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510(k) Data Aggregation
(219 days)
The ACIST RXi System is indicated for obtaining intravascular pressurements for use in the diagnosis and treatment of coronary and peripheral artery disease. The ACIST Navvus II MicroCatheter is intended for use with the ACIST RXi System.
The current RXi system obtains intravascular pressure measurements for use in the diagnosis and treatment of coronary and peripheral artery disease. The RXi measures intravascular pressure in a hyperemic state following administration of adenosine as fractional flow reserve (FFR). The proposed software update for the RXi system adds a diastolic pressure ratio (dPR), which measures intravascular pressure in a non-hyperemic (resting) state. Both current and proposed ACIST RXi Systems are used in conjunction with the Navvus Catheter.
The proposed RXi System console containing embedded software that provides the main user interface. The system is used with the Navvus catheter which contains a pressure sensor for acquisition of pressure distal (Pd) to a lesion. The proximal aortic pressure (Pa) is acquired via an interface to a third-party hemodynamic system. The system is intended for use in catheterization and related cardiovascular specialty laboratories to compute and display fractional flow reserve (FFR) using hyperemic agents and/or nonhyperemic indices of diastolic pressure ratio (dPR) and PdPa for physiological assessment of ischemic stenotic lesions.
Measurement of FFR requires simultaneously monitoring the blood pressures proximal and distal to a lesion while inducing hyperemia. dPR is a measure of the diastolic portion of the hemodynamic waveform and can be used by the physician to perform a physiologic assessment without inducing hyperemia in the patient.
The provided text describes the ACIST RXi System and Navvus II MicroCatheter, with a focus on a software update to include a diastolic pressure ratio (dPR) modality. The information primarily relates to the substantial equivalence determination for this medical device, rather than a clinical study evaluating an AI device's performance against human readers. Therefore, many of the requested points, particularly those pertaining to AI device performance evaluation criteria (e.g., sample size for test set, number of experts, adjudication method, MRMC study, training set details), are not present in the provided document.
However, I can extract information related to the device's performance and the study that demonstrated its substantial equivalence.
Here's a summary of the available information based on the provided text, addressing your points where possible and noting where information is not available:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for the dPR functionality were primarily based on demonstrating agreement with an FDA-cleared reference device (Volcano iFR Modality) when compared to FFR measurements.
| Acceptance Criteria (Performance Goals) vs. Reference iFR compared to FFR | Reported Device Performance (RXi dPR compared to FFR, and dPR vs iFR) |
|---|---|
| Diagnostic accuracy: Not explicitly stated as a goal for dPR vs FFR, but indirectly implied by seeking agreement with iFR. | Accuracy of dPR (cutpoint 0.89) vs. FFR (cutpoint 0.80): 76.39% |
| Sensitivity: Pre-determined performance goal of 90% (for dPR vs iFR comparison) | Sensitivity for dPR vs iFR: 99.68% (Higher than pre-determined goal) |
| Specificity: Pre-determined performance goal of 84% (for dPR vs iFR comparison) | Specificity for dPR vs iFR: 88.92% (Higher than pre-determined goal) |
| Agreement of diagnostic accuracy between dPR and iFR compared to FFR. | Diagnostic accuracy of dPR compared to iFR: 93.89% (This confirms the agreement, supporting substantial equivalence) |
| Zero Drift: |
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(106 days)
To measure pressure in blood vessels including both coronary and peripheral vessels, during diagnostic angiography and or any interventional procedures. Blood pressure measurements provide hemodynamic information, such as fractional flow reserve, for the diagnosis and treatment of blood vessels.
