PAH with positive acute vasoreactivity testing can be treated by calcium channel blocker (CCB) only, but some of these patients do not maintain their NO along their life. We aimed to review long-term follow-up of this population and find predictive factors to the loss of CCB efficiency.

From the French national registry, we retrospectively collected data and outcomes from all newly diagnosed idiopathic, heritable, or anorexigen-induced PAH treated by CCB only, between 2007 and 2019. We isolated 3 groups of patients depending on the occurring of CCB failure: no failure, early failure (during the first year) or late failure. CCB failure was defined by the addition of a specific therapy (prostacyclin, ERA and PDE5i), death or transplant-list inscription.

95 patients were included. 28 presented the event of interest during the first year and 12 later. Early CCB failure was significantly associated with older age at diagnosis (64.6±15.2 versus 39.9±16.5 y.o.; p < 0.0001), tobacco use (75% versus 36%; p = 0.0011), venous O2 saturation (67.4±10.3 versus 73.8±7.3 mmHg; p = 0.0395) and poorer hemodynamic features during acute vasoreactivity testing at baseline. Late CCB failure was significantly associated with lower walk-test performance (434±150 versus 532±106 meters, p = 0.049), higher rate of elevated cardiac enzymes (33% versus 4%; p = 0.0078), higher mean pulmonary arterial pressure (40.8±8.0 versus 29.5±8.9 mmHg; p = 0.0008) and lower venous O2 saturation (73.3±5.7 versus 65.4±3.4 mmHg; p = 0.0151) at the 1-year evaluation. Risk assessment tools showed a lower proportion of low-risk status in the failing groups. Mortality was higher in case of CCB failure (p < 0.001).