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The Merci® Retriever is intended to restore blood flow in the neurovasculature by removing thrombus in patients experiencing ischemic stroke. Patients who are ineligible for treatment with intravenous tissue plasminogen activator (IV t-PA) or who fail IV t-PA therapy are candidates for treatment. The Merci Retriever is also indicated for use in the retrieval of foreign bodies misplaced during interventional radiological procedures in the neuro, peripheral and coronary vasculature.

Like the predicate device, the design of the modified Merci Retriever consists of a flexible, tapered Nitinol core wire. This distal end is shaped into a helix and a platinum coil is threaded over and attached to the distal end. Polymer filaments are attached to the distal end. The core wire proximal to the helix is coated with a hydrophilic coating. A torque device is provided with Retriever to facilitate manipulation. An insertion tool is provided with Retriever to introduce Retriever into Microcatheter during the procedure.

The provided text describes a 510(k) submission for a modified Merci Retriever, a medical device used for removing thrombus in ischemic stroke patients and retrieving foreign bodies. However, this document primarily focuses on demonstrating substantial equivalence to a predicate device rather than presenting a performance study with detailed acceptance criteria and supporting data as one would expect for a novel device or a clinical trial.

Therefore, many of the requested sections (acceptance criteria, specific study details, ground truth, expert involvement, MRMC study, sample sizes for training/test sets) cannot be extracted from the provided text because the document does not contain this type of performance study. The core of this submission is a "Testing Summary" stating that "Results of design verification and validation testing performed on the modified Merci Retriever confirm that the device conforms to the required specifications and establish substantial equivalence to the predicate device." This suggests that the evaluation was likely focused on engineering specifications and direct comparison to a previously cleared device, not a clinical performance study with defined acceptance criteria for metrics like sensitivity, specificity, etc.

Here's a breakdown of what can and cannot be provided based on the input:

1. A table of acceptance criteria and the reported device performance

• Explanation: The document does not specify quantitative acceptance criteria for device performance (e.g., successful clot retrieval rates, recanalization rates) or present data from a clinical study to demonstrate such performance. The submission aims to establish substantial equivalence based on design verification and validation testing, not a clinical outcome study against predetermined performance metrics.

2. Sample sized used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Sample Size for Test Set: Not applicable / Not available. The document refers to "design verification and validation testing," which typically involves bench testing, material testing, and potentially animal studies, rather than human clinical trials with a "test set" in the context of AI or diagnostic device performance evaluation.
• Data Provenance: Not applicable / Not available. No clinical data or human subject data is described.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

• Not applicable / Not available. The concept of "ground truth" established by experts for a test set is relevant to studies evaluating diagnostic accuracy or AI performance. This document does not describe such a study.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

• Not applicable / Not available. Adjudication methods are used to establish ground truth in studies involving human interpretation or clinical endpoints. This information is not present.

5. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

• No. An MRMC study was not done. This device is an endovascular retriever, not an AI-assisted diagnostic tool.

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done

• Not applicable / No. This device is a physical medical instrument, not a software algorithm.

7. The type of ground truth used (expert concensus, pathology, outcomes data, etc)

• Not applicable / Not available. The document describes a physical medical device and its substantial equivalence to a predicate device, focusing on engineering and material specifications rather than clinical outcomes with a defined "ground truth."

8. The sample size for the training set

• Not applicable / Not available. There is no mention of a "training set" as this is not an AI/machine learning device.

9. How the ground truth for the training set was established

• Not applicable / Not available. There is no mention of a "training set" or "ground truth" in the context of device performance in the provided document.

Summary of what the document does state regarding acceptance/testing:

The submission focuses on "substantial equivalence" to a predicate device (Merci® Retriever, K081305). The "Testing Summary" on page 1 states:

"Results of design verification and validation testing performed on the modified Merci Retriever confirm that the device conforms to the required specifications and establish substantial equivalence to the predicate device."

And then explicitly lists:

"The modified Merci Retriever is substantially equivalent to the predicate device with regard to intended use, operating principal, design concept, materials, shelf life, packaging and sterilization processes."

This indicates that the "acceptance criteria" were met by demonstrating that the modified device's specifications (design, materials, functionality) were sufficiently similar to the predicate device, or met internal engineering requirements, to justify an equivalence claim rather than requiring new clinical performance data against specific endpoints.

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The Merci® Retriever is intended to restore blood flow in the neurovasculature by removing thrombus in patients experiencing ischemic stroke. Patients who are ineligible for intravenous tissue plasminogen activator (IV t-PA) or who fail IV t-PA therapy are candidates for treatment. The Merci® Retriever is also indicated for use in the retrieval of foreign bodies misplaced during interventional radiological procedures in the neuro, peripheral and coronary vasculature.

