Does lasix affect the heart?

It can cause loss of potassium in your body and a low potassium can cause irregular heart beat.

Indirectly Laxis does affect the heart. What are you experiencing?

Lasix (furosemide) is a loop diuretic (water pill) that prevents your body from absorbing too much salt, allowing the salt to instead be passed in your urine.

Lasix treats fluid retention (edema) in people with congestive heart failure, liver disease, or a kidney disorder such as nephrotic syndrome. This medication is also used to treat high blood pressure (hypertension).

https://www.drugs.com/lasix.html

Some cardiovascular side effects are listed in the link below.

https://www.drugs.com/sfx/lasix-side-effects.html