating), or shortness of breath.

The insured emergency medicine physician ordered a chest x-ray and EKG, and both results returned normal. Lab studies were ordered, and her CBC and Chem 7 were essentially normal, but the urinalysis was positive for urinary tract infection. The patient, who was already taking Macrobid, was given ceftriaxone and Toradol in the emergency department.

A CPK and CKMB were ordered and were within normal results. A troponin level test was ordered, and the specimen collected; however, the test was subsequently cancelled at 9:00 p.m. Around this time, the patient was given a diagnosis of chest pain of uncertain origin, and she was given instructions to follow up with her primary care physician and return to emergency department if symptoms changed or worsened. The patient was discharged from the ED to home at 9:58 pm. Ten minutes prior to discharge, even though the test was marked as cancelled, an elevated troponin result was received, and no further action was taken.

The following day, the patient returned to the ED with complaints of worsening chest pain, and a 12 lead EKG revealed ST segment elevation myocardial infarction (STEMI). The patient was taken immediately to the cardiac catheterization lab, where it was discovered that she had 100 percent blockage of the left anterior descending (LAD) artery. Coronary stents were placed, resulting in restoration of blood flow to the myocardium.

Follow-up cardiac testing revealed decreased cardiac ejection fraction (EF), a measurement of the heart’s ability to properly pump blood with each contraction. The previous year, she had a normal EF of 75 percent, but after being discharged from the hospital, it was at a mere 20 percent. Six months following the placement of the stent, her EF improved to 45 percent.

What Went Wrong?

In the case of the 87-year-old male, despite the patient’s extensive cardiac history and pain presentation, MI was not included in the differential diagnosis as the physician explored potential causes of the patient’s symptoms. As a result, there was difficulty obtaining expert support during treatment. Following the incident, experts agreed that an EKG should have been ordered, citing that standard of care requires this test as part of the cardiac workup. If the physician had ordered an EKG, the MI may have been prevented or treated, potentially extending the patient’s life.

Regarding the case of the 55-year-old female, emergency medicine experts indicated that they believe standard of care was not met. They agreed that based on the patient’s history of hypertension and smoking, as well as her presenting complaints of chest pain and left arm tingling, that she should have received additional evaluation and a cardiology consultation. They also commented that she should not have been discharged with an elevated troponin result. There was no clear explanation as to why the test had been marked cancelled at 9:00 p.m., and the insured physician stated that she must have reviewed another patient’s normal troponin result as a mistake prior to discharge.

The cardiology reviewer concluded that based on the patient’s symptoms and elevated troponin, she should have been admitted to a monitored bed and been anticoagulated. Had this occurred, her subsequent MI and resulting cardiac damage could have been avoided. Some experts who participated in this trial agree that they would have, at a minimum, kept the patient in the ED until the original troponin results returned, following up with a second troponin level test three hours later.

Risk Management Takeaways:

• Emergency physicians should always conduct the appropriate diagnostic tests when a patient presents to the emergency department with chest pain, rather than use clinical judgment alone to rule out an acute coronary syndrome. It is particularly important to hold discharge decisions until all diagnostic tests have been completed.
• Physicians should take the necessary steps to ensure accurate patient identification, address any abnormal findings, and review all available clinical information to avoid misdiagnoses.
• Physicians should carefully consider the “whole picture” of evaluation findings that may affect the decision to admit the patient to the hospital for observation. If subsequent episodes of chest pain occur in the hospital on a cardiac monitor, there is a better chance of survival or favorable outcome.
• Emergency departments should conduct an internal review of diagnostic testing processes to avoid mistakes, such as cancelled tests and misidentification.
• Emergency departments should establish a process for post-discharge follow-up calls to revisit symptoms of patients with high-risk diagnoses such as chest pain of uncertain etiology.

For further guidance on this issue, Curi members are encouraged to reach out to our Claims and Risk Management Departments at 800-328-5532.