Oral Anticoagulant Use In Patients With Chronic Heart Failure At The Time Of First Visit To A Canadian Heart Failure Network (CHFN) Outpatient Clinic, 1999-2008

Abstract:

BACKGROUND: Anticoagulation is indicated in many patients with heart failure (HF) and is often introduced by community physicians prior to specialist consultation. To understand the prevalence of anticoagulation in the outpatient community of HF patients, we reviewed the CHFN prospective database for patients on coumadin at their first visit.
METHODS AND RESULTS: Among 16,073 HF patients in the CHFN database, 68.9% were male and 31.1% were female. 3,870 (24.1%) were on warfarin at their first CHFN clinic visit and, of these, 73.7% were male and 26.3% female which reflects more men and fewer women on warfarin compared to the full HF patient cohort (p<0.001). There was also a difference in age (male/female: 66.9+/-0.26 and 69.4+/-0.46 yrs in warfarin cohort versus 66.6+/-0.13 and 68.9+/-0.22 yrs in full cohort; p<0.001). Among those on warfarin, atrial fibrillation was present in 45.9%, transient ischemic attack in 4.4%, and an unspecified reason in 49.7%. The prevalence of mechanical valves was not reported. At the time of this first CHFN visit, if on warfarin, an INR was entered into the database in 3,870 (67.1%) patients and the distribution of INR's are provided in the table.
Across different LV sizes (left ventricular end diastolic dimension LVEDD), 26.0% of males vs 47.1% of females were on warfarin with an LVEDD <55mm compared to 30.7% of males vs 14.2% of females with an LVEDD >65mm p<0.001. Similar significant differences were observed between preserved and low LVEF (>40 and <20%, p<0.001).
CONCLUSION: While warfarin is often prescribed for HF patients prior to referral to a HF specialist in the CHFN, standard therapeutic INR levels are observed in only half, sub therapeutic levels in one third, and INR's >4 in 3.7%. Females with a low LVEF or high LVEDD were less likely than males to be on warfarin. Indications for, and monitoring of, warfarin remain challenges in clinical practice. Check lists and computerized programs may be beneficial to identify interventions for those at highest risk.