All‐cause mortality predicted by peak oxygen uptake differs depending on spirometry pattern in patients with heart failure and reduced ejection fraction

AIMS: In patients with heart failure and reduced ejection fraction (HFrEF), it remains unclear how exacerbated impairments in peak exercise oxygen uptake (V̇O(2peak)) caused by coexistent obstructive or restrictive ventilatory defects affect mortality risk. We evaluated in patients with HFrEF, whether demonstrating either an obstructive or restrictive‐patterned ventilatory defect on spirometry affects V̇O(2peak) to yield all‐cause mortality risk predicted by V̇O(2peak) that is spirometry pattern specific. METHODS AND RESULTS: We retrospectively analysed resting spirometry and treadmill cardiopulmonary exercise testing data of patients with HFrEF (left ventricular ejection fraction ≤ 40%). The study sample (N = 329) was grouped by spirometry pattern: normal [Group 1: N = 101; forced expiratory volume in 1 s (FEV(1))/forced vital capacity (FVC) ≥ 0.70; FVC ≥ 80% predicted], restrictive without airflow obstruction (Group 2: N = 104; FEV(1)/FVC ≥ 0.70; FVC < 80% predicted), or obstructive (Group 3: N = 124; FEV(1)/FVC < 0.70). Patients were followed up to 1 year for the endpoint of all‐cause mortality. V̇O(2peak) was higher in Group 1 versus Groups 2 and 3 (13.4 ± 4.0 vs. 12.1 ± 3.7 and 12.2 ± 3.3 mL/kg/min, respectively; P = 0.014). Over the 1 year follow‐up, n = 9, n = 16, and n = 12 deaths occurred in Groups 1–3, respectively, with corresponding crude survival rates of 88%, 81%, and 92%, respectively (log‐rank; P = 0.352). V̇O(2peak) was associated with all‐cause mortality (crude hazard ratio = 0.77; P < 0.001). In multivariate analyses, a significant V̇O(2peak)‐by‐spirometry group interaction yielded 1.99 (95% confidence interval, 1.14–3.46) and 2.43 (95% confidence interval, 1.44–4.11) higher mortality risk associated with V̇O(2peak) in Group 2 versus Groups 1 and 3, respectively. CONCLUSIONS: Demonstrating a restrictive pattern on spirometry yields the severest mortality risk associated with V̇O(2peak). Using spirometry to screen patients with HFrEF for ventilatory defects has a potential role in improving risk stratification based on V̇O(2peak).