We read with great interest the article by Seko, et al.¹⁾ on serum vascular endothelial growth factor (VEGF) and transforming growth factor (TGF) -β1 levels in patients with atrial fibrillation. However, some aspects of their methodology and discussion seem questionable.
First, because of low serum VEGF levels, they eliminated 7 cases from an initial 20 patients with atrial fibrillation and thus only discussed the remaining 13 cases. It is reasonable to select the population on the basis of a factor which might influence the results. However, it is not reasonable from a validity standpoint to select the population on the basis of the results.
Secondly, they reported that the serum VEGF levels were undetectable in normal control subjects.²⁾ On the contrary, their results indicated that the serum VEGF levels after defibrillation were still higher than those in control subjects, and they did not explain the reason. If the study subjects had other underlying heart diseases, they should have been discussed.
In addition, they stated that VEGF levels in patients with acute myocardial infarction returned rapidly to the normal range after reperfusion therapy.²⁾ If atrial fibrillation was directly involved in VEGF secretion and the half life of VEGF was so short, then the serum VEGF levels might have returned rapidly to the normal range after defibrillation therapy. However, although the second blood sampling was done between 24 hours to 57 days after defibrillation, the serum VEGF levels were still higher than those in normal control subjects. Thus, we are obliged to question whether only atrial fibrillation really influenced the VEGF secretion.