ALT Angioedema Attacks before and after Administration of NTLA-2002. The severity and length of angioedema attacks in individual patients during the 8-week screening period, the 16-week primary observation period, and the post–primary observation period are represented by colored bars, with the width of each bar indicating the duration of the attack. Patient data are presented from top to bottom according to the trial group and length of follow-up. Baseline is defined as the period from the date of informed consent to randomization. Gray bars represent the interval between the beginning of the screening period for the individual patient and the last assessment of that patient as of the data-cutoff date. Bars that end in arrowheads indicate that the patient is still participating in the trial. Patients were permitted to resume long-term prophylaxis after week 16.