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Reproducibility of peripheral arterial tonometry measurements in male cardiovascular patients
Markus Nil1, Daniela Schäfer, Thomas Radtke
1Preventive Cardiology & Sports Medicine, University Clinic for Cardiology, Inselspital, University Hospital, Bern, Switzerland; Exercise Physiology, Institute for Human Movement Sciences, ETH Zurich, Zurich, Switzerland.
Insights
Reproducibility of peripheral arterial tonometry (EndoPAT) in coronary artery disease (CAD) patients is limited. The reactive hyperemic index (RHI) showed moderate variability, insufficient for individual patient monitoring, and poor reliability for detecting treatment effects.
Area of Science:
- Cardiovascular Medicine
- Vascular Biology
- Medical Device Technology
Background:
- Peripheral arterial tonometry (EndoPAT) is increasingly used to assess microvascular endothelial function in patients with cardiovascular risk factors.
- Limited data exists on the reproducibility of EndoPAT parameters specifically in patients with coronary artery disease (CAD).
Purpose of the Study:
- To quantify the reproducibility of key EndoPAT parameters in a cohort of male patients with stable coronary artery disease (CAD).
- To assess the clinical utility of EndoPAT for monitoring individual patient changes and detecting treatment effects in this population.
Main Methods:
- Repeated EndoPAT measurements were conducted in 78 male patients with stable CAD.
- Key parameters analyzed included reactive hyperemic index (RHI) and various PAT ratios (PAT ratio90-150 s, PAT ratio90-120 s, PAT ratiopeak response).
- Statistical analyses included calculation of mean, standard deviation (SD), coefficient of variation (CV), intraclass correlation coefficient (ICC), and least significant change (LSC).
Main Results:
- The mean RHI was 1.84 (SD 0.36).
- Coefficients of variation (CV) for RHI, PAT ratio90-150 s, PAT ratio90-120 s, and PAT ratiopeak response were 17.0%, 25.4%, 26.1%, and 25.0%, respectively.
- Intraclass correlation coefficients (ICCs) ranged from 0.45 to 0.51, indicating moderate to poor reliability. The least significant change for RHI was 47.2%.
Conclusions:
- While the CV for RHI was moderate, the precision is insufficient for monitoring individual patient changes, requiring >47% variation to be significant.
- Poor ICCs highlight the challenges in detecting treatment effects within homogenous populations like stable CAD patients using EndoPAT.
- Further research may be needed to refine EndoPAT protocols or explore alternative methods for assessing endothelial function in CAD.
Background:
Assessment of endothelial function of the microvasculature by peripheral arterial tonometry (EndoPAT(®)) has gained increasing popularity in patients with cardiovascular risk factors. Only limited knowledge about its reproducibility in patients with coronary artery disease (CAD) is available. We therefore aimed to quantify reproducibility of EndoPAT(®) parameters in patients with stable CAD.
Design:
EndoPAT(®) measurements were performed repeatedly in 78 male patients (age 66 ± 8 years) with CAD on stable medication. We calculated overall mean, standard deviation (SD), coefficient of variation (CV) and intraclass correlation coefficient (ICC) of the following parameters: reactive hyperemic index (RHI), PAT ratio of the postocclusion period 90-150 s as used for calculation of the RHI (PAT ratio90-150 s) and 90-120 s (PAT ratio90-120 s) as used for the often employed Framingham RHI (F-RHI), as well as PAT ratio of the peak hyperemic response (PAT ratiopeak response). Additionally, least significant changes (LSC) for individual subjects and minimum sample sizes for parallel and cross-over design studies were calculated.
Results:
Mean RHI was 1·84 (SD 0·36). For RHI, PAT ratio90-150 s , PAT ratio90-120 s , and PAT ratiopeak response the CVs were 17·0%, 25·4%, 26·1%, and 25·0%, respectively. The ICCs were 0·45, 0·49, 0·48 and 0·51, respectively, and LSC for RHI was 47·2%.
Conclusions:
CV of RHI in our population was moderate; however, we consider this precision insufficient to monitor changes in individual patients, as they would need to exceed 47% to show a significant change. Further, the poor ICCs reflect the difficulty of detecting treatment effects in homogenous populations, such as patients with stable CAD.
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Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.
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Prepare for the Procedure: