I-STAT CARDIAC TROPONIN (CTNI) TEST

K031739 · I-Stat Corporation · MMI · Sep 2, 2003 · Clinical Chemistry

Device Facts

• Record ID: K031739
• Device Name: I-STAT CARDIAC TROPONIN (CTNI) TEST
• Applicant: I-Stat Corporation
• Product Code: MMI · Clinical Chemistry
• Decision Date: Sep 2, 2003
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1215
• Device Class: Class 2

Intended Use

The i-STAT® cTnI Test is an in vitro diagnostic test for the quantitative measurement of cardiac troponin I in heparinized whole blood or plasma samples. Cardiac troponin I measurements can be used as an aid in the diagnosis and treatment of myocardial infarction and in the risk stratification of patients with acute coronary syndromes with respect to their relative risk of mortality. The cartridge is to be used with the i-STAT 1 Analyzer, but not the i-STAT Portable Clinical Analyzer or the Philips Medical Systems (formerly Agilent Technologies) Blood Analysis Module (BAM). As part of the i-STAT System, the cTnI test is to be used by trained health care professionals in accordance with a facility’s policies and procedures.

Device Story

i-STAT cTnI is a single-use cartridge-based diagnostic test for point-of-care use. User applies ~16 microliters of fresh whole blood to cartridge; inserts into thermally controlled i-STAT 1 Analyzer. Device performs automated two-site ELISA: sample incubated with enzyme-linked antibody conjugate; analyte captured by monoclonal anti-cTnI antibody; sandwich complex treated with substrate; alkaline phosphatase cleavage produces amperometric signal. Analyzer measures signal; displays/stores results; transmits via infrared to printer or database. Used by trained healthcare professionals in clinical settings. Provides rapid quantitative cTnI levels to assist clinicians in diagnosing myocardial infarction and assessing mortality risk in acute coronary syndrome patients.

Clinical Evidence

Clinical performance was evaluated at three external sites comparing i-STAT cTnl (whole blood/plasma) to the Stratus CS (plasma) in patients with acute, severe, and prolonged chest pain (N=189). Deming regression analysis showed a correlation coefficient of 0.975 for i-STAT whole blood vs. Stratus CS plasma. Bench testing confirmed the lower limit of detection (0.02 ng/mL), insensitivity to hematocrit (0-65% PCV), and consistent detection of various cTnl isoforms (83-122% relative response). Imprecision studies (Level 1-3 controls) showed CVs ranging from 7.6% to 8.5%.

Technological Characteristics

Two-site ELISA; electrochemical detection. Cartridge contains plastic conduits, sensor chips, heating elements. Analyte captured by monoclonal anti-cTnI antibody; detection via alkaline phosphatase-labeled polyclonal antibody. Amperometric signal measurement. Connectivity: infrared data transfer. Conforms to EN61326 EMC. Requires i-STAT 1 Analyzer.

Indications for Use

Indicated for quantitative measurement of cardiac troponin I in heparinized whole blood or plasma to aid in diagnosis and treatment of myocardial infarction and risk stratification of patients with acute coronary syndromes.

Regulatory Classification

Identification

A creatine phosphokinase/creatine kinase or isoenzymes test system is a device intended to measure the activity of the enzyme creatine phosphokinase or its isoenzymes (a group of enzymes with similar biological activity) in plasma and serum. Measurements of creatine phosphokinase and its isoenzymes are used in the diagnosis and treatment of myocardial infarction and muscle diseases such as progressive, Duchenne-type muscular dystrophy.

Predicate Devices

• Dade Behring Stratus® CS Cardiac Troponin I TestPak (K981098)

Submission Summary (Full Text)

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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
DEVICE AND INSTRUMENT TEMPLATE

A. 510(k) Number:
K031739

B. Analyte:
Troponin I

C. Type of Test:
Electrochemical two site ELISA

D. Applicant:
i-STAT Corporation

E. Proprietary and Established Names:
i-STAT® cTnI Test

F. Regulatory Information:

1. Regulation section:
21 CFR §862.1215

2. Classification:
Class II

3. Product Code:
MMI

4. Panel:
Chemistry (75)

G. Intended Use:

1. Intended use(s):
The i-STAT® cTnI Test is an in vitro diagnostic test for the quantitative measurement of cardiac troponin I in heparinized whole blood or plasma samples. Cardiac troponin I measurements can be used as an aid in the diagnosis and treatment of myocardial infarction and in the risk stratification of patients with acute coronary syndromes with respect to their relative risk of mortality.
The cartridge is to be used with the i-STAT 1 Analyzer, but not the i-STAT Portable Clinical Analyzer or the Philips Medical Systems (formerly Agilent Technologies) Blood Analysis Module (BAM). As part of the i-STAT

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System, the cTnI test is to be used by trained health care professionals in accordance with a facility’s policies and procedures.

