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The Trevo Retrievers are indicated for use to restore blood flow in the neurovasculature by removing thrombus for the treatment of acute ischemic stroke to reduce disability in patients with a persistent, proximal anterior circulation, large vessel occlusion, and smaller core infarcts who have first received intravenous tissue plasminogen activator (IV t-PA). Endovascular therapy with the device should start within 6 hours of symptom onset.

The Trevo ProVue and XP ProVue Retrievers consist of a flexible, tapered core wire with a shaped self-expanding section at the distal end for clot capture and removal. Radiopaque platinum wires in the shaped section and radiopaque markers on the distal end allow fluoroscopic visualization. The Trevo Retrievers have a hydrophilic coating to reduce friction during use. A torque device and an insertion tool are provided with the Retrievers. The Trevo Retrievers are delivered to the site of occlusion in the neurovasculature through a microcatheter. The torque device may be used to lock the core wire of the Trevo Retriever to the microcatheter during the procedure, allowing the Trevo Retriever and microcatheter to be retracted as a system through the guide catheter and removed from the body with captured clot.

The acceptance criteria for the Trevo ProVue and XP ProVue Retrievers, a neurovascular mechanical thrombectomy device, are derived from the clinical study, bench testing, animal studies, and various regulatory requirements. The study supporting these criteria is primarily the MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) trial, with additional non-clinical and animal studies.

Here's a breakdown of the acceptance criteria and reported device performance:

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document does not explicitly state "acceptance criteria" for each performance metric with specific thresholds (e.g., "must achieve X%"). Instead, the assessment is based on demonstrating safety and effectiveness as compared to medical management alone, or meeting benchmarks set by non-clinical testing. Where specific targets are not given, the trial's statistically significant improvement or demonstration of comparable safety/effectiveness serves as the "meeting" of the criteria.

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

The primary clinical study supporting the device's expanded indication for the Trevo Retrievers was the MR CLEAN trial.

• Test Set Sample Size:

  • TREVO FDA Cohort: 120 patients (from the IAT arm, met specific criteria) (N=120 for primary safety; N=96 for primary effectiveness after exclusions).
  • Medical Management (MM) Control Group: 249 patients (after exclusions for IV t-PA timing).
  • Total Patients in MR CLEAN (originally randomized): 500 patients (233 IAT, 267 control).

• Data Provenance:

  • Country of Origin: The Netherlands (MR CLEAN was conducted in every endovascular hospital center in the Netherlands).
  • Retrospective or Prospective: Prospective, randomized, open-label, controlled, multicenter trial.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

The document mentions expert review for several endpoints:

• Recanalization and Occlusion Assessment (Table 4 & 5):
  • Number of Experts: "Consensus review by up to three readers" for occlusion assessment (Table 4). "Consensus review by at least three readers" for TICI score recanalization (Table 5).
  • Qualifications: The document does not explicitly state the specific qualifications (e.g., years of experience, subspecialty) of these readers/experts. However, given the nature of the study (neurovascular stroke treatment), it is highly probable they were experienced neurologists, neuroradiologists, or stroke specialists involved in the study's clinical centers.

4. Adjudication Method for the Test Set

• Adjudication Method: "Consensus review by up to three readers" or "at least three readers" was used for evaluating arterial occlusion and recanalization (TICI scores). This implies a method where multiple experts independently (or collectively) assess the imaging and arrive at a joint decision. The specific process (e.g., if there were disagreements, how they were resolved beyond just "consensus") is not detailed beyond "consensus review."

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size of Human Reader Improvement

• No, a typical MRMC comparative effectiveness study, as often seen for diagnostic AI, was not performed in this context.
  • The MR CLEAN trial directly compared patient outcomes with and without the device (with medical management), rather than evaluating how human readers' diagnostic accuracy or treatment decisions improved with AI assistance.
  • The Trevo Retrievers are a mechanical device for thrombectomy, not a diagnostic AI algorithm intended to assist human readers in interpreting images. Therefore, the concept of "how much human readers improve with AI vs. without AI assistance" does not directly apply to this device's clinical evaluation.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Study Was Done

• Yes, in essence, the "device" (Trevo Retrievers) was evaluated in a standalone manner as a treatment in the context of the clinical trial.
  • The MR CLEAN trial evaluated the performance of the neurovascular mechanical thrombectomy device (Trevo Retrievers) in conjunction with best medical management against best medical management alone. This is effectively a "standalone" evaluation of the device's therapeutic effect, rather than an "algorithm only" evaluation, as it's a physical medical device.
  • The device's performance is measured by its direct impact on patient outcomes when used by clinicians, not as an interpretive AI tool.

7. The Type of Ground Truth Used

• Clinical Outcomes/Expert Assessment (Blinded):
  • Primary Effectiveness (mRS): The 90-day mRS assessment was performed by an assessor who was blinded to the subject's treatment allocation. This is a high-quality method for establishing ground truth for functional independence.
  • Imaging-based Endpoints (Occlusion/Recanalization): Assessed by a consensus review by up to three/at least three readers (presumably domain experts) after 24 hours using CTA or MRA and the AOL/TICI scales.
  • Safety Endpoints: Based on collected adverse events, neurological assessments (NIHSS), and mortality data, which are objective clinical measures or physician-reported events.
  • Animal Studies: Safety ground truth established by intra-procedural angiography and histopathology assessments performed by experts.

