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Poor adherence to anticoagulation guidelines in patients with non-valvular atrial fibrillation treated in a tertiary cardiology unit
  1. Guan Sen Kew1,
  2. Mabel Tan2,
  3. Toon Wei Lim1,3
  1. 1National University Hospital, Singapore, Singapore
  2. 2Singapore General Hospital, Singapore, Singapore
  3. 3National University Heart Centre, Singapore, Singapore
  1. Correspondence to Guan Sen Kew, National University Hospital, 1E Kent Ridge Road, NUHS Tower Block, Level 9, Singapore 119228, Singapore; kewguansen{at}


Introduction Atrial fibrillation (AF) is a well-known cause of strokes and all major society guidelines recommend oral anticoagulants (OAC) such as vitamin K antagonists (VKA) for patients with concomitant risk factors to prevent them. However, compliance with these guidelines is historically poor. This study aims to evaluate the adherence to CHADS2 (congestive heart failure, hypertension,age ≥75 years, diabetes mellitus and prior stroke or transient ischaemic attack) guidelines, explore reasons and evaluate outcomes for non-adherence in a tertiary cardiology unit.

Materials and methods A retrospective study of patients admitted into a tertiary cardiology unit from January to March 2010.

Results Of 1826 unique cardiac patients screened, 163 (8.9%) of them had non-valvular AF or atrial flutter. Their mean age was 69.8 years and 58.9% were men. Of the 54 patients on warfarin with documented international normalised ratio (INR), only 22 (40.7%) of them had an INR within the therapeutic range (INR less than two in 22 (40.7%) and greater than three in 10 (18.5%)). Of the 119 patients with CHADS2 greater than or equal to two, only 46 (38.7%) were discharged with warfarin. Among the remaining 73 (61.3%) patients, the most common reasons for not prescribing warfarin include history of bleeding (n=24, 32.9%), no reason documented (n=17, 23.3%) and patient preference (n=12, 19.2%). On follow-up, patients on warfarin were found to have better survival outcomes (mean 1522±41 days) as compared with (mean 1255±63 days) in patients not on OAC (p value=0.001).

Conclusions Few patients who require anticoagulation receive it in accordance with the guidelines even in a tertiary cardiology unit. There are many impediments to the effective use of VKA for stroke prevention among patients with AF.

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