New dabigatran safety concerns

April 15, 2012

The safety of dabigatran is being called into question again. Concern has arisen about an increased risk of myocardial infarction in patients who are treated with the drug.

A recently completed subanalysis of the data from the RE-LY trial found that although there was an overall increased risk for MI in the dabigatran group, further analysis of events in a subgroup of patients with existing ischemic heart disease did not show an increased risk of MI. This study included only patients with atrial fibrillation (AF) who were randomized to receive either dabigatran or warfarin.

A recent meta-analysis of 7 trials of dabigatran confirms an increased MI risk with the drug. The authors of both articles agree that there is an overall MI risk with dabigatran, but that the benefits outweigh the risk in patients with AF. The lead author of the meta-analysis suggests that more study is needed to clarify the risk across a broader range of indications and patient types.

Bleeding risk outweighs benefit of aspirin use

The net benefit of aspirin in the prevention of cardiovascular disease and nonvascular events continues to be unclear. A recent meta-analysis of 9 randomized placebo-controlled studies sought to determine the impact (and safety) of aspirin on vascular and nonvascular outcomes in primary prevention.

The analysis included a total of 100,000 participants. Results showed that during a mean follow-up of 6 years, aspirin treatment reduced total cardiovascular events by 10%, driven primarily by a reduction in nonfatal MI, but there was a 30% increased risk of bleeding events. The number needed to treat to prevent 1 cardiovascular event was 120, compared with 73 for causing a nontrivial bleed.

The authors concluded that the small increase in benefit in the context of a significant increase in risk of bleeding does not justify routine use of aspirin for primary prevention of cardiovascular events. Further study is needed to identify subsets that may have a favorable risk/benefit ratio.

Source: Seshasai SRK, Wijesuriya S, Sivakumaran R, et al. Effect of aspirin on vascular and nonvascular outcomes: Meta-analysis of randomized controlled trials. Arch Intern Med. 2012;172:209-216.

ACCP publishes updated guidelines for antithrombotic therapy/thrombosis prevention

The American College of Chest Physicians has updated the guideline for antithrombotic therapy and thrombosis prevention. This document was last published in 2009. There are a number of changes regarding use of vitamin K antagonists (VKA). Selected highlights include:

The full Executive Summary is available at http://chestjournal.chestpubs.org/content/141/2_suppl/7S.full.

Source: Guyatt GH, Akl EA, Crowther M, et al; American College of Chest Physicians Antithrombotic Therapy and Prevention of Thrombosis Panel. Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest. 2012;141(2 suppl):7s-47s.

Anna D. Garrett is a clinical pharmacist at Mission Hospital, Asheville, N.C., and president of Find Your Best Thinking, a health and wellness coaching company. Contact her at anna@findyourbestthinking.com