Table 2.
Characteristics of Randomized, Controlled Trials Comparing Adjusted-dose Warfarin plus Aspirin to Adjusted-dose Warfarin Alone
| Author (Reference) | Year | Study Population | N | Age (mean yrs) | Sex (% male) | Warfarin* Plus Aspirin INR Target (mean) | Aspirin Dose | Warfarin*-only INR Target (mean) | Blinding | Duration F-up (mean) |
|---|---|---|---|---|---|---|---|---|---|---|
| Mechanical Heart Valve Trials | ||||||||||
| Single Intervention Trials (Comparing a single warfarin regimen with and without aspirin) | ||||||||||
| Laffort (15) | 2000 | Mechanical Mitral (60%) and Aortic + Mitral (40%) Valve Patients | 229 | 63 | 50 | 2.5 to 3.5 (3.04) | 200 mg qd | 2.5 to 3.5 (3.03) | open-label | 1 yr |
| Turpie (16) | 1993 | Mechanical† Aortic (46%), Mitral (44%) and Multiple (10%) Valve Patients | 370 | 58 | 51 | 3.0 to 4.5 (3.0) | 100 mg qd | 3.0 to 4.5 (3.1) | double-blinded aspirin, open-label warfarin | 2.5 yrs |
| Dale (12,17) | 1977 | Mechanical Aortic (100%) Valve Patients | 148 | 51‡ | 75 | TT 10% nl | 500 mg bid | TT 10% nl | double-blinded aspirin, open-label warfarin | 2 yrs |
| Altman (13) | 1976 | Mechanical Aortic (26%) and Mitral (74%) Valve Patients | 122 | NR | 75 | PT 1.8 to 2.3 × nl | 500 mg qd | PT 1.8 to 2.3 × nl | open-label | 2 yrs |
| Double Intervention Trials (Comparing moderate intensity warfarin plus aspirin versus higher intensity warfarin alone) | ||||||||||
| Meschengieser (18) | 1997 | Mechanical Aortic (66%), Mitral (29%) and Aortic + Mitral (4%) Valve Patients | 503 | 53 (median) | 58 | 2.5 to 3.5 (3.11) | 100 mg qd | 3.5 to 4.5 (3.98) | open-label | 2 yrs (median) |
| Post-Myocardial Infarction Trials | ||||||||||
| Single Intervention Trials (Comparing a single warfarin regimen with and without aspirin) | ||||||||||
| Huynh (19) | 2001 | Post-Myocardial Infarction (100% NQW) and Unstable Angina Patients with h/o CABG | 89§ | 67 | 79 | 2.0 to 2.5 (NR) | 80 mg qd | 2.0 to 2.5 (NR) | double-blinded W and A | 1 yr|| |
| Double Intervention Trials (Comparing moderate intensity warfarin plus aspirin versus higher intensity warfarin alone) | ||||||||||
| Hurlen (20) WARIS-2 | 2002 | Post-Myocardial Infarction (41% NQW) Patients | 2424§ | 60 | 77 | 2.0 to 2.5 (2.2) | 75 mg qd | 2.8 to 4.2 (2.8) | open label | 4 yrs |
| Van Es (21) ASPECT-2 | 2002 | Post-Myocardial Infarction (40.6% NQW, 46.7% QW) and Unstable Angina (12.6%) Patients | 647§ | 62 | 75 | 2.0 to 2.5 (2.4) | 80 mg qd | 3.0 to 4.0 (3.2) | open-label | 1 yr|| |
| Atrial Fibrillation Trials | ||||||||||
| Single Intervention Trials (Comparing a single warfarin regimen with and without aspirin) | ||||||||||
| Lechat (22) | 2001 | High-Risk¶ Non-Valvular Atrial Fibrillation Patients | 157 | 74 | 48 | 2.0 to 2.6 (NR) | 100 mg qd | 2.0 to 2.6 (NR) | double-blinded aspirin | 0.84 yr|| |
Specific oral anticoagulant: warfarin,16,19,20 acenocoumarin,13 phenoprocoumon or acenocoumarol,21 fluindione,22 not reported.12,15,17,18
Twenty-four percent of patients had tissue valves with atrial fibrillation or h/o thromboembolism.
Age at time of AVR >2 years (mean 42 months) prior to study entry.
All three post-MI trials had a third “aspirin-only” arm; overall numbers enrolled were 135,19 3630,20 and 993.21
Trial was stopped early due to slow enrollment.
h/o thromboembolic event OR age >65 and h/o HTN (>160/90), recent CHF episode, or EF <40%.
N. number enrolled; INR, international normalized ratio; TT, thrombotest; PT, prothrombin time; nl, normal; CHF, congestive heart failure; h/o, history of; AVR, aortic valve repair; EF, ejection fraction; CABG, coronary artery bypass grafting; qd, daily; NQW, non-Q-wave; QW, Q-wave.