2. **Indication(s) for use:**
The i-STAT Cardiac Troponin I (cTnI) test is an in vitro diagnostic test for the quantitative measurement of cardiac troponin I in heparinized whole blood or plasma. Measurements of cardiac Troponin I are used in the diagnosis and treatment of myocardial infarction and as an aid in the risk stratification of patients with acute coronary syndromes with respect to their relative risk of mortality.

3. **Special condition for use statement(s):**
4. **Special instrument Requirements:**
i-STAT 1 Analyzer

## H. Device Description

The i-STAT cTnI is contained in a single cartridge. In use, the user scans a barcode and then places approximately 16 microliters of fresh whole blood in the cartridge. The cartridge is inserted into the thermally controlled i-STAT 1 Analyzer, and all analytical steps are performed automatically. Patient and user information may be entered into the analyzer via a keypad during the automated analysis cycle. The cTnI test cartridge is assembled from plastic components that provide the conduits for fluid handling and house the sensor chips and heating elements necessary for temperature control and signal measurement.

Upon insertion of the cartridge into the analyzer, it performs several quality checks. The sample and enzyme-linked antibody conjugate are incubated for a predetermined period of time under temperature control. The sample is discarded and the substrate/wash solution is brought over the alkaline phosphatase captured on the cTnI sensor. The enzyme cleaves the substrate giving rise to an amperometric signal which the analyzer measures. The result is displayed and stored in memory for possible transfer via infra red to a printer or to electronic databases.

## I. Substantial Equivalence Information:

1. **Predicate device name(s):**
Dade Behring Stratus® CS Cardiac Troponin I TestPak

2. **Predicate K number(s):**
K981098

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3. Comparison with predicate:

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Assay Methodology | Two Site ELISA | Two Site ELISA |
| Capture antibodies | Monoclonal | Monoclonal |
| Enzyme label | Alkaline Phosphatase | Alkaline Phosphatase |
| Differences | | |
| Item | Device | Predicate |
| Enzyme detection | Electrochemical | Fluorescent |
| Sample type | Whole blood or Plasma | Plasma |
| Enzyme label antibody | Polyclonal | Monoclonal |

J. Standard/Guidance Document Referenced (if applicable):
FDA’s Guidance for the Content of Premarket Submissions for Software Contained in Medical Devices.
NCCLS guideline EP9-A2: Method Comparison and Bias Estimation Using Patient Samples.
Conforms to EN61326 EMC.

K. Test Principle:
Two Site Elisa. The analyte, cardiac Troponin I is captured by a probe impregnated with a monoclonal anti-cTnI antibody. The sample is discarded. The probe is treated with a second reagent composed of anti-cTnI polyclonal antibodies which are tagged with Alkaline Phosphatase. After washing, the sandwich complex is treated with a substrate which upon being cleaved by the captured alkaline phosphatase produces and electronic signal which is read by the i-STAT analyzer.

L. Performance Characteristics (if/when applicable):

1. Analytical performance:
a. Precision/Reproducibility:
Three levels of plasma controls were tested as duplicates 20 times over a period of 37 days in four different locations (in-house and three clinical sites) using three different lots of i-STAT cTnI cartridges with 25 different i-STAT analyzers.

| Site | Control Level | Mean | Within-Lot %CV | Lot-to-Lot %CV | Vial-to-Vial %CV | Total %CV |
| --- | --- | --- | --- | --- | --- | --- |
| i-STAT | 1 | 0.58 | 5.2 | 2.3 | 3.1 | 6.1 |
| | 2 | 2.36 | 4.2 | 2.4 | 4.0 | 5.9 |
| | 3 | 33.65 | 5.0 | 3.3 | 2.6 | 6.1 |
| Site 1 | 1 | 0.49 | 6.3 | 2.9 | 7.0 | 9.4 |
| | 2 | 2.01 | 5.3 | 4.1 | 9.7 | 11.4 |
| | 3 | 31.52 | 6.5 | 2.9 | 5.3 | 8.4 |

