Aspirin Administration In Patients Research Articles

Delay of Aspirin Administration in patients after Stroke Code Activation, who are not candidates for tissue Plasminogen Activator (t-PA) or Mechanical Thrombectomy (MT) pre- and post-COVID pandemic. (P7-5.021)

<h3>Objective:</h3> To determine factors involved in delay of aspirin administration in patients, who are evaluated after stroke code activation and are not candidates for IV t-PA or MT pre- and post-COVID pandemic. <h3>Background:</h3> Majority of patients, who are evaluated in emergency department (ED) after stroke code activation are not candidates for IV-t-PA or MT. Such patients can be candidates for aspirin as secondary stroke prevention. Ordering and administering aspirin is, sometimes, delayed due to various factors, which leads to delay in care of patients. Assessing and addressing these factors are paramount in timely administration of aspirin. <h3>Design/Methods:</h3> This is a retrospective chart review and quality improvement project. The approval from institutional IRB was obtained. <h3>Results:</h3> EMR of 264 patients (105 patients in 62 days pre-COVID; 159 patients in 120 days post COVID) was reviewed. 153 patients (57 pre- COVID, 96 post-COVID) were excluded as they were not candidates for aspirin (on anticoagulant = 31; intracranial hemorrhage = 28; initial presentation seizures = 26 and others = 68). 111 patients (48 pre-COVID, 63 post-COVID) were included in analysis. Demographics of included patients were: average age = 62.1 (range: 23–94) years, male = 49, female = 62. Average interval between stroke code activation and aspirin ordered by healthcare provider (HCP) was 191 minutes pre-COVID and 165 minutes post-COVID pandemic. Average interval between aspirin ordered by HCP and administered by nursing staff was 295 minutes pre-COVID and 255 minutes post-COVID pandemic. <h3>Conclusions:</h3> Delay in ordering and administering aspirin was seen in pre- as well as post-COVID pandemic. Delay in administering aspirin by nursing staff was primarily due to failure to order aspirin STAT and erroneously keeping patient nothing per oral by HCP. Proper education of HCP and nursing staff is paramount for timely and correctly ordering, and administering aspirin and hence to improve quality of care to patients. <b>Disclosure:</b> Dr. Anjum has nothing to disclose. Dr. Parvathaneni has nothing to disclose. Dr. Javalkar has nothing to disclose. Dr. Chernyshev has nothing to disclose.

Kinetics of Circulating Extracellular Vesicles Over the 24-Hour Dosing Interval After Low-Dose Aspirin Administration in Patients atCardiovascular Risk.

Extracellular vesicles (EVs) are small vesicles deriving from all cell types during cell activation, involved in transcellular communication, and regarded as predictors of vascular damage and of cardiovascular events. We tested the hypothesis that, in patients on chronic low-dose aspirin treatment for cardiovascular prevention, aspirin may affect the release of EVs within the 24-hour interval. We enrolled 84 patients, mostly at high or very high cardiovascular risk, on chronic low-dose aspirin treatment. The numbers of circulating EVs (cEVs) and annexinV+ cEVs (total, platelet-derived, endothelial-derived, and leucocyte-derived) were assessed immediately before, and after 10 and 24 hours of a witnessed aspirin administration. Platelet cyclooxygenase 1 (COX-1) recovery was characterized by measuring serum thromboxane B2 (sTXB2 ) at the same timepoints. Nine healthy participants were also enrolled. In patients, daily aspirin administration acutely inhibited after 10 hours following aspirin administrations the release of cEVs (total and leukocyte-derived) and annexinV+ cEVs (total, platelet-derived, endothelial-derived, and leukocyte-derived), with a rapid recovery at 24 hours. The inhibition after 10 hours suggests a COX-1-dependent mechanism. Interestingly, the slope of platelet-derived and of annexinV+ platelet-derived cEVs were both directly related to sTXB2 slope and COX-1 messenger RNA, raising the hypothesis that vice versa, cEVs may affect the rate of COX-1 recovery and the subsequent duration of aspirin effect. In healthy participants, no circadian difference was observed, except for leukocyte-derived cEVs. Our findings suggest a previously unappreciated effect of aspirin on the kinetics of a subset of cEVs possibly contributing to the cardioprotective effects of this drug.

