Abstract Background There is limited evidence on the differences in procedural outcomes between sexes after de novo cardiac implantable electronic device implantation (CIED). Furthermore, it is unclear whether any sex-based disparities have changed over the years. Purpose To compare procedural outcomes of de novo CIED implantation between sexes and study the trends of these outcomes over a 11-year period in a nationally representative sample. Methods Using the National Inpatient Sample, all hospitalisations between 2004 and 2014 for de novo CIED implantation were included, stratified by sex. Multivariable logistic regression was performed to 1) examine the association between sex and in-hospital complications of CIED implantation, expressed as odds ratios (OR) with 95% confidence intervals (CI), and 2) analyse trends of in-hospital outcomes by assessing the interaction term between time (years) and sex as covariates. Results Out of 2,815,613 hospitalisations for de novo CIED implantation, 41.9% were performed on women. Women were associated with increased adjusted odds of major adverse cardiovascular events (composite of mortality, thoracic and cardiac complications; OR 1.17 95% CI 1.16, 1.19), procedure-related bleeding (OR 1.13 95% CI 1.12, 1.15), and local complications (thoracic: OR 1.42 95% CI 1.40, 1.44, cardiac: OR 1.44 95% CI 1.38, 1.50). (p<0.001 for all) Notably, there was no difference in odds of all-cause mortality between sexes (OR women: 0.96 95% CI 0.94, 1.00). The odds of adverse complications in the overall CIED cohort were persistently raised in women throughout the study period, whereas similar odds of all-cause mortality across the sexes were observed throughout the study period (see Figure). Conclusion In a national cohort of CIED implantations we demonstrate that women are at a persistently higher risk of procedure-related adverse events other than mortality compared to men. This trend is concerning and warrants further work on procedural techniques to neutralise these sex disparities. Trends of odds of complications in women Funding Acknowledgement Type of funding source: Private company. Main funding source(s): This work constitutes part of a PhD for MOM that is supported by Medtronic Ltd. Medtronic Ltd. was not involved in the conceptualization, design, conduct, analysis, or interpretation of the current study.