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| Site | Control Level | Mean | Within-Lot %CV | Lot-to-Lot %CV | Vial-to-Vial %CV | Total %CV |
| --- | --- | --- | --- | --- | --- | --- |
| Site 2 | 1 | 0.54 | 4.7 | 4.0 | 6.2 | 8.2 |
| | 2 | 2.23 | 5.3 | 3.0 | 6.2 | 8.3 |
| | 3 | 32.90 | 5.4 | 3.1 | 5.5 | 7.9 |
| Site 3 | 1 | 0.50 | 5.3 | 5.7 | 2.4 | 7.3 |
| | 2 | 2.04 | 5.0 | 6.6 | 4.2 | 8.3 |
| | 3 | 29.20 | 6.4 | 2.9 | 4.5 | 7.8 |

b. Linearity/assay reportable range:
Whole blood and plasma samples from three donors were tested. For whole blood the original cTnI negative samples were spiked and assayed in duplicate in three separate i-STAT cTnI cartridges. The samples were diluted in equal masses with the original negative samples and assayed under the same conditions. For plasma the three samples were tested as original samples and combined in equal masses.

Recovery Study Whole Blood

| Whole Blood Sample | Concentration | Diluted Concentration | % Recovery |
| --- | --- | --- | --- |
| A | 2.05 | 1.04 | 101 |
| B | 6.31 | 3.14 | 100 |
| C | 27.04 | 14.05 | 104 |

Recovery Study Plasma

| Plasma Sample | Concentration | Diluted Concentration | % Recovery |
| --- | --- | --- | --- |
| A | 2.41 | - | - |
| B | 7.50 | - | - |
| C | 29.35 | - | - |
| A+B | - | 4.69 | 95 |
| B+C | - | 18.90 | 103 |
| A+C | - | 16.89 | 106 |

Performance characteristics of i-STAT cTnI have been established in the range from 0.02 to $35.00\mathrm{ng / mL}$.

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c. Traceability (controls, calibrators, or method):
Not applicable

d. Detection limit:
Analytical sensitivity was determined to be 0.02 ng/mL based on two standard deviations from a sample with zero concentration.

The 20% and 10% functional sensitivities were estimated from whole blood samples measurements to be 0.07 and 0.1 ng/mL, respectively.

e. Analytical specificity:
Related muscle proteins were tested for cross reactivity at concentrations of 1000 ng/mL.

| Cross reactants | % Crossreactivity |
| --- | --- |
| Troponin C (cardiac) | <0.002 |
| Troponin T (cardiac) | 0.65 |
| Troponin I (skeletal) | <0.002 |
| Troponin T (skeletal) | <0.002 |

Interference testing was performed with the substances listed below and found to have less than a 10% change at the concentrations listed below, when added to a plasma pool containing approximately 2 ng/mL of cTnI.

| Generic Name | Test Level uMol/L | Average cTnI ng/mL | % change |
| --- | --- | --- | --- |
| Control | NA | 1.75 | NA |
| Acetaminophen | 1660 | 1.76 | 0.6 |
| Acetylsalicylic Acid | 3330 | 1.78 | 1.7 |
| Allopurinol | 294 | 1.84 | 5.1 |
| Ampicillin | 349 | 1.78 | 1.7 |
| Ascorbic Acid | 227 | 1.78 | 1.7 |
| Atenolol | 37.6 | 1.8 | 2.9 |
| Caffeine | 308 | 1.83 | 4.6 |
| Captopril | 23 | 1.83 | 4.6 |
| Chloramphenicol | 155 | 1.79 | 2.3 |
| Diclofenac | 169 | 1.75 | 0 |
| Digoxin | 6.15 | 1.81 | 3.4 |
| Dopamine | 5.87 | 1.67 | -4.6 |
| Enalaprilat | 0.86 | 1.81 | 3.4 |

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| Generic Name | Test Level uMol/L | Average cTnI ng/mL | % change |
| --- | --- | --- | --- |
| Erythromycin | 81.6 | 1.74 | -0.6 |
| Furosemide | 181 | 1.82 | 4.0 |
| Sodium Heparin | 36 U/mL | 1.58 | -9.7 |
| Sodium Heparin | 90 U/mL | 1.41 | -19.4 |
| Ibuprophen | 2425 | 1.79 | 2.3 |
| Isorbide Dinitrate | 636 | 1.72 | -1.7 |
| Methyldopa | 71 | 1.85 | 5.7 |
| Nicotine | 6.2 | 1.76 | 0.6 |
| Nifedipine | 1.156 | 1.79 | 2.3 |
| Phenytoin | 198 | 1.76 | 0.6 |
| Propranolol | 7.71 | 1.82 | 4.0 |
| Salicylic Acid | 4340 | 1.69 | -3.4 |
| Theophylline | 222 | 1.77 | 1.1 |
| Verapamil | 4.4 | 1.82 | 4.0 |
| Warfarin | 64.9 | 1.79 | 2.3 |

f. Assay cut-off:
The reference range was established from 162 whole blood and plasma samples of apparently healthy donors using duplicate measures with three different lots of i-STAT cTnI cartridges. The 0 to 97.5% range results spanned from 0 to 0.03 ng/mL.

