Author + information
- Bernhard Meier, MD⁎ ()
- ↵⁎Swiss Cardiovascular Center Bern, University Hospital, Freiburgstrasse, CH-3010, Bern, BE 3010, Switzerland
The comment by Harper and Haqqani, namely that a patent foramen ovale (PFO) is unlikely to confer a significant mortality disadvantage, indirectly acknowledges that it might. Paradoxical embolism through a PFO can unequivocally have devastating consequences, including death. Hence, even if no significant risk for mortality has yet been proven, people die from it (1). This must suffice to take the matter seriously. If there was a simple vaccination to close the PFO, it would be a world standard. Implantation of a device in the heart, with an inherent risk for mortality as well, needs proof of superiority over the natural course. This proof (or disproof) is subject to time. About 1,000 patients have been randomized between device closure and natural course in a variety of trials in progress. Device implantation should show any disadvantage quite early as its risks are front-loaded. An advantage, however, takes many years to unveil because events from a PFO are fortunately rare (rarer than we initially thought), but not absent. None of the trials has been stopped prematurely, which speaks against a disadvantage without compromising the hope for an advantage of PFO closure.
The theory of selective mortality of the PFO is indeed not in keeping with the finding that the fewer PFOs in the elderly are larger in size (2). The theory of late spontaneous fusion by increasing left atrial pressure with age could explain that. Conversely, there is hard evidence for the first theory (people do die from PFOs) but not for the second. The fact that patients with mitral stenosis had a passable PFO in <1% according to Harper and Haqqani is not sufficiently explained by either theory. The bulging of the atrial septum into the right atrium in mitral stenosis is likely to render catheter passage from the inferior vena cava more difficult as the PFO is hidden behind this bulge in a region where the septum now is tangential to the catheter path, making probing for the PFO unyielding. Many PFOs go undetected under these circumstances, although they are not fused but simply functionally closed by elevated left atrial pressure and moved out of target for access from the inferior vena cava.
- American College of Cardiology Foundation