The pyrimido-pyrimidine derivative, dipyridamole, pos- sesses antiplatelet effects but does not have a proven role in patients with SIHD. The combination of aspirin and dipyri- damole was not clearly superior to aspirin alone in preventing reinfarction in the PARIS (Persantine-Aspirin Reinfarction Study).722 Because dipyridamole vasodilates coronary resis- tance vessels and can provoke exercise-induced myocardial ischemia, it is not recommended for secondary prevention in patients with SIHD.748,749 4.4.2.1.2. Oral Anticoagulant Therapy. Fibrinolytic function can be disturbed in patients with IHD, particularly related to activation of the extrinsic coagulation pathway leading to formation of thrombin. Thrombin, in turn, generates fibrin and promotes platelet activation and aggregation, thereby amplifying the activity of both the coagulation and platelet pathways.750 752 These observations have provided a poten- tial rationale for antithrombotic therapy in patients with SIHD. A systematic review of randomized trials of oral anticoagulants with and without antiplatelet therapy among 20 000 patients with IHD, however, failed to provide evi- dence of benefit from anticoagulation, and it is not recom- mended.753 Similarly, there is no evidence that individuals with defects in the coagulation system, such as G1691A factor V Leiden, G20201A prothrombin, G455A fibrinogen chain, G10976A factor VII, or the plasminogen activator inhibitor-1 4G/5G polymorphisms, are at higher risk of cardiac events, and they should not receive anticoagulation therapy solely to prevent such events.754 756 4.4.2.2. Beta-Blocker Therapy Class I 1. Beta-blocker therapy should be started and continued for 3 years in all patients with normal LV function after MI or ACS.757 759 (Level of Evidence: B) 2. Beta-blocker therapy should be used in all patients with LV systolic dysfunction (EF <40%) with heart failure or prior MI, unless contraindicated. (Use should be limited to carvedilol, metoprolol succinate, or bisoprolol, which have been shown to reduce risk of death.)