INTRODUCTION — Replacement of a diseased heart valve aims to relieve symptoms and prolong life but also exchanges the native disease for potential prosthesis-related complications. The frequency of serious complications depends upon the valve type and position, and other clinical risk factors. Complications include embolic events, bleeding, valve obstruction (due to thrombosis or pannus), infective endocarditis, structural deterioration (particularly for bioprosthetic valves), paravalvular regurgitation, hemolytic anemia, and patient-prosthesis mismatch.

Thromboembolic- and anticoagulation-related problems are by far the most frequent complications of mechanical valves. The long-term risk of thromboembolism is generally lower with bioprosthetic valves, though there is an increased risk of thromboembolism for bioprosthetic as well as mechanical valves early after valve implantation.

The anticoagulants used to prevent valve thrombosis and thromboembolic events in patients with prosthetic heart valves are vitamin K antagonists (VKA; eg, warfarin; generally for long-term therapy) and heparin (mainly unfractionated heparin or low molecular weight heparin; generally for short-term bridging therapy), with indications as described below. Aspirin is recommended as an antiplatelet agent in addition to anticoagulation in patients with mechanical valve prosthesis and is suggested in patients with bioprosthetic aortic or mitral valves. (See "Antithrombotic therapy for mechanical heart valves".)

This topic will review management of bleeding and invasive procedures in patients receiving antithrombotic therapy to reduce the risk of prosthetic valve thrombosis and thromboembolism. Indications for antithrombotic therapy for prosthetic valves, therapeutic use of VKA, endocarditis prophylaxis, evaluation of valve function, other complications of prosthetic valves (including valve thrombosis and thromboembolism), and management of antithrombotic therapy in pregnant patients with prosthetic heart valves are discussed separately. (See "Antithrombotic therapy for mechanical heart valves" and "Overview of the management of patients with prosthetic heart valves" and "Antimicrobial prophylaxis for the prevention of bacterial endocarditis" and "Diagnosis of mechanical prosthetic valve thrombosis or obstruction" and "Management of antithrombotic therapy for a prosthetic heart valve during pregnancy".)

MANAGEMENT OF OVERANTICOAGULATION AND BLEEDING — The risk of major bleeding with vitamin K antagonist (VKA; eg, warfarin) begins to rise steeply when the International Normalized Ratio (INR) increases to values ≥5 (figure 1), although some patients have bleeding at therapeutic or even subtherapeutic INR levels. However, rapid reversal of anticoagulation, leading to subtherapeutic INRs, increases the risk of valve thrombosis and thromboembolism. Given these concerns, we suggest an individualized approach based largely on expert opinion that is generally consistent with the 2014 American Heart Association/American College of Cardiology (AHA/ACC) and 2012 European Society of Cardiology guideline recommendations [1,2]:

Overanticoagulation without bleeding

●For patients who are not bleeding and have an INR ≥6, VKA should be temporarily discontinued to permit a gradual reduction in INR; small doses (1 or 2.5 mg) of oral vitamin K may be administered to help hasten the fall in INR in patients with a high risk of bleeding. Higher doses of vitamin K are avoided in the absence of bleeding. The INR should be monitored closely so that VKA can be restarted when the INR reaches the therapeutic range.

●If the INR is >10 and there is no bleeding, VKA should be discontinued and doses of 1 to 2.5 mg of oral vitamin K should be administered, with close INR monitoring [2].

Low-dose (1 to 2.5 mg) vitamin K safely corrects the excessive degree of anticoagulation more rapidly than simply withholding VKA, and, in contrast to higher doses of vitamin K, low-dose vitamin K does not make the patient temporarily resistant to further therapy with VKA [3]. (See "Management of warfarin-associated bleeding or supratherapeutic INR", section on 'INR >10 without bleeding'.)

Oral vitamin K replacement has been preferred to the intravenous route, as it will result in a more gradual decrease in the INR and lessen the chance of a subtherapeutic INR and risk of thromboembolism. However, low-dose intravenous vitamin K (1 to 2.5 mg) can be used to safely lower INRs >6 [4]. Since vitamin K is equally effective via oral and intravenous routes and there is a risk of anaphylaxis with the intravenous route; the oral route is generally preferred [1].

