Background: Percutaneous coronary intervention (PCI) is associated with a short hospital stay and fast recovery. However, it might be related to insufficient implementation of lifestyle changes after the procedure. Conversely, coronary artery bypass grafting (CABG) is a highly invasive technique that requires a prolonged hospital stay and long rehabilitation with more opportunities for education. This study aimed to evaluate the impact of CABG on adherence to lifestyle modifications and knowledge about coronary artery disease (CAD) in comparison with PCI. We also evaluated the level of education and tried to define groups of patients that might require targeted education. Methods: Data was collected using a self-designed 56-item questionnaire. Questions assessed the knowledge of CAD risk factors and the level of their control. Results: The study group consisted of 155 consecutive patients admitted to the Cardiology Department. Patients with a history of PCI (68%) (at least 8 weeks before) were included in the prior-PCI group, and patients with previous surgical revascularization (also at least 8 weeks before) were assigned to the prior-CABG group (32%). The knowledge score was higher in the prior-CABG group. The median (IQR) results in the prior-PCI vs. prior-CABG group were, respectively: 20 (12–24) vs. 22 (19–25) [points, per 31 max.]; p = 0.01. Similar results were obtained in the level of risk control (prior-PCI vs. prior-CABG, respectively: 6 (4–7) vs. 7 (6–8) [points, per 15 max.]; p = 0.002). Conclusions: The method of treatment of CAD might impact the implementation of lifestyle modifications after the procedure. More effort is required to improve secondary prevention, especially in PCI patients.