(73 days)
Micrus MicroCoil Systems are intended for endovascular embolization of intracranial aneurysms.
Micrus MicroCoil Systems are platinum embolic coils ("MicroCoils") attached to Device Positioning Units (DPUs (single use, sterile). The Micrus MicroCoil Systems are available in a 10-System size (compatible with 10 and 14 sized microcatheters) and 18-System size (compatible with 14 and 18 sized microcatheters). Both 10 and 18 sizes are available in various diameters/dimensions. Shapes can be spherical, helical, or straight. Lengths range from 1 to 30 centimeters and diameters range from 2 to 20 millimeters. Implant material for the non stretch resistant MicroCoils is a platinum alloy: implant material for the stretch resistant MicroCoils is a platinum alloy and a stretch resistant member (non-absorbable polypropylene suture).
A MicroCoil is detached from its Device Positioning Unit through heat shearing of a highly oriented, high tensile strength polyethylene (PE) fiber upon the clinician's command. The Device Positioning Unit is then removed from the microcatheter and discarded.
A Micrus MicroCoil System connects to a Micrus Connecting Cable (single use, sterile) which traverses the sterile field to connect to a Micrus Detachment Control Box (DCB) (reusable, non-sterile). The Connecting Cable and Detachment Control Box are sold separately. A MicroCoil System plus Connecting Cable and Detachment Control Box is referred to as a Micrus MicroCoil Delivery System.
This response is structured based on the provided document, K031578. The information regarding acceptance criteria and the study that proves the device meets them is primarily found in sections G and H.
Acceptance Criteria and Device Performance Study for Micrus MicroCoil Systems
This submission focuses on a labeling change for the Micrus MicroCoil Systems, specifically a change to the "Indication for Use" statement based on clinical outcomes from the International Subarachnoid Aneurysm Trial (ISAT). The device itself (Micrus MicroCoil System) remains unchanged from its predicate devices K002056 and K022420. Therefore, the device's technical acceptance criteria were established and met in the predicate device clearances, and the current submission provides a summary of those non-clinical tests. The "study that proves the device meets the acceptance criteria" in this context refers to the clinical evidence (ISAT) used to justify the broader indication for use.
1. Table of Acceptance Criteria and Reported Device Performance (Non-Clinical Tests)
The following table summarizes the non-clinical tests and results, previously reviewed for the predicate devices, for which the Micrus MicroCoil System was found "Equivalent." These represent the fundamental performance acceptance criteria for the device itself.
| Test / Characteristic | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Aneurysm Packing / Detachment Reliability | - Complete occlusion of aneurysms. |
- Detachment reliability. | - No filling defects evident on angio.
- No premature detachment / auto-detach caused by exposure to blood, body fluids, body temperatures or repeated manipulation.
- 100% first detach-cycle detachment achieved. |
| Coil Stability / Aneurysm Occlusion | - Positional stability and aneurysm occlusion. | - Positional stability and aneurysm occlusion maintained through 6 months of implant. - No coil compaction present at 6-month angio. |
| GDC Bench Marking | - Established specifications for delivery force, tensile strength, and stiffness. - Micrus Stretch Resistant MicroCoil must be substantially equivalent to predicates. | - Showed substantial equivalence in delivery force, tensile, and stiffness. |
| Coil Stiffness/Softness | - Stiffness limit desired for Finishing Stretch Resistant MicroCoil. | - Finishing Stretch Resistant MicroCoil and Helical Stretch Resistant MicroCoil stiffness is within desired stiffness limit. |
| Friction in the Microcatheter (Delivery Force) | - Average push force must be substantially equivalent to predicates. | - Finishing Stretch Resistant MicroCoil and Helical Stretch Resistant MicroCoil average push force exhibit comparable delivery forces. |
| MDR Database Review | - Review for clinical risks. | - MSR01 risk assessment includes and addresses all risks encountered in review of predicate device MDR review. |
| Biocompatibility of Materials | - Meets the requirements of ISO 10993. | - The only new material in the Micrus Stretch Resistant MicroCoil is polypropylene monofilament # 6523, which is identical to the pre-approved GDC stretch resistant suture. (Implies compliance by equivalence to approved material). |
| Sterilization Validation | - Minimum Sterility Assurance Level of 10-6. | - Passed minimum sterility assurance level of 10-6. |
| Shelf Life Test | - No performance degradation after 1 year of shelf life aging. | - Minimum tensile strength after 1 year accelerated aging shows no degradation. |
| Tensile Strength | - Tensile strength of suture ball tip and MicroCoil to DPU must be substantially equivalent to predicates. | - Tensile strength meets desired strength criteria. |
| Durability (Reliability after Fatigue) | - Withstand deployment and retraction 6 times in a tortuous anatomy. | - No knotting, no breakage, no stretching occurred. - Durability meets desired durability criteria. |
| MRI Compatibility of Implant | - No change impacting MRI compatibility. | - No change was made which would impact MRI compatibility. (Implies existing compatibility from predicates is maintained, thus meets this inherent criterion). |
Acceptance Criteria for Clinical Outcomes (New Indication for Use):
The acceptance criteria for the expanded "Indication for Use" are implicitly derived from the results of the ISAT study, which demonstrated clinical superiority of endovascular coiling over surgical clipping for ruptured intracranial aneurysms.
