Lung water estimation on cardiac magnetic resonance imaging for predicting adverse cardiovascular outcomes in patients with heart failure

Abstract

Objectives: Pulmonary congestion is a central feature of heart failure (HF) seen in acute decompensated state as well as in chronic stable disease. The present study sought to determine whether simplified cardiac magnetic resonance imaging (CMR)-derived lung water density (LWD) measurement has prognostic relevance in predicting adverse cardiovascular outcomes in patients with HF and left ventricular ejection fraction (LVEF)<50%.

Methods: Eighty consecutive patients referred for CMR with HF and LVEF<50% along with 22 healthy age- and sex-matched controls were prospectively recruited. LWD was the lung-to-liver signal intensity ratio multiplied by 70% (estimated hepatic water density). The primary endpoint was composite of all-cause mortality or HF-related hospitalization within 6 months from CMR.

Results: The mean LWD was significantly higher in HF patients compared to healthy controls (19.78 ± 6.1 vs 13.6 ± 2.3; p < 0.001). The mean LWD was significantly different among patients with NYHA class I/II and NYHA class III/IV (17.88 ± 4.8 vs 21.77 ± 1.08; p = 0.004). At 6 months, the primary endpoint was reached in 12 (15%) patients. Patients with "wet lungs" (LWD > 18.1%) had higher incidence of adverse cardiovascular outcomes compared to patients with "dry lungs". LWD was an independent predictor of adverse cardiovascular outcomes in multivariable analysis. At the optimal cut-off of LWD > 23.38%, the sensitivity and specificity were 91.67 and 91.18%, respectively, to predict adverse cardiovascular outcomes.

Conclusion: LWD on CMR is independently associated with increased risk of mortality and HF-related hospitalization in HF patients with LVEF<50%.

Advances in knowledge: Non-invasive quantitative estimation of LWD on CMR can improve risk stratification and guide management in HF patients.

Figure 1.

Axial (a) and coronal (b) localizer images demonstrating the six sagittal slice locations covering the right and left lung from apices. The liver should be included within the right-sided slices.

Figure 2.

Sagittal HASTE (Half Fourier Single-shot Turbo Spin-Echo)images(a and b) with the tracing of maximum cross-section of the right (in a) and left (in b) lung. The operator-selected region of interest (ROI) for the liver is also depicted.

Figure 3.

Box plot demonstrating the mean lung water density in healthy controls (13.6 ± 2.3), HF patients with NYHA functional class I/II (17.9 ± 4.8) and HF patients with NYHA functional class III/IV (21.8 ± 1.1). [NYHA:New York Heart Association]

Figure 4.

Receiver-operating-characteristic (ROC) curve for lung water density with area-under curve = 0.93.