An observational study in Peripheral Artery Disease, sponsored by Medtronic Endovascular. Terminated at 5 sites in United States. Open to participants aged 40 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-04-11.
Sponsored by Medtronic Endovascular · Observational
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.
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.
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.
PAD Positive Cohort
Healthy Cohort
Exclusion Criteria:
PAD Positive Cohort
Healthy Cohort
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 · Diagnostic Test: ABI · Diagnostic Test: TBI
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 · Diagnostic Test: ABI · Diagnostic Test: TBI
FlowMet-R is a noninvasive blood flow measurement.
Ankle Brachial Index is a ratio-metric blood pressure measurement in the ankle and arm.
Ankle Brachial Index is a ratio-metric blood pressure measurement in the toe and arm.
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).
Time frame: Initial, three month, and six month time points.
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).
Time frame: 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).
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Within three and six months following initial visit.
| Milestone | Healthy | Peripheral Artery Disease |
|---|---|---|
| Started | 52 | 143 |
| Completed | 52 | 83 |
| Not completed | 0 | 60 |
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).
| probability | Peripheral Artery Disease (1) vs Not PAD | Peripheral Artery Disease (2) vs Not PAD | Critical Limb Ischemia (CLI) vs Not CLI |
|---|---|---|---|
| Sensitivity (Initial) | 0.80 (0.73 to 0.87) | 0.78 (0.71 to 0.85) | 0.82 (0.66 to 0.98) |
| Specificity (Initial) | 0.78 (0.70 to 0.87) | 0.86 (0.78 to 0.94) | 0.78 (0.72 to 0.84) |
| Area Under the Curve (Initial) | 0.84 (0.78 to 0.89) | 0.87 (0.82 to 0.92) | 0.86 (0.80 to 0.93) |
| Sensitivity (3 months) | 0.52 (0.38 to 0.67) | 0.57 (0.44 to 0.71) | 1.00 (1.00 to 1.00) |
| Specificity (3 months) | 0.63 (0.46 to 0.81) | 0.77 (0.60 to 0.95) | 0.91 (0.84 to 0.97) |
| Area Under the Curve (3 months) | 0.58 (0.45 to 0.71) | 0.67 (0.54 to 0.80) | 0.95 (0.86 to 1.00) |
| Sensitivity (6 months) | 0.74 (0.62 to 0.86) | 0.73 (0.62 to 0.84) | 1.00 (1.00 to 1.00) |
| Specificity (6 months) | 0.58 (0.41 to 0.74) | 0.67 (0.48 to 0.86) | 0.59 (0.48 to 0.69) |
| Area Under the Curve (6 months) | 0.62 (0.49 to 0.74) | 0.67 (0.54 to 0.79) | 0.79 (0.39 to 1.00) |
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).
| probability | Vascular Intervention Within 3 Months | Vascular Intervention Within 6 Months |
|---|---|---|
| Sensitivity | 0.60 (0.30 to 0.90) | 0.59 (0.35 to 0.82) |
| Specificity | 0.49 (0.37 to 0.60) | 0.56 (0.45 to 0.67) |
| Area Under the Curve (AUC) | 0.52 (0.32 to 0.71) | 0.54 (0.39 to 0.69) |
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).
| probability | PAD Participants With Significant Stenosis |
|---|---|
| Sensitivity | 0.61 (0.51 to 0.72) |
| Specificity | 0.61 (0.48 to 0.75) |
| Area Under the Curve (AUC) | 0.63 (0.53 to 0.73) |
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.
| percentage of stenosis | PAD Participants With Significant Stenosis |
|---|---|
| Stenosis Percentage | 67.9 ± 32.5 |
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.
| mmHg / mmHg | 0 to 3 Months | 0 to 6 Months | 3 to 6 Months |
|---|---|---|---|
| Changes in Ankle Brachial Index (ABI) | 0.09 ± 0.23 | 0.08 ± 0.31 | 0.03 ± 0.22 |
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.
| mmHg / mmHg | 0 to 3 Months | 0 to 6 Months | 3 to 6 Months |
|---|---|---|---|
| Changes in Toe Brachial Index (TBI) | 0.08 ± 0.24 | 0.10 ± 0.25 | 0.02 ± 0.18 |
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.
| units on a scale | 0 to 3 Months | 0 to 6 Months | 3 to 6 Months |
|---|---|---|---|
| Changes in Rutherford Classification | -0.39 ± 1.4 | -0.62 ± 1.5 | -0.26 ± 1.2 |
Collected over Adverse events were collected from the baseline assessment visit throughout 6-month follow-up.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Healthy | 0/52 (0%) | 0/52 (0%) | 0/52 (0%) |
| Peripheral Artery Disease | 4/143 (2.8%) | 6/143 (4.2%) | 2/143 (1.4%) |
| Event | Healthy | Peripheral Artery Disease |
|---|---|---|
| AmputationSurgical and medical procedures | 0/52 | 3/143 |
| Femoral Artery BypassSurgical and medical procedures | 0/52 | 1/143 |
| Femorofemoral BypassSurgical and medical procedures | 0/52 | 1/143 |
| Non-Healing Left Leg UlcerSkin and subcutaneous tissue disorders | 0/52 | 1/143 |
| Cerebrovascular AccidentNervous system disorders | 0/52 | 1/143 |
| Event | Healthy | Peripheral Artery Disease |
|---|---|---|
| Pain during FlowMet-R AssessmentInjury, poisoning and procedural complications | 0/52 | 1/143 |
| HematomaVascular disorders | 0/52 | 1/143 |
Site-reported demographic and medical history data are presented based on the assigned cohort using the definitions for Healthy and PAD (2) in the Groups and Interventions Section. Baseline information was not collected for one participant; therefore, a total of 194 participants were included in baseline analysis.
| Age, Continuous(years) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| Mean | 60.0 ± 13.0 | 70.4 ± 9.6 | 67.0 ± 11.8 |
| Sex: Female, Male(Participants) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| Female | 35 | 56 | 91 |
| Male | 28 | 75 | 103 |
| Ethnicity (NIH/OMB)(Participants) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| Hispanic or Latino | 4 | 32 | 36 |
| Not Hispanic or Latino | 59 | 99 | 158 |
| Unknown or Not Reported | 0 | 0 | 0 |
| Race (NIH/OMB)(Participants) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| American Indian or Alaska Native | 0 | 0 | 0 |
| Asian | 1 | 1 | 2 |
| Native Hawaiian or Other Pacific Islander | 0 | 0 | 0 |
| Black or African American | 5 | 21 | 26 |
| White | 55 | 78 | 133 |
| More than one race | NA | NA | NA |
| Unknown or Not Reported | 2 | 31 | 33 |
| Region of Enrollment(participants) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| United States | 63 | 131 | 194 |
| Weight(pounds) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| Mean | 183.4 ± 44.8 | 178.4 ± 42.6 | 180.5 ± 43.1 |
| Height(inches) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| Mean | 66.1 ± 4.1 | 66.5 ± 4.3 | 66.4 ± 4.2 |
| Body Mass Index(lbs/(in^2)*703) | Healthy | Peripheral Artery Disease (Including Critical Limb Ischemia) | Total |
|---|---|---|---|
| Mean | 28.7 ± 7.3 | 28.2 ± 5.7 | 28.4 ± 6.3 |
3 further baseline measures are reported on the registry.
Documents are hosted by the registry — open the source record to download them.
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