Variation in warfarin thromboprophylaxis after mitral valve repair: does equipoise exist and is a randomized trial...

There are limited data available to inform decision making regarding warfarin thromboprophylaxis early after mitral valve repair.

We studied 13,082 patients from The Society of Thoracic Surgeons Adult Cardiac Surgery Database (STS ACSD) who underwent primary mitral valve repair between January 1, 2008, and June 30, 2010. Excluded were those having other major concomitant operations or with an indication/contraindication to warfarin. The predictors of warfarin administration at dismissal were evaluated.

In this cohort (median age 58 years; 59% male), warfarin was prescribed at hospital dismissal for 46% (5,963) of patients. Median postoperative length of stay was 5 days overall (6 days warfarin versus 5 days, p < 0.0001). Substantial surgeon and center variation existed, and multivariable analysis identified that warfarin use was more common among patients with postoperative atrial fibrillation (odds ratio [OR] 4.04, 95% confidence interval [CI]: 3.57 to 4.58), postoperative neurologic events (stroke OR 1.72, 95% CI: 1.08 to 2.71; transient ischemic attack/reversible ischemic neurologic deficit OR 6.29, 95% CI: 2.67 to 14.84), and preoperative arrhythmia (OR 2.49, 95% CI: 1.84 to 3.38). Warfarin use was less common among patients having surgery in the more recent era (OR 0.92, 95% CI: 0.89 to 0.96, per half-year increase in date of surgery), those requiring intraoperative transfusion of red blood cells (OR 0.82, 95% CI: 0.71 to 0.96), and patients with advanced heart failure (New York Heart Association functional class IV OR 0.77, 95% CI: 0.59 to 1.00).

At present, half of patients are prescribed warfarin after isolated mitral valve repair in North American cardiac surgical practice which may impact the length of hospital stay. Although patient-level predictors of warfarin prescription exist, center- and surgeon-level variations are prominent. There is a pressing need for a randomized trial both to guide therapy and to ascertain the potential for resource conservation.