FlowMet-R Blood Flow Measurement for the Diagnosis of Peripheral Artery Disease and Critical Limb Ischemia

FlowMet-R Blood Flow Measurement for the Diagnosis of Peripheral Artery Disease (PAD) and Critical Limb Ischemia (CLI)

Non-randomized, multi-center, longitudinal study of healthy subjects and subjects with PAD who are scheduled for ABI, TBI, and either Duplex Ultrasound or Angiographic assessments in a vascular clinic.

Study Overview

• Status: Terminated
• Conditions: Peripheral Artery Disease
• Intervention / Treatment: Diagnostic test: FlowMet-R; Diagnostic test: ABI; Diagnostic test: TBI

Detailed Description

Patients scheduled for peripheral vascular examination and healthy controls will be measured with the FlowMet-R, a noninvasive blood flow monitor, and compared to gold standard diagnostics - ABI, TBI, and Doppler Ultrasound. Sensitivity and specificity of the FlowMet-R device output in diagnosing PAD and CLI will be assessed on initial visit, 3-month followup, and 6-month followup.

• Study Type: Observational
• Enrollment (Actual): 195

Contacts and Locations

Study Locations

• United States
  • Iowa
    • Des Moines, Iowa, United States, 50266
      • The Iowa Clinic
  • Missouri
    • Chesterfield, Missouri, United States, 63017
      • Mercy Research
  • New York
    • New York, New York, United States, 10029
      • The Mt. Sinai Hospital
  • Ohio
    • Columbus, Ohio, United States, 43214
      • Ohio Health
  • Texas
    • Austin, Texas, United States, 78705
      • Ascension Seton

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 40 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

• Sampling Method: Probability Sample

Study Population

The PAD cohort population is persons who have known or suspected peripheral artery disease, and are being seen at a vascular clinic for evaluation.

The Healthy cohort population is adult persons over 40 without history of PAD and who are not currently suspected of suffering from PAD.

Description

Inclusion Criteria:

PAD Positive Cohort

• Subject meets PAD positive criteria
• Subject is willing and able to provide informed consent
• Subject is willing and able to comply with study procedures
• Subject is able to understand the study procedures
• Subject is scheduled for vascular examination that includes noninvasive assessments as standard of care: ABI, TBI, and either a Duplex Ultrasound or Angiogram

Healthy Cohort

• Subject is willing and able to provide informed consent.
• Subject is willing and able to comply with the study procedures.
• Subject is able to understand the study procedures.
• Subject has no history of positive PAD diagnosis, and is not currently suspected of having PAD.

Exclusion Criteria:

PAD Positive Cohort

• Subject is under 40 or unable to consent.
• Subject has any medical condition, which, in the judgment of the Investigator and/or designee, makes the subject a poor candidate for the investigational study.
• Subject is excluded from analysis if no stenosis is found during Doppler but Tibial disease is suspected and Tibial ultrasound is not able to be performed.
• Subject does not have a suitable finger to attach the FlowMet-R probe.
• Subject does not have a suitable 1st or 2nd digit to attach FlowMet-R probe on the limb of interest.
• Subject has undergone revascularization within the last 90 days
• Subject cannot lay safely in a supine position.

Healthy Cohort

• Subject is under 40 or unable to consent.
• Subject has any medical condition, which, in the judgment of the Investigator and/or designee, makes the subject a poor candidate for the investigational study.
• One or more limbs has a prior or current diagnosis of PAD, or is reasonably suspected of having a diagnosis of PAD.
• Subject does not have a suitable finger to attach the FlowMet-R probe.
• Subject does not have a suitable 1st or 2nd digit to attach FlowMet-R probe.
• Subject has undergone revascularization within the last 90 days

