The Impact of Abdominal Obesity on Cardiopulmonary Fitness in Chinese Heart Failure Patients

Abstract

Introduction There is an inverse relationship between abdominal obesity measured by waist circumference (WC) and cardiopulmonary fitness (peak oxygen consumption, VO2peak) among healthy white people. However, knowledge of Chinese heart failure patients remains scant because heart failure patients generally experience significant impaired cardiopulmonary fitness, and Asian populations tend to have more abdominal fat compared to white populations. Hypothesis Abdominal obesity based on Asian WC cut-off points results in significant changes in VO2peak and the WC can negatively impact the VO2peak in Chinese heart failure patients. Methods This is a cross-sessional study. Data was collected from 72 heart failure patients with NYHA classI∼IV (80% II) with mean ejection fraction of 46.5%. VO2peak was measured during a symptom-limited bicycle exercise test; and WC was measured between the lower rib and the iliac crest. Abdominal obesity was defined by the recommended Asian cut-off points (90 cm for men, 85 cm for women). Other clinical variables were collected from electronic medical records. Non-parametric tests, Spearman's correlation coefficients, and a linear regression model were used with p-value Results Among 72 patients, mean age was 65.4 (range: 36∼91); 80.6% were male; and mean BMI was 24.4 kg/m2 with 45 (63%) classified as abdominally obese. Overall, significant lower VO2peak value was found in the abdominal obesity group including men and women (-2.6 mL/kg/min, 95%CI: -4.5, -0.8) than in the normal WC group. When patients were stratified into two gender groups and three age groups (young: Conclusion Recommended Asian WC thresholds for abdominal obesity are a useful instrument for detecting clinically, statistically relevant decreases in VO2peak among Chinese heart failure patients. For male patients or those under 60, WC was inversely associated with their VO2peak. For each 5∼6cm increase in WC, reducing VO2peak showed a clinically significant decrease of 1 mL/kg/min among Chinese heart failure patients. Further research with larger samples sizes is needed to support WC as a cardiopulmonary fitness self-management tool.