Reply to Weatherald et al.: Pulmonary Vascular Resistance in Pulmonary Arterial Hypertension: La Pièce de Résistance?

From the Authors:

We thank Weatherald and colleagues for their supportive comments, and pleasant reminiscence of French cuisine, on our recent report on risk reduction and hemodynamics after initial dual combination of therapies in pulmonary arterial hypertension (1). We fully agree on the importance of pulmonary vascular resistance combined with imaging of the right heart, as there may be dissociation (2), although this is unlikely when pulmonary vascular resistance decreases by more than 50–60% (3). Their other points are also well taken. 1) Redundancies in pulmonary arterial hypertension risk scores easily occur, as most parameters of prognostic relevance are inevitably related to right ventricular function. We could indeed have acknowledged this with greater clarity. 2) Sex differences in risk scores are of great clinical relevance in relation to the greater capacity of the female right ventricle to adapt to increased afterload, as recently reemphasized (4). 3) The inevitable failure of initial dual-combination therapy in high-risk patients strongly argues in favor of their treatment with initial triple-combination therapies.

We like to add that not only initial high-risk patients fail and that the definition of a high-risk status may vary greatly from one score to another. Over half of treated patients actually remain with poor prognosis intermediate or high-risk status whatever the scoring system. This calls for earlier and more intensive combination therapies with parenteral prostanoids and more intensive follow-up with repetitive right heart catheterizations and imaging modalities (5).