Low molecular weight heparin bridging for atrial fibrillation: is VTE thromboprophylaxis the major benefit?

Paucity of data has led to a lack of consensus regarding indications for, and risk-benefit ratio of, low molecular weight heparin 'bridging' for cardioembolic prevention in patients with atrial fibrillation (AF) until their INR levels are in therapeutic range. Using a hospital database, we compared AF patients ≥65 years who were bridged (n = 265) with patients who were not bridged (n = 4532) after hospital discharge. Patients who failed to achieve a therapeutic INR within 30 days were excluded. CHADS₂ scores (congestive heart failure, hypertension, age ≥75, diabetes, stroke), bleeding risk and co-morbidity scores were assessed. Unadjusted and adjusted odds ratios for outcome events (death, stroke, hemorrhage and venous thromboembolism (VTE) within 30 days of discharge were compared. Bridged patients, as compared to those not bridged, were younger (74.7 ± 6.6 vs. 78.5 ± 7.7 years), less likely to be white (36 vs. 51%), and less likely to have CHADS₂ scores ≥2 (67 vs. 84%), all P < 0.001. There was no significant difference in bleeding risk (bridged vs. not bridged: 1.5 ± 7 vs. 1.7 ± 6). In logistic models adjusting for age, white race, bleeding risk, CHADS₂ and Comorbidity scores, bridging was significantly associated with lower mortality and a decreased odds ratio for VTE (both P < 0.01) but not for stroke or hemorrhage (both P > 0.80). Although we found insufficient evidence of either lower stroke or greater bleeding risk with bridging, our data suggest the possibility that LMWH bridging in patients with AF is associated with lower risks of VTE and death within 30 days of discharge.