Antiplatelet therapy is effective in the prevention of stroke or death in women: subgroup analysis of the European Stroke Prevention Study (ESPS)

Aspirin in the prophylaxis of coronary artery disease

Aspirin has been used for more than 100 years, but its mechanisms of action have only been understood in the past 20 years. Aspirin interferes with arachidonic acid metabolism in platelets and endothelial cells and thereby reduces thromboxane A2 and prostacyclin. It also has other mechanisms of action, including anti-inflammatory roles, protection from oxidative stress, enhancement of fibrinolysis, and suppression of plasma coagulation and platelet-dependent inhibition of thrombin generation. It has been used for primary and secondary prevention of myocardial ischemia, and for primary and secondary prevention of cerebrovascular ischemia. We review the 5 pivotal studies relating to primary prevention for cardiovascular risk and the many studies relating to secondary prevention of myocardial ischemia. We also review the utility of aspirin in primary prevention of myocardial infarction and stroke. We conclude that aspirin is one of the most potent drugs ever discovered and that its effects extend well beyond those of cycloxoxygenase enzyme inhibition. Aspirin treatment does not preclude control of underlying and comorbid conditions such as diabetes mellitus, hypertension, and dyslipidemia. For most patients, a daily dose of 325 mg is optimal. Patients must understand the potential for gastrointestinal upset and hemorrhagic complications. The utility of aspirin is greater in coronary artery disease prevention than in cerebrovascular prevention.

Ten-year trends in stroke incidence and mortality in the FINMONICA Stroke Study

BACKGROUND AND PURPOSE

The trends in stroke incidence reported so far have not been entirely consistent, although declining trends in mortality from stroke have been reported from a number of studies around the world. This study aims to evaluate the 10-year trends (from 1983 through 1992) in incidence, attack rate, and mortality of stroke in the Finnish population.

METHODS

A population-based stroke register was set up in the early 1980s to collect data on all suspected events of acute stroke that occurred in the population aged 25 to 74 years permanently residing in three geographic areas of Finland: the provinces of Kuopio and North Karelia in eastern Finland and the Turku-Loimaa area in southwestern Finland. Trends in age-standardized attack rates, incidence, and mortality were calculated for the period studied.

RESULTS

During the 10-year study period, 11 392 acute stroke events occurred in the monitored populations. A statistically significant decline was observed in the pooled FINMONICA data, both in the incidence of stroke (-1.7% with 95% confidence interval [CI], -3.0% to -0.5% per year in men; -2.2% with 95% CI, -3.6% to -0.7% per year in women) and in mortality from stroke (-5.2% with 95% CI, -8.2% to -2.2% per year; -4.7% with 95% CI, -8.2% to -1.2% per year). The attack rate of stroke also declined significantly in both sexes. When the areas were considered separately, the declining trends were observed within each area. The decline in incidence of stroke was, however, statistically significant only among men and women in Kuopio and among women in Turku/Loimaa. Mortality declined significantly in all three areas among men but among women only in Kuopio. The incidence to mortality rate ratio increased during the study period, indicating a steeper fall in mortality than in incidence.

CONCLUSIONS

A substantial decline in both stroke incidence and mortality was observed in the adult and elderly population in the FINMONICA study areas. Part but not all of the decline in stroke mortality, observed also in the official mortality statistics, can be attributed to the decline in stroke incidence during this 10-year period.