Bleeding — In patients who are bleeding with a therapeutic or high INR, the risk of major bleeding (eg, not amenable to local control, life threatening, causing hemodynamic instability) must be weighed against the risk of valve thrombosis.

●Bleeding in patients who are therapeutically anticoagulated or over-anticoagulated often comes from a pathologic cause (eg, gastrointestinal lesion, urinary infection) that should be identified and treated.

●If the risk from continued bleeding that is inaccessible to local control (particularly intracerebral bleeding) is considered greater than the risk of valve thrombosis, cessation of anticoagulation should be accomplished by the use of 2.5 to 5 mg of oral or intravenous vitamin K, and either a four-factor prothrombin complex concentrate (PCC) or, if a PCC is not available, fresh frozen plasma (FFP). PCC containing significant levels of coagulation factors II, VII, IX, and X (known as four-factor PCC), when available, are preferred over three-factor PCC or FFP (table 1). A four-factor PCC has been approved by the United States Food and Drug Administration for urgent reversal of VKA in patients with acute major bleeding. Three-factor PCCs contain low concentrations of factor VII and thus may require coadministration of FFP to lower an elevated INR effectively. (See "Management of warfarin-associated bleeding or supratherapeutic INR", section on 'Serious/life-threatening bleeding' and "Reversal of anticoagulation in intracranial hemorrhage", section on 'Warfarin'.)

The INR should be monitored frequently, and doses of vitamin K may be repeated at 12-hour intervals if needed. A repeated dose of PCC has not been studied in this setting and may increase the risk of thrombosis. Thus, repeated doses of PCC should be given only in the setting of life-threatening bleeding when the coagulopathy is due to continued VKA effect; in such cases, PCC doses should be given at least six hours apart.

The approach described above is generally consistent with the 2014 AHA/ACC valve guideline, which states that administration of FFP or PCC is reasonable in patients with mechanical valves and uncontrollable bleeding who require reversal of anticoagulation [2].

Recombinant activated factor VII (rFVIIa) is not recommended for VKA reversal in individuals with prosthetic heart valves because of lack of evidence of efficacy and concern for risk of thrombosis, especially in the elderly [5,6]. A study in healthy controls given VKA demonstrated correction of the INR and other coagulation tests with rFVIIa but no decrease in bleeding in a skin punch biopsy model [6].

●The optimal time to resume VKA therapy after a major bleeding episode is uncertain. Considerations include the site and cause of the bleeding and interventions performed to stop the bleeding or treat its cause. (See "Management of warfarin-associated bleeding or supratherapeutic INR", section on 'Resumption of anticoagulation after bleeding'.)

MANAGEMENT OF ANTITHROMBOTIC THERAPY FOR INVASIVE PROCEDURES

General considerations — Management of antithrombotic therapy in the patient with a prosthetic (particularly mechanical) valve who is undergoing an invasive procedure or surgery should take into account the type, location, and number of prosthetic heart valves; other patient risk factors for thromboembolism; and the type of procedure [2]. Since limited evidence is available, the recommendations presented here are based largely on expert opinion.

Standardized protocol — As suggested in the 2012 American College of Chest Physicians (ACCP) guidelines, a standardized procedure for perioperative anticoagulant therapy may aid efficient patient management [7]. Components may include advance planning of perioperative anticoagulant management (including anticoagulant discontinuation and resumption and bridging therapy, as applicable), providing patients and providers with a calendar outlining the timing of anticoagulant changes and INR testing, providing education on injection technique for any outpatient low molecular weight heparin (LMWH) therapy, and assessment of postoperative hemostasis.

When discontinuation of anticoagulation is required, general guidelines for the duration of vitamin K antagonist (VKA) discontinuation are provided below (see 'Our approach' below). However, individual responses to discontinuation of anticoagulation vary widely, so careful monitoring, including International Normalized Ration (INR) testing on the day before and the day of the procedure, is required. (See "Perioperative management of patients receiving anticoagulants", section on 'Warfarin interruption'.)

