Managing the Heart Valve“ Oral Anticoagulation Therapy”Dr. Atul A. Maslekar (AIIMS) FICS, FIACSSr. Consultant – Cardiothoracic SurgeonNarayana Multispecialty Hospital - Ahmedabad

Anatomy of Heart Valve

Classification of Prosthetic Heart Valve

• Mechanical Valves• Ball & Cage• Tilting disc• Bileaflet

• Biological Valve• Auto grafts• Homografts• Xenografts• Biovine Pericardial

Picture of Mechanical Valve

Tilting disc valve Ball and cage valveBileaflet valve

Picture of Biological Valve

Porcine (pig)stentless valve

Porcine (pig)stented valve

Bovine (cow)Pericardial stented valve

Management of Patients with Prosthetic Heart valve

Antithrombotic therapy:• Fewer complications of Valvular Heart Disease can be

more devastating than systemic embolic.• Patients with mechanical heart valve receive life long,

high intensity oral anticoagulation therapy to prevent thromboembolic complications.

• Antithrombotic therapy can reduce although not eliminate the likelihood of the catastrophe.

• Unfortunately, antithrombotic therapy carries a substantial risk of bleeding depending upon

– Drugs used– Intensity of anticoagulation– Individual

Risk of Thromboembolism / Bleeding

Sex: Women have a slightly higher risk of both thromboembolism and bleeding than men.

• Incidence of ThromboembolismWomen: 0.86 per 100 patient year.

Men: 0.6 per 100 patient year.• Incidence of Bleeding

Women: 3.1 per 100 patient year Men: 2.4 per 100 patient yearAge: ≤ 50 yr Thromboembolic risk of 0.1 per 100 patient year > 50 yr Thromboembolic risk of 0.8 per 100 patient year

Risk of bleeding did not vary much with age for patients ≤ 70 yr, but was

twice for pt > 70 yrs.Position of valve: Aortic: 0.5 per 100 patient years Mitral: 0.9 per 100 patient year

Double valve: 1.2 per 100 patient year.Position & Type of valve is not likely to affect risk of Bleeding.

All adverse events Incidence rate for Different age group

All Adverse events according to valve position

Incidence of all Adverse events according to valve type

Adverse Events

Minor : Reported but not requiring additional test or

admission.

Major : Requiring treatment. At least 2 units of blood.

Life Threatening : Leading to Cardiac ArrestNeeding Surgical Intervention

Irreversible Sequelae.

Risk factors for Adverse events

• Intensity of treatment• Patient Characteristics

» H/O GI Bleed» H/O stroke» Co morbid Conditions» Age is controversial • Frequency of Blood testing» Patient Compliance» Additions/ Subtraction of Medicines» Changes in diet

Blood Test for Optimal Anticoagulation

• PT: Traditional method of determining efficacy of anticoagulation

• INR: A mathematical calculation that corrects for the results attributable to the variable sensitivities of thromboplastic agents

Ranges

• Healthy People : INR 0.9 – 1.0• PT with AF : INR 2 – 2.5• PT with Mech. valve

Mitral INR : 3- 3.5

Aorta INR : 2 – 2.5 Double INR : 3.5 – 4.0

• INR < 2 : Thromboembolism• INR > 5 : Bleeding

What is an optimal anticoagulationtherapy?

One at which the Incidence of both Thromboembolic and Bleeding Complications are the least.

Factors affects INR

Medicine : Aspirin Anti Inflammatory

Antibiotics

OCP’s

Food : Spinach

Lettuce Brocolli

Liver

Management of Adverse Events

Bleeding: 2 general principle 1. attempt to Identify 2. Is there a possibility to

lower the anticoagulationMinor: > Observe & record

> Repeat PT / INR > Reassurance

Major: > Admission> Attempts to Identify the source> Repeat PT/ INR> FFP / Fresh blood / Vit K

Life Threatening: > Admission (urgent)> Urgent Blood transfusion(Blood /

FFP)> Special Investigation> Surgical (Invasive) Intervention

Management of Adverse efforts –Thrombosis

Prosthetic valve obstruction may be caused by– Thrombus– Pannus– Combination

Knowledge of clinical presentation & special Investigation (TOE) is essential as treatment varies,

Pannus: Thrombolytic therapy ineffectivevalve thrombectory / replacement

Thrombus: Thrombolysis therapy - Streptokinase- Urolinase

Duration depends upon resolution of Pressure gradient, valve area + disc movements

Aspirin in Combination withanticoagulants

• Met analysis supports the concept that the rate of thromboemboli is diminished with aspirin in Combination with VIT K antagonist.

