Comparison of cardiorespiratory fitness in black or african American versus caucasian patients with heart failure

Purpose: Cardiopulmonary exercise testing (CPX) is a well-established assessment with important insight into prognosis and therapeutic efficacy in patients with heart failure (HF). Prior studies have identified several clinical differences between Black or African American (B-AA) and Caucasian patients with HF. Differences in key CPX responses between these two groups require further investigation. Methods: Using a database consisting of subjects with symptomatic HF who had undergone CPX for inclusion in various prospective randomized clinical trials, we identified 198 (n = 94 [47%] B-AA; n = 105 [53%] Caucasian) patients with a qualifying baseline CPX. Significant univariate predictors of peak oxygen uptake (Vo2peak) were included in a multivariate linear regression model. Results: When compared with Caucasian patients, B-AA were younger (mean ± SD = 54.8 ± 10.0 vs 57.9 ± 9.6 yr, P =.03), had higher C-reactive protein (CRP) (median [IQR] = 4.9 [2.3, 8.8] vs 1.9 [0.6, 5.5] mg/L, P <.0001), lower hemoglobin (13.0 ± 1.8 vs 13.8 ± 1.6 g/dL, P =.003), and lower left ventricular ejection fraction (LVEF) (40 [32, 51] vs 53 [43, 59]%, P <.00010). During CPX, B-AA patients also had lower Vo2peak (14.6 ± 3.9 vs 17.6 ± 4.8 mL·kg−1·min−1, P <.0001). No differences were observed between B-AA and Caucasian in the minute ventilation/carbon dioxide production (Ve/Vco2) slope (P =.14). The difference in Vo2peak between B-AA and Caucasian was largely attenuated after adjusting for age, body mass index, CRP, N-terminal pro-brain natriuretic peptide, hemoglobin, LVEF, and peak HR (14.1: 95% CI, 13.2-14.9 vs 15.6: 95% CI, 14.4-16.8 mL·kg−1·min−1, P =.053). Conclusions: Directly measured Vo2peak was significantly lower in B-AA than in Caucasians with HF. This is largely explained by differences in clinical characteristics, whereas no significant differences were observed in the Ve/Vco2 slope