Assessment of flow-mediated dilation (FMD) at maximum dilatory peak (MDP) vs 60 or 90 seconds post-cuff deflation was found to be more accurate and precise in healthy individuals and patients with type 2 diabetes mellitus (T2DM), according to a study published in Angiology.
In this study, 95 healthy persons (mean age, 56.4 + 4.6 years; 53% men) and 72 patients with T2DM (mean age, 56.7 + 6.5 years; 75% men) were enrolled and underwent FMD assessment at MDP, and at 60, and 90 seconds. Of those, 24 healthy participants and 12 patients with T2DM had a repeat FMD at 28 days.
FMD was higher when assessed at MDP vs 60 and 90 seconds in healthy participants (mean differences: MDP vs 60 seconds, 1.14%; 95% CI, 0.6-1.7; P <.0001; MDP vs 90 seconds, 1.9%; 95% CI, 1.3-2.5) and in patients with T2DM (mean differences: MDP vs 60 seconds, 1.0%; 95% CI, 0.1-1.9; MDP vs 90 seconds, 2.3%; 95% CI, 1.3-3.2).
Intraindividual variability was lowest when FMD was assessed at MDP vs 60 and 90 seconds (15.0% vs 23.2% and 40.0%, respectively), which resulted in a more than 2-fold reduction in the necessary sample size for clinical trials.
“This study demonstrates that using the individual MDP compared with measuring FMD at predefined time points leads to significantly higher FMD values in both healthy middle-aged subjects and subjects with T2DM with improved precision and accuracy,” noted the investigators. “Using the traditional approach may thus lead to inaccurate results and potentially misleading conclusions. Furthermore, using individual MDP for determining FMD improves reproducibility (ie, intraindividual variability) lowering the sample size needed in clinical trials to detect a difference in FMD.”
Study limitations include the ethnic homogeneity of the cohort, and the fact that patients with T2DM were taking medications that may have affected FMD.
“Our approach of intense training for sonographers and FMD analysts as well as determining the MDP during analysis is more time labor-intense and more time-consuming than measuring FMD at predefined time points,” noted the study authors. “At a clinic, it would be necessary to designate a suitable person with a high understanding and experience of this methodology to train the respective personnel, making sure the overall conditions to carry the measurements out are met and to implement quality controls.”
Herbrand T, Coester H-V, Sansone R, et al. Improving the assessment of flow-mediated dilation through detection of peak time in healthy subjects and subjects with type 2 diabetes [published online December 30, 2020]. Angiology. doi: 10.1177/0003319720984884