Like the predicate devices, the modified Merci Retriever consists of a flexible, Nitinol core wire with shaped loops at the distal end. A radiopaque coil covers the tip allowing visualization under fluoroscopy.

The Retriever is placed distal to the thrombus or foreign body through a microcatheter. The Retriever and microcatheter are pulled back to engage the thrombus or foreign body in the loops of the Retriever. The Retriever, the thrombus or foreign body, and the microcatheter are then removed from the body.

The provided documents describe a 510(k) submission for a modified Merci Retriever, a device used to remove thrombus in ischemic stroke patients and retrieve foreign bodies. However, this submission focuses on demonstrating substantial equivalence to predicate devices rather than a study proving the device meets specific acceptance criteria based on performance metrics.

Here's a breakdown based on the information provided and what is missing:

1. Table of Acceptance Criteria and Reported Device Performance

• Indications for Use
• Function
• Materials used | "The modified Merci Retriever is equivalent to the predicate devices. The indications for use, function, and materials used are substantially equivalent." | This is the primary "acceptance criterion" for a 510(k) submission, not performance metrics. No specific quantitative performance criteria (e.g., success rates, complication rates) are provided. |
  | Material Suitability | "All materials used... are suitable for the intended use." | "All materials used in the manufacture of the Retriever are suitable for the intended use of the device and have been used in numerous previously cleared products." | This is a qualitative statement, not a specific, measurable criterion with associated performance data. |
  | Required Specifications (General) | Met required specifications for completed tests. | "All devices met the required specifications for the completed tests." | This is a general statement. The specific tests and their required specifications are not detailed in the provided text. It likely refers to bench testing (e.g., mechanical, biocompatibility) rather than clinical performance. |

Missing Information:

• Specific, quantitative performance-based acceptance criteria (e.g., a target success rate for thrombus retrieval, a maximum allowable device-related complication rate, specific mechanical test thresholds).
• Detailed results of the "completed tests" that led to the statement "All devices met the required specifications."

2. Sample Size Used for the Test Set and Data Provenance

This information is not provided in the given text.

• Sample Size: No information on the number of patients or cases used for any clinical testing. The submission focuses on substantial equivalence based on device characteristics rather than new clinical data from a dedicated test set.
• Data Provenance: Not mentioned.

3. Number of Experts Used to Establish Ground Truth and Qualifications

This information is not provided. As no clinical or imaging study data is presented, there's no mention of ground truth establishment by experts.

4. Adjudication Method

This information is not provided.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

This information is not provided. The submission does not describe a clinical study comparing human readers with and without AI assistance. This device is a physical medical device (retriever), not an AI diagnostic tool.

6. Standalone (Algorithm Only) Performance Study

This information is not applicable/not provided. The Merci Retriever is a physical medical device, not an algorithm, so a standalone algorithm performance study is not relevant.

7. Type of Ground Truth Used

This information is not provided. If bench testing was performed, the "ground truth" would be the engineering specifications. For clinical performance, it would typically be clinical outcomes or expert adjudication, but no such data is presented.

8. Sample Size for the Training Set

This information is not applicable/not provided. This is a physical device, not a machine learning algorithm, so there is no "training set."

9. How the Ground Truth for the Training Set was Established

This information is not applicable/not provided.

Summary of the Study Discussed (510(k) Submission):

The provided documents describe a 510(k) Premarket Notification for a modification to the Merci® Retriever. The "study" described is essentially the documentation and rationale presented to the FDA to demonstrate substantial equivalence to previously cleared predicate devices (Merci® Retriever K033736 and Modified Merci® Retriever K061059).

• Purpose of the "Study": To demonstrate that the modified Merci® Retriever is as safe and effective as existing legally marketed predicate devices, mainly by showing that its indications for use, function, and materials are substantially equivalent.
• Key Findings: The submission states that the modified device is substantially equivalent, and that "All materials used in the manufacture of the Retriever are suitable for the intended use of the device and have been used in numerous previously cleared products" and "All devices met the required specifications for the completed tests."
• Nature of the Evidence: The evidence primarily comprises:
  • Comparison of design features and materials to predicate devices.
  • Statements regarding the suitability of materials.
  • A general statement that "all devices met the required specifications for the completed tests" (likely referring to bench testing, but details are not provided).
• Clinical Data: No new clinical trial data, human subject testing, or expert reviews of clinical outcomes are detailed in the provided text for this specific 510(k) modification. This type of submission often relies on a comparison to predicate devices, and sometimes existing clinical data for the predicate device, rather than new, extensive clinical studies for minor modifications.

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