Evidence Favoring the Use of Anticoagulants in the Hospital Phase of Acute Myocardial Infarction

Abstract

Since the last comprehensive review of anticoagulation in acute myocardial infarction four additional randomized control trials have been reported. The overwhelming majority of all trials favored anticoagulation. Rates of thromboembolism were higher in the control, and hemorrhagic complications in the anticoagulated group. Pooling of all randomized control trials gives mean case fatality rates of 19.6% for the control and 15.4% for the anticoagulated group, a relative reduction of 21% (P less than 0.05 or less than 0.001, depending on the analytic method). Five of six randomized control trials reported "no effect" because the difference favoring anticoagulation was not statistically significant. However, sample sizes in these "negative" papers were too small to protect against missing a 21% reduction in true case fatality rate due to anticoagulation (beta greater than 0.10). All patients who present no specific contraindication should receive anticoagulants during hospitalization for infarction.

Analysis of the Treatment of Acute Myocardial Infarction Using Ambulance Records in Japanese Cities

“…Reports have described the shortening of decision time by means of early recognition of symptoms by education of patients, 5 the 'chain of survival' concept advocated by the American Heart Association, 6 thrombolytic therapy, 7-13 anticoagulant therapy, 7,8,14,15 emergency PTCA, 13,[16][17][18][19][20][21][22][23] assisted circulation 24,25 and a system to determine the effect of prehospital-initiated treatment of myocardial infarction. 26,27 Many reports have shown that case-fatality rates of AMI patients arriving quickly at specialty institutions are decreased by recanalization therapy and assisted circulation in contrast to patients not so treated.…”

How to assess new treatments

“…Larger estimates of treatment effects have been shown in nonrandomized, compared with randomized, studies. 6,7 In addition to being randomly assigned, the allocation of study participants (that is, into which group a patient will be assigned) must be adequately concealed. The treating physician, participant, and anybody else associated with outcome assessment must be unaware of the randomization sequence.…”

Is Renal Artery Stenting the Correct Treatmentof Renal Artery Stenosis?

“…Thus, all such observations suggest but are unable to establish the relative benefit of revascularization or the true value of the baseline test strategy to predict outcome with differing treatments. This limitation, the absence of a robust and appropriate control group, has led to false conclusions, later disproved with appropriate randomized trials, about the utility of a wide variety of clinical therapies, including surgery for Ménière's disease, 101 warfarin for acute myocardial infarction, 102 portosystemic shunts, 103 and antiarrhythmic therapy after myocardial infarction. 104 This is likely to be important for patients with renal artery hypertension.…”