Despite heart failure being a prothrombotic state, a study of almost 300 patients was unable to find any evidence that aspirin reduced death, myocardial infarction or stroke in patients in sinus rhythm.
There was also no long-term benefit seen with warfarin therapy.
"The study did not demonstrate superiority of warfarin over no antithrombotic therapy for any primary or secondary outcome," the UK researchers said (Am Heart J 2004;148:157-64).
"However, warfarin was generally associated with more favourable outcomes and less serious adverse events than either aspirin or no antithrombotic therapy."
The researchers randomised participants to one of three groups: no antithrombotic treatment, aspirin (300 mg), or warfarin (target INR 2.5).
Patients using aspirin were more likely to be hospitalised, mainly for worsening heart failure, in the first year of follow-up, compared with people using warfarin or no therapy. They also experienced significantly more serious adverse gastrointestinal events.
Associate Professor Joseph Hung, head of cardiovascular medicine at Sir Charles Gairdner Hospital, Perth, said the trend towards worsening heart failure might be due to the deleterious effect of high-dose aspirin on inhibiting vascular wall prostacyclin synthesis and on renal function.
"These results should not be extrapolated to low dose (75-150 mg aspirin daily), which most physicians use for cardiovascular prophylaxis in patients with ischaemic heart disease," Professor Hung said.
Professor Henry Krum, consultant physician at the Alfred Heart Failure Centre, Melbourne, and head of clinical pharmacology at Monash University, said the findings backed the results of the another recent trial that found no evidence of benefit with warfarin or aspirin in heart failure.
"There is no overwhelming mandate to use warfarin or aspirin... in patients with sinus rhythm and heart failure unless there is compelling reasons to do so above the fact that they have heart failure," Professor Krum said.~MO