8. The Sample Size for the Training Set

• Not Applicable in the traditional sense for an AI/algorithm: The information provided describes the regulatory approval of a physical medical device (mechanical thrombectomy retriever), not an AI algorithm. Therefore, there is no "training set" for an AI model.
• The clinical data from the MR CLEAN trial serves as the pivotal clinical evidence supporting the device's effectiveness and safety, analogous to a validation set for an AI, but it's not a "training set" for an algorithm.

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

• Not Applicable: As explained above, this is a physical medical device, not an AI algorithm, so there is no "training set" or ground truth establishment process for an AI model. The "ground truth" for the device's performance is established through rigorous clinical trials and non-clinical testing as described in the previous sections.

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The Trevo XP ProVue Retriever (4x30mm) is intended to restore blood flow in the neurovasculature by removing thrombus in patients experiencing ischemic stroke within 8 hours of symptom onset. Patients who are ineligible for intravenous tissue plasminogen activator (IV t-PA) or who fail IV t-PA therapy are candidates for treatment.

The Trevo XP ProVue Retriever (4x30mm) consists of a flexible, tapered core wire with a shaped section at the distal end. It is designed to restore blood flow in the neurovasculature by removing thrombus in patients experiencing ischemic stroke. Radiopaque platinum wires in the shaped section and radiopaque markers on the distal end allow fluoroscopic visualization. Retriever dimensions are indicated on the product label. The Retriever has a hydrophilic coating to reduce friction during use. A torque device is provided with the Retriever to facilitate manipulation. The torque device is used to lock the core wire to the microcatheter during the procedure. Locking of the torque device to the wire allows the microcatheter and Retriever to be retracted as a system during clot retrieval. An insertion tool is provided to introduce the Retriever into a microcatheter. The proximal end of the device is compatible with the Abbott guide wire extension to facilitate removal or exchange of a catheter while maintaining the Retriever position in the vessel.

The provided text describes a 510(k) premarket notification for the Trevo XP ProVue Retriever (4x30mm). This document focuses on demonstrating substantial equivalence to a predicate device, rather than proving performance against specific acceptance criteria for a new clinical outcome. Therefore, many of the requested items (e.g., sample size for test set, number of experts for ground truth, MRMC study, training set details) are not explicitly present in the provided text as they are typically associated with de novo approvals or significant device modifications requiring new clinical evidence.

However, I can extract information related to the acceptance criteria for bench and animal testing, and the study methodologies employed to demonstrate substantial equivalence.

Here's the information derived from the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for each test were "meets acceptance criteria." The device performance is generally stated as having met these unspecified criteria. The document emphasizes substantial equivalence to the predicate device through bench and animal testing.

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

• Bench Testing: The sample sizes for individual bench tests are not explicitly stated in the summary document. The phrasing "All samples meet acceptance criteria" suggests that a sufficient number of devices were tested per manufacturing and quality control standards, but the exact N is not provided.
• Animal Testing: The document mentions that a "larger diameter device (6x30mm) than the subject device (4x30mm)" was used for animal studies as a "worst case." The number of animals used is not specified.
• Data Provenance: The bench and animal studies were conducted by Concentric Medical, Inc. (the submitter). These are prospective studies performed specifically for this 510(k) submission. No country of origin for the data is explicitly mentioned beyond the submitter's location in Mountain View, California, USA.

3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications

• Bench Testing: No external experts are mentioned for establishing ground truth for the bench tests. These tests are industrial performance evaluations against internal specifications.
• Animal Testing: The animal studies were conducted in compliance with GLP regulation (21 CFR Part 58), which implies qualified personnel (e.g., veterinarians, pathologists, study directors) were involved in the conduct and evaluation, but their specific number or qualifications are not detailed.
• Clinical Data: No clinical study was performed for this 510(k) submission (stated in the document as "No clinical study was performed as there is no change to the indications for use or the fundamental scientific technology for the subject device."). Therefore, no experts were used to establish ground truth from a clinical test set.

4. Adjudication Method for the Test Set

Not applicable, as no human-read test set or clinical study requiring adjudication is described. The evaluations were based on quantifiable bench tests and animal observations.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, an MRMC comparative effectiveness study was not done. The document explicitly states: "No clinical study was performed as there is no change to the indications for use or the fundamental scientific technology for the subject device."

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

This refers to a medical device in the context of hardware, specifically a "thrombus retriever" catheter. The concept of "standalone algorithm performance" is not applicable here as it is not an AI/software device.

7. The Type of Ground Truth Used

• Bench Testing: Ground truth for bench tests is based on engineering specifications and physical measurements, which are inherently objective and quantitative (e.g., tensile strength, radial force, dimensions).
• Animal Testing: Ground truth in animal studies would typically involve pathological examination and observations for adverse events (e.g., "evidence of arterial transmural dissection or perforation"). This is based on direct biological and histological assessment.

8. The Sample Size for the Training Set

Not applicable. This device is a physical medical instrument (thrombus retriever), not a machine learning algorithm requiring a training set.

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

Not applicable. This device is a physical medical instrument (thrombus retriever), not a machine learning algorithm.

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