Anticoagulant responses to warfarin vary among patients, based on genetic factors, diet, concomitant medications, and disease state. We evaluated the effectiveness and safety of a 10mg warfarin initiation nomogram in an Asian population. Retrospective cross-sectional audit studies were conducted from March 2009 to March 2010. The use of a 10mg-loading dose to initiate warfarin treatment resulted in 33(84.6%) patients attaining a therapeutic INR within four days (mean time, 2.6 days). There was no significant correlation between age, gender, race, and serum albumin for the time to reach a therapeutic INR. A significant correlation was noted for patient's baseline INR and time to reach a therapeutic INR (P<0.05). No significant differences were observed in time to reach a therapeutic INR in patients treated with specific class of concomitant drugs or patients with specific disease states. The overall incidence of over-anticoagulation was 35.9%; however, no bleeding episodes were encountered. In conclusion, the use of a 10mg warfarin nomogram was effective in rapidly achieving a therapeutic INR. However, the nomogram's safety is debatable owing to the high over-anticoagulation rate warfarin-administered patients. Caution is recommended in the initiation of warfarin treatment using the 10mg nomogram.
Direct coronary angioplasty with stent implantation is an effective treatment for acute myocardial infarction. The use of adjunctive abciximab, a platelet glycoprotein IIb/IIIa receptor antagonist is expensive. We report on three cases of direct coronary angioplasty complicated by extensive thrombus formation that were successfully treated with attenuated dosing of abciximab via the intracoronary route. All patients presented with acute myocardial infarction complicated by cardiogenic shock or eminent cardiogenic shock. Abciximab was administered after balloon dilatation when extensive thrombus formation was noted and persisted despite repeated inflations. In all three patients a single 10 mg vial of intracoronary abciximab was administered, resulting in complete dissolution of thrombus, allowing successful deployment of stents. Thus, a single 10 mg intracoronary bolus dose of abciximab may be sufficient to achieve high local concentrations of antiplatelet activity. This facilitates thrombus dissolution and allows the safe deployment of a stent to normalise intracoronary rheology.
The potential use of ancrod, a purified isolate from the venom of the Malaysian pit viper, Agkistrodon rhodostoma, in decreasing the frequency of cyclic flow variations in severely stenosed canine coronary arteries and causing thrombolysis of an acute coronary thrombus induced by a copper coil was evaluated. Open-chest, anesthetized dogs were used. Ancrod was given intravenously (8 U/kg) over 1 hour and caused a significant reduction in the frequency of cyclic flow variations (5.8 +/- 0.7 to 3.6 +/- 0.8 cyclic flow variations per 30 minutes, p less than 0.05), whereas control animals failed to decrease the frequency of their cyclic flow variations over the same time period (5.3 +/- 0.3 to 5.0 +/- 0.4 cyclic flow variations per 30-minute period). Twenty-seven dogs had a coronary thrombus induced by a copper coil positioned directly in a major coronary artery; of these, four died of ventricular fibrillation prior to treatment, eight received an infusion of saline and showed no thrombolysis over 5 hours, and three died of ventricular fibrillation during the initial part of an intravenous infusion of ancrod. The remaining 12 dogs received ancrod intravenously (16 U/kg); six demonstrated lysis of the coronary thrombus (mean time to lysis, 65 +/- 20 minutes). The concentrations of ancrod used in these studies produced a severe decrease in systemic fibrinogen concentration and a significant decrease in the inhibitor of plasminogen activator levels. Thus, ancrod decreases the frequency of cyclic flow variations in stenosed canine coronary arteries and may cause coronary thrombolysis in approximately 50% of animals within 65 +/- 20 minutes of its intravenous administration.