Microvascular Complications in Diabetes Patients with Heart Failure and Reduced Ejection Fraction—Insights from the Beta-Blocker Evaluation of Survival Trial

AIMS: The role of microvascular complications in the risk conferred by diabetes in heart failure with reduced ejection fraction (HFrEF) is unknown. METHODS AND RESULTS: We studied 2707 HFrEF patients in the Beta-blocker Evaluation of Survival Trial (BEST), stratified into three groups: no diabetes and diabetes without or with microvascular complications (neuropathy, nephropathy, or retinopathy). The risks of the composite of cardiovascular death or heart failure hospitalization, and all-cause death, were studied using Cox regression analyses adjusted for other prognostic variables. Overall, 964 (36%) patients had diabetes, of which 313 (32%) had microvascular complications. Patients with microvascular complications had more severe symptoms (New York Heart Association class IV 12% vs. 9% diabetes with no complications and 7% no diabetes), and worse quality of life (Minnesota Living with Heart Failure median score 60 vs. 54 and 51 points). In patients with diabetes and complications, the rate of the composite outcome was 50 per 100 person-years of follow-up (compared with 34 and 29 in those with diabetes and no microvascular complications and participants without diabetes, respectively). Compared to patients without diabetes, the adjusted hazard ratio (HR) for the composite outcome was 1.44 [95% confidence interval (CI) 1.22-1.70] and 1.18 (95% CI 1.03-1.35) for patients with diabetes with and without complications, respectively. The risk of all-cause mortality was similarly elevated: adjusted HR 1.42 (95% CI 1.16-1.74) and 1.20 (95% CI 1.01-1.42), respectively. CONCLUSION: In HFrEF, diabetes with microvascular complications is associated with worse symptoms and outcomes than diabetes without microvascular complications. Prevention of microvascular complications has the potential to improve HFrEF outcomes.