Impact of severe obesity on heart transplantation outcomes: A meta-analysis of survival and complications

Abstract

Background

Heart transplantation (HT) is the standard treatment for end-stage heart failure, but severe obesity (Body Mass Index [BMI] ≥ 35 kg/m²) is linked to worse outcomes and is considered a relative contraindication. Obese patients face increased perioperative risks, longer wait times, and reduced survival, though improved clinical care may mitigate some effects. As obesity rates rise, the suitability of the current BMI is increasingly debated. Evidence remains limited and inconsistent, highlighting a need for clearer guidance. This systematic review and meta-analysis assess the impact of severe obesity on survival and post-transplant complications in HT recipients.

Methods

This systematic review and meta-analysis followed preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines and was registered in PROSPERO (CRD420251036442). We included cohort studies and randomized controlled trials (RCTs) (2000–2025) comparing outcomes in adult heart transplant recipients with a BMI ≥ 35 kg/m² vs lower BMI. Primary outcomes were mortality and post-transplant complications. Searches were conducted in PubMed, Scopus, Embase, and Cochrane CENTRAL. Multiple reviewers did data extraction and bias assessment (ROBINS-I) independently. Random-effects models were used for statistical analysis, with heterogeneity assessed via I², and sensitivity analyses performed. Publication bias was evaluated using funnel plots.

Results

The search strategy retrieved 1,697 articles or abstracts, 595 were excluded for being duplicates, and 59 full-text articles were selected for full-text analysis. Of these, 9 cohorts were included, 7 from the United States and 2 from Canada, with 218,272 patients, of whom 206,459 had a BMI < 35 and 11,813 had a BMI ≥ 35kg/m².

Conclusion

This meta-analysis shows that severe obesity (BMI ≥ 35 kg/m²) remains associated with higher rates of infection, graft failure, and post-transplant mortality, despite advances in care. These outcomes likely reflect underlying immune and metabolic dysfunctions in obese patients, emphasizing the need for tailored strategies to improve long-term survival after heart transplantation.