Race, exercise training, and outcomes in chronic heart failure: findings from Heart Failure - a Controlled Trial Investigating Outcomes in Exercise TraiNing (HF-ACTION)

Abstract

Background: The strength of race as an independent predictor of long-term outcomes in a contemporary chronic heart failure (HF) population and its association with exercise training response have not been well established. We aimed to investigate the association between race and outcomes and to explore interactions with exercise training in patients with ambulatory HF.

Methods: We performed an analysis of HF-ACTION, which randomized 2331 patients with HF having an ejection fraction ≤35% to usual care with or without exercise training. We examined characteristics and outcomes (mortality/hospitalization, mortality, and cardiovascular mortality/HF hospitalization) by race using adjusted Cox models and explored an interaction with exercise training.

Results: There were 749 self-identified black patients (33%). Blacks were younger with significantly more hypertension and diabetes, less ischemic etiology, and lower socioeconomic status versus whites. Blacks had shorter 6-minute walk distance and lower peak VO2 at baseline. Over a median follow-up of 2.5 years, black race was associated with increased risk for all outcomes except mortality. After multivariable adjustment, black race was associated with increased mortality/hospitalization (hazard ratio [HR] 1.16, 95% CI 1.01-1.33) and cardiovascular mortality/HF hospitalization (HR 1.46, 95% CI 1.20-1.77). The hazard associated with black race was largely caused by increased HF hospitalization (HR 1.58, 95% CI 1.27-1.96), given similar cardiovascular mortality. There was no interaction between race and exercise training on outcomes (P > .5).

Conclusions: Black race in patients with chronic HF was associated with increased prevalence of modifiable risk factors, lower exercise performance, and increased HF hospitalization, but not increased mortality or a differential response to exercise training.

Figure

Adjusted event curves for all-cause mortality/hospitalization* (A) and cardiovascular mortality/HF hospitalization^† (B). *Adjusted for peak VO₂ by Weber class, KCCQ symptom stability score, blood urea nitrogen, country, EF, sex, β-blocker dosage, mitral regurgitation (MR) grade, and ventricular conduction.^†Adjusted for loop diuretic dose, EF, MR grade, ventricular conduction, KCCQ symptom stability score, blood urea nitrogen, sex, age, peak VO₂ by Weber class, and V_E/VCO².