Cardiovascular diseases, particularly coronary heart disease (CHD) caused by atherosclerosis, have the highest worldwide incidence and mortality rate of any type of disease. Aside from risk factors associated with lifestyle and comorbidities, infectious agents such as Borrelia burgdorferi sensu lato spirochetes, which cause Lyme disease, may also play a role in the development of cardiovascular disease. A growing number of scientific papers have mentioned Lyme carditis. The aim of this study was to find the level of anti-Borrelia IgG antibodies in the blood serum of patients with advanced coronary heart disease. Materials and methods: The study group included 70 patients undergoing coronary artery bypass grafting (CABG) and off-pump coronary artery bypass (OPCAB) surgery aged 50 to 82 (average 68.26). The ELISA test was used to detect anti-Borrelia/IgG antibodies in the blood serum. Serological testing revealed seropositivity in 34.29% of patients and ‘borderline results’ in 17.14% of patients. We found a link between antibody levels and tick bites but not with other risk factors for the development of CHD. Conclusions: These findings support the idea that, as one of many factors, the contact with spirochetal antigens may indicate a potential positive correlation with the formation of cardiovascular changes. More research, not only at the diagnostic level but also at the advanced research level, is needed.