A randomized controlled trial on Aspirin and complex regional pain syndrome after radius fractures.

Complex regional pain syndrome (CRPS) is often diagnosed in patients who are recovered with surgery or injury. CRPS is usually diagnosed in patients recovering from distal radius fractures. The aim of study was the effects of aspirin in prevention of the complex regional pain syndrome (CRPS) following a fracture of distal radius. In a double-blind, randomized controlled trial, 91 patients with unilateral extra-articular distal radius fractures were randomly allocated to receive either placebo (PLA) or 500 mg of aspirin (ASA) daily for 7 days. The effect of aspirin on the occurrence of CRPS was evaluated. The patients were assessed clinically and radiographically in the second, fourth and twelfth weeks by a physician who was unaware of the treatment allocation. Ninety-one patients (ASA, n=44; PLA, n=47) were enrolled in the study. The prevalence of CRPS in all patients was 16.5%. The prevalence of CRPS in the aspirin group was lower (13.6%) than the placebo group (19.1%), but this difference was not statistically significant. The only significant difference was the lower rate of regional osteoporosis seen in the radiographs of aspirin group. Mean age was significantly higher in the patients with CRPS. Also, comminuted distal radius fractures (A3-type) were significantly more common in the patients with CRPS. Administration of aspirin in patients with a distal radius fracture was associated with a lower incidence of CRPS, but, not statistically significant. Further investigations needs to be done with a larger sample size, longer follow-up period and multi-center design.

Evaluation of the antihypertensive effect of nocturnal administration of acetylsalicylic acid: a cross-over randomized clinical trial.

Several studies have shown that evening intake of aspirin has antihypertensive effect in healthy adults, which has not been proven in patients with cardiovascular disease, who mostly take aspirin in the morning. We have evaluated the antihypertensive effect of bedtime administration of aspirin in patients with cardiovascular disease already treated for hypertension. This is a multicenter randomized triple-blind placebo-controlled crossover trial, with hypertensive patients treated with aspirin for secondary prevention. There was a baseline-randomized assignment to 2-month periods of bedtime aspirin (100 mg) first and morning-time aspirin later, or inversely, both periods separated by an open label 2-4 weeks period of morning-time aspirin. At the start and end of each treatment period, a 24-h ambulatory blood pressure monitoring was performed. The main outcome measure was mean 24-h blood pressure. The analyses were performed according to the intention-to-treat principle. Overall, 225 patients were randomized. No significant differences were observed in ambulatory blood pressure by time of intake of usual low doses of aspirin. The mean SBP/DBP was 123.2/69.9 (95% CI 121.58-124.9/68.86-76.86) with bedtime administration and 122.4/68.8 (95% CI 120.76-124.01/67.85-69.83) with daytime administration (P = 0.3 and P = 0.23 for SBP and DBP, respectively). Administering aspirin at bedtime rather than in the morning does not modify the 24-h ambulatory blood pressure in hypertensive patients in secondary cardiovascular prevention.The trial was registered with ClinicalTrials.gov (number NCT01741922).

Preoperative continuation of aspirin administration in patients undergoing major abdominal malignancy surgery.

In contrast to that in a nonoperative setting, it has been shown that perioperative administration of aspirin did not decrease the rate of death or myocardial infarction but increased major bleeding risk. Since these conflicting results might be due to concurrent use of anticoagulants and a lower thrombotic risk of patients, this cohort study was carried out for patients at a high thrombotic risk without concurrent use of anticoagulants. Medical records for patients who underwent major abdominal malignancy surgery and who were on a preoperative antiplatelet regimen were reviewed. The patients were divided into two groups according to perioperative antiplatelet management: administration of all preoperative antiplatelet agent-suspended (no aspirin) group and only aspirin administration-continued (aspirin) group. The incidence of symptomatic thromboembolic events, frequency of exogenous blood transfusion within 30 days after surgery and the amount of intraoperative bleeding were compared between the two groups. After propensity score matching, 105 patients of each group were matched. The incidence of perioperative thromboembolic events in the no-aspirin group was significantly higher than that in the aspirin group [7/105 (6.7%) vs 0/105 (0%), 95% CI 1.44-∞, P = 0.016]. In contrast, neither the frequency of exogenous transfusion [21.0% vs 11.4%, 95% CI 0.88-4.38 P = 0.110] nor the amount of intraoperative bleeding [median (interquartile range), ml: 230 (70-500) vs 208 (50-500), P = 0.325] was different between the two groups. Although the sample size is relatively small, our findings suggest that continuation of aspirin administration is likely to reduce the thrombotic risk but unlikely to increase the bleeding risk of patients who undergo major abdominal surgery for malignancy.

