Clinical outcomes of a combined transcatheter and minimally invasive atrial septal defect repair program using a 'Heart Team' approach

Atrial septal defects have traditionally been surgically corrected using a median sternotomy approach. Contemporary transcatheter and minimally invasive approaches allow for less invasive atrial septal defect repair with  improved cosmesis and eliminate the need for median sternotomy. Clinical outcomes of a Canadian multidisciplinary ‘Heart Team’ atrial septal defect repair program are presented.

Repair of atrial septal defects (ASD) have traditionally been performed through median sternotomy for many decades, however contemporary practice includes transcatheter-based approaches and minimally invasive endoscopic mini-thoracotomy approaches [1‐3]. Long-term data show that median sternotomy repair of ASD is effective [4]. Catheter-based approaches have the benefit of no surgical scar, but require ongoing antiplatelet therapy and favourable anatomy for procedural success [5]. Minimally invasive endoscopic mini-thoracotomy has previously been shown to improve cosmesis with similar outcomes as median sternotomy for ASD closure [6‐10]. Although research into minimally invasive surgical approaches is being actively pursued, access to minimally invasive approaches is limited to select centers of excellence in Canada [11]. A hybrid approach involving both cardiac surgery and interventional cardiology expertise is emerging as the preferred strategy for minimally invasive intervention [11, 12]. At our centre in London, Ontario, Canada, ASD repair is evaluated by a combined multidisciplinary team approach involving both interventional cardiology and cardiac surgery services since 2009. We present our single centre ‘Heart Team’ experience comparing early and late clinical outcomes of transcatheter device closure and mini-thoracotomy ASD repair in a Canadian setting.

In total, 61 patients underwent a minimally invasive approach to ASD closure. Twenty-eight patents underwent transcatheter device-based closure, and 33 underwent surgical closure. Figure 1 shows an Amplatzer septal occluder device (St. Jude Medical, St. Paul, MN, USA) in Panel A, along with a fluoroscopic image of the device immediately after deployment (Panel B). Figure 1 also shows a typical right mini-thoracotomy incision in the post-operative setting, showing excellent cosmesis (Panel C) along with an intraoperative view of the autologous pericardial patch being sewn to close the ASD (Panel D).

Surgical patients were younger than the transcatheter group, with a median age of 37 versus 57 (p < 0.001). Surgical patients also had a lower overall body mass index (BMI), with a mean of 25 versus 28.2 (p = 0.01). Otherwise, preoperative patient characteristics were similar between groups, as shown in greater detail in Table 1.

Predictably, all ASDs in the transcatheter group were secundum defects with the exception of a single patent foramen ovale (PFO). The surgical group contained 5 sinus venosus defects with partial anomalous pulmonary venous connections, 3 PFOs, 1 unroofed coronary sinus, and 1 partial atrioventricular septal defect (AVSD). Similarly, defect size was significantly larger in the surgical group (2.35 versus 1.65 cm, p = 0.002). There were 2 device failures, necessitating referral for surgical repair at similar rates as previously reported [14]. In the surgical group, 26 were approached through a right anterior mini-thoracotomy, while 7 were female patients who underwent a peri-areolar incision. Three patients underwent concomitant tricuspid valve repair, 2 patients underwent mitral valve repair, and 2 patients underwent cryoablation. Detailed procedural data is shown in Table 2.

The median hospital length-of-stay for the transcatheter group was 1 day, with no patient requiring admission to intensive care (ICU). Length of stay was longer in the surgical group with median ICU length of stay of 1 day, with a median hospital stay of 5 days (p = < 0.0001 for each versus the transcatheter group). Otherwise, no significant peri-procedural outcome differences were detected between the intervention groups. Five patients in each group experienced paroxysmal atrial fibrillation post-procedure. A single patient in the transcatheter group suffered a bleeding complication from the femoral puncture site that resolved with additional manual pressure and did not require blood product transfusion. A single patient in the surgical group received 2 units of packed red blood cells for an asymptomatic hemoglobin level below 70 g/L during the post-operative ICU stay. No patients required transfusion of additional products such as plasma, platelets, cryoprecipitate, or recombinant activated factor VII. Detailed results for peri-procedural outcomes are shown in Table 3.

Follow-up time ranged from 0.5–56.5 months in the transcatheter group and 0.3–89.0 months in the surgical groups. Median follow-up time was 8.3 months in the transcatheter group and 15 months in the surgical group (p = 0.3). Four residual shunts were identified on post-operative TTE versus 2 in the surgical group (p = 0.4). All residual shunts were asymptomatic, and graded as trace to mild. On Kaplan-Meier analysis, the 2 curves appeared divergent; however, they were not found to be significantly different by the log-rank test statistic (Fig. 2). The proportional hazard assumption was not violated. Log-log plots showed parallel curves, and the hazard function between groups was not statistically significant using Schoenfeld residuals (p = 0.27). The adjusted Cox proportional hazard model failed to show a significant difference in risk of residual shunt between groups (HR 0.41, 95% CI: 0.02–8.60). Detailed adjusted results of the multivariable Cox proportional hazard model are shown in Table 4. Similarly, there was no significant difference in late complications, defined as a composite of significant residual shunt (greater than mild on Doppler colour flow), device erosion, endocarditis, device thrombosis, thromboembolism, or stroke (Fig. 3). When subdividing the surgical group by defect complexity/additional procedures, no differences in any residual shunt were found (p = 0.45, Fig. 4).

