The patency of foramen ovale (FO) in fetal circulation is very important, and premature closure of FO could be associated with several pathological conditions.

We report a patient in whom premature closure of FO in fetal life was associated with late clinical onset of mitral valve stenosis and subsequent development of irreversible pulmonary hypertension (PH).

The patient showed persistent PH after birth, which completely regressed at the age of 8 months. However, the patient developed heart failure due to mitral valve lesions (hammock valve) at the age of 11 months and underwent artificial valve replacement. The patient subsequently developed severe PH, which was refractory to anti-PH therapy with sildenafil and bosentan in addition to home oxygen.

This case illustrates that mitral stenosis can be overlooked during early neonatal life, and thus emphasizes the need for close follow-up for potential existence of mitral stenosis and later clinical manifestation in patients with premature FO closure even when initial careful examination of the mitral valves does not indicate any abnormalities. In addition, premature closure of FO could cause pulmonary vascular disease, which may lead to later development of irreversible PH.