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Letter to the Editor |
Address correspondence to: Phillip E. Gates, Human Cardiovascular Research Laboratory, Department of Integrative Physiology 354 UCB, University of Colorado, Boulder, Colorado, 80309. E-mail: phillip.gates{at}colorado.edu.
To the editor:
We thank Dr. Tritos et al. (1) for their interest in our work (2) and welcome the opportunity to address their concerns. They and others have found increased left ventricular mass in obese subjects and suggest that magnetic resonance imaging is a preferable method for cardiovascular evaluation in obese populations. Our population consisted of healthy, normotensive men with a wide range of age and adiposity. Indeed, of the 113 men, only four had a body mass index greater than 30 kg/m2, and none had a body mass index greater than 35 kg/m2. The concern that our findings are different from those reported in obese subjects may well reflect a population difference between our healthy men and obese counterparts. To this end, our primary focus was to use regression and part correlation analysis to determine whether adiposity contributes to the changes in left ventricular structure and function that occur with aging. We showed, for the first time in healthy men, that adiposity was associated with differences in left ventricular structure and diastolic function. We consider these findings to be consistent with existing data on obese men, although the strength of the associations may be greater in the obese. In healthy men, other factors associated with aging may exert dominant effects on left ventricular mass, masking an effect of adiposity in our cohort. The subsample analysis was included to present our data in a more conventional way, but this analysis is consistent with the regression analysis conducted on all 113 men, a sample size that we considered to have adequate power. Although we agree that evolving magnetic resonance imaging technology may improve the ability to detect small differences in left ventricular mass, our method has been established in the peer-reviewed literature to detect differences in left ventricular mass with age, hypertension, heart failure, cardiomyopathy, valvular heart disease, and with pharmacological and lifestyle interventions. Most pertinent to this discussion, surface echocardiography has been used successfully to document increased left ventricular mass and abnormal diastolic function in obese subjects in five studies cited by Danias et al. (3).
As reiterated by Dr. Tritos et al. (1), a number of mechanisms are associated with age-associated changes to left ventricular structure and function. Our purpose was to raise the possibility that adiposity is associated with these left ventricular changes and that aging is needed to provide adequate exposure to this deleterious stimulus (2). Our statistical analysis supported the concept that adiposity may contribute to differences in left ventricular structure and diastolic function with aging in healthy men. In the Discussion, we noted that the mechanisms by which adiposity may exert an influence on the left ventricle are uncertain and that other factors exert influences with aging. We did not intend this to be interpreted as an explanation of our data or a comprehensive list of all candidate mechanisms. Rather, we hoped to make the point that the underlying mechanisms contributing to changes in left ventricular structure and function, and the potential role of adiposity in healthy men, need to be elucidated. The fact that this is also true in obese populations is an important issue raised by Dr. Tritos et al. (1).
Human Cardiovascular Research Laboratory, Department of Integrative Physiology (P.E.G., C.L.G., D.R.S., D.D.C.), University of Colorado, Boulder, Colorado 80309; and Department of Medicine (Cardiology and Geriatric Medicine) (D.R.S.), University of Colorado Health Sciences Center, Denver, Colorado 80262
Received December 2, 2003.
References
This article has been cited by other articles:
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  P. E. Gates, C. L. Gentile, D. R. Seals, and D. D. Christou Authors' Response: Adiposity Contributes to Differences in Left Ventricular Structure and Diastolic Function with Age in Healthy Men J. Clin. Endocrinol. Metab., March 1, 2004; 89(3): 1485 - 1486. [Full Text] [PDF]
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