RESUMO
BACKGROUND: Pulmonary arterial hypertension is managed with vasodilators, and till date no specific drug has been identified with sufficient degree of success. Potassium channels have been implicated in the pathogenesis of primary pulmonary arterial hypertension. We undertook this study to assess the acute effect of oral nicorandil in patients of pulmonary arterial hypertension. METHODS AND RESULTS: We studied acute hemodymanic response of 40 mg oral nicorandil in 10 patients with primary pulmonary arterial hypertension aged between 15 and 39 years (mean age 27.2 +/- 6.7 years). Responders (Group I) were defined as those with > or =20% reduction of pulmonary vascular resistance index and no change or increase in cardiac index; and non-responders (Group II) were those with < 20% reduction of pulmonary vascular resistance index. There were 7 responders (pulmonary vascular resistance index decreased from 22.8 +/- 9.3 to 17.9 +/- 6.5 Wood units) and 2 non-responders (pulmonary vascular resistance index decreased from 26 +/- 3.5 to 25 +/- 1.0 Wood units). The maximum reduction in pulmonary vascular resistance index from baseline was 29.77 +/- 6.53% (23.7-40.5%) in responders and 7.3 +/- 4.2% (4.3-10.3%) in non-responders. The study was halted prematurely in one patient who developed hypotension, requiring intravenous inotropes. CONCLUSIONS: Our results suggest that nicorandil significantly decreases pulmonary artery pressure in primary pulmonary arterial hypertension acutely and can be cautiously tried for the therapeutic use in primary pulmonary arterial hypertension. Further studies are warranted.