Although silent heart attacks are unusual, they happen in enough people (including your brother) to make them worth talking about. When a coronary artery becomes blocked and heart muscle is injured during a myocardial infarction (MI), most individuals have striking symptoms, such as chest discomfort, indigestion, nausea, or shortness of breath. However, there are a few people who do not feel anything. This may have something to do with the pattern of nerves emanating from the heart, which differs between individuals. In other words, we are all wired differently. Also, not everyones cardiac nerves function equally. For example, people with diabetes are more likely to have silent heart attacks because their medical condition tends to injure nerves.