Warfarin therapy decreased the composite endpoint of death, recurrent myocardial infarction, and ischemic stroke after an incident acute MI with atrial fibrillation among patients who had chronic kidney disease of all severities, according to a report published online March 4 in JAMA.
In a prospective nationwide cohort study involving 24,317 such patients in Sweden, warfarin provided this benefit without raising the risk of bleeding during 1 year of follow-up. Approximately half of the study participants had CKD of stage 3 or higher. Only 22% were given warfarin at hospital discharge, said Juan Jesus Carrero, Ph.D., of the Center for Molecular Medicine, Karolinska Institutet, Stockholm, and his associates.
During follow-up, there were 9,002 composite endpoint events: 3,551 deaths, 4,573 recurrent MIs, and 878 ischemic strokes. Across all categories of CKD severity, patients taking warfarin had 5.8% fewer deaths, 2.2% fewer MIs, and 1.8% fewer ischemic strokes than those not taking warfarin. Yet the relative risk of bleeding events was not significantly higher with warfarin, regardless of the severity of CKD, the investigators said (JAMA 2014 March 4 [doi:10.1001/jama.2014.1334]).
These findings refute the results of some earlier observational studies in which warfarin therapy raised the risk of death or stroke in severe CKD, which prompted a modification of treatment guidelines. Ironically, patients with CKD potentially have the most to gain from using prophylactic warfarin, since their renal dysfunction puts them at additional risk of stroke and death, Dr. Carrero and his colleagues noted.
This study was supported by the Swedish Foundation for Strategic Research. Dr. Carrero reported no potential financial conflicts of interest; his associates reported ties to numerous industry sources.