(RxWiki News) Blood thinners are commonly given after heart surgery to reduce the risk of blood clots, strokes and other complications. The question is how much they reduce the risk.
A recent study compared complications among patients who underwent aortic valve replacement surgery. It found lower rates of stroke, blood clots, bleeding incidents and cardiovascular deaths among those who continued taking the blood thinner warfarin after surgery.
The highest rates of cardiovascular deaths occurred among those who stopped taking warfarin within six months of their valve replacement surgery.
"Follow post-surgery medical instructions."
The study, led by Charlotte Mérie, MD, of the Department of Cardiology at Copenhagen University Hospital Gentofte in Denmark, aimed to find out whether taking warfarin after surgical aortic valve replacement was linked to any complications.
The complications the researchers were looking for included blood clots, bleeding incidents and cardiovascular deaths after the patient's surgery. The data came from records of 4,075 patients who had prosthetic aortic valve replacement surgery between January 1997 and December 2009. These patients were able to be tracked an average of 6.6 years.
The researchers calculated the risk of complications among those who continued taking warfarin versus those who stopped at several different points after surgery. Among those who stopped taking warfarin, the rate of strokes was a little more than double the rate of those who continued taking warfarin (7 per 100 person-years compared to 2.7).
The rate of blood clots among those who stopped taking warfarin was about three times the rate of those who continued warfarin (13 compared to 4 clots per 100 person-years).
The rate of bleeding incidents was approximately double in those who stopped taking warfarin compared to those who continued (11.9 compared to 5.4 per 100 person-years). The biggest difference in rates occurred in the rates of cardiovascular deaths. For those who stopped taking warfarin in the first one to three months after surgery, the rate of death related to heart problems was a little over 8 times as much (31.7 compared to 3.8 per 100 person-years) as those who continued taking warfarin.
That difference in rates narrowed as more time passed after surgery. Among those who stopped taking warfarin three to six months after surgery, the rate was a little more than three times higher for cardiovascular death than that of patients who continued warfarin (6.5 compared to 2 deaths per 100 person-years).
Therefore, the researchers concluded that stopping warfarin within six months of surgery for aortic valve replacement was linked to a considerably higher rate of cardiovascular death.
The study was published November 27 in JAMA. The research was funded by the Research Fund of the Department of Cardiology at Copenhagen University Hospital Gentofte in Denmark.
One author reported receiving payments for lectures and consultancy unrelated to this study's topics from Servier and Bayer. Another author has received consultancy fees from Cardiome, Sanofi-Aventis, Merck and Bristol-Meyers Squibb. Another received a grant from the Danish Agency for Science, Technology and Innovation.