Itanium came out before AMD's x86-64 instruction set and, thus, did not rely on the x86 instruction set. Itanium relied on what's known as the IA-64 architecture, a Very Long Instruction Word ...
Some would say that all x86 instructions are crazy, especially if you are accustomed to reduced instruction set computers. The x86, like other non-RISC processors, has everything but the kitchen sink.