When the coronary artery fistula is small and its effects are negligible, it may remain unrecognized during childhood. In fact, the average age for a patient at diagnosis is in the mid 20s. If the fistula is small and causes no adverse symptoms, it is often left untreated even after discovery.

However, many coronary artery fistulae continue to enlarge over time and eventually cause ischemia, or the deprivation of oxygen-rich blood to the heart tissues, which may cause fatigue and/or dyspnea (breathlessness) during exertion. Patients may also develop arrhythmias and heart failure sometimes occurs. In these cases, closure of the fistula is necessary.