Anyone died with mitral valve insufficiency?

Yes: But there isn't any need since it's a treatable condition. Mild to moderate mitral insufficiency doesn't require treatment. Acute severe or chronic symptomatic severe mr require treatment. Chronic severe mr without symptoms needs careful followup.

Yes if neglected: My professors used to say no one dies with chronic mitral regurgitation which is true unless it doesn't get fixed when it becomes severe. Patients with severe mitral regurg even though they are asymptomatic should get a surgical opinion and consider repair. The short and long term results after surgery before heart failure begins is dramatically better.