Fans are warned he may never return to the band as he focuses on his health.
The veteran rocker 'died for several minutes' after collapsing following a concert in Turkey in June, his manager has revealed. The 67-year-old will postpone a final decision until next year but his current condition means he is not fit enough to take part in the band's final full-electric European tour, which starts next month.
Manager Simon Porter said in a statement: "Although Rick is recovering well and is now able to lead a relatively normal day-to-day life, he's far from being fit enough to undertake the rigours of Quo's touring schedule.
"Perhaps now is the time to reveal that Rick 'died' for several minutes, which resulted in mild cognitive impairments, for which he continues to receive support."
The band is due to play the Birmingham Barclaycard Arena on December 16.