The need to interrupt anticoagulation and allow INR to return to near-normal levels prior to surgical or other invasive procedures is generally accepted to prevent peri-procedural bleeding. Bridge therapy using a short-acting anticoagulant provides protection against thromboembolism during this period, but also increases the risk of bleeding. There is a need to identify which patients would benefit from bridge therapy without putting them at undue risk of bleeding. The decision whether or not to implement bridge therapy must be undertaken with a clear understanding of the risks and benefits for the individual patient; bleeding vs. thromboembolism. There is fairly broad acknowledgement that patients at low risk of thromboembolic event probably do not need to be bridged, and that higher risk patients should probably receive bridge therapy, but what constitutes “high” or “low” risk is not universally agreed upon. The American College of Chest physicians have provided guidance in the 8th update to the guidelines on anticoagulation.1 For patients classified as “high risk” the need for peri-procedural bridging typically outweighs the risk of bleeding; those in the “low risk” category can discontinue anticoagulation therapy for a short period without creating undue risk of thromboembolic event. Treatment with a low-molecular weight heparin (LMWH) is usually preferred over the use of unfractionated heparin (UFH) in terms of both cost and convenience since LMWHs can be administered on an out-patient basis without the need for continual monitoring. In the June issue of Circulation, Pengo and colleagues report a 30 day prospective clinical trial to assess the effects of 2 different LMWH bridging protocols in 1262 peri-operative patients. Patients were classified as high or low-intermediate risk (see Table 1).2
Per protocol (see Table 2), oral anticoagulants were to be discontinued 5 days prior to the scheduled procedure, all patients in the high thromboembolic risk group were assigned to protocol A (70 anti-factor Xa units/kg LMWH twice daily) those in the low-intermediate risk group received once daily dosing (57 anti-factor Xa units/kg LMWH) (Table 2) 5 days prior to procedure, stopping ≥ 12 hours prior to the procedure and resuming at least 12 hours post-procedure. Oral anticoagulants were to be resumed 1 day after procedure at 150% of prior dose.
This study was conducted at 22 separate facilities in Italy. Atrial fibrillation was the most common reason for anticoagulation (51.7%), while venous thromboembolism and mechanical valves accounted for 16.6% and 15.1% respectively. The indication for the remaining 11.5% was valvular heart disease, biological prosthetic valve or “other.”
Patients (88%) had their oral anticoagulants discontinued 3–5 days prior to the procedure and bridging was initiated in that same timeframe for 90% of patients. In 96.4% of the subjects, LMWH was resumed on the day after the procedure.
There were 5 post-procedural thromboembolic events, all in the high risk group. LMWH was not administered per protocol in 3 of these patients—2 because of elevated INR; no explanation was provided for the single ...