Parashath Noah, Laws of Ziziyoth, Page 17-18:
9. (cont'd) Ibid. (5) A coat or shirt which has four corners, formed by the lapels and lower front corners, does not require ziziyoth. However, since some Authorities maintain that it does require ziziyoth, a G-d-fearing person should round off one corner, and one will then certainly not be obliged to affix ziziyoth.
The coast which we wear (called abayyi, in Arabic) have rounded lapels, and thus do not require ziziyoth.]
This learning should be in memory of Maran, HaRav HaGaon Ovadia Yosef, ztz'l.