A Study on Complication and Monitoring of Warfarin in Post-Valve Surgery
Introduction:This study was carried out to determine the incidence of complication related to
warfarin in patients with valve surgery and identify potential risk factors for complication and study
its monitoring aspects.
Methods:A combined retrospective and prospective observational study including a total of 185
patients who underwent mechanical valve replacement in Shahid Gangalal National Heart Centre.
The study was conducted from 4 November 2006 till 1 February 2007.
Results:There were a total of 141 episodes of bleeding. Among them signifi cant bleeding occurred
in 15.7% patients, major bleeding was 3.2 per 100 patient-years (3.8%) and minor bleeding was
11.8 per 100 patient-years (11.9%). Epistaxis (16.8%) was the most common bleeding complication.
Menorrhagia was the most common bleeding complication in females with 20.5 per 100 patient-years
(27.4%). Thromboembolic complications occurred at the rate of 2.3 per 100 patient-years. Patients on
warfarin were outside the INR target range 67.8% of the time, with 21% INR values above range and
46.8% INR values below range. However, dose adjustment was done only 31.8% of times when INR
was outside range.
Conclusions:There is high incidence of bleeding complication in patients on warfarin and
hypertension is signifi cantly associated with bleeding. Diffi culty in tightly controlling INR probably
is related to high incidence of bleeding. Better patient education, stricter adjustment of INR, frequent
monitoring of INR at peripheral hospitals and standardization of the test at different hospitals are
suggested to reduce the warfarin related complications.
Key Words: bleeding complication, heart valve surgery, warfarin
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