Impact of Body Mass Index on Stroke in Extracorporeal Cardiopulmonary Resuscitation: Data from the Extracorporeal Life Support Organization Registry

<b>Objective:</b> We aimed to characterize the impact of body mass index (BMI) on stroke in patients receiving extracorporeal cardiopulmonary resuscitation (ECPR). <b>Methods:</b> We queried the Extracorporeal Life Support Organization registry for patients receiving ECPR (2020-2024). Patients were categorized into five BMI groups: underweight (<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), class 1 obesity (30-34.9 kg/m²), and class 2 obesity or above (≥35 kg/m²). A generalized additive model (GAM) analysis was used to identify the BMI range with the greatest stroke risk. Multivariable regression was used to compare odds of stroke between standard BMI groups and normal weight. Propensity score matching was used to compare stroke and mortality between normal weight and the BMI group with the highest predicted stroke risk. <b>Results:</b> Of 6390 patients (median age = 57.5, 68.6% male), 470 (7.4%) had a stroke during ECMO support (4.5% ischemic; 3.4% hemorrhagic). A total of 9.6% (<i>n</i> = 131) of class 1 obesity patients experienced stroke compared with 6.6% (<i>n</i> = 111) of normal weight, 6.9% (<i>n</i> = 79) of class 2 obesity or above, 6.9% (<i>n</i> = 143) of overweight, and 5.4% (<i>n</i> = 6) of underweight patients (<i>p</i> = 0.01). The GAM analysis showed a highest predicted stroke risk for class 1 obesity patients (<i>n</i> = 1366), which was confirmed by multivariable regression (adjusted odds ratio (aOR) = 1.63, 95%CI = 1.01-2.62, <i>p</i> = 0.045). After propensity matching (<i>n</i> = 357 each), class 1 obesity was associated with ischemic (aOR = 2.01, 95%CI = 1.02-4.08, <i>p</i> = 0.047) but not hemorrhagic stroke. Odds of hospital mortality were higher in both class 1 and 2 obesity patients compared with normal weight. <b>Conclusions:</b> Class 1 obesity was associated with increased odds of ischemic but not hemorrhagic stroke compared with normal weight patients.