Could afib make my heart failure worse, if i don't get it cardioverted?

Afib: In patients with systolic dysfunction of the heart, atrial fibrillation can cause about a 20% decrease in cardiac efficiency. Cardioversion can help this but keeping the heart in sinus rhythm in such a patient can be a problem.

A fib: If you a fib is not controlled then yes it can depress your heat function. Most people with a fib can get the rate controlled with medications. Ablation is done when medications fail to control the rate.

A fib heart failure: Rate controlled atrial fibrillation will not worsen your heart failure. There is an entity "tachycardia induced heart failure". This can happen if the rate of a fibrillation is uncontrolled for a period of time. Every patient should get an attempt at cardioversion however the success arte depends on cardiac chamber sizes, duration of a.Fib.