If you look in Winbase.h in WinInc you will see how it suppose to be to work in both 32 and 64 bit:
@DefProto WINBASEAPI, HeapCreate, stdcall, , <:DWORD, :SIZE_T, :SIZE_T>, 12
@DefProto WINBASEAPI, HeapDestroy, stdcall, , <:HANDLE>, 4
@DefProto WINBASEAPI, HeapAlloc, stdcall, , <:HANDLE, :DWORD, :SIZE_T>, 12
@DefProto WINBASEAPI, HeapReAlloc, stdcall, , <:HANDLE, :DWORD, :LPVOID, :SIZE_T>, 16
@DefProto WINBASEAPI, HeapFree, stdcall, , <:HANDLE, :DWORD, :LPVOID>, 12
@DefProto WINBASEAPI, HeapSize, stdcall, , <:HANDLE, :DWORD, :LPCVOID>, 12
@DefProto WINBASEAPI, HeapValidate, stdcall, , <:HANDLE, :DWORD, :LPCVOID>, 12
@DefProto WINBASEAPI, HeapCompact, stdcall, , <:HANDLE, :DWORD>, 8
@DefProto WINBASEAPI, GetProcessHeap, stdcall, , <>, 0
@DefProto WINBASEAPI, GetProcessHeaps, stdcall, , <:DWORD, :PHANDLE>, 8