INHALED NITRIC-OXIDE AS A SCREENING AGENT FOR SAFELY IDENTIFYING RESPONDERS TO ORAL CALCIUM-CHANNEL BLOCKERS IN PRIMARY PULMONARY-HYPERTENSION

In a subset of patients with primary pulmonary hypertension (PPH), hig h doses of oral calcium-channel blockers (CCB) produce a sustained cli nical and haemodynamic improvement. However, significant side-effects have been reported during acute testing with CCB, Therefore, to identi fy accurately patients who may benefit from long-term CCB therapy, the re is a need for a safe, potent and short-acting vasodilator. The aim of this study was to compare the acute response to inhaled nitric oxid e (NO) and oral high doses of CCB in 33 consecutive patients with PPH, A significant acute vasodilator response was defined by a fall in bot h mean pulmonary artery pressure and total pulmonary resistance by >20 %, Ten patients responded acutely to NO, nine of whom responded acutel y to CCB, without any complications. The 23 other patients failed to r espond to NO and CCB, In these nonresponders, nine serious adverse eve nts were observed with CCB (38%). There was no clinical or baseline ha emodynamic feature predicting acute vasodilator response. Long-term or al treatment with CCB was restricted to the nine acute responders and a sustained clinical and haemodynamic improvement was observed in only six patients. In primary pulmonary hypertension, the acute response r ate to high doses of calcium-channel blockers is low (27%), Serious ad verse reactions to high doses of calcium-channel blockers during acute testing are frequently observed in nonresponders, It is concluded tha t nitric oxide may be used as a screening agent for safely identifying patients with primary pulmonary hypertension who respond acutely to c alcium-channel blockers and may benefit from long-term treatment with these agents.