Comorbidities and cause-specific outcomes in heart failure across the ejection fraction spectrum: A blueprint for clinical trial design

Background: Comorbidities may differently affect treatment response and cause-specific outcomes in heart failure (HF) with preserved (HFpEF) vs. mid-range/mildly-reduced (HFmrEF) vs. reduced (HFrEF) ejection fraction (EF), complicating trial design. In patients with HF, we performed a comprehensive analysis of type 2 diabetes (T2DM), atrial fibrillation (AF) chronic kidney disease (CKD), and cause-specific outcomes. Methods and results: Of 42,583 patients from the Swedish HF registry (23% HFpEF, 21% HFmrEF, 56% HFrEF), 24% had T2DM, 51% CKD, 56% AF, and 8% all three comorbidities. HFpEF had higher prevalence of CKD and AF, HFmrEF had intermediate prevalence of AF, and prevalence of T2DM was similar across the EF spectrum. Patients with T2DM, AF and/or CKD were more likely to have also other comorbidities and more severe HF. Risk of cardiovascular (CV) events was highest in HFrEF vs. HFpEF and HFmrEF; non-CV risk was highest in HFpEF vs. HFmrEF vs. HFrEF. T2DMincreased CV and non-CV events similarly but less so in HFpEF. CKD increased CV events somewhat more than non-CV events and less so in HFpEF. AF increased CV events considerably more than non-CV events and more so in HFpEF and HFmrEF. Conclusion: HFpEF is distinguished fromHFmrEF and HFrEF by more comorbidities, non-CV events, but lower effect of T2DM and CKD on events. CV events are most frequent in HFrEF. To enrich for CV vs. non- CV events, trialists should not exclude patients with lower EF, AF and/or CKD, who report higher CV risk. (c) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).