Equal Antiplatelet Effects of Aspirin 50 or 324 mg/Day in Patients After Acute Myocardial Infarction

This study explores the effects on some hematological parameters of a low-dose aspirin regimen (50 mg/day) versus a conventional aspirin treatment with reported antithrombotic efficacy (324 mg/day), in patients with acute myocardial infarction. Fifteen patients were randomized into 3 equal groups receiving 50 mg or 324 mg aspirin or placebo, daily for 21 days. Compared with placebo, bleeding time was significantly and similarly prolonged with both aspirin doses (+ 71 ± 22% and + 69 ± 20%, mean ± S.D.). Aspirin 50 mg/day suppressed arachidonate-induced platelet aggregation and secondary phase aggregation after ADP and adrenaline. Collagen aggregation was inhibited by 44 ± 15%. In no case were differences in the antiplatelet effects of the two doses observed. The effects of 50 mg/day persisted without attenuation during the observation period. Platelet thromboxane B2 generation during arachidonate-induced aggregation was inhibited by 95 ± 2 and 99 ± 1% compared to placebo group after 50 and 324 mg/day, respectively (P between doses <0.05). No change was observed with any treatment in coagulation time, prothrombin time or plasma thromboplastin time. Thus, in patients with acute myocardial infarction, the antiplatelet effects of aspirin 50 mg/day are stable over time and superimposable on those of 324 mg/day. The antithrombotic efficacy of aspirin 50 mg/day remains to be tested clinically.

Physiological response in healthy subjects and in patients after myocardial infarction, elicited by a new computerised version of the Raven Coloured PM 47 as a mental stress test

The Raven Progressive Matrices Test, in its various versions, has frequently been used in research on stress related diseases. In this paper the preliminary data relating to the administration of this version of test performed by a personal computer are presented. The "Coloured" version of the PM 47 was used, with the addition of a series of visual and acoustic stress stimuli; a maximum 30-second matrix presentation time was also introduced. Two groups took part in the test modified in this way: the first was made up of 23 male subjects aged 30 to 65 who had had a myocardial infarction in the previous six months; the second, a control group of the first, was composed of an equal number of subjects, without present or past cardiovascular or psychiatric disorders or illness. Frontal EMG, skin conductance response, peripheral temperature, heart rate and respiration rate were recorded at rest and during the test administration. The results obtained from the psychophysiological profile carried out on the two groups demonstrated the effectiveness of the methodology used in eliciting constant and stable stress responses.

Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dipyridamole echocardiography

Dipyridamole echocardiography test (DET) has gained acceptance due to its safety, feasibility, diagnostic accuracy and prognostic power. The main limitation of the test is a less than ideal sensitivity in some patient subsets, such as those with limited coronary artery disease. Atropine with dipyridamole might theoretically combine to become a synergistic ischaemic stress test, by increasing myocardial oxygen demand through chronotropic stress and by reducing flow supply through a shortening of the diastolic interval under maximal coronary vasodilation. The aim of this study was to assess the effects of the addition of atropine to DET. Three hundred and twenty-one patients (age = 58 +/- 9 years), referred for testing in the echo lab, were initially studied by DET. Of these, 151 were stopped during or within the 2 min following dipyridamole infusion because of achievement of a predetermined end-point: obvious echocardiographic positivity (n = 137), severe chest pain (n = 3), diagnostic ST segment changes (n = 7) or limited side effects (n = 4). In another three cases, atropine was not given due to a history of glaucoma or severe prostatic hypertrophy. In the remaining 167 patients with a negative DET test, atropine (0.25 mg intravenously, repeated every min up to a maximum of 1 mg, if necessary) was added, starting 3 min after the end of the dipyridamole infusion. The dipyridamole-atropine echo test (DETA) was positive in 32 and negative in 135 patients, and no major side effects occurred in any patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Equal antiplatelet effects of aspirin 50 or 324 mg/day in patients after acute myocardial infarction

This study explores the effects on some hematological parameters of a low-dose aspirin regimen (50 mg/day) versus a conventional aspirin treatment with reported antithrombotic efficacy (324 mg/day), in patients with acute myocardial infarction. Fifteen patients were randomized into 3 equal groups receiving 50 mg or 324 mg aspirin or placebo, daily for 21 days. Compared with placebo, bleeding time was significantly and similarly prolonged with both aspirin doses (+ 71 +/- 22% and + 69 +/- 20%, mean +/- S.D.). Aspirin 50 mg/day suppressed arachidonate-induced platelet aggregation and secondary phase aggregation after ADP and adrenaline. Collagen aggregation was inhibited by 44 +/- 15%. In no case were differences in the antiplatelet effects of the two doses observed. The effects of 50 mg/day persisted without attenuation during the observation period. Platelet thromboxane B2 generation during arachidonate-induced aggregation was inhibited by 95 +/- 2 and 99 +/- 1% compared to placebo group after 50 and 324 mg/day, respectively (P between doses less than 0.05). No change was observed with any treatment in coagulation time, prothrombin time or plasma thromboplastin time. Thus, in patients with acute myocardial infarction, the antiplatelet effects of aspirin 50 mg/day are stable over time and superimposable on those of 324 mg/day. The antithrombotic efficacy of aspirin 50 mg/day remains to be tested clinically.