Intramuscular penicillin prophylaxis and valve progression in adults with mild rheumatic heart disease: a propensity score-matched cohort study.

Valve progression occurred in 2.0% of patients without prophylaxis and in 1.7% of patients with prophylaxis (RR 0.84; 95% CI 0.16-4.54; p = 1.000).

New valve disease developed in 2.0% and 2.6% of patients, respectively (RR 1.27; 95% CI 0.29-5.56; p = 0.714).

The composite outcome occurred in 4.1% of the no-prophylaxis group and 4.3% of the prophylaxis group (RR 1.06; 95% CI 0.35-3.15; p = 1.000).