Long-term effect of chronic oral anticoagulation with warfarin after acute myocardial infarction

Efficacy and safety of aspirin combined with warfarin after acute coronary syndrome : A meta-analysis

A comprehensive meta-analysis was performed to investigate whether the combination of high-/low-dose of aspirin and various intensities of warfarin (W) offer greater benefit than aspirin (ASA) alone. A total of 14 randomized clinical trials (RCTs) having 26,916 patients with acute coronary syndrome (ACS) met inclusion criteria. The efficacy and safety of all outcomes which included myocardial infarction (MI), all-cause death, stroke, and bleeding were calculated. The overall outcomes analysis showed there was no significant difference in the risk of MI (relative ratio [RR] 0.959, 95 % confidence interval [CI] 0.78-1.04, P = 0.308), stroke (RR 0.789, 95 % CI 0.57-1.09, P = 0.145), and all-cause death (RR 1.007, 95 % CI 0.93-1.09, P = 0.87) between the combination group and ASA group. The subgroup analysis suggested that ASA (≤100 mg/day) plus W (mean international normalized ratio [INR] 2.0-3.0) decreased the risk rate of stroke (RR 0.660, 95 % CI 0.50-0.87, P = 0.003). There was a lower risk of MI (RR 0.605, 95 % CI 0.47-0.77, P < 0.0001) as well as stroke (RR 0.594, 95 % CI 0.45-0.79, P < 0.0001) between W (INR 2.0-3.0) combined with ASA (mean dose ≥100 mg/day) and ASA. However, the risk of major bleeding (RR 1.738, 95 % CI 1.45-2.08, P < 0.0001) and minor bleeding (RR 2.767, 95 % CI 2.12-3.61, P < 0.0001) was almost doubled in the combined groups. Compared with ASA, high-dose aspirin with moderate-intensity warfarin (INR 2.0-3.0) may better reduce the risk of MI and stroke but confer an increased risk of bleeding.

Cardiological aspects of stroke prevention

Many cardiac disorders and their treatment are associated with an increased risk for ischemic or hemorrhagic stroke, so it is important for cardiologists to be aware of recent advances in the field of stroke prevention. Atrial fibrillation (AF) is the most common cardiac disorder associated with a substantial risk for ischemic stroke (IS). The availability of implantable cardiac monitoring devices has substantially increased the detection rate of occult AF after IS. The 4 new oral anticoagulants have advantages when compared with warfarin, the standard therapy in AF to prevent IS, demonstrating a reduced risk for IS or intracerebral hemorrhage. Patients with cardiomyopathy, cardiac valve replacement, recent myocardial infarction, larger aortic arch atheroma and patent foramen ovale all have some level of increased risk for IS. The best approach for IS prevention in these disorders remains unsettled and varying approaches are recommended.

Genetic risk factors for major bleeding in patients treated with warfarin in a community setting

The influence of warfarin pharmacogenomics on major bleeding risk has been little studied in long-term users and non-specialist care settings. We conducted a case-control study to evaluate associations between CYP2C9*2/*3, VKORC1(1173), and CYP4F2*3 variants and major bleeding among patients treated with warfarin in a community setting. We calculated major bleeding odds ratios, adjusting for race, duration of warfarin use, age, gender, and body mass index. In 265 cases and 305 controls with 3.4 and 3.7 mean years of warfarin use, respectively, CYP4F2*3 was associated with decreased major bleeding risk (odds ratio: 0.62; 95% confidence interval: 0.43-0.91). CYP2C9*2/*3 and VKORC1(1173) had null associations overall, but there was a nonsignificant increase in major bleeding risk in patients with duration <6 months (odds ratio: 1.30; 95% confidence interval: 0.60-2.83; odds ratio: 1.23; 95% confidence interval: 0.57-2.64, respectively). In summary, in the largest study of warfarin pharmacogenomics and major bleeding to date, we found a 38% lower risk in patients with CYP4F2*3, potentially reflecting interaction with warfarin and dietary vitamin K intake and warranting additional evaluation.

Protecting the Brain and the Heart

Novel anticoagulants (NOACs) are the recent therapeutic breakthrough in the prophylaxis of stroke in patients with nonvalvular atrial fibrillation (NVAF). Patients with NVAF seem to have a high atherosclerotic burden, but it has not yet been established whether these agents also protect against cardiovascular disease (CVD). Different NOACs could have cardioprotective properties of different importance, but data come only from indirect comparisons. Patients with NVAF are at risk of stroke when there is concomitant atherosclerosis that also necessitates optimal treatment to reduce CVD risk. Combining antiplatelets with anticoagulants is a common clinical scenario and not always justified by current data and guidelines, putting patients at unnecessary bleeding risk. This review provides current knowledge about the cardioprotective properties of NOACs, the clinical importance of the link between CVD and NVAF, and the pitfalls of combining antiplatelet therapy with warfarin or NOACs.

[Prevention of cardioembolic stroke]

Stroke and atrial fibrillation (AF) constitute a true vascular epidemic with catastrophic consequences. The most common and devastating complication of AF is cardioembolic stroke but this catastrophic event can be predicted and prevented. Accurate etiologic diagnosis of stroke is essential for effective prevention. The percentage of cryptogenic ischemic strokes is too high and detection of AF and other causes of cardioembolic events should be improved. Cardioembolic cerebral ischemia can be prevented. However, because of physician inertia, lack of patient adherence and the problems of vitamin K antagonists, many patients are at risk of cerebral ischemia. Recently, major advances with drugs such as dronedarone, dabigatran and FXa inhibitors have opened the way to improving stroke prevention, as reflected in therapeutic guidelines, and neurologists should be familiar with these drugs. There is reason to hope that much suffering can be avoided.

Low doses of acetylsalicylic acid increase risk of gastrointestinal bleeding in a meta-analysis

BACKGROUND & AIMS

We performed a meta-analysis of data from randomized trials to estimate the risk of all-cause mortality and bleeding (and especially gastrointestinal [GI] bleeding) in patients treated with low doses of acetylsalicylic acid (ASA) (75-325 mg/d), alone or in combination with other medications.

METHODS

We searched 10 electronic databases (until October 2010) and collected data on adverse events in randomized controlled studies that evaluated low doses of ASA, alone (35 trials) or in combination with anticoagulants (18 trials), clopidogrel (5 trials), or proton pump inhibitors (PPIs; 3 trials). We analyzed data using random-effects meta-analysis and meta-regression, applying Peto's odds ratio (OR) for adverse events.

RESULTS

Low doses of ASA alone decreased the risk for all-cause mortality (relative risk, 0.93, 95% confidence interval [CI], 0.87-0.99), largely because of effects in secondary prevention populations. The risk of major GI bleeding increased with low doses of ASA alone (OR, 1.55; 95% CI, 1.27-1.90), compared with inert control reagents. The risk increased when ASA was combined with clopidogrel, compared with aspirin alone (OR, 1.86; 95% CI, 1.49-2.31), anticoagulants vs low doses of ASA alone (OR, 1.93; 95% CI, 1.42-2.61), or in studies that included patients with a history of GI bleeding or of longer duration. Importantly, PPI use reduced the risk for major GI bleeding in patients given low doses of ASA (OR, 0.34; 95% CI, 0.21-0.57).

CONCLUSIONS

In a meta-analysis, low doses of ASA increased the risk for GI bleeding; risk increased with accompanying use of clopidogrel and anticoagulant therapies, but decreased in patients who took PPIs.