The Added Value of Exercise Stress Echocardiography in Patients With Heart Failure

Abstract

Doppler echocardiography can provide reliable and repeatable measures of cardiac index (CI), whereas lung ultrasound (LUS) represents a quantitative approach to assess pulmonary congestion. We tested the hypothesis that simultaneous assessment of CI and LUS during exercise stress echocardiography (ESE) may define heart failure (HF) outpatients with different risk of adverse outcome. Standard transthoracic echocardiography and LUS (B-lines) evaluation were assessed during semisupine ESE. CI and B-lines were measured at baseline and peak exercise. Resting plasma B-type natriuretic peptide levels were also evaluated. We enrolled 105 HF patients (87 males; age 62 ± 11 years; New York Heart Association class I to III) with reduced left ventricular ejection fraction (30 ± 7%). Patients were classified into 4 profiles: (1) peak CI ≥4.0 l/min/m² and peak B-lines <15 (no evidence of congestion or hypoperfusion, n = 47); (2) peak CI ≥4.0 l/min/m² and peak B-lines ≥15 (congestion with adequate perfusion, n = 23); (3) peak CI <4.0 l/min/m² and peak B-lines <15 (hypoperfusion without congestion, n = 13); and (4) peak CI <4.0 l/min/m² and peak B-lines ≥15 (congestion and hypoperfusion, n = 22). There were 21 cardiovascular deaths and 18 hospitalizations for worsening HF during a median follow-up of 29 months. Multivariate predictors of the combined end point were peak hemodynamic profiles (hazard ratio [HR] 1.62, 95% confidence interval [CI] 1.19 to 2.21; p = 0.002), B-type natriuretic peptide (HR 1.00, 95% CI 1.00 to 1.01; p = 0.001), and rest E/e' (HR 1.09, 95% CI 1.03 to 1.15; p = 0.002). Survival analysis showed a worse survival in patients with ESE-derived D profile, followed by patients with C, B, and A profile (log-rank: chi-square = 40.5; p <0.0001). In conclusion, dual evaluation of CI and LUS during ESE is useful for risk stratification of HF patients with reduced ejection fraction. Evidence of pulmonary congestion and low CI at peak ESE identifies a subgroup with a very high risk of adverse outcome.