DISCUSSION
Transcatheter ASD closure is a well-established procedure. However, closure of ASD in the elderly population is to be performed with caution as many patients may have a masked restrictive left ventricular physiology, which is not detectable using routine echocardiographic parameters 11. In the presence of a restrictive left ventricular physiology, more left atrial blood is shunted across the ASD to the right atrium and there is a decreased amount of blood flowing into the restrictive left ventricle, a physiology very much akin to a “Lutembacher’s Syndrome” 12. This often leads to symptoms of heart failure due to an increase in pulmonary blood flow and a decrease in cardiac output, which is a strong indication to close off the interatrial septal communication. Patients with old age, chronic obstructive airway diseases, diabetes mellitus, hypertension and ischemic heart disease are particularly at risk of developing restrictive left ventricular physiology 13. Echocardiogram depicting severely dilated atriums should raise the suspicion of a restrictive left ventricular physiology even though conventional echocardiographic diastolic measurements do not suggest so. During balloon occlusion of the ASD, all pulmonary venous blood is forced into the left ventricle, causing an abrupt volume loading of the restrictive left ventricle leading to an increase in left ventricular end-diastolic pressure and acute pulmonary edema. Nevertheless, this does not preclude ASD closure. Previous attempt to condition the left ventricle by diuresing the patients 2-3 weeks prior to the closure has yielded variable results. Creating a fenestration at the atrial septal occluder with as a pop-off to offload the left ventricle is generally a more accepted way of treatment 13-14. Self-created fenestration usually closes off spontaneously. Its purpose is to buy time for the left ventricle to remodel while the fenestration closes gradually over time. To date, there is generally no consensus as the degree of elevation of left ventricular end-diastolic pressure that warrants the creation of fenestration or the size of the fenestration. However, our center has a low threshold of creating a small fenestration in patients with severely dilated atriums and the fenestration is deemed adequate if the left ventricular end-diastolic pressure post-closure is less than 20mmHg.
Often, elderly patients with ASD also present with atrial fibrillation. Currently, there is no consensus as to how this group of patients should be treated. Generally, there is 2 mainstays of treatment - rhythm or rate control. One may attempt electrophysiological ablation to revert the patient to sinus rhythm prior to the closure of ASD16, or close the ASD and treat the atrial fibrillation medically. In the presence of atrial fibrillation combined with a CHA2DS2-VASc score of more than 1, there is a need for thromboprophylaxis 5. Although anticoagulant therapy has been preferred choice for thromboembolic stroke, the increased risk of bleeding especially in the elderly population may be a factor for LAA closure. In addition, since atrial septal closure is indicated, there is a role in closing the left atrial appendage in the same setting. In the absence of an ASD, consideration is made to weigh the risks and benefits of LAA occlusion, especially procedural related complications such as the risk of cardiac tamponade and injury to the adjacent structures during trans-septal puncture. In patients with existing ASD, a trans-septal puncture is not necessary and hence the procedure is much simplified. Transcatheter ASD closure utilizes similar equipment, sheath and approach as LAA closure. The procedure time is slightly increased if both procedures are carried out together. Our series demonstrated a high rate of success in LAA closure. If the transesophageal echocardiogram immediately after the procedure shows total occlusion of the LAA, ASD closure can be performed right away. If there is any doubt to the LAA closure, there is always the option of deferring the ASD closure to a later date. Performing both procedures in the same setting brings about significant cost advantage and improved patient experience.
A recent report recommended performing these two procedures simultaneous in patients with enlarged atriums without atrial fibrillation17. We are of the opinion that many amongst those in sinus rhythm may continue to remain so for an extended period. Patients with paroxysmal or newly onset atrial fibrillation may be treated via transcatheter ablation. Indiscriminately closing the LAA during ASD closure increases procedural cost and may even increase the patient’s risk for procedure-related complications 17-18. We, therefore opined that such a simultaneous approach should be patient-specific rather than universal. In our case, we selected only patients with chronic atrial fibrillation. In this group of patients, LAA closure may be indicated even though patients do not have contraindications for oral anticoagulants. Our study offers the prospect of a novel indication for LAA closure in patients who are suitable candidates for transcatheter ASD closure with chronic atrial fibrillation. The presence of chronic atrial fibrillation can be an indication for left atrial appendage closure regardless of what the CHADS2, CHA2DS2-VASc and HAS-BLED scores may be.