2. Comparison studies:
a. Method comparison with predicate device:
Studies were carried out at three clinical sites with patients in any hospital department who presented with acute, severe, and prolonged chest pain. Up to three samples, drawn at different times, could be taken from any one patient. Data from 189 samples were included in the data set. All testing was performed by end-user personnel. Samples were drawn by venipuncture using heparinized evacuated tubes. Operators analyzed whole blood in duplicate using three different i-STAT cTnI cartridges, for a total of 6 whole blood measurements. The tubes were then centrifuged and analyzed by the laboratory in duplicate using the predicate device and again in duplicate for three different i-STAT cTnI cartridges, for a total of 6 plasma measurements. Analysis of the method comparison data was undertaken in accordance with the recommendations set forth in the NCCLS guideline EP9-A2: Method Comparison and Bias Estimation Using Patient Samples. Of 2241 test method data points, 3 were determined to be within-method outliers and excluded from subsequent analysis. Deming regression analyses were performed on the first replicate of each sample, on average duplicate values and on the whole data set against the predicate. Results from a

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representative subset with n=189 and a range from 0 to 46.27 ng/mL gave a slope of 0.883, an intercept of 0.029, and a correlation (r) of 0.975.

b. Matrix comparison:
Deming regression analysis was performed comparing the plasma data set against the whole blood data set. A slope of 1.002, an intercept of -0.01, and a correlation (r) of 0.991 were obtained.

3. Clinical studies:
a. Clinical sensitivity: Not performed
b. Clinical specificity: Not performed
c. Other clinical supportive data (when a and b are not applicable):

4. Clinical cut-off:
Clinical cut-off was not independently established for this device.

5. Expected values/Reference range:
The reference range was established from 162 whole blood and plasma samples of apparently healthy donors using duplicate measures with three different lots of i-STAT cTnI cartridges. The 0 to 97.5% range results spanned 0 to 0.03 ng/mL

M. Instrument Name:
i-STAT 1 Analyzer

N. System Descriptions:
1. Modes of Operation:
The i-STAT 1 Analyzers are portable clinical analyzers designed to be used at the point of patient care. The analyzers employ single-use cartridges containing biosensor chips to perform diagnostic tests on whole blood. Whole blood is introduced into the sample well of the cartridge at the blood entry port. After closure, the cartridge is inserted into the cartridge door of the analyzer. Insertion of the cartridge initiates a precisely controlled and monitored sequence of steps performed by the instrument without user intervention. Results are calculated, displayed and stored in memory to be transmitted at some later time via an infra red link for printing and database storage.

2. Software:
FDA has reviewed applicant's Hazard Analysis and software development processes for this line of product types:
Yes ☐ X or No ☐

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3. **Sample Identification:**
Bar code reader is incorporated into the system.

4. **Specimen Sampling and Handling:**
Whole blood samples are applied directly into the sample well of the cartridge.

5. **Assay Types:**
The i-STAT analyzer is cable of performing assays for sodium, potassium, chloride, ionized calcium, glucose, blood urea nitrogen, pH, carbon dioxide, oxygen, hematocrit, creatinine, lactate, Celite Activated Clotting Time (ACT), and Prothrombin Time (PT).

6. **Reaction Types:**
All assays are performed in self-contained cartridges which output an amperometric signal which is detected and processed by the analyzer.

7. **Calibration:**
All cartridges contain an enclosed aqueous calibrator (with the exception of ACT and PT).

8. **Quality Control:**
A set of controls, the i-STAT Cardiac Markers Control set is available.

O. Other Supportive Instrument Performance Characteristics Data Not Covered In The "L. Performance Characteristics" Section Of the SE Determination Decision Summary.

Not Applicable

P. **Conclusion:**
Based upon the information provided, I recommend that the i-STAT cTnI Test be found substantially equivalent to predicate devices according to 21 CFR §862.1215.