European Heart Journal Advance Access originally published online on October 5, 2005
European Heart Journal 2005 26(24):2742-2743; doi:10.1093/eurheartj/ehi573
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Impaired left ventricular function in obesity?: reply
Department of Clinical and
Experimental Medicine
Excellence Centre for Cardiovascular
Disease
Second University of Naples
Naples I-80122
Italy
Tel: +39 081 5666707
Fax: +39 081 5666736
E-mail address: ferdinando.sasso{at}unina2.it
We read with interest the letter from Barker et al. on our work ‘Effects of insulin on left ventricular function during dynamic exercise in overweight and obese subjects’.1 We thank Barker et al. for their comments that need our reply.
First, it is clear from our manuscript that the metabolic hypothesis for cardiac impairments in overweight/obese people is only a suggestion. We observed a significant correlation between insulin resistance and myocardial dysfunction, as we have already described in Type 2 diabetic subjects,2 but we have not investigated the potential biochemical mechanisms. The mismatch of substrate utilization and myocardial flow suggested for diabetic cardiomiopathy could be implicated also in obesity,3 but this remains to be proved.
Secondly, it is obvious that LVEF cannot exceed 100%. We simply reported in the results section, the changes in LVEF in the three groups, but we did not state that we expected that LVEF could increase indefinitely. As can be seen from the title, the aim of our investigation was to study the effect of insulin on ventricular function during exercise and not the reduced ventricular performance of obese subjects. The discussion, as a consequence, is centred on the difference between the two performed tests, thus revealing the effect of insulin. In other words, it does not matter if the size of delta LVEF is partly, totally, or not dependent on rest LVEF, because our aim was to stress the possible action of insulin on the variable, and the repeated measure ANOVA we performed revealed the statistical difference between insulin and saline infusion. This remains even if LVESV is not different. Moreover, we would like to underline that the statement by Barker et al. ‘left ventricular end systolic volume is a more reliable indicator of cardiac function than LVEF’ is referred to an investigation performed on patients with myocardial infarction.4 We remind that our patients had no evidence of pre-existing, structural, or ischaemic heart disease, nor, in particular, were recovering from myocardial infarction.
It is relevant to stress that data from the literature on cardiac function in obese people are scattered and inconclusive. Some authors did not demonstrate impairments, but more recently some others did.5 Our results do not pretend to be conclusive, but certainly support the second.
We did not report the values of heart rate and blood pressure simply because of editorial limitations. However, as stated in the results section, they did not significantly differ between the two tests, so they would add nothing more to what already discussed.
References
- Sasso FC, Carbonara O, Nasti R, Marfella R, Esposito K, Rambaldi P, Mansi L, Salvatore T, Torella R, Cozzolino D. Effects of insulin on left ventricular function during dynamic exercise in overweight and obese subjects. Eur Heart J 2005;26:1205–1211.
[Abstract/Free Full Text] - Sasso FC, Carbonara O, Cozzolino D, Rambaldi P, Mansi L, Torella D, Gentile S, Turco S, Torella R, Salvatore T. Effects of insulin-glucose infusion on left ventricular function at rest and during dynamic exercise in healthy subjects and non insulin dependent diabetic patients. J Am Coll Cardiol 2000;36:219–226.
[Abstract/Free Full Text] - Iozzo P, Chareonthaitawee P, Rimoldi O, Betteridge DJ, Camici PG, Ferrannini E. Mismatch between insulin-mediated glucose uptake and blood flow in the heart of patients with type 2 diabetes. Diabetologia 2002;45:1404–1409.[CrossRef][ISI][Medline]
- White HD, Norris RM, Brown MA, Brandt PW, Whitlock RM, Wild CJ. Left ventricular end-systolic volume as the major determinant of survival after recovery from myocardial infarction. Circulation 1987;76:44–51.
[Abstract/Free Full Text] - Salvadori A, Fanari P, Giacometti E et al. Kinetics of catecholamines and potassium, and heart rate during exercise testing in obese subjects: heart rate regulation in obesity during exercise. Eur J Nutr 2003;42:181–187.[CrossRef][ISI][Medline]
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