Combination Therapy in Pulmonary Arterial Hypertension: Single Centre Long-term Experience.

Background: Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary vascular bed and causes right heart failure and death. Combination therapy which targets three different pathways is necessary due to the progressive nature of the disease. In patients with PAH, there are two approaches in combination therapy: "first-line up-front" and "sequential add-on" treatment. In "firstline up-front" treatment, patients receive double or triple drug therapy from the start. In the "sequential add-on" approach, a single drug is initially started and then according to the patient's requirements, a second or third drug is added. There is insufficient evidence about the efficiency and safety of treatment approaches. In this study, we aimed to evaluate the treatment approach in patients with PAH at a tertiary centre.

Methods: Pulmonary arterial hypertension was diagnosed according to clinical, echocardiographic and right heart catheterization findings. The patients received bosentan, sildenafil and iloprost treatment in accordance with guidelines recommendations. Clinical worsening in patients was defined as death, requirement of hospitalization for PAH, a 15% decline in the six-minute walk test (6MWT) distance, deterioration in functional capacity, and symptoms and findings of right heart failure.

Results: At the end of the follow-up period, clinical and echocardiographic findings, brain natriuretic peptide (BNP) levels and oxygen saturation were similar between patients who completed the study with monotherapy and with combination therapy. The follow-up period was significantly longer in patients who required combination treatment. Two patients (6.9%) died and four patients (13.8%) were hospitalized due to recurrent symptoms and findings of right heart failure. At the end of follow-up, 10 patients (34.5%) completed the study with a single drug, 15 patients (51.7%) with two drugs and four patients (13.8%) with three drugs.

Conclusion: In this study, combination therapy was given to patients as "sequential add-on therapy". At the end of the follow-up period, monotherapy was sufficient in 34.5% of patients of the study group and in eight patients, sildenafil or prostaglandin analogues were added; a total of 15 patients (48.4%) completed the study under dual therapy. Four patients (12.9%) received combination therapy with three drugs.