This study aims to analyze the effect of Pulmonary Endarterectomy (PEA) on patients' self-confidence in managing their chronic illness. Patients' confidence (or self-efficacy) will be measured using the following questionnaires: 10-item Perceived Efficacy in Patient-Physician Interaction Scale (PEPPI), Self-Efficacy for Managing Chronic Diseases 6-item Scale (SEMCD-6), Sullivan's cardiac self-efficacy scale 13-items (SCSES). The association between improved confidence and better physical results will be analyzed, such as being able to walk longer (6 mint walk test (6-Minute Walk Test)). Ultimately, this study will help understanding the psychological side of recovery and might lead to better support programs to help patients feel more capable and live better lives after their operation.