Q&A: Nonischemic myocardial injury

Q: There seems to be a knowledge deficit around nonischemic myocardial injury, even among cardiologists. Could you provide some guidance around this diagnosis and advice for educating physicians?

A: This is an interesting question. Nonischemic myocardial injury refers to damage to the heart muscle, the myocardium, and it occurs without a decrease in the blood supply, which would result in ischemia.

Now unlike an ischemic injury, which is caused by inadequate blood flow to the heart due to conditions like coronary artery disease or a myocardial infarction, nonischemic myocardial injury can result from a lot of different things, including infections.

Viral infections like myocarditis, which is inflammation of the myocardium, can directly damage heart muscle which can lead to a myocardial injury. Toxic exposures can also lead to it. Drugs and chemicals do awful things—they can damage the muscle and cause myocardial injury. Things like alcohol and chemotherapy drugs are very toxic, as are other medications.

As far as autoimmune disorders, I've said this a million times in my life: I think we are at the very tip of the iceberg when it comes to autoimmune diseases and actually figuring out how they work. But systemic lupus erythematosus or rheumatoid arthritis can lead to inflammation of the heart muscle and myocardial injury. Any type of issue where inflammation is occurring everywhere in your body, that would include your lungs and your heart muscles, can cause a myocardial injury.

Or it could be something commonly seen like genetic disorders. Certain genetic conditions can certainly predispose somebody to muscle abnormalities like nonischemic myocardial injury. Some of these would be familial cardiomyopathies, endocrine disorders, hormone imbalances, and thyroid issues.

Now as far as diagnosing it, we need to do a comprehensive evaluation. We need to look at a combination of things like lab values, ECGs, imaging, and sometimes even invasive procedures. Providers might have to do biopsies.

Gathering these patients' medical history is one of the most important things. Look for risk factors for heart disease, know any recent infections that they might have had, look at their autoimmune statuses or if they are high risk for toxic exposures or any other type of medical issue that I mentioned above, and then evaluate their symptoms.

Do they have chest pain? Do they have shortness of breath, fatigue, or signs of heart failure? Look for swelling, especially in their extremities. Are they having difficulty breathing when they're laying down?

And then the physical exam, obviously, is extremely important. Check their vital signs, their heart sounds, their lung sounds, pulses, signs of fluid overload or heart failure, etc.

Then providers should do some of the usual labs, like cardiac biomarkers and troponin levels, which are indicators of myocardial injury. Elevated troponin levels, however, could also just suggest myocardial damage. They should also do a complete white count, which can tell whether the person has an infection, inflammation, or anemia.

Basic metabolic panels can show their electrolyte levels, kidney function, and glucose levels, which could all cause problems. And then some of our inflammatory markers, like C-reactive proteins or an ESR rate, can also tell us things related to myocarditis and inflammation.

Imaging is one of the things they might do to look for inflammation, edema, or fibrosis, or any other structural abnormalities that the patient might have. And then, as mentioned, biopsies are valuable in severe cases to assist with figuring out what's going on. They might want to review the histology results of the biopsies.

As far as educating providers, this diagnosis is a tricky one. When I approach a provider, I like to come from a posture of “please explain something to me,” and I do it in a way that is nonjudgmental. I often do have questions of my own based on what they've documented. So, I usually go to them and say, “This is my understanding of myocardial injury. Can you help me understand what yours is?” And if we have a good long conversation, we can usually come to an agreement on what we should be looking for. It also gives me a better understanding of what they think it is. Then we can throw it back and forth. I can say, “Well, I read this literature and it said this,” and so on.

Last, your physical posture is very important when approaching providers for any education, and the same holds true here.

Editor’s note: Sharme Brodie, RN, CCDS, CCDS-O, a CDI education specialist at ACDIS/HCPro, answered this question on the ACDIS Podcast. Contact her at sharme.brodie@hcpro.com.