Daley Blind, 29, suffered dizziness during Ajax's Champions League defeat to Valencia earlier this month, and has now been diagnosed with cardiomyopathy.
This heart muscle inflammation will keep Blind out of action indefinitely, with the severity of the problem still yet to be released.
Blind took to Twitter to update fans, he said: "First of all I want to thank you for all the messages you have sent me, I really appreciate it. They help me, so thank you for that.”
"Second, Ajax just posted an update online about my condition. The most important thing is I'm feeling good at the moment. I'm trying to come back as soon as possible. Again, thank you for everything, and I'll see you guys soon."
Blind spent four years at Manchester United before returning to Ajax in a £14.1million move in July 2018.
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