Functional status was not significantly different between groups at follow-up, with a similar spread of follow-up NYHA status (p = 0.21). No patients suffered from headaches at follow-up. A single patient in the transcatheter group suffered a stroke following discharge from hospital secondary to device thrombosis. This patient has been followed by Haematology for a hypercoagulable state, which had previously resulted in multiple peripheral arterial interventions requiring femoral embolectomy, infra-inguinal bypass, and bypass graft thrombosis. Detailed results of patients at follow-up are presented in Table 5. A subgroup analysis of surgical patients was completed for those with simple defects (secundum defects and PFOs) compared with more complex, as well as those with isolated ASD repair compared with those receiving additional procedures. Predictably, cardiopulmonary bypass and cross clamp times were longer in repairs of complex defects and in multiple procedures. In the complex defect group, the median bypass time was significantly longer at 164 min (IQR 149–189 min) versus 112 min (IQR 99–127 min), p = 0.001. Cross-clamp time was also longer, with a median complex defect time of 103 min (IQR 81–123 min) versus 60 min (IQR 54–71 min), p < 0.001. This finding was consistent in the additional procedures group with median cardiopulmonary bypass times of 152 min (IQR 136–211 min) versus 112 min (99–135 min), p = 0.012. Cross-clamp times were similarly longer in those receiving additional procedures, with median times of 110 min (IQR 72–123 min) versus 61 min (54–72 min), p = 0.009. Although surgical times were consistently longer in both the complex defect and additional procedure surgical groups, significant complications were not detected.

Interest in minimally invasive options for ASD closure has increased with the advantage of better cosmesis in younger patients. Surgically, the right minithoracotomy and peri-areolar approaches in female patients allow avoidance of median sternotomy and reduced scar length. Our data shows that outcomes of transcatheter and minimally invasive surgical ASD repair are similar overall, with no significant difference seen in functional outcomes, headache, or amount of residual shunt. Although residual shunt in particular trended higher with transcatheter intervention, these tended to be mild, clinically insignificant shunts that did not result in a difference in functional status.

The number of peri-procedural complications was low in both groups and it is expected to be difficult to show a significant difference between the groups at small sample sizes. Similarly, showing a mortality difference between the two groups is also expected to require much larger sample sizes. As previously reported for other minimally invasive surgery, hospital and ICU length-of-stay was much shorter for transcatheter methods [6]. However, this immediate benefit was balanced by a trend toward higher residual shunt in the transcatheter group.

Late device migration or embolization is always a concern in transcatheter patients, although we did not see any such events in early follow-up. Delayed device erosion and embolization remains a possibility.

One patient in the transcatheter closure group experienced device thrombosis in the setting of multiple arterial thromboses and interventions. The importance of predisposition to arterial thrombosis is especially important in transcatheter closure and should be taken into account when selecting patients for device versus surgical closure.

Our centre uses an integrated, multidisciplinary ‘Heart Team’ approach in the evaluation of such patients, involving both cardiac surgery and interventional cardiology physician expertise. The collaborative nature of atrial septal defect closure at our institution allows for open discussion and facilitates optimal care. A ‘Heart Team’ approach is increasingly encouraged as the preferred method by which patient care decisions are made [15]. The closure approach selected is largely driven by patient-specific criteria outlined in the Methods section.

To the best of our knowledge, this is the first Canadian study directly comparing transcatheter and minimally invasive ASD closure and our data shows that both approaches can be used successfully. As with any new team-based approach, there is a learning curve that must be negotiated to develop a fruitful program however our data shows that overall complication rates are low with high procedural success rates.

Our observational study has a number of important limitations including limited sample size, single-centre data, and differences in follow-up duration. The small sample size increases the risk of Type 2 error. Also, it can lead to failure of detection of rare outcomes or complications. The possibility that a larger sample size could result in different comparative results between the two groups cannot be excluded.

With any observational study, the risk of systematic error is present. In our case, unavoidable selection bias exists, in that there are specific criteria for transcatheter ASD closure. Taking into account the limitations of a small sample size outlined above, this bias could lead to more favourable results in a larger population. Patients undergoing transcatheter closure were older and had a larger BMI but were otherwise comparable for baseline demographics. Notwithstanding the above, there remains the issue of unmeasured confounding inherent to the interpretation of non-randomized studies. Finally, referral bias may be a factor given that patients were selected from a single quaternary care centre.

Overall, given the similar clinical outcomes of both groups, transcatheter and minimally invasive approaches to ASD closure are both safe and feasible in appropriately selected patients and represent attractive alternatives to traditional median sternotomy.