Can a fast heart rate damage your heart?

A fast heart rate may be a manifestation of pre-existing heart disease which is causing a decrease in the function of the heart and the increase in rate is secondary. But a primary rhythm disorder of the heart with persistent high rates can also damage the heart. This situation is known as tachycardiomyopathy. This can occur in long standing atrial fibrillation with fast rates or persistent junctional re-entrant tachycardia (PJRT).