Body mass index and effectiveness of reperfusion strategies:: Implications for the management of patients with ST-elevation myocardial infarction

Background: Fibrinolytic therapy has maximum dose limit in patients with ST-elevation myocardial infarction (STEMI). Consequently, obese patients receive lower dose of fibrinolytic per kg body weight compared to lower weight patients. Whether the relatively lower dose results in lower effectiveness of fibrinolytic agents versus primary percutaneous coronary interventions (PCI) in patients with higher body mass index (BMI) is not known. Methods: We analyzed 7,630 STEMI patients receiving primary PCI (46%) or fibrinolysis (54%) <24 hours of symptom onset from the MITRA PLUS registry. The relative effectiveness of the 2 reperfusion strategies on in-hospital death (adjusted with propensity scores) and bleeding were studied in 3 BMI groups: I-BMI 20-24.9 kg/m(2) (n=2,277), II-BMI 25-29.9 kg/m(2) (n=3,763), and III-BMI >= 30 kg/m(2) (n=1,590). Results: BMI was inversely related to death, shock, stroke, and bleeding in patients treated with either reperfusion strategy. However, compared with primary PCI, fibrinolysis was associated with higher adjusted death with similar relative adjusted difference in all 3 groups (group I OR 1.69, 95% CI 1.19-2.44; group II OR 1.89, 95% CI 1.39-2.56; group III OR 1.85, 95% CI 1.08-3.22). Conclusions: Compared with primary PCI, fibrinolysis was associated with relatively similar higher risk of death in all 3 BMI groups. Whether the differences in death between fibrinolysis and primary PCI in the high-BMI categories can be reduced by higher fibrinolytic doses without increasing bleeding risks needs evaluation in future studies.