INR testing on the day before surgery enables timely use of low-dose oral vitamin K to reduce the need for blood products or deferral of the surgical procedure. If the INR is 1.5 to 1.9 on the day before surgery, administration of a low dose of oral vitamin K (eg, 1 to 2.5 mg) is likely to reduce the INR to 1.4 or less on the day of surgery [8]. However, in patients with mechanical valves who require interruption of VKA therapy, high-dose vitamin K should not be routinely administered before invasive procedures since this will significantly delay and reduce the effects of re-anticoagulation with VKA after the procedure [3].

The decision on whether or not to use bridging with heparin during the period that the INR is subtherapeutic is based upon the risk of valve thrombosis and thromboembolism as discussed below. (See 'When to bridge' below.)

Avoidance of surgery for three months after valve surgery — The risk of thromboembolism is highest in the first few months after mechanical or bioprosthetic mitral replacement or mitral valve repair, so one method to reduce thromboembolic risk is to wait at least three months after valve surgery for elective noncardiac surgery, when feasible. (See "Antithrombotic therapy for mechanical heart valves", section on 'Early heparin bridging' and "Antithrombotic therapy for surgical bioprosthetic valves and surgical valve repair", section on 'Approach for surgical bioprosthetic valves'.)

For patients with bioprosthetic valves, anticoagulation is generally recommended only in the early post-surgical period (unless other indications for anticoagulation are present); VKA therapy is suggested for only three months postoperatively in patients with mitral bioprosthetic valves and possibly also patients with aortic bioprosthetic valves. (See "Diagnosis of mechanical prosthetic valve thrombosis or obstruction" and "Antithrombotic therapy for surgical bioprosthetic valves and surgical valve repair", section on 'Approach for surgical bioprosthetic valves'.)

Our approach — The following approach is based upon assessment of bleeding risk associated with the surgical procedure and thrombotic risk associated with the patient's valve type and other clinical factors. Our recommendations are based upon the 2014 American Heart Association/American College of Cardiology (AHA/ACC) valve guidelines (figure 2) [2] and are in general agreement with 2012 European Society of Cardiology (ESC) valve guidelines and the 2012 ACCP perioperative antithrombotic therapy guidelines [1,7].

Minor surgical and other procedures

Approach to minor procedures — For patients with mechanical valves who are undergoing minor procedures in which bleeding is easily controlled (eg, minor dermatologic procedure, dental extraction), continuation of VKA anticoagulation with a therapeutic INR is advised. Similar recommendations are included in the AHA/ACC, ESC, and ACCP guidelines [1,2,7]. As an example, given the low bleeding risk of anterior eye surgery, particularly for cataract removal or glaucoma, it can generally be performed without change in anticoagulant therapy. In preparation for procedures during which VKA will be continued, it is important to confirm that the INR does not exceed the therapeutic range prior to the procedure (exact timing of testing is individualized). (See "Perioperative management of patients receiving anticoagulants" and "Management of anticoagulants in patients undergoing endoscopic procedures".)

For a minor dental procedure (eg, tooth extraction or endodontal [root canal] procedure), we suggest continuing the VKA with coadministration of an oral antifibrinolytic agent (eg, tranexamic acid 4.8 percent administered off label as an oral rinse of 5 mL [swish for one minute and spit] taken 5 to 10 minutes before the dental procedure and three to four times daily for one to two days after the procedure). An alternative approach for minor dental procedures is to stop VKA therapy for two to three days before the procedure (which is expected to result in an INR of 1.6 to 1.9 on the day of the procedure, although individual responses vary) without giving vitamin K.

