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

Abstract

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 (FEV₁ )/forced vital capacity (FVC) ≥ 0.70; FVC ≥ 80% predicted], restrictive without airflow obstruction (Group 2: N = 104; FEV₁ /FVC ≥ 0.70; FVC < 80% predicted), or obstructive (Group 3: N = 124; FEV₁ /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 .

Keywords: CPET; Exercise capacity; Exercise intolerance; HFrEF; Spirometry.