The proposed OptoMonitor is a software upgrade that includes software modifications allowing for the calculation of dPR index, and revised labeling relevant to this change. This device and its components are considered accessories to catheter pressure transducers and are intended for use with leqally marketed catheters. The OptoMonitor with the new dPR calculation is an upgraded version of the software embedded in the previously cleared OptoMonitor's Display Unit. The OptoMonitor comprises the exact same hardware as cleared version with most of the software remaining unchanged, except for the display unit software which in addition to the current calculation of Fractional Flow Reserve (FFR), the upgraded version will also calculate the diastolic pressure ratio (dPR). dPR is a resting index which consists in calculating the ratio of Pd and Pa over the diastolic portion of the heart beat cycle. dPR is a resting index for the diagnostic of the severity of stenosis equivalent to iFR (instantaneous wave-Free Ratio). IFR calculates the ratio of Pd and Pa over 75% of the diastolic portion. The OptoMonitor is composed of 3 parts: The Hybrid Cable Unit (HCU), the Signal Conditioner Unit (SCU) and the Display Unit (DU). There are no changes to the device hardware (HCU and SCU) from device system cleared under K142598. The device is a non-sterile, non-patient contact device.
Here's a breakdown of the acceptance criteria and study information for the OptoMonitor with dPR software upgrade, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly present a table of "acceptance criteria" for the dPR software update itself. Instead, it compares the dPR's diagnostic performance against iFR (the reference standard and reference device) and FFR. The "reported device performance" are the accuracy, specificity, and sensitivity of dPR.
| Metric | Acceptance Criteria (Implied by equivalence to iFR) | Reported Device Performance (dPR) | Notes |
|---|---|---|---|
| Accuracy | Equivalent to iFR | 97.1% [95.7%, 98.1% @95% CI] | Compared to iFR as a reference standard, using a cut-off of 0.89. |
| Specificity | Equivalent to iFR | 95.9% [93.6%, 97.5% @95% CI] | Compared to iFR as a reference standard, using a cut-off of 0.89. |
| Sensitivity | Equivalent to iFR | 98.4% [96.6%, 99.3% @95% CI] | Compared to iFR as a reference standard, using a cut-off of 0.89. |
| Diagnostic Performance vs. FFR | Not statistically different from iFR vs. FFR | Not statistically different from diagnostic performance of iFR vs. FFR, with 95% confidence interval significantly overlapping. | This assesses if dPR (cut-off=0.89) vs FFR (cut-off=0.80) performs similarly to iFR (cut-off=0.89) vs FFR (cut-off=0.80). |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size: Not explicitly stated. The performance metrics (accuracy, specificity, sensitivity) were "calculated from both CONTRAST² and VERIFY ²² studies." The exact number of patients or cases from these studies used for the dPR analysis is not provided.
- The document implies that the data is retrospective, as it is based on re-analysis of existing study data (CONTRAST and VERIFY). The country of origin for these studies is not specified in this document.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
This information is not provided in the document. The ground truth for the dPR analysis appears to be the iFR itself (as a "reference standard") and FFR. The qualifications of the original investigators/experts who conducted the CONTRAST and VERIFY studies and established FFR/iFR values are not detailed.
4. Adjudication Method for the Test Set
This information is not provided in the document. The analysis appears to be a direct comparison of calculated dPR values against iFR and FFR values from existing studies, rather than a new adjudication process involving human reviewers.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- Was a MRMC study done? No. The document explicitly states: "No animal studies or clinical investigations are included with this submission."
- Effect Size of Human Readers with/without AI assistance: Not applicable, as no human reader study was conducted.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, a standalone study was performed. The reported accuracy, specificity, and sensitivity for dPR (97.1%, 95.9%, and 98.4% respectively) are results of the algorithm's performance in calculating dPR and comparing it to iFR from existing studies. The dPR calculation is an automated software function on the OptoMonitor.
7. Type of Ground Truth Used
The ground truth used for evaluating dPR's performance was:
- Instantaneous wave-Free Ratio (iFR): Explicitly stated as the "reference standard."
- Fractional Flow Reserve (FFR): Used as a comparative measure to assess the diagnostic performance of dPR vs FFR and iFR vs FFR.
8. Sample Size for the Training Set
This information is not provided in the document. The document describes a "software upgrade" to calculate dPR, indicating that the algorithm was likely developed and validated on internal datasets, but the size of any training data is not mentioned.
9. How the Ground Truth for the Training Set Was Established
This information is not provided in the document. Given that the dPR calculation is a derivation from existing physiological measurements (Pd and Pa pressures), the "training" might involve tuning the algorithm to accurately replicate known iFR values or align with FFR correlations from existing clinical data. The exact method of establishing ground truth for any potential training set is not detailed.
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