NPPB and idiopathic pulmonary arterial hypertension: Another possible explanation could be that patients with IPAH also show a degree of coronary microvascular dysfunction, as reported previously.28 Another interesting finding is that there was an association between peripheral microvascular function and diastolic dysfunction on echocardiography and CMR, and also with semiquantitative measures of cardiac function (i.e. 6MWD, DLCO, and NT-proBNP levels).