Response to the Letter to the Editor entitled “Carotid artery atherosclerosis,low and high volumes of high-intensity interval training in patients after myocardial infarction: the precision of measurement embarks on a precise measurement protocol”

Dear Editor,

In response to the Letter to the Editor entitled “Carotid artery atherosclerosis, low and high volumes of high-intensity interval training in patients after myocardial infarction: the precision of measurement embarks on a precise measurement protocol.” We appreciate Dr. Saleh’s interest in our study “Vascular-endothelial adaptations following low and high volumes of high-intensity interval training in patients after myocardial infarction.” We welcome the opportunity to address the concerns raised regarding carotid intima-media thickness (cIMT) measurements and clarify our methodology.

We concur with Dr. Saleh’s emphasis on the importance of precise measurement protocols in cIMT assessment. While our article may not have adequately conveyed all aspects of our methodology, we assure that our cIMT determinations were conducted by personnel with extensive training in the technique, adhering rigorously to international guidelines prevalent at the time of the study.^1,2

Regarding the specific measurement site, we prioritized the first 1 cm segment distal to the carotid bifurcation. In cases where atheromatous plaques were present in this segment, measurements were necessarily extended up to 2 cm. Crucially, regardless of the initial measurement location for each patient, subsequent post-intervention measurements were performed at the same marked site, ensuring consistency across time points. ³

We acknowledge Dr. Saleh’s valid point concerning electrocardiogram-gated cIMT measurements. While we did not employ this technique, we recognize its potential to enhance measurement precision, as evidenced by the literature cited. ⁴ We appreciate this suggestion and agree it could have been included in our study limitations. To mitigate measurement bias, we implemented several strategies. Multiple measurements were taken at each assessment time point (minimum of 3 per carotid artery, totaling 6 per patient). The mean of these measurements was used for analysis. Automated software was utilized for measurements, which, while uncommon in clinical practice, is indispensable in a research setting like ours. The same experienced sonographer performed all measurements, further reducing inter-observer variability.

We emphasize that cIMT was a secondary variable in our study. The statistically significant sub-millimetric changes observed in cIMT in the HIIT intervention groups are interpreted cautiously, acknowledging their limited clinical relevance. The primary value of our findings, as elucidated in our discussion and conclusion, lies not in the effect of HIIT on atherosclerosis as measured by cIMT but rather in the changes in endothelial function and oxidative stress, proposing HIIT as a strategy with anti-atherogenic potential. We agree that further research examining the effect of HIIT on cIMT in high cardiovascular-risk patients is warranted to understand vascular-endothelial function changes better. Such studies should incorporate current methodological recommendations for both techniques and clinical trial design.