The 32-year-old is due to begin treatment in a London hospital on Monday, but made the trip to Villa Park to watch his side's tie with Chelsea.
Petrov released a statement shortly after arriving at the ground, and revealed a picture of Muamba sitting up in bed had inspired him, along with numerous well-wishes, to get back to health.
"I would like to thank all of the people who have left messages of support. The response has been overwhelming and I appreciate it very much," Petrov said. "This is a difficult time for my family and myself and I ask people to respect my privacy.
"With the help and love of my family, my team-mates, all of my friends in football, Aston Villa and all of the fans, I am sure I will beat this illness and I am determined to do this.
"I saw the picture released [on Friday] by Fabrice Muamba, my fellow player, and it has inspired me as has all of the support in the past 24 hours. For me, football will have to take a back seat for a while, but I'm here to support my team-mates. Thank you to everyone."