Can untreated strep throat cause damage to the heart in someone with mitral valve prolapse?

Possibly: The attack rate of rheumatic heart disease for untreated strep throat has been quoted as 1/200.Antibiotic treatment within 9-10 days of first symptoms cuts this risk dramatically, but every day of delay is a problem. The mitral and aortic valve, as well as the heart in general can be effected. This would aggravate any underlying problem.