Dhiraj Gupta (Liverpool, UK) overviews developments in two left atrial appendage (LAA) occlusion devices, which have helped make the implant procedure safer, easier and quicker. He also highlights current challenges related to overall peri-procedural patient management.
Current scientific guidelines recommend lifelong oral anticoagulation for the majority of atrial fibrillation patients to reduce their risk of thromboembolic stroke. However, there remains a substantial minority of atrial fibrillation patients who are not candidates for oral anticoagulation because they have a prior history of serious bleeding, or are at high risk of bleeding with such therapy. For these patients, non-pharmacological options for reducing stroke risk in patients with atrial fibrillation are needed. It has been shown that some 90% of left atrial thrombi in atrial fibrillation are located in the left atrial appendage (LAA), and this has prompted the development of devices and interventional techniques to occlude the LAA.
The two most commonly used percutaneous devices in clinical practice today are the Watchman device (Boston Scientific) that has a plug-only design, and the Amplatzer Cardiac Plug (ACP, St Jude Medical) with a distal lobe and a proximal disc.
The seminal PROTECT AF randomised trial demonstrated a significant decrease in haemorrhagic strokes and increased survival in the LAA occlusion arm with Watchman when compared to warfarin. However, some of these long-term benefits were partially offset by the relatively high number of acute procedure-related adverse events.
Recent developments in device design have helped make the implant procedure safer, easier and quicker. The latest generation of Watchman, Watchman-FLX, has a number of design enhancements including an increased number of struts, a closed distal end, and the ability to fully recapture and reposition the device if needed. Watchman-FLX received the CE mark approval in November 2015, and will be rolled out widely in early 2016. The incidence of peri-procedural complications were already more than halved in the PREVAIL trial as compared to PROTECT AF, and more contemporary data from experienced centres show a device complication rate of 2-3%, mirroring our own data at Liverpool Heart and Chest Hospital, Liverpool, UK.
Similarly, the second generation of the ACP, Amplatzer Amulet Left Atrial Appendage Occluder, was released in 2013 with a number of modifications. These include a deeper distal lobe and more anchoring hooks to reduce risk of embolisation, a more overriding disc to allow better seal of the LAA, a longer waist to navigate more challenging LAA anatomies, and a recessed female screw to reduce risk of thrombus formation. Furthermore the Amulet comes pre-assembled in contrast to the ACP that needed assembly by the operator before deployment; this not only makes the procedure quicker and less cumbersome, but also reduces the risk of complications such as air and device embolisation. A few European centres have published their early experience with Amulet with good results. Analysis of the 40 consecutive Amulet implants performed at our own hospital (Liverpool Heart and Chest Hospital) showed 100% procedural success, zero complications, and a mean procedure time of less than 90 minutes. Furthermore, follow up imaging at 6-8 weeks showed total absence of leak in 92% cases, and only mild residual leak in 8%.
These improvements in design in both Watchman-FLX and Amulet should make left atrial appendage occlusion implant even safer than before.
Although the implant per se has become reasonably straightforward, challenges still remain related to overall patient management peri-procedure. These patients often have complex medical issues, and their assessment should ideally involve a multi-disciplinary team. At our hospital, every case is assessed by a team that consists of the implanting cardiologist, a stroke physician and a non-interventional cardiologist with an interest in cardiac imaging. If need be, specific advice from other disciplines such as gastroenterology and haematology is sought to ensure that patients are offered the most appropriate treatment. Close collaboration with the referring physician is also required to make decisions about the optimal post-implantation anticoagulation strategy. Although randomised trials were performed with a 45-day course of warfarin followed by dual antiplatelet therapy until six months after the procedure, recent studies have shown dual antiplatelet inhibition to be safe, and this has become standard practice in several centres, including ours.
A major challenge going forward is to ensure equitable and ready access to LAA closure for appropriate patients. At present, reimbursement policies through private health insurance companies are variable, and access via public health-funded systems is patchy. For instance, the National Health Service (NHS) England has approved this procedure in only10 hospitals across the country, and that too as part of a ‘Commissioning through Evaluation’ programme lasting three years. Given that 5-10% of all atrial fibrillation patients have a genuine inability to tolerate lifelong oral anticoagulation, the potential pool of patients who could benefit from LAA closure is huge. Positive cost-efficacy analyses for this technology should help in increasing access over time, but these would require careful long-term follow-up, and it is the responsibility of all implanting physicians to ensure that these data are collected meticulously.
Dhiraj Gupta is a consultant cardiologist at Liverpool Heart and Chest Hospital, UK