Tiwary, who coached India at the Rio Olympics, suffered the stroke on Wednesday morning and CT scans revealed multiple blood clots in his brain.
The Indian archer qualified despite bowing out in the preliminary round of the individual men's recurve event in the Shanghai World Cup.
India won their first-ever silver medal, after losing to South Korea in the final, in the World Outdoor Target Archery Championship.
The men's archery team made history by entering their maiden team final in the 43rd World outdoor target archery championship.
India garnered most of the gold medals on offer for the fourth successive day at the 12th South Asian Games, as their swimmers, archers and track-and-field athletes ensured the top position on the medals tally remained unchallenged, in Guwahati, on Tuesday.