Continuous aspirin administration in patients of myocardial infraction during their hospital stay - a clinic audit

This audit was performed to check whether all patients suffering from myocardial infarction have received aspirin in dose of 160 - 325 mg during their stay in the medical ward in Mayo hospital Lahore. Objectives: The audit was performed to assess the application of ACC/AHA guidelines for management of patients with acute MI regarding administration of aspirin in a dose of 160-325 mg daily during their stay in the hospital. Criteria of audit: A dose of 160-325 mg of aspirin should be continued indefinitely daily after an attack of MI7. Standard of audit: All patients who have been diagnosed to have acute myocardial infarction should receive 160- 325 mg of aspirin daily during hospital stay and continuously thereafter. Material and methods: A retrospective audit was conducted in medical ward in Mayo hospital, Lahore in which notes of patients who were admitted with a diagnosis of acute myocardial infarction from 1st Jan 2005 to 31st August 2005 were studied. Results: We found that patients included in this audit had a mean age of 56 years +/- 13.55 out of which 45 patients 84% were discharged, 2% were discharged on request, 4 % were shifted to CCU, 6% left against medical advice and 2% expired. We found out that out of 45 cases only 24.4 % of cases were given aspirin in the recommended dose of 160- 325 mg daily, 40 % of patients received only 75 mg aspirin daily, while 33.3 % of them got 150mg daily and 2.2 % of patients did not receive aspirin during their stay in the hospital.

Celecoxib interferes to a limited extent with aspirin-mediated inhibition of platelets aggregation.

The aim of the study was to analyze the interaction between celecoxib and low dose aspirin for COX-1 binding and its consequences on the aspirin-mediated antiplatelet effects. We investigated ex vivo the interaction between celecoxib and aspirin for COX-1 binding and measured the resulting antiplatelet effects. We applied mechanism-based pharmacokinetic-pharmacodynamic (PKPD) modelling to analyze these data and to predict in vivo platelet aggregation for different doses and administration schedules of aspirin and celecoxib. The predictions of the PK-PD model were consistent with results from previous studies that investigated interaction between aspirin and celecoxib. The modelling results indicate that celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. The extent of this interaction can be substantial (up to 15% increase in platelet aggregation by 200mgday(-1) celecoxib when combined with low dose aspirin) during the first days of aspirin administration in patients who are already treated with celecoxib, and it cannot be prevented by separate administration of the interacting drugs. At the recommended therapeutic doses, celecoxib can attenuate to a limited extent the in vivo antiplatelet effects of low dose aspirin. Patients receiving a combination of low dose aspirin and the recommended doses of celecoxib were not identified to have increased risk of cardiovascular and cerebrovascular events due to competition between these drugs for COX-1 binding. Interaction between low dose aspirin and other COX-2 inhibitors and its clinical consequences requires further investigation.

Aspirin for secondary prevention after stroke of unknown etiology in resource-limited settings: a decision analysis

