Is Medicare A, B, and D enough health insurance? Do you need a $200+/month supplement to cover a heart bypass?

Is Medicare A, B, and D enough health insurance? Do you need a $200+/month supplement to cover a heart bypass? Is Medicare A, B, and D enough health insurance? Do you need a $200+/month supplement to cover a possible triple bypass at age 71? How much will a triple bypass cost? What much will come out of my savings?
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http://www.medicare.gov/
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