| Clinical Outcome Parameter | Acceptance Criteria (based on ISAT findings) | Reported Device Performance (ISAT results for endovascular patients, including Micrus MicroCoils) |
|---|---|---|
| Dependency or Death at 1 Year (Primary Outcome) | Significantly better outcome (lower incidence of dependency or death) for endovascular coiling compared to surgical clipping. | 23.7% of endovascular patients were dependent or dead at 1 year. (Compared to 30.6% for surgical patients). |
| Relative Risk Reduction | Positive relative risk reduction demonstrating benefit of endovascular coiling. | 22.6% relative risk reduction for endovascular patients versus surgical. |
| Absolute Risk Reduction | Positive absolute risk reduction demonstrating benefit of endovascular coiling. | 6.9% absolute risk reduction for endovascular patients versus surgical. |
| Risk of Rebleeding at 1 Year | Acceptably low risk of rebleeding, even if slightly higher than surgical clipping, given overall outcome benefits. | 2 per 1276 for endovascular patients. (Compared to 0 per 1081 for surgical patients). |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for the Clinical Test Set (ISAT):
- Total patients enrolled: 2143
- Patients randomly assigned to endovascular treatment with platinum coils: 1073
- Patients randomly assigned to neurosurgical clipping: 1070
- Data Provenance: The study was a "multi-center study published in the Lancet," referred to as the International Subarachnoid Aneurysm Trial (ISAT). It involved patients with ruptured intracranial aneurysms. The data is prospective as it involved random assignment and follow-up. The document does not explicitly state the countries of origin for all participating centers, but "International" implies multiple countries, likely involving European and other centers given its publication in The Lancet and prior clinical practice in Europe. Micrus Corporation received CE Marking in May 2000 and FDA clearance in January 2001, joining ISAT in February 2001, indicating its international scope prior to US market entry.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
The ISAT study was a large, randomized controlled trial comparing two treatment modalities for ruptured intracranial aneurysms. The "ground truth" for the primary outcome (neurological assessment of dependency at 1 year) was established through clinical outcomes data collected directly from patients. The document states, "The primary outcome was a neurological assessment of dependency at 1 year (using the Rankin neurological outcome scale)." This implies that trained clinical personnel (e.g., neurologists, nurses, or other healthcare professionals) conducted these assessments. The exact number of experts/assessors is not specified, but for a trial of this magnitude, it would involve numerous qualified healthcare professionals at each participating center, following standardized protocols for outcome assessment. Their qualifications would be as medical professionals trained in neurological assessment and the use of the Rankin scale.
4. Adjudication Method for the Test Set
The document does not explicitly describe an adjudication method for the primary outcome assessment itself (neurological assessment of dependency). For large, multi-center trials like ISAT, it is common best practice to have:
- Standardized training for assessors.
- Centralized review of case report forms.
- Possibly masked outcome assessment (though not explicitly stated whether assessors were blinded to treatment arm).
- A Clinical Events Committee (CEC) to adjudicate serious adverse events or difficult-to-classify outcomes.
The text primarily focuses on the direct "Findings" from the collected data, implying a robust methodology for data collection and analysis rather than a specific "adjudication" of the primary outcome by external experts.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, an MRMC comparative effectiveness study was not done as part of this submission or the ISAT. ISAT was a randomized controlled trial comparing treatment modalities (endovascular coiling vs. surgical clipping) and their clinical outcomes, not comparing human reader performance with or without AI assistance. The Micrus MicroCoil System is a physical device, not an AI diagnostic tool.
6. Standalone Performance Study (Algorithm Only)
No, a standalone (algorithm only) performance study was not conducted. The Micrus MicroCoil System is a medical device, not an algorithm or AI system for diagnosis or standalone analysis. Its performance is assessed through its physical characteristics and clinical outcomes when used in patients.
7. Type of Ground Truth Used for the Clinical Test Set (ISAT)
The ground truth used for the clinical test set (ISAT) was outcomes data, specifically:
- Clinical outcomes: Neurological assessment of dependency at 1 year using the Rankin neurological outcome scale.
- Survival data: Implied by "dependent or dead at 1 year."
- Rebleeding events: Documented occurrence of rebleeding at 1 year.
This is direct patient outcome data, collected prospectively as part of the randomized controlled trial.
8. Sample Size for the Training Set
- For the non-clinical tests (physical performance, durability, etc.): Not applicable in the context of "training set" as these are engineering and materials tests, not machine learning based.
- For the clinical justification (ISAT): Not applicable. ISAT was a clinical trial used for validation/comparison, not a "training set" for a device, as the Micrus MicroCoil System is a physical medical device and not a data-driven model requiring a training phase for its core function.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there was no explicit "training set" in the context of an AI/ML algorithm or data-driven model described in this submission. The "ground truth" for evaluating the clinical efficacy of the device (as part of endovascular coiling) was established through the rigorous, prospective data collection and follow-up within the ISAT clinical trial design.
§ 882.5950 Neurovascular embolization device.
(a)
Identification. A neurovascular embolization device is an intravascular implant intended to permanently occlude blood flow to cerebral aneurysms and cerebral ateriovenous malformations. This does not include cyanoacrylates and other embolic agents, which act by polymerization or precipitation. Embolization devices used in other vascular applications are also not included in this classification, see § 870.3300.(b)
Classification. Class II (special controls.) The special control for this device is the FDA guidance document entitled “Class II Special Controls Guidance Document: Vascular and Neurovascular Embolization Devices.” For availability of this guidance document, see § 882.1(e).