Pacemaker or ICD surgery — VKA therapy is generally continued in patients undergoing pacemaker or implantable cardioverter-defibrillator (ICD) surgery. In patients at moderate to high risk of thromboembolism undergoing nonemergency surgery for pacemaker and ICD surgery, the BRUISE CONTROL trial, which randomly assigned these patients to heparin bridging or continued VKA, found that device pocket hematomas were significantly more common in the heparin-bridging group [9]. The study included many patients with mechanical heart valves, and in those patients, an INR of up to 3.5 was allowed. This study supports continued VKA therapy rather than bridging anticoagulation in patients undergoing cardiac implantable electronic device insertion. (See "Perioperative management of patients receiving anticoagulants", section on 'Settings in which continuing the anticoagulant may be preferable'.)

Cardiac catheterization — As noted in the 2014 AHA/ACC valve guidelines, the acceptable level of anticoagulation in patients with prosthetic heart valves undergoing cardiac catheterization depends on the specific procedure being performed [2]. Many patients with a mechanical valve undergoing cardiac catheterization do not require bridging anticoagulation with heparin, since no or only minor modification of VKA dosing is required for low to moderate risk procedures and even when VKA is held for high-risk procedures, only patients with risk factors for thrombosis require bridging. (See 'With no risk factors for thrombosis' below and 'Major or minor procedures with risk factors for thrombosis' below.)

The management of antithrombotic therapy in patients receiving long-term anticoagulation undergoing percutaneous coronary intervention (PCI) is discussed separately. Similar considerations apply to patients undergoing diagnostic coronary angiography for suspected coronary artery disease. (See "Periprocedural management of antithrombotic therapy in patients receiving long-term oral anticoagulation and undergoing percutaneous coronary intervention".)

The following comments address two other clinical settings: cardiac catheterization performed to evaluate conditions other than coronary syndromes (eg, valvular heart disease or chronic heart failure) and procedures that pose high risks of bleeding such as transseptal or left ventricular puncture.

Preprocedural management — In each patient, we assess the risk of periprocedural bleeding if the anticoagulant is continued and the risk of thrombosis if anticoagulant is withheld. When time allows, we suggest the following approach to preprocedural management of anticoagulation:

•For low- to moderate-risk procedures (eg, right heart catheterization and/or coronary angiography), we measure the INR at least two days in advance of the procedure. We make adjustments to the VKA dose to allow the INR to be at the lower end of the target range (or just below 2 when risk of bleeding is higher) the morning of the procedure.

-For procedures with a low bleeding risk such as coronary angiography from a radial artery approach and/or right heart catheterization from a forearm or antecubital vein, no modification of VKA dosing may be needed. Arterial and venous access via an upper extremity site may allow for reduced risk of major access-related bleeding in patients with an INR of 1.5 to 3.

-For procedures anticipated to involve placement of a large sheath in the femoral artery, we allow the INR to fall below 2.

•For higher-risk procedures such as transseptal or left ventricular puncture in patients with an INR maintained between 2.5 to 3.5, we suggest holding the VKA at least four to six days to allow the INR to fall to the normal (not anticoagulated) range [10]. As noted above, individual responses to discontinuation of anticoagulation vary widely, so careful monitoring is required, including INR testing on the day before and the day of the procedure. The INR is tested on the day before the procedure. If the INR is 1.5 to 1.9 on the day before the procedure, administration of a low dose of oral vitamin K (eg, 1 to 2.5 mg) on the day before the procedure is likely to reduce the INR to 1.4 or less on the day of the procedure [8]. (See 'Standardized protocol' above.)

The role of bridging anticoagulation with heparin prior to a procedure in selected patients with risk factors for thrombosis is discussed below. (See 'Major or minor procedures with risk factors for thrombosis' below.)

Intraprocedural management — Intraprocedural anticoagulant management involves continued weighing of the risks and benefits of anticoagulation, including the following steps:

●Preference for radial arterial and/or forearm/antecubital venous access over femoral access for anticoagulated patients.

●Management of intraprocedural unfractionated heparin based upon INR at the time of the procedure.

●Minimizing use of vitamin K and prothrombin complex concentrate (PCC; or fresh frozen plasma [FFP] if four-factor PCC is unavailable). (See 'Reversal of anticoagulation for emergency procedures with significant bleeding risk' below.)

