PFO with patent foramen ovale (PFO), especially in combination with atrial septal expansion tumor (ASA), is gradually being recognized as a source of paradoxical thrombosis. The annual incidence of recurrent stroke and transient ischemic attack (TIA) in patients with PFO and paradoxical embolism ranges from 0% to 15%. If PFO is combined with ASA, the risk of recurrent cerebrovascular accident is significantly increased. Interventional occlusion may be more advantageous compared to pharmacological treatment.
Patient data.
One hundred eighty patients with atrial septal traffic and at least one preoperative unexplained thromboembolic event underwent percutaneous interventional occlusion. All patients were excluded from any embolic conditions and in situ arterial thrombosis for which a cause could be found, such as atherosclerosis, chronic or paroxysmal atrial fibrillation (Af), left heart thrombosis, or significant mitral valve malformation.
Preoperative investigations.
Neurological examination, CT/MRI of the brain, Doppler (Doppler) ultrasonography, 12-lead ECG, coronary angiography, 24-h long-range ECG (Holter), transesophageal and 2D ultrasound, standard blood tests, thrombotic propensity tests (C and S-reactive protein, antithrombin III, lupus anticoagulant, specific antibodies, homocysteine, prothrombin 20210, coagulation V to Leiden factor), in addition, lower extremity Doppler ultrasound was performed in some patients to rule out deep vein thrombosis.
TEE diagnosis for standard ASA.
Bottom diameter ≥ 15 mm and drifting interatrial septum amplitude ≥ 15 mm. diagnosis of PFO: intravenous injection of ultrasound contrast agent with tiny bubbles across the interatrial septum and no left-to-right shunt. An atrial septal defect (ASD) was defined if there was a left-to-right shunt in addition to a right-to-left shunt during the injection of the contrast medium, or if there was a fissure or gap in the middle of the septum, or if there was an ASD that resembled a PFO, or if there was a typical PFO morphology without an atrial septal gap.
Implantation technique.
The diameter of PFO or ASD extension was determined in all patients by measuring the balloon with NMT or AGA, and the blocker was implanted under TEE and radiographic guidance according to the operating rules.
Post-intervention treatment.
All patients were on aspirin 100 mg/d for 6 months.
Follow up.
12-lead ECG and transthoracic ultrasound were performed at 1 month, 3 months, 6 months and 1 year, and TEE was done after 3 months. MRI/CT and physical examination were performed if there were neurological symptoms.
Complications.
All 180 patients were successfully implanted with blockers and one patient had one suspected air embolism with a good prognosis. 3 patients developed fever and improved on their own.
Follow-up.
The average follow-up was 40 months (4 to 88 months), and the annual incidence of recurrent thromboembolic events was 0.16%.
Death.
One patient died 9 months after the implantation procedure for unknown reasons.
Recurrent paradoxical embolism.
One patient presented with unexplained coronary embolism. The patient had a stroke prior to implantation and had an abnormal preoperative coronary angiogram. 30 months after implantation of the blocker, a left ventriculogram showed left ventricular posterior wall dyskinesia and the diagnosis of unexplained coronary embolism was made.
Residual right-to-left shunt.
The success rate of complete occlusion was 95.5% at 6 months and 97.2% at 18 months. 4 cases showed residual shunts.
Need for second blocker implantation.
Four patients required implantation of a second blocker to close all atrial septal traffic. In two patients, different blockers were implanted sequentially and no residual shunts were found. The other two patients had both blockers implanted, and one of them had a small residual shunt after 18 months of follow-up.
Thrombosis.
One patient presented with small thrombotic adhesions on the left atrial surface of the blocker, and no increase in thrombus or re-embolic events were found on review. A patient with a history of bladder cancer developed deep vein thrombosis in the right lower extremity 3 months after the implantation procedure.
Cardiac arrhythmias.
Five patients had atrial fibrillation, which was treated with oral warfarin. five patients developed supraventricular tachycardia and premature ventricular contractions, which were able to terminate spontaneously.
Discussion.
As secondary prevention of recurrent paradoxical embolism, the currently acceptable options are: antiplatelet therapy and/or anticoagulation, surgical suture closure of PFO and interventional blocking therapy. The risk of recurrence after the first paradoxical embolic event is reported in the previous literature to be 3.4 to 3.8% per year. Oral anticoagulation therapy is not effective in preventing embolic events. Probably due to case selection and/or surgical technique, the annual embolic recurrence rate of surgical suture closure of PFOs ranges from 7.5 to 20%.
Percutaneous interventional occlusion of PFO provides a safe and effective method. 97.2% effective occlusion success rate at 18 months, with a 2.8% incidence of residual right-to-left shunt and no major complications. One patient died during follow-up, one recurrence of unexplained paradoxical embolism (coronary embolism), and the annual risk of recurrent thromboembolism or another major noncardiac event (MACE) was 0.32%.
To avoid the influence of atherosclerosis on the study results, interventional blocking of atrial septal traffic was found to be highly effective in preventing recurrent thromboembolic events after excluding patients with arterial thrombosis, atrial arrhythmias, atherosclerosis, and thromboembolic lesions of the left heart system. If patients are strictly screened, blocking therapy can completely prevent paradoxical thromboembolic events.
Sixteen patients had unexplained paradoxical coronary artery embolism before implantation. In AMI, less than 1-6% of the patients lacked a diagnosis of coronary artery disease. Closure of atrial septal traffic may be a treatment for unexplained paradoxical coronary thrombosis.
Interventional occlusion of atrial septal traffic is safe and reliable as a secondary prevention for patients facing paradoxical thromboembolism. It has a high success rate, few complications, and good long-term results.