Apex domains cannot have CNAME records.
Question and response
Question
dig ischemicartery.com. NS
Answer
ischemicartery.com. 5 NS ns4cgs.name.com.
ischemicartery.com. 5 NS ns3gnv.name.com.
ischemicartery.com. 5 NS ns1psw.name.com.
ischemicartery.com. 5 NS ns2fhn.name.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0