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Healthy; Healthy cohort is an age-matched population (over 40 years old) without history of PAD or suspected PAD. Healthy cohort will receive FlowMet-R measurement, Ankle Brachial Index (ABI), and Toe Brachial Index (TBI) measurements.	Diagnostic test: FlowMet-R; FlowMet-R is a noninvasive blood flow measurement.; Diagnostic test: ABI; Ankle Brachial Index is a ratio-metric blood pressure measurement in the ankle and arm.; Diagnostic test: TBI; Ankle Brachial Index is a ratio-metric blood pressure measurement in the toe and arm.
Peripheral Artery Disease; PAD cohort is all-comers to the vascular lab that are scheduled to undergo assessment for Peripheral Artery Disease (PAD) or have a planned endovascular or surgical intervention to address PAD and will receive FlowMet-R measurement in addition to their routine standard of care.	Diagnostic test: FlowMet-R; FlowMet-R is a noninvasive blood flow measurement.; Diagnostic test: ABI; Ankle Brachial Index is a ratio-metric blood pressure measurement in the ankle and arm.; Diagnostic test: TBI; Ankle Brachial Index is a ratio-metric blood pressure measurement in the toe and arm.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sensitivity and Specificity of FlowMet-R for Diagnosis of PAD and CLI	Primary objective is to determine the efficacy of FlowMet-R measurements in diagnosing PAD & CLI. All patients were combined from healthy & PAD groups to form one cohort, ABI and TBI were then used to assign patients in PAD (1), PAD (2) & CLI. FlowMet-R data (comprised of blood flow measurements and/or feature analysis of the blood flow waveform) were used to create a predictive model of PAD severity. This model was used to generate diagnostic receiver operating characteristic (ROC) curves for PAD and, independently, CLI, at three time points. ROC curves were used to compute the peak sensitivity, peak specificity, and area under the curve (AUC) at the initial, 3-month and 6-month time points. Sensitivity, specificity and AUC are unitless. Sensitivity is the percentage of true positives & specificity is the percentage of true negatives at the location on the ROC curve where it was closest to the upper left of the unit square from an ROC curve (peak).	Initial, three month, and six month time points.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sensitivity and Specificity of FlowMet-R for Prognosis of Requiring a Peripheral Vascular Intervention	ROC curves for predicting if a patient will undergo intervention following their initial visit were generated using FlowMet-R measurement data. ROC curves were used to compute the peak sensitivity, peak specificity, and area under the curve (AUC) within the 3-month and 6-month time points, separately. Sensitivity, specificity and AUC are unitless. Sensitivity is the percentage of true positives & specificity is the percentage of true negatives at the location on the ROC curve where it was closest to the upper left of the unit square from an ROC curve (peak).	Within three and six months following initial visit
Sensitivity, Specificity and Area Under the Curve (AUC) of FlowMet-R in Diagnosing Significant Stenosis	ROC curves for predicting a patient has significant stenosis, defined by greater than 50%, in at least one peripheral artery will be generated using FlowMet-R measurement data. ROC curves will be used to compute the peak sensitivity, peak specificity, and area under the curve (AUC) at the initial visit. Sensitivity, specificity and AUC are unitless. Sensitivity is the percentage of true positives & specificity is the percentage of true negatives at the location on the ROC curve where it was closest to the upper left of the unit square from an ROC curve (peak).	Initial visit
Stenosis Percentage	A correlation test will be performed between FlowMet-R and stenosis percentage. The correlations between the acceleration time from the FlowMet-R device and peripheral artery stenosis will be computed using a Pearson correlation. Correlation will be computed using available FlowMet-R data from PAD participants with significant stenosis, defined by greater than 50%, in at least one peripheral artery at the initial visit.	Initial visit
Changes in Ankle Brachial Index (ABI)	The outcome ABI is a ratio of blood pressures in the arm and ankle. Values less than 1 generally indicate narrower arteries. The outcome used the change in ABI for: 0 to 3 months, 0 to 6 months, and 3 to 6 months. The correlation with this outcome was estimated using the corresponding change in acceleration time from the FlowMet-R device.	Within three and six months following initial visit.
Changes in Toe Brachial Index (TBI)	The outcome TBI is a ratio of blood pressures in the arm and toe. Values less than 1 generally indicate narrower arteries. The outcome used the change in TBI for: 0 to 3 months, 0 to 6 months, and 3 to 6 months. The correlation with this outcome was estimated using the corresponding change in acceleration time from the FlowMet-R device.	Within three and six months following initial visit.
Changes in Rutherford Classification	Rutherford Classification is an ordinal scale that ranges from 0 to 6 and is used to measure peripheral arterial disease severity and chronic limb threatening ischemia. Higher values indicate more severe disease. The changes for Rutherford Classification were computed for: 0 to 3 months, 0 to 6 months, and 3 to 6 months. The correlation with this outcome was estimated using the corresponding change in acceleration time from the FlowMet-R device.	Within three and six months following initial visit.

Collaborators and Investigators

• Sponsor: Medtronic Endovascular
• Collaborators: ICON plc

Study record dates

Study Major Dates

• Study Start (Actual): December 9, 2019
• Primary Completion (Actual): November 21, 2022
• Study Completion (Actual): November 21, 2022

Study Registration Dates

• First Submitted: October 7, 2019
• First Submitted That Met QC Criteria: October 7, 2019
• First Posted (Actual): October 9, 2019

Study Record Updates

• Last Update Posted (Actual): April 11, 2025
• Last Update Submitted That Met QC Criteria: March 25, 2025
• Last Verified: March 1, 2024

More Information

Terms related to this study

• Keywords: Claudication; Peripheral Artery Disease; Critical Limb Ischemia
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Pathologic Processes; Chronic Disease; Disease Attributes; Atherosclerosis; Arteriosclerosis; Arterial Occlusive Diseases; Peripheral Vascular Diseases; Chronic Limb-Threatening Ischemia; Ischemia; Peripheral Arterial Disease
• Other Study ID Numbers: 30081919

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No