VKA can generally be restarted as soon as the procedure is completed.

Major surgical procedures

With no risk factors for thrombosis — For patients with current generation bileaflet mechanical aortic valves and no other risk factors for thrombosis who are undergoing invasive procedures, VKA anticoagulation can be temporarily interrupted without bridging while the INR is subtherapeutic [2].

●VKA is stopped approximately three to five days prior to the procedure (aiming for an INR <1.5 at the time of a major surgical procedure). However, individual responses to discontinuation of anticoagulation vary widely, so careful monitoring, including INR testing on the day before and the day of the procedure, is required.

●The INR is checked on the day prior to the procedure. If the INR is 1.5 to 1.9 on the day before the procedure, administration of a low dose of oral vitamin K (eg, 1 to 2.5 mg) on the day before the procedure is likely to reduce the INR to 1.4 or less on the day of the procedure [8].

●VKA is restarted as soon after the procedure as prudent management of bleeding risk allows, typically 12 to 24 hours after the procedure. It will take a few days for the INR to reach a therapeutic level.

Major or minor procedures with risk factors for thrombosis

When to bridge — Bridging anticoagulation is recommended for patients undergoing invasive or surgical procedures during the perioperative time period when the INR is subtherapeutic in patients with both of the following features (figure 2) [2]:

●Significant bleeding risk, for which an INR <1.5 is considered essential

●One of the following valve types:

•Mechanical aortic valve plus an additional thromboembolic risk factor (atrial fibrillation, previous thromboembolism, hypercoagulable condition, left ventricular ejection fraction <30 percent, or more than one mechanical valve)

•Older generation mechanical aortic valve

•Mechanical mitral or tricuspid valve replacement

Choice of heparin for bridging — When bridging is required, either subcutaneous LMWH or intravenous UFH is used (table 2 and figure 2). Subcutaneous LMWH is more convenient to use and may result in a more predictable degree of anticoagulation. When used as a "bridging" therapy in patients with mechanical valve prostheses, LMWH may be more cost-effective than UFH [11,12]. A potential concern is that, if severe bleeding occurs, the effect of LMWH cannot be reversed as easily as that of UFH [13]. (See "Heparin and LMW heparin: Dosing and adverse effects".)

Given these competing concerns, major society guidelines offer differing recommendations on choice of heparin product for bridging. The AHA/ACC valve guidelines recommend either intravenous UFH or subcutaneous LMWH [2]. ESC guidelines favor use of intravenous UFH over subcutaneous LMWH in this setting [1]. The 2012 ACCP guidelines discuss use of intravenous UFH or therapeutic dose subcutaneous LMWH [7].

How to bridge

●VKA is stopped two to four days prior to the procedure (aiming for an INR <1.5 on the day at the time of a major surgical procedure) and restarted as soon after the procedure as bleeding risk allows, typically 12 to 24 hours after the procedure.

●During bridging, we favor continuation of aspirin (81 to 100 mg per day) except when there is risk of major bleeding complications, such as with neurosurgical, prostate, or posterior eye procedures. When there is risk of major bleeding, we suggest stopping aspirin five days prior to the procedure and restarting aspirin as soon after the procedure as bleeding risk allows, typically within 24 hours after the procedure.

●Bridging anticoagulation with intravenous UFH (eg, initial 18 units/kg/hour; no bolus) adjusted to achieve an activated partial thromboplastin time (aPTT) that is 1.5 to 2 times control [7] or subcutaneous therapeutic weight-adjusted, twice daily LMWH (eg, enoxaparin 100 international units/kg [equivalent to 1 mg/kg] every 12 hours) is started when the INR is falls below the therapeutic range (typically about 48 hours prior to the procedure).

●Intravenous UFH is stopped four to six hours before the procedure. When subcutaneous LMWH is used, the last dose is administered 24 hours before the procedure.

●Use of postoperative bridging with heparin is individualized based upon the risk of bleeding and risk of thrombosis. Intravenous UFH or subcutaneous LMWH should be restarted as soon as possible after the procedure, considering both the risk for bleeding and the adequacy of surgical hemostasis [7].