Background: Seventy-one percent of worldwide stroke mortality and 77.5% of worldwide stroke disability-adjusted life years (DALYs) lost occur in lowand middle-income countries (LMIC). This disproportionate burden of stroke in LMIC is due to resource limitations in both prevention and treatment. In addition to risk factor modification, aspirin is an inexpensive and effective medication for secondary stroke prevention. However, only 3.8% of patients with prior stroke in low-income countries take antiplatelet agents, compared to 53.1% in high-income countries. One reason for this is that without access to CT to distinguish ischemic stroke (IS) from intracerebral hemorrhage (ICH), clinicians must balance presumed risks of aspirin administration in patients with potential ICH against potential benefits of secondary prevention in patients with possible IS. In order to assist clinicians practicing in resource-limited settings, we conducted a decision analysis to determine the impact of administering aspirin as long-term secondary preventive therapy to all patients after stroke when CT is not available to distinguish IS from ICH. Methods: We used a Markov state transition model to evaluate the potential outcomes of two strategies for long-term secondary prevention after stroke of undetermined etiology: administering aspirin to all patients versus not administering aspirin to any patients. Data on the risks and benefits of aspirin use after IS and ICH were obtained from meta-analyses and large series. Sensitivity analyses were performed across the worldwide reported range of the proportion of strokes due to ICH and the 95% confidence intervals of aspirin-associated relative risks in patients with ICH. Findings: For patients with stroke of unknown etiology, long-term aspirinwas the preferred treatment strategy across theworldwide reported range of the proportion of strokes due to ICH. At 34% of strokes due to ICH (the highest proportion reported in a large epidemiologic study), the benefit of aspirin remained beyond the upper bounds of the 95% confidence intervals of aspirin-associated post-ICH relative risks most concerning to clinicians (ICH recurrence risk andmortality risk if ICHrecurs on aspirin). Based on the estimated11,590,204 strokes inLMIC in2010, ourmodel predicts that aspirin therapy for secondary stroke prevention in all patients in these countries could lead to an estimated yearly decrease of 84,492 recurrent strokes and 4,056 stroke-related mortalities. Interpretation: The concern that the risks of aspirin in patients with stroke of unknown etiology could outweigh the benefits is not supported by our model, which predicts that aspirin for secondary prevention after stroke of undetermined etiology could lead to decreased stroke-related mortality and stroke recurrence. In the absence of a clinical trial to test this approach empirically, clinical decisions still require patient-specific assessment of risk and benefit. Funding: None. Abstract #: 01NCD001

Prehospital aspirin administration for acute coronary syndrome (ACS) in the USA: an EMS quality assessment using the NEMSIS 2011 database

IntroductionNational practice guidelines recommend early aspirin administration to reduce mortality in acute coronary syndrome (ACS). Although timely administration of aspirin has been shown to reduce mortality in ACS by 23%,...

Aspirin in Patients Undergoing Noncardiac Surgery

BackgroundThere is substantial variability in the perioperative administration of aspirin in patients undergoing noncardiac surgery, both among patients who are already on an aspirin regimen and among those who are not.MethodsUsing a 2-by-2 factorial trial design, we randomly assigned 10,010 patients who were preparing to undergo noncardiac surgery and were at risk for vascular complications to receive aspirin or placebo and clonidine or placebo. The results of the aspirin trial are reported here. The patients were stratified according to whether they had not been taking aspirin before the study (initiation stratum, with 5628 patients) or they were already on an aspirin regimen (continuation stratum, with 4382 patients). Patients started taking aspirin (at a dose of 200 mg) or placebo just before surgery and continued it daily (at a dose of 100 mg) for 30 days in the initiation stratum and for 7 days in the continuation stratum, after which patients resumed their regular aspirin regimen. The primary outcome was a composite of death or nonfatal myocardial infarction at 30 days.ResultsThe primary outcome occurred in 351 of 4998 patients (7.0%) in the aspirin group and in 355 of 5012 patients (7.1%) in the placebo group (hazard ratio in the aspirin group, 0.99; 95% confidence interval [CI], 0.86 to 1.15; P=0.92). Major bleeding was more common in the aspirin group than in the placebo group (230 patients [4.6%] vs. 188 patients [3.8%]; hazard ratio, 1.23; 95% CI, 1.01, to 1.49; P=0.04). The primary and secondary outcome results were similar in the two aspirin strata.ConclusionsAdministration of aspirin before surgery and throughout the early postsurgical period had no significant effect on the rate of a composite of death or nonfatal myocardial infarction but increased the risk of major bleeding. (Funded by the Canadian Institutes of Health Research and others; POISE-2 ClinicalTrials.gov number, NCT01082874.)

Early Administration of Aspirin in Patients Treated with Alteplase for Acute ischemic Stroke: A Randomized Controlled Trial: Zinkstok S, Roos Y; on behalf of the ARTIS investigators. Lancet 2012;380:731–7.

