Mycotic aneurysm is defined as an infection of the arterial wall either by fungi or bacteria. Although, a rare complication of infection, it is associated with high morbidity and mortality. We describe a 69-year-old female with a rare thoracic aortic mycotic aneurysm, with no clear source of infection and a predominantly atypical presentation, manifesting primarily as heart failure, at a rural community hospital. Our case also depicts the rapid development of aortitis and mycotic aneurysms. This case highlights the challenges in the diagnosis and management of this condition.