Abstract 20458: The Obesity Paradox: The Protective Effect of Obesity on Right Ventricular function using Echocardiographic Strain Imaging in patients With Pulmonary Hypertension

Introduction: A consistent, but puzzling clinical observation is that obesity confers an increased susceptibility to the development of cardiac disease, while at the same time affording protection against subsequent mortality (known as obesity paradox). Obesity is associated with RV dysfunction, but its effect on RV remodelling in patients with pulmonary hypertension (PHTN) has not been studied. Hypothesis: We evaluated the effect of obesity, and its interplay with diabetes, in patients with PHTN using RV echocardiographic strain imaging. Methods: 185 patients underwent echocardiographic imaging and pulmonary artery pressure was calculated using tricuspid jet velocity. RV longitudinal strain was performed from a focused RV apical 4-chamber view using speckle tracking software. Global and regional (mid wall) peak systolic RV longitudinal strain was then calculated. Results: Our sample (n=185, mean age 62+/-11yrs) consisted of 41.6% males. Patients with coronary artery disease, left sided heart failure, significant valvular disease, chronic obstructive pulmonary disease and history of pulmonary embolism were excluded. Global and Mid RV strain in patients with PHTN (n=84) was lower (-16.8+/-7 vs -18.9+/-6.3, P=0.0356 & -11.2+/-12.8 vs -18.9+/-9.2, P=0.0021 respectively) compared with patients without PHTN (n=101). Obese patients (BMI >30) without PHTN had lower Global and Mid RV strain (-17.2+/-6.2 vs -20.3+/-5.7, P=0.012 & -17.6+/-7.2 vs -21.9+/-7.3, P=0.004), even after excluding diabetic patients (-18.2+/-6.8 vs -22.1+/-8, P=0.032). Among patients with PHTN, obese patients had similar RV strain compared with non-obese patients (P=0.46). Interestingly, on excluding diabetic patients from PHTN group, non-diabetic obese patients with PHTN had higher Global and Mid RV strain (-21.7+/-5.7 vs -16.1+/-8, P=0.017 & -23.8+/-4.8 vs -17+/-9.4, P=0.009 respectively) compared to non-diabetic healthy patients; suggestive of protective effect of obesity on RV function in patients with PHTN. Conclusions: Obesity is associated with subclinical RV dysfunction as assessed by RV strain imaging, but paradoxically confers protective effect on RV function in patients with PHTN. Future studies should evaluate the clinical impact of this paradox.