BackgroundKnowledge about impact of age and comorbidities on outcome in patients with leadless pacemakers (LPM) is limited. ObjectivesTo analyse outcome in LPM patients according to age and comorbidities. MethodsThis Swiss, multi-centre, retrospective analysis includes all patients with LPM implanted between 2015 and 2022. Charlson-Comorbidity-Index (CCI) was determined and patients were divided into a low- (CCI ≤ 5) and high-comorbidity (CCI > 5) group. Peri-procedural complications, in-hospital death, and all-cause mortalities were assessed. Finally, all-cause mortality according to three groups (CCI ≤ 3, 4–5, >5) was compared to age and sex-adjusted mortality in the general Swiss population. Results863 patients (median age 81 years, 65% male, 42% with CCI > 5) were included. Peri-procedural/long-term complication rates did not differ between the low- vs. high-comorbidity groups (2.6% vs. 1.7%, p = 0.48 and 1.2% vs. 2.8%, p = 0.12, respectively). In-hospital (3.6% vs. 0.6%, p = 0.002) and all-cause mortality (HR 2.9, 95%CI 2.2–3.8, p < 0.001) were significantly higher in the high-comorbidity group resulting in a three-year mortality of 58% (95%CI 51–65%) vs. 22% (95%CI 17–27%) in the low-comorbidity group. In patients with a CCI ≤ 3, all-cause mortality was comparable to the age- and sex-adjusted mortality of the general Swiss population. ConclusionsIn elderly patients with high comorbidity, LPM implantation was not associated with increased peri-procedural/long-term complications. All-cause mortality in LPM patients with a CCI ≤ 3 was comparable to age- and sex-adjusted mortality in the general Swiss population. Despite a relatively high three-year mortality due to competing risk factors, LPM implantation is safe, even in elderly patients with high comorbidity. Condensed abstractIn this Swiss, multi-centre, retrospective cohort analysis, 863 patients implanted with a leadless pacemaker were included and divided into a high-comorbidity (with a CCI > 5) and low-comorbidity (with a CCI ≤ 5) group. There was no between group difference in terms of implantation outcomes and peri-operative or long-term complications. Furthermore, all-cause mortality during follow-up in patients with a CCI ≤ 3 was comparable to age- and sex-adjusted mortality in the general Swiss population. These data indicate that LPM implantation is a safe procedure, even in elderly patients with high comorbidity.