NEW YORK (Reuters Health) – The question of when to resume warfarin therapy after a patient has an intracranial hemorrhage is answered in the December issue of Stroke. The risks of recurrent intracranial hemorrhage (ICH) versus stroke over a 3-year timeframe are lowest when warfarin is restarted between 10 and 30 weeks after discontinuation, the authors report.

“Don’t rush to start the patient back on warfarin!” said Dr. Sam Schulman in an email to Reuters Health. “The risk of a new intracranial bleeding with early resumption outweighs the risk of ischemic stroke with late resumption.”

For their retrospective analysis, Dr. Schulman with McMaster University and Hamilton Health Sciences-General Hospital in Hamilton, Ontario, Canada, and colleagues in three tertiary care hospitals reviewed the charts of 2869 consecutive patients with verified intracranial hemorrhage.

The team identified 177 patients who survived the first week and had a cardiac indication for anticoagulation or previous stroke, and then calculated hazards of recurrent hemorrhage and of ischemic stroke over a range of anticoagulation resumption times.

Overall, resumption of warfarin increased the risk of ICH (hazard ratio, 5.6) and lowered the risk of ischemic stroke (HR, 0.11), according to the report.

Median survival among the 177 patients was 4.5 years. The researchers therefore evaluated a range of treatment horizons from 3 to 6 years.

“The total risk of intracranial hemorrhage and an ischemic event for the whole treatment period varies according to when warfarin is restarted,” they report. “Based on this combined risk, the optimal period of resumption of warfarin seems to be between 10 and 30 weeks from the index intracranial hemorrhage over a survival- and treatment-horizon of 3 years.”

“This goes against previous expert opinion that was based on insufficient data,” Dr. Schulman noted.

The authors point out that the 20-week window for resumption of warfarin therapy may help in tailoring treatment for patients with a perceived higher risk for bleeding versus stroke or vice versa.

“Patients at high risk of stroke (mechanical mitral valves, atrial fibrillation with previous stroke, etc.) should be at the short end of the interval,” Dr. Schulman elaborated. “Patients at high risk of rebleeding (subdural hemorrhage, lobar intracerebral hemorrhage, other tendency to bleeding) should be at the far end.”

Summing up, he and his colleagues write, “In contradiction to previous studies, our data suggest that warfarin resumption should be delayed at least a month from the index event.”

Reference:

Optimal Timing of Resumption of Warfarin After Intracranial Hemorrhage

Stroke 201;41.