Bronchiolitis obliterans syndrome (BOS), a form of chronic allograft rejection, has been shown to be associated with vascular remodeling and increased prevalence of pulmonary hypertension (PH) in lung allograft recipients. However, the role of secondary pulmonary hypertension (SPH) prior to transplantation as a risk factor for BOS remains unclear.
We conducted a single-center, retrospective study and examined the impact of SPH prior to lung transplantation (LT) on incidence and time to BOS onset. Secondary end points included the impact of SPH prior to LT on BOS severity, acute rejection episodes/severity, and overall survival. 92 subjects were screened between January 1995 to January 2008. 40 subjects were eligible for analysis. Exclusion criteria included incomplete documentation, less than twenty months follow up, anastomotic complications and re-transplantation. Subjects were divided into two groups, those with and without SPH. Pulmonary hypertension was defined as mean pulmonary artery pressure (mPAP) > 25 mmHg by right heart catheterization or right ventricular systolic pressure (RVSP) > 35 mmHg by trans-thoracic echocardiogram. BOS was defined by set international guidelines.
The incidence of BOS was not statistically different between patients with versus without SPH (64% vs. 53%; respectively, p = 0.425). The time to BOS onset was similar between the two groups (31.5 vs. 34.9 months, p = 0.878). SPH had no statistically significant impact on acute rejection episodes or overall survival. Minimal acute rejection episodes were the strongest predictor for BOS development (hazard ratio 1.433; p = 0.002).
Presence of SPH prior to LT was not associated with higher incidence or shorter time to BOS onset. The strongest predictor for BOS in this study cohort was recurrent acute minimal rejection episodes.
To our knowledge, this is the first clinical trial evaluating the impact of SPH prior to LT on incidence of BOS. It brings to light the importance of evaluating SPH as a risk factor for BOS. A prospective larger multi-center randomized blinded study is needed to further evaluate the results of this current study.
Mohammad Omari, No Financial Disclosure Information; No Product/Research Disclosure Information