• Aspirin in Combination with anticoagulants (INR 2.0-3.5) was associated with bleeding (minor) incidence of 1.1 – 5.1 % per patient year.

• Indian senario where INR control is poor due to Poor Patient Compliance, in addition of aspirin in dosage (75mg – 150 mg) may be beneficial)

Thromboleytic Therapy

• Thrombolytic therapy should be stopped at 24 hrs there is no hemodynamic improvement or after 72 hrs if recovery is incomplete.

• If successful IV heparin until OAC achieves INR 3-4

Risks of Thrombolytic Therapy

• Ineffective in 16% - 18% of patients• Acute mortality – 6%• Thromboembolism – 12%• Stroke – 3% - 10%• Major bleeding expiring - 5%• Recurrent Thrombosis – 1%

Patient's with large clot, with evidence of valve obstruction & NYHA III/ IV should under go immediate reoperation.

Regime that we follow - OAC

• OAC usually started on Day 1 Post-OP• Target INR is achieved by 4-5 days Post-OP• Use of LMWH/ Heparin in addition• PT / INR monitoring daily for the full 7 days.• Aspirin started is dose (75mg – 150mg) for Day

1. Target INR

• Mitral 3.0 – 3.5• Aorta 2.5 – 3.0• Doulle 3.5 – 4.0

OAC : Post discharge (Ideal)

• PT/ INR, 1 week post discharge• Every 15 days thereafter for 3 months• Once a month for 3 months• Once every 3 months for 6 months• 6 monthly there after.• Continue Aspirin for life.

Special Situations

• Pregnancy• Invasive Procedures

Special Situation - Pregnancy

• Unfortunately, no definite fixed guidelinesOAC crosses placenta

– Spontaneous Abortion– Premature birth– Still birth– Embryopathy

Highest risk - 6-12 weeks of Gestation

Dose related dependency

Vitale et al J. Am col. card 1999

warfarin > 5mg / day – 9% incidence of embryopathy

< 5 mg /day – low fetal complication but no embryopathy

• Meschengieser et al – Heart 1999 92 pregnancies in 59 women to MHV

31 pregnancies Subcut Heparin 1st trimester

warfarin – 2nd Trimester onwards 61 pregnancies OAC continued

• Abortion / fetal loss similar• Embolic effect 4.9% in Heparin gp

0.3% in OAC gp

• Chan et al – Arch. Inter. Med 2000 Review of literature• OAC throughout 6.4% embryopathy• Heparin 6 wks - 12 wks 9.2 % valve thrombosis

LMWH

• More promising– Does not cross placenta– No need for frequent patient.– Lower ½ life– Lower incidence of thrombocytopenia &

osteoporosis

No major recorded data.

Recommendations

Recommendations

Recommendations for Anticoagulation During Pregnancy inPatients With Mechanical Prosthetic Valves: After the 36th WeekIndication Class

1. Warfarin should be stopped no later than week 36 and heparinsubstituted in anticipation of labor.

2. If labor begins treatment with warfarin, a caesarian section should be performed.

3. In the absence of signification bleeding, heparin ca be resumed4 to 6 hours after delivery and warfarin begun orally

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Management of OAC during Invasive Procedure

• Assess the risk of bleeding v/s risk of Thrombosis• Elective Procedures

Minor :– Stop OAC for 1-2 days– Safely done if INR< 2.0– Restart OAC immediately.– Dose of Heparin / LMWH

Major:– Stop OAC 4-5 days prior– Switch to LMWH / Heparin– VIT K 24 hrs prior– Adequate reserve of FFP / Blood– Restart OAC as soon as possible.