The British rocker and his bandmate Francis Rossi have reworked and stripped down 22 of the band's hits for their new record, Aquostic (Stripped Bare).
The duo staged a one-off show for fans last week (ends26Oct14) and Parfitt was overcome with nerves.
He tells Britain's Daily Mirror newspaper, "Getting them (the songs) just right is important and there's a bit of tenseness creeping in. Deep down I've been quite frightened so at that first gig I had a little bit of a panic attack, which for a man in my state of health is not a good thing."
After many years of drug and alcohol abuse, the star has suffered a multitude of health problems including undergoing a quadruple heart bypass in 1997 and later suffering heart attacks in 2011 and 2013.