An increased right to left ventricle (RV:LV) diameter ratio, measured via computed tomography pulmonary angiography (CTPA), may help identify high-risk patients with suspected interstitial lung disease (ILD)/pulmonary hypertension (PH) and predict death or disease deterioration in patients with acute pulmonary embolism.
Researchers of a retrospective study reviewed consecutive patients with ILD and suspected PH who were referred to the Royal Brompton Hospital National Pulmonary Hypertension Service, London, United Kingdom, between 2005 and 2015. Results of the analysis were published in the journal CHEST.
Investigators sought to explore whether patients with ILD-associated PH (ILD-PH) would have a larger RV:LV ratio than patients without the disease and whether an increased RV:LV ratio is predictive of PH and linked to worse disease prognosis. ILD subtype, demographics, echocardiography, and detailed CTPA measurements were obtained from consecutive patients who underwent both CTPA and right heart catheterization (RHC). CT criteria were utilized to formally score fibrosis severity.
A total of 92 patients were included in the study. The mean patient age was 65±11 years; 64% of the patients were men. The mean forced vital capacity was 57±20% (predicted), the gas transfer was 22±8% (predicted), and the gas transfer coefficient was 51±17% (predicted). Overall, PH was confirmed in 78% of patients at RHC.
On univariate analysis, of all the CTPA-derived measures evaluated, an RV:LV ratio of ≥1.0 was strongly predictive of mortality or lung transplantation (hazard ratio [HR], 3.26; 95% CI, 1.49-7.13; P =.003), whereas invasive hemodynamic assessment was not predictive. Moreover, at multivariate analysis, the RV:LV ratio remained an independent predictor of mortality or lung transplantation (HR, 3.19; 95% CI, 1.44-7.10; P =.004), adjusting for an ILD diagnosis of idiopathic pulmonary fibrosis and CT-derived ILD severity.
A major study limitation is that its retrospective design leads to selection bias. In addition, all of the patients who were examined had a high pretest probability of PH or were being evaluated for lung transplantation.
The investigators concluded that an increased RV:LV ratio calculated at CTPA provides a simple, noninvasive, useful screening tool for risk stratification in patients with suspected ILD-PH. These findings should encourage closer follow-up, more aggressive treatment, and consideration of lung transplantation in these individuals.
Bax S, Jacob J, Ahmed R, B et al. Right ventricle to left ventricle ratio at CTPA predicts mortality in interstitial lung disease [published online July 24, 2019]. CHEST. doi:10.1016/j.chest.2019.06.033