The prognostic significance of lung function in stable heart failure outpatients

Abstract

Background: This study investigated the impact on all-cause mortality of airflow limitation indicative of chronic obstructive pulmonary disease or restrictive spirometry pattern (RSP) in a stable systolic heart failure population.

Hypothesis: Decreased lung function indicates poor survival in heart failure.

Methods: Inclusion criteria: NYHA class II-IV and left ventricular ejection fraction (LVEF) < 45%. Prognosis was assessed with multivariate Cox proportional hazards models. Two criteria of obstructive airflow limitation were applied: FEV₁ /FVC < 0.7 (GOLD), and FEV₁ /FVC < lower limit of normality (LLN). RSP was defined as FEV₁ /FVC > 0.7 and FVC<80% or FEV₁ /FVC > LLN and FVC <LLN.

Results: There where 573 patients in the cohort (85% of eligible patients in study period). Median follow-up was 4.7 years and 176 patients died (31%). Age, NYHA class, smoking, body mass index and LVEF were independent prognostic factors (p<0.01). Obstructive airflow limitation increased mortality using both criteria (HR_GOLD 2.07 [95% CI 1.45-2.95] p<0.01 and HR_LLN 2.00 [1.40-2.84] p<0.01) and was an independent marker when using LLN criteria (HR 1.74 [1.17-2.59] p=0.006). RSP was independently associated with mortality when defined as FVC < LLN (HR 1.54 [1.01-2.35] p=0.04) but not as FVC < 80%. Multivariate hazard ratios for a 10% decrease in predicted value of FEV1 or FVC were 1.42 (p<0.001) and 1.33 (p<0.001) in patients exhibiting airflow obstruction, and 1.36 (p=0.031) and 1.38 (p=0.041) in RSP.

Conclusions: Presence of obstructive airflow limitation indicative of COPD or RSP were associated with increased all-cause mortality, however only independently when using the LLN definition.

Keywords: COPD; Heart failure; Restrictive spirometry pattern; spirometry.