When and for Whom Do We Need to Close an Iatrogenic Atrial Septal Defect After MitraClip?
Article ID: CJ-22-0250
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Article ID: CJ-22-0250
Transseptal puncture has become increasingly common in interventional cardiology, including mitral valve intervention, left atrial appendage closure, and catheter ablation. Iatrogenic atrial septal defect (iASD) is an obligatory consequence of this procedure, but closure following MitraClip therapy is not routinely performed for all iASD, and currently no guidelines exist for managing this condition. When and for whom do we need to close an iASD after MitraClip?
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Transcatheter mitral valve edge-to-edge repair (TEER) as an alternative to mitral valve surgery in a selected high-risk cohort has proven to be safe and effective for improving mitral regurgitation (MR).1 TEER with the MitraClip system was approved in 2016 by the PMDA in Japan and widely used in patients with degenerative MR with a prohibitive risk for surgery and in those with accompanying functional MR symptoms despite the use of maximal guideline-directed medical therapy.2
TEER requires left atrial access through a transseptal puncture using a 24Fr guiding catheter and leaving a residual iASD (Figure 1). A small study reported a persistent iASD at 1 month in approximately 82% of all cohorts undergoing TEER,3 in 50% at 6 months,4 and in 24% at 1 year.5 Several underlying mechanisms that explain the development of iASD have been hypothesized: the longer duration of the MitraClip procedure, local trauma related to excessive duration of the procedure, use and manipulation of a larger sheath for clip deployment, residual high transmitral gradient, left ventricular hypertrophy, and increased left atrial pressure from residual MR.6
iASD after the MitraClip procedure. (A) Fluoroscopy image. (B) TEE image of the 24Fr SGC (yellow arrow) for the MitraClip system passing through the IAS (white arrow). (C) TEE image of the left-to-right shunt thorough the IAS after removal of the SGC. (D) TEE image of the right-to-left shunt thorough the IAS after removal of the SGC. IAS, intra-atrial septum; iASD, iatrogenic atrial septal defect; LA, left atrium; RA, right atrium; SGC, steerable guide catheter; TEE, transesophageal echocardiography.
Currently, there are no guidelines on the management of residual iASD following transseptal interventions (Figure 2). Routine closure for all iASD is not common after the MitraClip procedure. The European Society of Cardiology guidelines recommend iASD closure only for congenital ASD.7 Nevertheless, in real-world clinical practice, iASD-related acute clinical instability, such as persistent hypoxia and hemodynamic deterioration, would require immediate management. Retrospective studies reported that patients with persistent iASD following MitraClip had worse clinical outcomes.4,5 On the other hand, in a study conducted by Alachkar and colleagues, persistent iASD following the MitraClip procedure did not affect clinical outcomes.8
Transcatheter iASD closure. (A) TEE image of right-to-left shunt through the iASD. (B) Fluoroscopy image of the septal occluder (yellow arrow). (C) TEE image of closure of the iASD by the septal occluder (yellow arrow). IAS, intra-atrial septum; iASD, iatrogenic atrial septal defect; LA, left atrium; RA, right atrium; TEE, transesophageal echocardiography.
In this issue of the Journal, Takaya and colleagues9 demonstrate the prevalence, safety, and efficacy of transcatheter iASD closure following the MitraClip procedure by analyzing a Japanese large cohort. They report that (1) transcatheter iASD closure was required in 1% of those undergoing TEER with the MitraClip system; (2) the dominant reasons for transcatheter iASD closure were hypoxia with right-to-left shunt, and right-side heart failure (HF) with left-to-right shunt; (3) most of the closures (73%) were performed immediately after the MitraClip procedure and the hemodynamic and clinical deterioration resolved after iASD closure.
Since the approval of the MitraClip system in Japan, ≈5,000 severe MR patients have been treated as of April 2022. Takaya and colleagues report that iASD closure was required promptly in 0.8% of patients who underwent TEER.9 Lurz and colleagues immediately performed iASD closure in 4.6% of patients following TEER.10 We cannot ignore these reports of high incidence. In Japan, as of April 2022, 71 facilities have been approved to perform TEER using the MitraClip system, but only 33 are certified to perform transcatheter ASD closure. If hypoxia and right-side HF worsen rapidly after iASD formation and prompt transcatheter iASD closure is required, more than half of the facilities cannot respond promptly. In the report by Takaya and colleagues,9 1 patient had iASD after TEER, and a left-to-right shunt caused right HF, resulting in low cardiac output syndrome. The TEER was performed in an institute where transcatheter iASD closure was not certified, and the patient did not undergo prompt iASD closure. Urgent transportation of such patients to a certified institute to undergo iASD closure would be challenging due to their unstable hemodynamics. Current rules stipulate that transcatheter ASD closure must be performed by an ASD-certified operator in an ASD-certified facility. Flexible rules might be needed to avoid such a mismatch. At present, it is not known in which cases clinical deterioration such as hypoxia and right-side HF that require rapid transcatheter iASD closure will occur. Future research is warranted to clarify the optimal patient selection.
Following transseptal puncture using a small diameter sheath, such as ablation and left atrial appendage closure, the long-term patency rate up to 12 months after treatment is relatively low,11 whereas the long-term iASD patency rate after MitraClip can be 24%.5 The existence of iASD following TEER is associated with signs and symptoms of right heart and pulmonary circulatory volume overload, as well as increased rates of HF hospitalization and death. Lurz and colleagues10 investigated whether iASD closure post MitraClip procedure was superior to conservative medical therapy. In their study, 80 patients with an iASD, which was defined as fraction of pulmonary perfusion/fraction of systemic perfusion ≥1.3 and predominantly left-to-right shunt 30 days after TEER following MitraClip procedure, were randomized to conventional therapy and transcatheter iASD closure. There was no significant difference in the combined endpoints of death and HF hospitalization (iASD closure: 35% vs. conventional therapy: 50%, P=0.26) at 1 year post TEER. On the other hand, the combined endpoints were more frequent among patients with iASD as opposed to non-iASD (43% vs. 17%; P<0.0001) patients.
Shah and colleagues12 hypothesized that creating an iASD in patients with HF with preserved ejection fraction would reduce left atrial pressure and improve cardiovascular death and the incidences of cerebral infarction and HF hospitalization. However, iASD was not associated with better clinical outcomes among the cohort. We need further studies on the effects of iASD on the long-term prognosis in patients with impaired cardiac function who are indicated for TEER.
TEER using MitraClip is an established treatment for severe MR, and the number of these procedures will continue to increase. Currently, transcatheter ASD closure is reimbursed only for congenital origin and not for iASD, which should be revised in the near future.
In conclusions, this is the first study showing that the prevalence of iASD requiring transcatheter closure following TEER with the MitraClip system in a large Japanese cohort. Further studies are needed to clarify optimal timing and patient selection for the procedure.
