text_1: In patients with congenital heart defects, β-blockers significantly improve clinical heart failure outcomes.
text_2: Among 54 patients assigned to placebo, 30 improved (56%), 16 worsened (30%), and 8 were unchanged (15%); among 103 patients assigned to carvedilol, 58 improved (56%), 25 worsened (24%), and 20 were unchanged (19%).