A6509 The Obesity Paradox

Abstract

Objectives: A clue to the “Obesity Paradox” is that patients at the upper extreme of body mass and blood pressure often have youthful arterial pressure waveforms that show optimally-timed wave reflection in the proximal aorta and left ventricle. Central obesity may compress the aorta and conduit arteries in the abdomen, thus decreasing aortic stiffness and delaying return of wave reflection to the heart. Methods: Central aortic pressure waves and indices of wave reflection on the aortic pressure wave were generated from radial tonometry and calibrated to brachial cuff pressures (SphygmoCor, AtCor Medical, Sydney, Australia). Data recorded from 101 patients attending a cardiovascular outpatient clinic at Ruijin Hospital North, Shanghai (table). Subjects were divided into 3 groups according to their Body Mass Index (BMI < = 24 normal, 24–28 overweight, > = 28 obese; for Chinese population). Results: Brachial and aortic pressure values including Systolic (SP), Diastolic (DP), Pulse Pressure (PP), and carotid-femoral pulse wave velocity did not differ significantly between normal and overweight/obese group. Aortic SP and aortic PP were lower for the overweight/obese group than normal, while aortic DP was higher. Despite no difference in standard pressure measurement, there were significant changes (p < 0.05) in indices of aortic pressure wave reflection between normal and overweight/obese groups. Augmented Pressure, Augmentation Index, and pressure amplification (calculated as aortic SP ÷ brachial SP) decreased progressively as BMI increased. Conclusion: The Obesity Paradox, presently unexplained, is likely due to reduced central pressure wave reflection in overweight and obese persons. This study is continuing; the results may explain the obesity paradox in terms of arterial wave travel and reflection.