Ketamine antagonizes hypoxia-induced dopamine release in rat striatum

The purpose of this study is to investigate the hypothesis that ketamine, a non-competitive antagonist of the N-methyl-D-aspartate (NMDA) receptor, attenuates hypoxia-induced striatal dopamine release in vivo. High-speed chronoamperometric recording techniques, using Nafion-coated carbon fiber electrodes, were used to evaluate extracellular dopamine (DA) concentration in the striatum. KCl and DA were locally applied directly to the striatum of urethane-anesthetized Sprague-Dawley rats, in order to measure release and clearance, respectively, of DA. These anesthetized animals were paralyzed with D-tubocurarine and connected to a respirator to allow controlled respiration. Systemic concentrations of oxygen and carbon dioxide were altered by changing the partial pressure of O2, CO2, N2 of inspired air and the rate of the respirator. Our data indicate that lowering the respiratory rate from 90 to 20 times/min for 5 min, in room air, caused a decrease in blood O2 while increasing the CO2 concentration. These changes in blood gas concentration were reversible and reproducible. We also found that lowering the respiratory rates potentiated K(+)-induced DA release but not DA clearance in the striatum. In an attempt to induce hypercapnia, the room air was replaced with high CO2-containing air (15% CO2 + 20% O2 + 65% N2), and this change resulted in increased blood CO2 levels without lowering O2 concentration. The hypercapnia did not alter K(+)-induced DA release in the striatum. Next, we attempted to simulate anoxic hypoxia in the absence of hypercapnia. Respiration with pure N2 for 30 s resulted in lowering blood O2 without increasing CO2 levels. Both basal and K(+)-evoked DA releases were increased during N2-induced anoxic hypoxia. These data suggested that transient hypoxia facilitates DA release in the striatum. It has been suggested that NMDA is involved in many hypoxia-mediated responses. We also found that systemic application of ketamine, which itself did not affect blood O2 or CO2 levels, antagonized hypoxia-induced electrochemical responses. These data suggest that the increase in DA release in vivo during short-term hypoxia may probably be mediated through NMDA receptors.

Delayed neutropenia with ticlopidine

OBJECTIVE

To report a case of ticlopidine-induced neutropenia occurring 18 days after discontinuation of the drug.

CASE SUMMARY

A 68-year-old woman was placed on ticlopidine after a transient ischemic attack. Ten days later the drug was discontinued because the patient developed a rash. Eighteen days later she developed pneumonia and neutropenia, which were believed to be induced by ticlopidine.

DISCUSSION

Drug-induced neutropenia is serious and at times life-threatening. Ticlopidine-induced neutropenia has been described in patients receiving the medication. We report neutropenia occurring 18 days after discontinuation of ticlopidine.

CONCLUSIONS

Indications for prescribing ticlopidine must be closely followed. Complete blood cell count monitoring is imperative while the patient is receiving the medication. This case suggests that the duration of monitoring after the discontinuation of ticlopidine may need to be longer than the 14 days recommended by the manufacturer.

Ticlopidine and antiplatelet therapy

OBJECTIVE

To review the pharmacology, pharmacokinetics, clinical efficacy, and toxicity of ticlopidine. Comparisons with other antiplatelet agents are presented, with an emphasis on efficacy, and a recommendation is provided regarding ticlopidine's place in therapy.

DATA SOURCES

A MEDLINE literature retrieval of English-language journal articles from 1987 to January 1993 and references identified from bibliographies of review articles and clinical trials.

STUDY SELECTION

Randomized, blind, controlled studies of ticlopidine and other antiplatelet agents were preferentially selected.

DATA EXTRACTION

Clinical trials were reviewed in terms of study design, efficacy results, and toxicity.

DATA SYNTHESIS

Ticlopidine is a new antiplatelet agent with a distinct mechanism of action. In the largest trial of the drug for the prevention of stroke, it was found to be more effective than aspirin in reducing the risk of stroke or death. Clinical trials have also shown ticlopidine to decrease the rate of vascular death and myocardial infarction in patients with unstable angina, and to maintain venous graft patency after coronary artery bypass grafting. The use of ticlopidine in diabetic microangiopathy and peripheral vascular disease appears promising, but further studies are needed. Adverse reactions most commonly reported with ticlopidine are gastrointestinal complaints; the most severe reaction is transient neutropenia, which is seen in approximately 2.3 percent of patients and is severe in nearly 1 percent.

CONCLUSIONS

Ticlopidine is a reasonable alternative for use in preventing stroke among patients unable to take aspirin or those who do not benefit from aspirin therapy. Its use as first-line therapy is limited by its high cost and the occurrence of hematologic adverse effects.