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Impala is intended to record, store, and transfer a 12-lead resting electrocardiogram (ECG). Impala acquires four standard diagnostic-bandwidth leads (Leads I, II, V2, V4, or Leads I, II, V1, V4). The device derives four standard diagnosticbandwidth, Lead-III and unipolar limb leads aVR, aVF and aVL. The device also synthesizes Leads V1 or V2, V3, V5, V6, which are similar to but not identical to the same leads of a standard diagnostic 12-lead. The 4 synthesized chest leads are not intended for diagnostic use and may fail to show important findings limited to those leads. This device is not a substitute for a diagnostic 12-lead ECG and is contraindicated for use in ruling out any condition (including but not limited to certain ischemia/infarcts, Brugada syndrome) for which the diagnosis may be solely dependent on the synthesized leads.

The device also provides ECG measurements and ECG analysis (rhythm and morphological interpretation) using the acquired leads. The automated ECG analysis results are provisional and should not be used for clinical action if it has not been reviewed by a qualified physician capable of interpreting the ECG signal in the context of the patient's condition. The automated analysis may then be confirmed, edited, or qualified physician. ECG analysis should be used only as an adjunct to clinical history, symptoms, and the results of other non-invasive tests.

Impala is intended for use with patients aged 18 years and older. Impala is intended for use by healthcare professionals, or trained personnel in healthcare facilities (e.g. the doctor's office or hospital) and in acute settings.

Impala is a portable 12-Lead resting electrocardiograph (ECG) device that acquires 4 standard diagnostic-bandwidth ECG leads from a patient (I, II, V1 or V2, V4), derives 4 standard diagnostic-bandwidth leads (aVL, aVR, aVF, III), and using software generates the remaining leads (V2 or V1, V3, V5, V6) to create a 12-Lead ECG recording. The device can be used by healthcare professionals (HCPs) to record a reduced lead, diagnostic-bandwidth, resting ECG, where traditional 10 electrode, 12 lead ECG recorders are not practical to administer due to size, time, or need for specialized clinicians to administer. Examples may include physician offices, and remote and field locations.

The Impala hardware consists of the Impala ECG Module that connects to the Patient Lead Wire. The Patient Lead Wire is a single cable that includes five snap-on electrodes. Impala also consists of a mobile software application, the Impala App that executes on a mobile computing platform (MCP), such as an Apple iPhone smartphone. To record an ECG, the user positions standard off-the-shelf (OTS) ECG gel electrodes on the patient and snaps on the connectors in the Patient Lead Wire on to the electrodes. Impala allows for two options for which set of leads are acquired:

1. Lead Set 1: Leads {I, II, V2, and V4}, with electrodes on RA, LA, LL, V2, V4; and
2. Lead Set 2: Leads {I, II, V1, and V4} with electrodes on RA, LA, LL, V1, and V4.

Impala incorporates AliveCor's Corvair (K231010), a software as a medical device, to provide rhythm analysis, morphological analysis, and ECG measurements. Corvair has two modes of operation, Symptomatic Mode, which is used when the pre-test probability for a specific rhythm is high, and Asymptomatic Mode, which optimizes the PPV, by optimizing the specificity, to detect the various rhythms and morphologies. The user can choose which Impala Lead Set and which Corvair mode of determinations to utilize based on the target clinical application.

The Impala device, an electrocardiograph, underwent nonclinical testing to demonstrate its performance and substantial equivalence to a predicate device.

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

The document does not provide a specific table of acceptance criteria with corresponding performance metrics for the synthesized leads. However, it implicitly states an acceptance criterion related to the similarity of synthesized leads to standard 12-lead ECGs and the device's intended use.

| Acceptance Criteria (Implicit) | Reported Device Performance |
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| Synthesized leads are similar to corresponding standard 12-leads, and their display is not likely to confuse human interpreters, while acknowledging that significant differences may exist and these leads are not for diagnostic use to rule out certain conditions. | Results suggest that the synthesized leads tend to be similar to the corresponding 12-leads, so the display of these leads is not likely to confuse human interpreter. However, significant differences exist in many cases. Thus, the 4 synthesized chest leads are not intended for diagnostic use and may fail to show important findings limited to those leads. Further, this device is contraindicated for the diagnosis of any condition (including but not limited to certain ischemia/infarcts, Brugada syndrome) for which the diagnosis may be solely dependent on the synthesized leads. |

2. Sample size used for the test set and the data provenance:

• Sample Size: The test set for the performance of the synthesized leads utilized data from a proprietary AliveCor database described as consisting of 3,000 12-Lead ECGs. Additionally, two public databases (Physionet PTB-XL and the Common Standards for Quantitative Electrocardiography Standard Database (CSEDB) as referenced in IEC 60601-2-25) were used, though their specific sample sizes for this test are not explicitly stated.
• Data Provenance:
  • Proprietary Dataset: The 3,000 ECGs were acquired from clinical patients at the Mayo Clinic over several decades between 1985 and 2010.
  • Public Databases: Physionet PTB-XL and CSEDB. The origin countries are not specified for the public databases but are generally global or multi-center for such resources.
• Retrospective or Prospective: The proprietary dataset from the Mayo Clinic (1985-2010) is clearly retrospective. The nature of the public databases would also be retrospective.

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):

The document mentions that each ECG in the proprietary dataset "has a physician overread confirmed diagnosis with multiple diagnostic codes." It does not specify the number of physicians or their specific qualifications (e.g., years of experience as cardiologists/ECG interpreters) for establishing the ground truth for the test set ECGs.

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

The term "physician overread confirmed diagnosis" suggests that a physician reviewed the ECGs and assigned diagnoses. However, the exact adjudication method (e.g., single physician, consensus of multiple physicians, tie-breaking by a senior expert) is not specified.

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 MRMC comparative effectiveness study involving human readers with and without AI assistance was reported. The testing focused on the bench performance of the synthesized leads and their similarity to standard leads, rather than a human-in-the-loop diagnostic accuracy study. The device's automated ECG analysis (Corvair) is explicitly stated to be "provisional and should not be used for clinical action if it has not been reviewed by a qualified physician." This implies a human-in-the-loop is always required for clinical action, but no study comparing human performance with/without AI assistance was described.

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

Yes, a standalone performance evaluation of the algorithm for lead synthesis was performed. The "Bench performance testing" section specifically describes the evaluation of "the 4 synthesized chest leads generated by Impala from the 4 recorded leads in comparison with the corresponding chest leads of a standard 10-electrode resting 12-lead ECG." This is an algorithm-only evaluation of the lead synthesis component.

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

The ground truth for evaluating the synthesized leads was the corresponding chest leads of a standard 10-electrode resting 12-lead ECG. For the underlying diagnoses of the ECGs in the proprietary dataset, the ground truth was "physician overread confirmed diagnosis with multiple diagnostic codes."

8. The sample size for the training set:

The machine learning model for lead synthesis was trained on a dataset of approximately 110,000 12-Lead ECGs.

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

The training dataset of 110,000 ECGs was "acquired from clinical patients at the Mayo Clinic over several decades between 1985 and 2010. Each ECG has a physician overread confirmed diagnosis with multiple diagnostic codes." This indicates that the ground truth for the training set's clinical characteristics was established by physician overread and confirmed diagnoses. For the lead synthesis part of the training, the direct 12-lead ECG itself would serve as the ground truth against which the synthesized leads were learned.

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