This is a very important question that many people ask, especially after they or family members present to the emergency department of their local hospital, and are told they have had a “heart attack” even though they were not found to have any blockages in the arteries to the heart (AKA “clogged arteries”). Blood tests are now used to diagnose a “heart attack” more than anything else. For just over a decade, we have had the ability to test for certain proteins in the blood, which can only have come from heart muscle. The presence of such proteins in the blood means that the heart muscle has been injured in some way. Such “injury” may be broadly defined as “heart attack.” Our ability to measure these proteins, called cardiac troponin T (cTnT) or cardiac troponin I (cTnI), has marked a paradigm shift in how we diagnose a heart attack.
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The issue is that our blood tests for troponin are incredibly sensitive, and we have learned that troponin can appear in the blood even when rupture or erosion within a “clogged” artery has not occurred. In this case, a “type 2” heart attack is said to have occurred. A “type 2” heart attack is thought to occur because or restricted blood flow that is due to either increased oxygen demand or decreased supply. Such a supply-demand mismatch can occur due to reduced blood flow within the culprit artery due to spasm of the vessel, embolism of a foreign particle (possibly an air bubble) into the artery, from decreased blood flow in the artery due to dangerously low blood pressure, or from insufficient blood flow in the setting of anemia with increased demand due to stress or exertion.
The definition of type 2 heart attack is somewhat unsatisfactory because it is not really defined by what it is but rather what it is not. Nevertheless, it is important to distinguish between “type 1” and “type 2” heart attacks because the appropriate treatment can be very different. The best treatment for a type 2 heart attack is to correct the underlying condition and hence remove the cardiac insult. A holistic assessment is most useful at this point, considering conditions such as pneumonia, pulmonary embolus, or atrial fibrillation causing a rapid heart rate, which may produce a “supply-demand mismatch” in blood flow to the heart, resulting in heart muscle injury and a type 2 heart attack.
Let’s remember that not all heart attacks are created equally, and that a heart attack does not automatically mean that clogged arteries are the problem. It remains very important for all of us to still avoid the development of blocked arteries by eating a heart healthy diet, such as the Mediterranean diet. See our link for details!