In-tunnel closure of patent foramen ovale with a FlatStent EF™

Background: Devices for percutaneous closure of patent foramen ovale (PFO) are traditionally based on two opposing discs, leaving significant surface areas exposed in the left and right atrium. The FlatStent EF (TM) PFO Closure System (Coherex Inc., Salt Lake City, USA) represents a major departure from these devices because it is designed to focus primarily on the PFO tunnel, leaving minimal foreign material behind. Aim: To investigate the patient selection, effectiveness, and safety of in-tunnel closure with a FlatStent EF (TM) in patients with PFO of >= 4 mm tunnel length and < 12 mm diameter at preprocedural transoesophageal echocardiography (TEE). Results: Among 46 consecutive patients undergoing PFO closure, a FlatStent EF (TM) could be implanted and resulted in initial successful closure (< 5 bubbles during Valsalva manoeuvre) in 21 (46%) patients. TEE at 162 +/- 40 and 317 +/- 162 days after implantation demonstrated functional closure in 90% and 95% of cases, respectively. No device or air embolisation, pericardial effusion, or thrombus formation was documented. Small in-tunnel peri-device colour Doppler left to right flow was documented in 10% and 2-6 mm protrusion of FlatStent EF (TM) along right atrial septum without any residual flow/bubble shunting in 14%. Patients with suboptimal closure (> 5 bubbles during Valsalva manoeuvre and/or in-tunnel colour flow) had shorter tunnel on preprocedural TEE (5.3 +/- 1.5 vs. 10.8 +/- 3.5 mm; p = 0.003). There was no difference in TEE diameter (1.8 +/- 0.5 vs. 2.0 +/- 0.5 mm; p = 0.38) and stretched diameter by sizing balloon (6.3 +/- 2.5 vs. 6.3 +/- 1.0 mm; p = 1.00). Conclusions: In-tunnel PFO closure with a FlatStent EF (TM) represents an effective and safe option only in carefully selected patients with long tunnel (> 4 mm) regardless of the diameter if it is < 12 mm. These criteria are fulfilled in < 50% of consecutive candidates for PFO closure. The new phenomenon of in-tunnel peri-device flow and FlatStent EF (TM) protrusion along the right atrial septum were documented during systematic TEE follow up.