no matter what happens; in any circumstances; at any price
A set phrase expressing strong determination or inevitability regardless of obstacles or events.
No matter what happens, I won't give up until the end.
He is a person who keeps his promises no matter what.
A fixed expression composed of どんな (what kind of) + こと (thing/event) + が (subject marker) + あっても (even if there is). The phrase literally means 'even if any kind of thing happens' and has become a common idiomatic expression for 'no matter what'.