Simple algorithm to narrow down the candidates to receive echocardiography in patients with chronic liver disease for suspected pulmonary hypertension

Abstract

Aims: Portopulmonary hypertension (PoPH) is a subtype of pulmonary arterial hypertension related to portal hypertension. The definitive diagnosis of PoPH is made by invasive right heart catheterization. Alternatively, pulmonary arterial hypertension may be recognized noninvasively from the tricuspid regurgitant pressure gradient (TRPG), measured by echocardiography. In this study, we aimed to establish a simple algorithm to identify chronic liver disease patients with a high TRPG value in order to narrow down the candidates to receive echocardiography.

Methods and results: TRPG was measured by echocardiography in 152 patients with chronic liver disease. Factors predictive of TRPG >30 mmHg were investigated. There were 28 (18%) cases with TRPG >30 mmHg. Independent factors associated with a high TRPG were the presence of shortness of breath, high serum brain natriuretic peptide (BNP), and low serum albumin. Child-Pugh class or the presence of ascites, varices, or encephalopathy was not associated with TRPG. There was a correlation between the serum BNP and TRPG, and the optimal cutoff value of BNP by the Youden index was 122 pg/mL, and by 100% sensitivity was 50 pg/mL. A combination of these factors identified patients with a high probability of TRPG >30 mmHg (n = 12, positive predictive value [PPV] of 83%), no probability (n = 80, PPV 0%), and intermediate probability (n = 60, PPV 25-34%). This algorithm has reduced the number of patients needing echocardiography by 53%.

Conclusions: A simple algorithm using the presence of shortness of breath, serum BNP, and albumin levels can narrow down the candidates to receive echocardiography.

Keywords: hepatology; portal hypertension; screening and diagnosis.

Figure 1

Tricuspid regurgitant pressure gradient (TRPG) values in terms of background. Box plots of TRPG in terms of cirrhosis status (a), the presence of ascites, hepatic encephalopathy or esophageal varices (b), and the presence of shortness of breath (c). TRPG levels did not differ in terms of cirrhosis status, the presence of ascites, hepatic encephalopathy, or esophageal varices, while the TRPG was significantly high in patients with shortness of breath. TRPG, tricuspid regurgitant pressure gradient.

Figure 2

Correlation between the tricuspid regurgitant pressure gradient (TRPG) and serum brain natriuretic peptide (BNP) levels. Each patient is represented by an open circle. The TRPG is positively correlated with serum BNP (a), and negatively correlated with serum albumin (b). Alb, albumin; BNP, brain natriuretic peptide; TRPG, tricuspid regurgitant pressure gradient.

Figure 3

Algorithm for stratification of the probability of TRPG >30 mmHg. A combination of three independent factors (the presence of shortness of breath, serum BNP level, and albumin level) associated with high TRPG was used to construct a classification tree. Patients with shortness of breath and serum BNP >122 pg/mL had a high probability of TRPG >30 mmHg (n = 12, PPV 83%), while those with BNP <50 pg/mL, irrespective of shortness of breath, and those without shortness of breath and serum albumin ≤3.2 g/dL, irrespective of serum BNP, had low probabilities of TRPG >30 mmHg (n = 80, PPV 0%), and others had intermediate probability (n = 60, PPV 25–34%). Alb, albumin; BNP, brain natriuretic peptide; PPV, positive predictive value; TRPG, Tricuspid regurgitant pressure gradient.