A Retrospective Evaluation of Pulmonary Vasodilator Monotherapy and Sequential Combination Therapy in Thai Patients with Pulmonary Arterial Hypertension Associated with Congenital Heart Disease

Objective: This retrospective study evaluated the outcomes of Thai patients with pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD) treated with initial monotherapy and subsequent sequential combination therapy upon clinical worsening. Methods: Patients aged 1–65 years with a diagnosis of PAH-CHD who received initial monotherapy at Siriraj Hospital, Bangkok, Thailand, from January 01, 2013 to December 31, 2014 were included in this retrospective analysis. Clinical worsening was assessed using the 6-minute walking distance (6MWD) test. Results: A total of 88 patients who met study inclusion criteria had received initial monotherapy with either bosentan (n=6), sildenafil (n=47) or beraprost (n=35). Forty-four (50%) of these patients experienced a predefined clinical worsening event within 12 months of commencing treatment. Patients who received initial bosentan monotherapy were significantly less likely to experience clinical worsening compared with sildenafil and beraprost recipients at 12 months (16.7% vs. 38.3% and 71.4%, respectively; p=0.039), and 24 months (16.7% vs 61.7% and 77.1%, respectively; p=0.007). Thirty-three patients who failed initial monotherapy were subsequently prescribed sequential combination therapy. The 6MWD (mean ± standard error) increased significantly after commencement of sequential combination therapy from 208.9 ± 67.2 m before the addition of the second drug to 285.5 ± 92.1 m at 1 month (p=0.09) and 326.3 ± 62.7 m at 3 months (p=0.001). Conclusion: This retrospective analysis showed that PAHCHD patients who received initial bosentan monotherapy were significantly less likely to experience clinical worsening over 24 months than those who received sildenafil or beraprost. Sequential combination therapy initiated upon clinical worsening significantly improved 6MWD at 3 months. The findings support the use of sequential combination therapy in patients with PAH-CHD who fail initial monotherapy.