BOSTON – Patients with atrial fibrillation who also require hemodialysis receive no added antistroke benefit from warfarin treatment and may be more likely to have a major bleeding episode while on warfarin, based on a retrospective study of 302 patients at a single U.S. center.
“The safety and effectiveness of warfarin in patients with atrial fibrillation and chronic hemodialysis is questionable,” Dr. Lohit Garg said at the annual scientific sessions of the Heart Rhythm Society.
Dr. Garg noted that about 90% of patients in the review received aspirin, and they would also receive heparin three times a week as part of their hemodialysis protocol. ”It’s a good hypothesis” that aspirin plus heparin during hemodialysis might provide enough anticoagulation, but without warfarin the rate of stroke or transient ischemic attack was “pretty high,” 11%, “higher than [in] the general population, so aspirin and heparin may not be enough,” he said. The thromboembolic event rate with warfarin was 8%, not a statistically significant difference.
Dr. Garg and his associates reviewed patient charts at Beaumont Health System in Royal Oak, Mich., from 2009 to 2012 to find patients on chronic hemodialysis just diagnosed with new-onset atrial fibrillation (AF), and patients with chronic AF newly started on hemodialysis. They identified 724 such patients, and narrowed this down to 302 when they excluded those with valve disease or prosthesis, venous thromboembolic disease, coagulation or bleeding disorder, cancer, renal transplant, and a few other exclusions.
The study group included 119 patients (39%) who received warfarin and 183 (61%) who did not, at the discretion of their treating physicians. Patients averaged 77 years of age, and those who received warfarin and those who didn’t showed roughly similar rates of comorbidities, with no statistically significant differences between the two subgroups.
During an average follow-up of 2 years, the rates of thromboembolic events showed no statistically significant difference between the patients on warfarin and those not receiving the drug. Major bleeds occurred in 22% of the warfarin patients and 14% of those not on warfarin, a relative 53% increased risk with warfarin use that approached but did not reach statistical significance, reported Dr. Garg of the Heart Rhythm Center of Beaumont Hospital in Royal Oak, Mich.
Further, the major bleed subcategory of intracranial bleeds occurred in 10% of patients on warfarin and 4% of those off warfarin, a greater than doubled rate with warfarin, again a difference that approached but did achieve statistical significance. All the intracranial bleeds were fatal.
Dr. Garg also highlighted that these were high-risk patients, with 1.8-year average survival, and a median survival of about 2 years for both patients on warfarin and those off. During follow-up that extended as long as 5 years, 80% of patients died with similar mortality rates in the two treatment subgroups, 82% for those on warfarin and 79% for those who did not receive warfarin.
“We as cardiologists tend to prescribe warfarin” to patients like these, “but obviously we have to rethink this because it seems to harm patients without adding benefit,” commented Dr. Philipp Sommer, an electrophysiologist at the University of Leipzig (Germany).
Dr. Garg had no relevant financial disclosures.
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