The Amplatzer Amulet is Abbott’s left atrial appendage closure device. Unlike the WATCHMAN’s single-piece design, the Amulet uses two functional components — a distal lobe that anchors in the LAA neck and a proximal disc that seals the LAA ostium against the LA endocardium. The connecting waist allows independent adjustment of lobe and disc positioning.
How the system works
- Self-expanding nitinol mesh structure with polyester fabric within both the lobe and the disc.
- Delivered through a transseptal sheath; the lobe is deployed first into the appendage neck, then the disc is opened against the LA ostium.
- The lobe’s stabilising wires engage the LAA wall; the disc lays flush against the LA face to seal the ostium externally.
- Endothelialisation covers both surfaces over weeks to months.
Types / Variants
The current US device is the Amplatzer Amulet (Generation 2). Available in eight sizes covering LAA landing-zone diameters from 11 to 31 mm — broader range than WATCHMAN’s five sizes, giving better fit for marginal anatomies.
Design contrast vs WATCHMAN
| Feature | Amulet | WATCHMAN FLX |
|---|---|---|
| Architecture | Two-component lobe + disc | Single-piece frame with PET face |
| Seal mechanism | Disc seals at LA ostium externally | Frame face sits within LAA ostium |
| Sizing | Eight sizes (11-31 mm) | Five sizes (20-35 mm) |
| Depth requirement | Lower — disc handles ostial closure even with shallow lobe seating | Higher — entire device needs LAA depth |
| Post-implant regimen | Aspirin + clopidogrel then aspirin (no DOAC bridge for most) | Short DAPT or DOAC bridge then aspirin |
| 45-day TEE | Optional in some protocols | Standard |
Indications & candidate selection
Same overall indication as WATCHMAN: non-valvular AF with elevated stroke risk and a reason to discontinue long-term anticoagulation.
Amulet-favoured anatomies:
- Shallow appendages where WATCHMAN’s depth requirement is borderline.
- Chicken-wing morphology with a sharp early bend — the lobe seats in the proximal segment while the disc handles ostial closure.
- Large or oval ostia where the disc’s separate sizing accommodates better.
- Patients who cannot tolerate even a short DOAC bridge.
Key procedural considerations
Sizing
- Pre-procedure imaging (TEE +/- cardiac CT) defines LAA neck (landing zone) diameter and ostium diameter.
- Choose lobe size 2-6 mm larger than the LAA landing-zone diameter.
- The disc auto-sizes off the lobe choice — disc is roughly 6-8 mm larger than the lobe.
Release criteria
- Lobe fully expanded with stabilising wires engaged.
- Lobe axis aligned with appendage neck axis.
- Disc concave (slightly concave toward LA confirms tension is right; flat or convex suggests over-tension).
- No disc protrusion into adjacent structures.
- No peri-device leak >3 mm.
Trial context
The Amulet IDE trial randomised Amulet vs WATCHMAN 2.5 in non-valvular AF patients. Amulet was non-inferior on the primary efficacy endpoint (stroke, systemic embolism, cardiovascular death) and demonstrated more frequent immediate complete closure but with somewhat higher procedural complication rate. Real-world registries have refined the picture as operator experience has grown.
What to know in the lab
- Transseptal puncture: inferior-posterior, same as WATCHMAN; the Amulet sheath is generally larger.
- Engage the LAA with the delivery sheath stably before deploying the lobe — recapture is possible but each recapture risks anatomy disturbance.
- Deploy the lobe first; assess position before releasing the disc.
- Tug test the lobe before disc deployment.
- Confirm disc concavity on TEE — flat or convex disc means too much tension, recapture and redeploy.
Post-implant management
- Typical regimen: aspirin + clopidogrel for 1-6 months (institution-dependent), then aspirin alone long term.
- DOAC bridge is not required for most patients — a major operational difference vs WATCHMAN.
- Surveillance imaging at 45-90 days per institutional protocol; some centres image at 6 months instead of 45 days.
Common issues & troubleshooting
- Disc not flush with LA wall — over-tensioned; recapture, advance lobe slightly deeper, redeploy disc.
- Lobe protrusion — under-deployed lobe; recapture, advance further into appendage neck, redeploy.
- Peri-device leak around the disc — upsize or reposition; persistent leak is uncommon given the dual-component seal.
- Device-related thrombus on the disc — reinstate anticoagulation; reimage at 4-8 weeks.
- Pericardial effusion — same risk profile as WATCHMAN; transseptal-related more than device-related.