The early symptoms of Lyme disease that involve the heart are palpitations, chest pain, dizziness and passing out. It can occur as soon as one week after the tick bite.
Some patients may develop chronic inflammation of the sack around the heart (pericardium). This can cause sharp chest pains that increase with deep breaths or lying down. Over time the pericardium can thinken and adhere to the heart muscle. This can cause swelling in the lower extremities, abdomen and sometimes lightheadedness, shortness of breath and exercise intolerance.
87% of the patients that develop Lyme carditis also have some degree of AV block.
Lyme disease can also invade and inflame the heart muscle, resulting in myocarditis. This can lead to muscle weakening and abnormally fast heart rhythms.