Bruce McManus, CM, OBC, MD, PhD, FRSC, FCAHS, FRCPC, FCAP, FACC, FCCS

FAQ on What an Autopsy Might Reveal

Headshot of Dr. Monte WillisWritten By Monte Willis MD, PhD, FASCP, FCAP

Losing a loved one is always a painful and extremely challenging. When their death occurs suddenly or answers about the cause aren’t clear, this pain persists and may multiply. Deaths due to myocarditis often fall into categories of initially obscure cause, and they may especially elude physicians who are less familiar with this condition and the various ways it may present. To continue our mission of providing education on the condition and support for those affected by it, Myocarditis Foundation and Bruce McManus MD, PhD, specialist cardiovascular pathologist, offer partial answers to frequently asked questions about how an autopsy may lead to a diagnosis of myocarditis.

How might an autopsy lead to a myocarditis diagnosis?

Unlike many human ailments, myocarditis is rarely determined to be the cause of death based on symptoms or physical examinations. Myocarditis is most often assigned as a cause of death due to a high degree of suspicion of its presence based on a strategy involving many:

  • A patient’s physician or care team who have a careful history of events before death
  • Family members who observed what happened in the weeks, days or hours before death
  • The caring physician requests an autopsy
  • The physician who performs the autopsy has expertise related to the heart or requests such

As a rare disease, myocarditis is poorly understood by most people outside of healthcare and may be unfamiliar even to experienced physicians. Myocarditis is typically considered during an autopsy only when the caring clinicians involved have a strong understanding of this disease’s wide range of symptoms, an appreciation for its non-specific nature and believe it could indeed be a cause of death.

What test results might suggest myocarditis?

Because myocarditis may affect characteristic electrical activity, inflammation and damage of the heart may be suggested in life by electrocardiography (ECG) scans. Certain shapes of waves or tracings seen on ECGs, or the rate and rhythm of the heart as reflected on the ECG may point to the possibility of myocarditis. The details of these changes should be appraised by a cardiologist if at all possible, or other caregivers familiar with heart muscle damage.  Such ECG abnormalities may also suggest pericarditis, that is, inflammation of the heart’s membrane sac. Additional tests that might support the presence of myocarditis include:

  • An abnormal white blood cell count
  • Elevated C-reactive protein levels (CRP) (marker of inflammation)
  • Increased erythrocyte sedimentation rate (ESR) (marker of inflammation)
  • Elevated circulating troponin in the blood (marker of heart muscle damage)
  • Other markers of cardiomyocyte damage

How can physicians be certain myocarditis was a cause of death?

Many disease processes can be observed only by study of the patient’s tissues, including under a microscope. Pathologists, especially with specialist training, can undertake histological analysis of tissues with a microscope. Such tissues are taken in a systematic way from the heart including from the heart muscle of the pumping chambers called ventricles. The cutting and staining of the tissues includes standard stains and as well as what are called special stains. The latter stains may highlight areas of heart muscle injury and may even detect the presence of viral genes that are markers of viruses that can attack the heart muscle.  The disease processes associated with myocarditis can only be diagnosed these direct examinations and with expert study.  While it’s impossible to achieve sufficient tissue samples to assure exclusion or inclusion of myocarditis as the cause of heart disease by biopsy of tiny samples while a patient is alive, an autopsy provides much greater access to tissue for more thorough analysis.

So, in summary, study of the tissues (including the use of a microscope and special molecular techniques) can reveal a wide range of disease indicators, including:

  • Certain kinds of white blood cells including lymphocytes, macrophages and other inflammatory cells
  • Areas of cell death, particularly heart muscle cells (called cardiomyocytes) that may underlie heart failure or heart rhythm disturbances

The white cells play a role in fighting against cells infected by certain viruses to keep the body healthy, but they can also unintentionally damage uninfected cells, killing them as well. The microscopic analysis may detect any of these types of white cells, as well as the injured or dead cardiomyocytes, the vital cells that allow the heart to contract.

Can you give a bit more detail as to how myocarditis is diagnosed with the help of a microscope?

An experienced pathologist who understands myocarditis in its various forms and phases can identify it after death via histological patterns observable under the microscope and detected through an autopsy. While these histological patterns are not always definitive, they may include those with predominant cell infiltrates:

  • Lymphocytes and Macrophages: Myocarditis due to viral infection or autoimmune disorder
  • Eosinophils: Hypersensitivity myocarditis; may also indicate hypereosinophilic syndrome
  • Granulomas: Giant cell myocarditis or cardiac sarcoidosis, tuberculosis or fungus, or deposits of particulates like talc
  • Neutrophils: Myocarditis due to bacterial, fungal, or early viral infection, or ischemic cell death as seen in vascular occlusion

Histology can also provide information about the phase of myocarditis, including:

  • Acute (recent onset): Possibly virus and myocyte death evident alone or with early inflammatory infiltrate, or including myocyte damage and a more diffuse inflammatory cell infiltration
  • Subacute: Heavier cellular infiltrate and associated myocyte damage and apparent edema (excess water spreading the tissues apart), accompanied by dilation (enlargement) of the ventricular chambers that pump blood through the heart and body, thinned ventricular walls
  • Chronic: Evolving healing that includes patchy scarring of the heart muscle with/without much inflammation, and associated dilated chambers and usually thinned walls

What other clinical information supports a diagnosis of myocarditis and might encourage an autopsy to confirm or exclude?

Changes in the heart caused by myocarditis are almost impossible to see with the naked eye – even for the most experienced physicians. However, corresponding symptoms may support a request for an autopsy with gross and histological analysis. These symptoms could include mild or severe:

  • Chest pain
  • Rapid or irregular heartbeat
  • Shortness of breath
  • Faintness or lightheadedness
  • Fluid retention in the lower legs
  • Fatigue

Children with myocarditis often present with symptoms that include difficult/rapid breathing, fever, fainting, and/or discoloration of the skin.

Serology, or testing that identifies antibodies in the blood, can also help guide diagnosis. If antibodies to known common viral, bacterial, and other infectious agents that cause myocarditis, it may indicate such a cause of myocarditis. Further investigation is advised including performing an autopsy if the patient passes away.

Learn more about diagnosing myocarditis

Even a single life lost to myocarditis is too many. That’s why Myocarditis Foundation works tirelessly alongside families, patients, researchers, and physicians to support the search for understanding and for a cure. To learn more about how myocarditis is diagnosed, contact us today. Ready to join the fight? Make a donation to support our mission.

References

  1. Feldman AM, McNamara D. Myocarditis. The New England journal of medicine 2000;343:1388-98.
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