Influence of cardiac dysfunction and systemic inflammation on pulmonary function and airway responsiveness in obese subjects.

PURPOSE Obesity is associated with left ventricular diastolic dysfunction and altered heart rate variability, as well as pulmonary dysfunction. The relationship between asthma and cardiac dysfunction in severely obese subjects is unknown, although it has been hypothesized that cardiac dysfunction may contribute to increase airway hyper-responsiveness (AHR). This study aimed to determine if AHR is associated with left ventricular diastolic dysfunction and heart rate variability in severely obese subjects. METHODS Sixty-one subjects with severe obesity (BMI ≥35 kg/m2 with comorbidities) completed this study. All subjects completed respiratory questionnaires, spirometry, lung volume measurements, methacholine inhalation test, 24hour Holter monitoring and a complete echocardiography evaluation. Blood samples were obtained for measurement of metabolic markers. Subjects with AHR, defined by a provocative concentration of methacholine inducing a 20% fall in FEV1 (PC20) < 8 mg/ml, were compared with those with no AHR (PC20 ≥8 mg/ml). RESULTS According to these criteria, 32 subjects had AHR and 29 had no AHR(mean PC201.70 mg/ml and 15.3 mg/ml respectively, p < 0.001). The groups were similar for anthropometric data and comorbidities. Fasting glucose, Hb1Ac, total cholesterol, LDL, triglycerides, Apo-B, C-reactive protein (CRP) and pro-BNP levels were also comparable between groups (p > 0.05). CRP level correlated with PC20 (AHR, r=0.38, p=0.03). Indices of heart rate variability and overall cardiac function were similar in subjects with or without AHR but grade 2 left ventricular diastolic dysfunction was more prevalent in subjects with AHR (p=0.037). CONCLUSIONS Altered cardiac function, dysglycemia and dyslipidemia do not seem to be significantly associated with AHR in severely obese subjects in contrast to systemic inflammation.