Responder analysis for improvement in 6‐min walk test with ferric carboxymaltose in patients with heart failure with reduced ejection fraction and iron deficiency

AIM: Improving functional capacity is a key goal in heart failure (HF). This pooled analysis of FAIR‐HF and CONFIRM‐HF assessed the likelihood of improvement or deterioration in 6‐min walk test (6MWT) among iron‐deficient patients with chronic HF with reduced ejection fraction (HFrEF) receiving ferric carboxymaltose (FCM). METHODS AND RESULTS: Data for 760 patients (FCM: n = 454; placebo: n = 306) were analysed. The proportions of patients receiving FCM or placebo who had ≥20, ≥30, and ≥40 m improvements or ≥10 m deterioration in 6MWT at 12 and 24 weeks were assessed. Patients receiving FCM experienced a mean (standard deviation) 31.1 (62.3) m improvement in 6MWT versus 0.1 (77.1) m improvement for placebo at week 12 (difference in mean changes 26.8 [16.6–37.0]). At week 12, the odds [95% confidence interval] of 6MWT improvements of ≥20 m (odds ratio 2.16 [1.57–2.96]; p < 0.0001), ≥30 m (2.00 [1.44–2.78]; p < 0.0001), and ≥40 m (2.29 [1.60–3.27]; p < 0.0001) were greater with FCM versus placebo, while the odds of a deterioration ≥10 m were reduced with FCM versus placebo (0.55 [0.38–0.80]; p = 0.0019). Among patients who experienced 6MWT improvements of ≥20, ≥30, or ≥40 m with FCM at week 12, more than 80% sustained this improvement at week 24. CONCLUSION: Ferric carboxymaltose resulted in a significantly higher likelihood of improvement and a reduced likelihood of deterioration in 6MWT versus placebo among iron‐deficient patients with HF. Of the patients experiencing clinically significant improvements at week 12, the majority sustained this improvement at week 24. These results are supportive of FCM to improve exercise capacity in HF.