•Following a minor surgical or other invasive procedure when adequate hemostasis has been achieved, resumption of therapeutic dose UFH or LMWH is suggested after approximately 24 hours.

•Following major surgery or a high bleeding risk surgery or procedure, we resume therapeutic dose UFH or LMWH at least 48 to 72 hours after the procedure and when hemostasis is secure, or we completely avoid LMWH or UFH after the procedure. We do not administer therapeutic dose UFH or LMW heparin earlier than 48 to 72 hours after a procedure with a substantial bleeding risk. The timing of UFH or LMW heparin resumption depends on the anticipated bleeding risk and adequacy of postprocedural hemostasis for each patient.

●VKA should be reinstituted as soon as possible after the procedure (eg, 12 to 24 hours after the procedure and when there is adequate hemostasis) [7]. Intravenous UFH or subcutaneous LMWH should be discontinued once the INR has been in the therapeutic range for two consecutive days. Since LMWH therapy is inferior to VKA in preventing valve thrombotic complications, VKA should be re-introduced as soon as is prudent in consultation with the surgeon or interventionalist.

Evidence on perioperative management — Much of the available data on perioperative management of patients with prosthetic valves are from small, uncontrolled case series that often include patients with older generation prosthetic valves [7]. In these reports, thromboembolic risk was variable, depending upon the type and location of the valve prosthesis and upon a number of patient-specific clinical factors.

Most patients tolerate short-term interruption of anticoagulation without valve thrombosis or thromboembolism. This was illustrated in a report of 159 patients with mechanical valves who underwent a total of 180 noncardiac operations [14]. Oral anticoagulants were discontinued one to three days preoperatively and for one to seven days after surgery. There were no perioperative thromboembolic events. Although the risk appears to be low in most patients with mechanical valves, it should be recognized that most cases of valve thrombosis (70 percent in one series) occur during periods of inadequate anticoagulation [15]. (See "Diagnosis of mechanical prosthetic valve thrombosis or obstruction".)

The risk of bleeding is factored into decisions regarding interruption of VKA. Risks have been estimated for a number of surgical and gastrointestinal procedures (table 3A-B). Additional discussion of procedural bleeding risk is presented separately. (See "Perioperative management of patients receiving anticoagulants", section on 'Estimating procedural bleeding risk'.)

Limited data are available on the efficacy of bridging therapy in individuals with prosthetic valves. A small series demonstrated the potential value of basing the approach upon the location of the mechanical prosthetic valve [16]. In 16 operations on patients with only an aortic prosthesis, oral anticoagulation was discontinued for three to five days without IV UFH coverage. In 26 operations on patients with mechanical mitral prostheses, the patients were treated with IV UFH during the period when oral anticoagulation was discontinued; IV UFH was interrupted only for 12 hours at the time of surgery. There were no thromboembolic events in either group.

Reversal of anticoagulation for emergency procedures with significant bleeding risk — For a patient with a mechanical valve who is anticoagulated with a VKA and requires emergency surgery or an invasive procedure that entails a significant bleeding risk, reversal of anticoagulation can be accomplished by administration of an intravenous four-factor PCC or FFP [2]. Given the results of the randomized trial discussed below [17], four-factor PCC is preferred in this setting. In addition, low-dose (1 or 2 mg) oral vitamin K may be administered, which has a slower onset of effect but has a longer half-life than the effects of FFP or PCC. The decision to use a reversal agent depends upon the urgency of the surgery or procedure and the thrombotic and bleeding risks, with the understanding that both risks are increased in this setting.  

In patients with suspected acute coronary syndrome, the potential risk of promoting thrombogenicity is a consideration in determining whether to reverse anticoagulation prior to a procedure. (See "Periprocedural management of antithrombotic therapy in patients receiving long-term oral anticoagulation and undergoing percutaneous coronary intervention", section on 'Periprocedural bleeding'.)

