FORT WORTH -- The 47-year-old guitarist for the metal band Rigor Mortis died early Sunday after apparently suffering a seizure during a performance at The Rail Club in Fort Worth.Michael Scaccia, 47, of Arlington was pronounced dead at 12:26 a.m. in the emergency room at Texas Health Harris Methodist Hospital Fort Worth, according to the Tarrant County medical examiner's office. Police responded to a deceased person call at the club at 11:45 p.m. Saturday, according to records.Scaccia died of a sudden heart attack brought on by a heart disease, according to the medical examiners website on Sunday. Officials ruled it a natural death.Blabbermouth.net which describes itself as "the CNN of heavy metal and hard rock news," said Scaccia asked for strobe lights to be turned off, then collapsed and suffered a seizure.Rigor Mortis was performing at the club, 3101 Joyce Drive, in honor of lead vocalist Bruce Corbitt's 50th birthday."My brother is gone!," Corbitt wrote early Sunday on his Facebook page. "The only reason I am who I am is because of this man. If it wasn't for him I wouldn't even be in a band. RIP Mike Scaccia! The greatest guitar player I ever knew!"