Is there any difference in efficacy of oral sildenafil therapy in primary vs secondary Pulmonary Arterial Hypertension?

Abstract

Objective: Oral sildenafil, a phosphodiesterase 5 inhibitor,is now accepted mode of therapy for symptomatic Pulmonary arterial hypertension(PAH).As the pathobiologic mechanisms are different in primary and secondary PAH, we undertook this study to find out any significant difference in efficacy of oral sildenafil therapy in primary versus secondary PAH. Methods: It was an unicentric parallel group longitudinal study. After selection and baseline investigations,all the patients of primary and secondary PAH were given sildenafil in fixed doses (50 mg thrice daily). Study parameters: 1. Distance covered in 6 minute walk test (6MWT), 2.Pulmonary arterial pressure (PAP) by trans-thoracic Doppler echocardiography, 3.quality of life (QOL) score assessed by Minnesota living with heart disease questionnaire. At the end of 6 weeks, 6 MWT, PAP, QOL were compared to the baseline value. Results: 42 subjects completed the study.20 subjects had primary PAH and 22 had secondary PAH. Sildenafil therapy was effective in both groups in reducing PAP, increase in distance covered in 6 minute walk and reducing QOL score. Reduction of PAP is significantly more in primary PAH than secondary PAH but no such difference was found in 6 MWT and QOL score. Conclusion: Though lowering of pulmonary arterial pressure in primary PAH is significantly lower than secondary PAH, this is not translated in better symptomatic relief.