Abstract Introduction Brady-arrhythmias with subsequent need for permanent pacemaker implantation is after cardiac surgery. It is not known whether the need of a permanent pacemaker influences long-term prognosis after cardiac surgery. Methods This large, nationwide study included all patients who underwent cardiac surgery in Sweden 2006-2020. Data was obtained from the Swedish Cardiac Surgery Registry, The Swedish ICD and Pacemaker Registry, The Swedish National Patient Register, and the Swedish Cause of Death Register. Patients who received a permanent pacemaker within 30 days were compared to those who did not. Exclusion criteria were previous pacemaker or implantable cardioverter defibrillator implantation and death within 30 days. Missing data were handled by multiple imputation. Cox regressions models were used to obtain hazard ratios (HR) with 95% confidence intervals (95%CI). The model was adjusted for age at operation, sex, left ventricular ejection fraction (EF), type of surgery, previous myocardial infarction, diabetes, peripheral artery disease, chronic respiratory disease, hypertension and atrial fibrillation. Results In total, 74 606 patients were included out of which 2 150 (2.9%) received a pacemaker within the first 30 days after cardiac surgery. Those who had a pacemaker implanted were older, more often female, had lower EF and significantly more often atrial fibrillation and peripheral artery disease. These patients were less likely to have diabetes, hypertension and previous myocardial infarction. Pacemaker implantation was associated with a higher risk of all-cause mortality (adjusted HR: 1.09 (95%CI=1.00-1.19), p=0.035, Figure 1) and heart failure hospitalization (adjusted HR: 1.45 (95%CI=1.30-1.62), p<0.001). Cardiovascular mortality had similar estimates but did not reach statistical significance (HR: 1.09 (95%CI=0.99-1.24), p=0.15). Conclusions The presence of brady-arrhythmias requiring permanent pacemaker implantation after cardiac surgery is associated with a higher risk of mortality and heart failure hospitalization. Measures should be taken to minimize the risk of injury to the conduction system leading to brady-arrhythmias during cardiac surgery.