Aspirin not needed with anticoagulation/clopidogrel after MI, PCI in AF

September 15, 2013

A 12,000-patient Danish study suggests that the addition of one antiplatelet agent to oral anticoagulation is sufficient.

A Danish study of over 12,000 patients with atrial fibrillation (AF) who had a myocardial infarction (MI) or percutaneous coronary intervention (PCI) suggests that the addition of one antiplatelet agent to oral anticoagulation is sufficient. The review also found that the best agent to add is clopidogrel (vs. aspirin).

The study used nationwide registries to track 12,165 patients with AF who were hospitalized for MI or PCI; about 61% were men, and the mean age was 75. Nearly two-thirds were treated with multiple antithrombotic drugs at baseline, and 38.3% received oral anticoagulation therapy.

Triple antithrombotic therapy is commonly used in patients with multiple indications for antithrombotic therapy. The data suggest that replacing triple therapy regimens with oral anticoagulation and clopidogrel will carry a lower risk of bleeding and no additional risk of recurrent thrombotic events, the authors indicated.

An accompanying editorial cautioned against extrapolating these results to the newer target-specific anticoagulants, citing that adding dual antiplatelet agents to the new agents would be likely to cause more bleeding than benefit.

Sources: Lamberts M, Gislason GH, Olesen JB, et al. Oral anticoagulation and antiplatelets in atrial fibrillation patients after myocardial infarction and coronary intervention. J Am Coll Cardiol. 2013;Epub ahead of print. Markowitz SM. Antithrombotic regimens in patients with atrial fibrillation and coronary disease: Optimizing efficacy and safety [editorial]. J Am Coll Cardiol. 2013;Epub ahead of print. June 4, 2013 in the Journal of the American College of Cardiology.

Smoking increases risk of VTE in post-op period

Evidence about the effect of smoking on venous thromboembolism risk (VTE) is limited and inconsistent. A subanalysis of the Million Women Study (U.K.) examined the incidence of VTE in relation to smoking habits, both in the absence of surgery and in the first 12 post-operative weeks.

Of the women included in this study, 4,630 (mean age 56) were admitted to the hospital for or died of VTE. Current smokers had a significantly increased incidence of VTE compared with those who never smoked (adjusted RR 1.38), with significantly greater risks in heavier (>15 cigarettes per day) vs. lighter smokers.

Current smokers were also more likely to have surgery than those who never smoked (RR 1.12), 95% CI 1.12-1.13). Among women who had surgery, the incidence of VTE in the first 12 postoperative weeks was significantly greater in current smokers than for those who never smoked (RR 1.16).

Smoking increases the overall risk of VTE regardless of whether the patient is post-op. However, the risk is greater in the post-operative period. Because of this, smoking should be considered in the assessment of VTE risk in patients undergoing surgery.

Source: Sweetland S, Parkin L, Balkwill A, et al. Smoking, surgery, and venous thromboembolism risk in women. Circulation. 2013;127:1276–1282.
Newer generation heart valve may allow for lower intensity anticoagulation

Researchers recently presented findings of a study using low-dose warfarin to prevent complications with a newer-generation mechanical aortic valve.

The interim results reflect assessment of 375 patients whose preoperative risk factors for thromboembolism (TE) required aortic valve replacement and who met high-risk criteria that included chronic atrial fibrillation, left ventricular ejection fraction <30%, ventricular aneurysm, an enlarged left atrium of >50 mm in diameter, and spontaneous echo contrast in the left atrium.

The patients were randomized to receive either lower-dose warfarin (n=190; INR 1.5-2.0) or to continue standard-dose warfarin (INR 2.0-3.0), for three months following mechanical AVR with the On-X mechanical valve.

All of the patients received 81-mg aspirin daily, and INR was adjusted according to home monitoring. Their mean age was 55.2, and 79% were male.

With an average follow-up of 3.42 years, the patients in the low-dose warfarin group had a mean INR of 1.89, compared with 2.50 in the standard-dose group. The low-dose group had significantly lower major and minor bleeding event rates, and there were no significant differences between the two groups in terms of stroke, transient ischemic attack, or total neurological events. There were no significant differences in all-cause mortality between the low-dose and standard-dose groups.

The study is ongoing.

Source: Puskas JD, Nichols D, Gerdisch M, et al. Reduced anticoagulation after mechanical aortic valve replacement: Interim results from the PROACT randomized FDA IDE trial. American Association for Thoracic Surgery 2013 Annual Meeting. May 6, 2013; Minneapolis, MN. Abstract 1.