A stepwise composite echocardiographic score predicts severe pulmonary hypertension in patients with interstitial lung disease

Figures

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  FIGURE 1. Cohort identification and exclusion. A flow diagram describing the methodology of the study, from patient identification and selection to the development and validation of the echocardiography (echo) score in the derivation (n=210) and validation (n=61) cohorts; the latter derived from the same population over the same time period, but with some missing brain natriuretic peptide (BNP) and pulmonary function testing (PFT) data from the time of right heart catheterisation (RHC). CT: computed tomography; PH: pulmonary hypertension; ILD: interstitial lung disease; HRCT: high-resolution CT.

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  FIGURE 2. Severe pulmonary hypertension (PH) in interstitial lung disease (ILD) stepwise composite echocardiographic score. If an overall score of ≥7 is achieved, then the score is positive for the prediction of severe PH with a mean pulmonary arterial pressure (PAP) ≥35 mmHg. Where the right ventricular systolic pressure (RVSP) is >64 mmHg, the score is positive and no further analysis is necessary. Where RVSP is not available or intermediate then each step is continued until either a score of ≥7 is achieved, or if the final score is <7, in which case the score is negative and severe PH is unlikely. NA: not available; RV: right ventricle; LV: left ventricle.

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  FIGURE 3. Line plots demonstrating the effect of increasing unavailability of tricuspid regurgitation on the echocardiographic score area under the curve (AUC) for severe pulmonary hypertension (PH) analysis and its effect on sensitivity. Given the frequent “real-life” difficulty assessing tricuspid regurgitant velocity (TRV) at echocardiography in interstitial lung disease (ILD) patients, models were created to demonstrate the effect of increasing unavailability of TRV on a) the AUC of the echocardiographic score and b) the sensitivity of the score in predicting severe PH. We simulated an increasing level of unavailable TRV by randomly blinding available TRV values, with 100 iterations (by bootstrapping), and calculated the AUC and sensitivity following each iteration. We tested levels of TRV unavailability ranging between 8% (observed in the original cohort) and 60% (by 1% increments). The line plots show that AUC for the echo score is preserved across a wide spectrum of TRV unavailability (a). In addition, there was a minor reduction in the sensitivity of the score, despite a dramatic reduction in TRV availability from 93% to 40%, as opposed to TRV alone (using a cut-off of 4 m·s−1,…