In an open-label, randomized multicenter trial involving 181 patients (including some patients with prosthetic valves) who were receiving a VKA, had an INR >2, and needed rapid reversal of anticoagulation for an urgent surgical or invasive procedure, a single dose of a four-factor PCC was shown to be superior to FFP in rapid INR reduction and hemostasis [17]. All patients received vitamin K, and the doses of PCC and FFP were based on INR and patient weight. Effective hemostasis was achieved in 90 percent in the PCC group versus only 75 percent of patients in the FFP group (difference 14.3 percent, 95% CI 2.8-25.8). The safety profile was similar for both treatments, with thromboembolism in 7 percent of PCC-treated patients versus 8 percent of FFP-treated patients. The relevance of this study to patients on VKA therapy for a mechanical heart valve is unclear; the reasons for VKA therapy in this study were arrhythmia in 42 percent, vascular disease in 21 percent, a previous thromboembolic event in 17 percent, and a prosthetic heart valve (type not specified) or joint in only 16 percent.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac valve disease".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Prosthetic valves (The Basics)")

●Beyond the Basics topic (see "Patient education: Warfarin (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Patients taking vitamin K antagonist (VKA; eg, warfarin) to prevent thrombotic and thromboembolic complications of prosthetic valves may become overanticoagulated. The risk of major bleeding with VKA begins to rise steeply when the International Normalized Ratio (INR) increases to ≥5. However, rapid reversal of anticoagulation, leading to subtherapeutic INRs, increases the risk of valve thrombosis and thromboembolism. (See 'Management of overanticoagulation and bleeding' above.)

•If the INR is ≥6 without bleeding, VKA should be stopped to permit a gradual reduction in INR; small doses (1 or 2.5 mg) of oral vitamin K may be administered to hasten the fall in INR in patients with a high risk of bleeding.

•If the INR is >10 without bleeding, VKA should be discontinued and 1 to 2.5 mg of oral vitamin K should be administered, with frequent INR monitoring.

●Bleeding in patients who are therapeutically anticoagulated or overanticoagulated often comes from a pathologic cause (eg, gastrointestinal lesion, urinary infection) that should be identified and treated. (See 'Bleeding' above.)

●In patients who are bleeding with a therapeutic or high INR, the risk from major bleeding must be weighed against the risk of valve thrombosis. If the risk from continued bleeding that is inaccessible to local control (particularly intracerebral bleeding) is considered to be greater than the risk of valve thrombosis, cessation of anticoagulation should be accomplished by the use of 2.5 to 5 mg of oral or intravenous vitamin K, and either a four-factor prothrombin complex concentrate (PCC) or, if PCC is not available, fresh frozen plasma (FFP). If only a three-factor PCC is available, supplementation with FFP may be needed. (See "Management of warfarin-associated bleeding or supratherapeutic INR", section on 'Serious/life-threatening bleeding' and 'Bleeding' above.)

●The risk of thromboembolism is highest in the first few months after mechanical or bioprosthetic mitral replacement or mitral valve repair, so one method to reduce thromboembolic risk is to wait at least three months after valve surgery for elective noncardiac surgery, when feasible. (See 'General considerations' above.)

●Interruption of anticoagulation in individuals with a mechanical heart valve should be minimized to reduce the risk of valve thrombosis. However, patients may require cessation of VKA anticoagulation to reduce the risk of bleeding at the time of some invasive procedures. Our approach considers the risk of bleeding with the procedure (table 3A-B) along with the risk of valve thrombosis. (See 'Our approach' above.)

●For the patient with a mechanical heart valve undergoing a minor procedure in which bleeding is easily controlled (eg, minor dermatologic procedure, dental extraction, or permanent pacemaker implantation), continuation of VKA anticoagulation with a therapeutic INR is advised. (See 'Approach to minor procedures' above.)

●When a VKA is discontinued in preparation for a procedure, assessment of the need for bridging anticoagulation with heparin is based upon patient- and prosthesis-specific risk factors for thromboembolism (figure 2). (See 'Major or minor procedures with risk factors for thrombosis' above.)