The Micah True Autopsy Explained (2024)

By Tom Meersman

With the release of

Micah True's autopsy results, the takeaway message has been that he died of heart disease. If you're one of the countless athletes who started running because you thought it was good for your health, you probably found this news disheartening. How could True, an ultramarathoner who became famous for his all-consuming passion for running, have died of heart disease?
Let's take a look at the autopsy findings.
The most significant findings of True's autopsy were the presence of cardiomyopathy and mild dehydration. Cardiomyopathy is "heart disease" insofar as it's a pathological condition affecting the cardiac tissues. However, it has nothing to do with high cholesterol or atherosclerotis, two conditions colloquially associated with the term "heart disease." Cardiomyopathy can be associated with heart failure and comes in several forms. In the case of True, whose left ventricle was reported to be "dilated and enlarged," we're looking at the most common form, dilated cardiomyopathy.
"But wait," you're thinking, "I thought having a big heart was good for exercise." That's true, provided it's the right type of enlargement.
Dilated cardiomyopathy is often idiopathic, meaning no cause can be identified. There's an enlargement in the size of the heart due to dilation of the tissue, not due to increased thickness of the wall of the ventricle. The effect is a thin and enlarged heart wall that, like an overstretched water balloon, is too thin to contract effectively to pump blood to the rest of the body. The total volume of the heart is increased, but only because the wall of the heart has become thinner.
Thickening of the heart can regularly occur as result of exercise, but usually in the form of left ventricular hypertrophy (LVH). LVH is a common non-pathological finding in athletes, wherein the heart tissue thickens and strengthens due to the conditioning of exercise. This is a thickening of normal, healthy cardiac tissue that results in the heart pumping blood more strongly and efficiently. This is not a type of cardiomyopathy, and is not the condition described in True's autopsy.
There is also obstructive cardiomyopathy, also called hypertrophic obstructive cardiomyopathy (HCM). This is usually congenital and inherited. Often, patients have no physical complaints. In fact, HCM is often only discovered post-mortem. It's a common cause of sudden cardiac death in young athletes in the U.S. In HCM the cardiac tissue is enlarged and thick (not dilated). In contrast to LVH, the heart becomes so large that it can “block” itself from effectively pumping and refilling with blood. Essentially, the heart tissue is thick but ineffective and rigid. This is also not the condition described in True's autopsy.
What autopsy reports can’t tell us definitively is what killed True. It’s reasonable to imagine a situation in which a runner with dilated cardiomyopathy and mild dehydration, who is out on a run, has their cardiac output decrease to the point of medical emergency. Was this the (im)perfect storm that killed Caballo Blanco? We will never know for sure.
In the meantime, this is another reminder that, even though as a runner you may feel completely healthy, sometime even invincible, you should get regular health screenings--which will pick up things like cardiomyopathy--and seek immediate care if you think something may be acutely wrong. Otherwise, don't sweat it.
The last influence that Micah True would want to have on the world would be to discourage others from running. We can honor his death by continuing his legacy, and keep on running!

Tom Meersman is a physician assistant who practices in emergency medicine/urgent care. A resident of Palatine, Ill., he's a lifelong runner and triathlete with a marathon best of 3:26.