Yet Another Way to Lower Homocysteine

The foramen ovale connecting the right and left atrium in utero fails to close in a quarter of adults.1 Patent foramen ovale (PFO) is roughly twice as common among people with cryptogenic stroke before age 60 years, approaching 50%.2 In 2017, 3 clinical trials established PFO closure as effective secondary stroke prophylaxis in well-selected patients.3 While the pathogenic mechanism of PFO stroke remains uncertain, paradoxical embolus is the obvious suspect. If peripheral blood returning to the right atrium contains an embolus from subclinical venous thrombosis, this could traverse the PFO through the left chambers to aorta and brain, bypassing the physical filtering effect of pulmonary capillaries. However, only 5% of patients with strokes who harbor a PFO have an identified venous thrombus.4