Europace Advance Access originally published online on June 6, 2007
Europace 2007 9(9):854-855; doi:10.1093/europace/eum115
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LETTERS TO THE EDITOR
IMA—the role of oxidative stress: reply
Onassis Cardiac Surgery Center
2nd Department of Cardiology
356 Syngrou Avenue
176 74 Athens
Greece
Tel: +30 210 9493 000 Fax: +30 210 9493 373 E-mail address: esbarouni{at}yahoo.gr/ elbee{at}ath.forthnet.gr
We appreciate Dr Roy's interest in our study ‘The ischaemia modified albumin in radiofrequency catheter ablation’1
and we address their comments as follows.
Ischaemia modified albumin increases immediately following balloon inflation and at 30 min and returns to baseline values in 6–12 h, in coronary angioplasty,2,3 it is therefore unlikely that sampling after the completion of the procedure of the radiofrequency (RF) ablation, during which multiple applications are usually delivered, could have missed any significant IMA rise.
All blood samples were immediately frozen at –70°C and stored until assayed, the official recommendations being that time from blood drawing to freezing should be <1 h and the storage temperature lower than –20°C. In addition, the IMA assay was completed within 30 min of removing the samples from the freezer when this time interval should be <1.5 h. We are, therefore, certain that the handling of our samples has been appropriate.
IMA levels, indeed, change in relation to albumin; they may increase when albumin is low as in end stage renal failure and liver chirrosis and we have excluded such patients by protocol. However, albumin plasma levels are not expected to vary in relation to RF ablation per se, so any changes in IMA in association to this procedure cannot be attributed to albumin variations.
IMA levels, indeed, increase in relation to ischaemia in any vascular territory, other than the coronary circulation; it has recently been shown to increase during the first 24 h of a brain infarct4 as well as in association with intermittent claudication,5 but we have excluded such patients from our study.
Hypoxia, acidosis, free radicals, and sodium and calcium pump disruptions can all induce changes in the binding capacity of the NH2 terminus of the albumin to bind metals such as cobalt, copper, and nickel. These may occur in conditions other than ischaemia and this may be a limitation in the use of IMA as a marker of ischaemia. Careful selection of patients in future studies is, therefore, needed.
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[1] Sbarouni E, Georgiadou P, Panagiotakos D, Livanis EG, Theodorakis GN, Kremastinos DTh. Ischaemia modified albumin in radiofrequency catheter ablation. Europace (2007) 9:127–9.
[2] Bar-Or D, Winkler JV, VanBenthysen K, Harris L, Lau E, Hetzel FW. Reduced albumin-cobalt binding with transient myocardial ischemia after elective percutaneous transluminal coronary angioplasty: a preliminary comparison to creatine kinase-MB, myoglobin, and troponin I. Am Heart J (2001) 141:985–91.[CrossRef][Web of Science][Medline]
[3] Sinha MK, Gaze DC, Tippins JR, Collinson PO, Kaski JC. Ischemia modified albumin is a sensitive marker of myocardial ischemia after percutaneous coronary intervention. Circulation (2003) 107:2403–5.
[4] Abboud H, Labreuche J, Meseguer E, Lavallee PC, Simon O, Olivot JM, et al. Ischemia-modified albumin in acute stroke. Cerebrovasc Dis (2006) 23:216–20.[CrossRef][Web of Science][Medline]
[5] Troxler M, Thompson D, Homer-Vanniasinkam S. Ischemic skeletal muscle increases serum ischemia modified albumin. Eur J Vasc Endovasc Surg (2006) 31:164–9.[CrossRef][Web of Science][Medline]
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