The association between obesity and bleeding after percutaneous coronary intervention (PCI) is not well defined. We investigated the impact of body mass index (BMI) on PCI-related bleeding, and whether bivalirudin, compared to heparin, used as PCI anticoagulant modifies this relationship.

From 2000 to 2009, 16,783 patients who underwent PCI were grouped according to 6 BMI groups: underweight (<18.5 kg/m²), “normal” weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), class I (30-34.9 kg/m²), class II (35-39.9 kg/m²), and class III obesity (≥40 kg/m²). Bivalirudin was used in 11,433 patients and heparin in 5,350. In-hospital major bleeding (hematocrit drop ≥15% or gastrointestinal bleeding) and need for transfusion rates were collected.

The incidence of major bleeding varied significantly throughout the BMI spectrum (5.6% vs 2.5% vs 1.9% vs 1.6% vs 2.1% vs 1.9%, respectively, from underweight to class III obese patients, P < .001). The incidence of transfusion across BMI followed the same reverse J-shape curve (10.9% vs 6.6% vs 3.6% vs 3.4% vs 3.8% vs 5.6%, P < .001). After adjustment for potential confounding factors, underweight patients had neither an increased risk for major bleeding nor an increased risk for transfusion compared with “normal” weight patients. Class I obese patients had a lower risk of major bleeding (odds ratio [OR] 0.68 [95% CI 0.48-0.97]). Overweight, class I, and II obese patients had a lower risk of transfusion (respectively, OR 0.68 [0.55-0.84], 0.68 [0.53-0.87], and 0.66 [0.48-0.92]). The highest BMI patients had neither an increased risk for major bleeding (class II and III obesity) nor an increased risk for transfusion (class III obesity). The same reverse J-shaped relationship to BMI seen in the overall population for the raw incidence of major bleeding was found when the population was divided according to type of anticoagulant used as follows: bivalirudin or heparin. Likewise, the “need for transfusion” relationship to BMI is not altered by bivalirudin use.

The better outcome for bleeding seen in patients in the middle of the BMI spectrum suggests the existence of a “bleeding obesity paradox,” which persists after adjustment by confounding factors and exists irrespective of the anticoagulant used.