Early Administration of Aspirin in Patients Treated with Alteplase for Acute ischemic Stroke: A Randomized Controlled Trial: Zinkstok S, Roos Y; on behalf of the ARTIS investigators. Lancet 2012;380:731–7.

Clinical outcomes of low-dose aspirin administration in patients with variant angina pectoris

Variant angina pectoris (VAP) is different to classical atherosclerotic AP in terms of etiology, treatment, and prognosis [1,2]. However, the role of acetylsalicylic acid (aspirin), indispensable for management of AP and acute coronary syndrome associated with atherosclerotic plaque, is unclear in patients with VAP and large dose (325 mg daily) of aspirin can aggravate coronary artery vasospasm in patients with VAP [2,3]. However, there is no current available data regarding clinical outcomes in patients with VAP prescribed with low dose aspirin. We investigated one-year clinical outcomes of low dose aspirin usage in patients with VAP diagnosed by ergonovine provocation test. Between June 2000 and May 2009, a total of 424 patients visited Chonnam National University Hospital was analyzed and all patients had positive results on intracoronary ergonovine provocation test. Patients were divided into two groups by prescription of aspirin as a discharge medication: aspirin group (n=202, 54.1± 11.1 years, 71.8% male) and non-aspirin group (n=222, 51.6± 10.6 years, 62.2% male). Student's t-test, chi-square test, and Kaplan–Meier method were performed using SPSS for Window 17.0. Protocol for ergonovine provocation test was similar to other Korean studies regarding VAP [4,5]. Primary study outcomes were composite one-year readmission rate associated with recurrent angina, cardiac death, and percutaneous coronary intervention (PCI) during one-year follow-up period. Aspirin group was more older (54.1±11.1 vs. 51.6±10.6 years, p=0.018) and had more male patients (71.8% vs. 62.2%, p=0.039). There were more patients presented with ST-elevation myocardial infarction at initial hospital visit in aspirin group (9.4 vs. 2.8%, p= 0.005) and unstable AP or VAP in non-aspirin group (71.2 vs. 80.1%, p=0.037). Other baseline characteristics and laboratory findings were similar between two groups. On baseline coronary angiogram, insignificant coronary artery stenosis (defined as less than 70% of stenosis in one or more epicardial coronary arteries) was more frequently observed in aspirin group (48.0 vs. 27.0%, pb0.001). However, diffuse coronary artery spasm provoked by intracoronary ergonovine test was more frequently observed in non-aspirin group (29.2 vs. 43.7%, p=0.002). At discharge, all patients received at least one or more calcium-channel blocker at maximally tolerable dose with or without nitrate. A total of 387 patients (91.3%) completed one-year follow-up. Occurrence of composite events was similar between two groups (21.9 vs. 21.0%, p=0.901) including readmission rate due to recurrent angina (19.3 vs. 19.0%, p=1.000), cardiac death (1.1 vs. 1.0%, p=1.000), and PCI 0(1.6 vs. 1.0%, p= 0.676) (Table 1). In subgroup analysis by presence of insignificant coronary artery stenosis, one-year clinical outcomes were not different. Fig. 1A showed one-year readmission-free survival associated with recurrent angina between two groups and there was no difference (log-rank p=0.959). Similar results were observed in patients with or without insignificant coronary artery stenosis in survival analysis (Fig. 1B and C). Initial point of our present study was that aspirin has efficacy in improvement of clinical outcomes in concomitant VAP and insignificant coronary artery stenosis. Although prior studies have shown that significant coronary artery stenosis is associated with a worse prognosis in patients with VAP, there is a report that variant angina with mild fixed coronary stenosis has a good prognosis during long-term follow-up [6,7]. On the basis of study results, low-dose aspirin combinationwith calcium-channel blocker should be considered in patients with concomitant VAP and significant coronary artery stenosis. In our current study, low-dose aspirin was prescribed in nearly 50% of study patients by decision of cardiologists. Because there is no definitive evidence of high prescription rate, we evaluated independent predictors of aspirin administration in all patients. Only an insignificant coronary artery stenosis on baseline coronary angiogram was a predictor of aspirin prescription at discharge (odd ratio 2.50, 95% confidence interval 1.59 to 3.75, pb0.001). Although ST-segment elevationmyocardial infarction at initial presentation was potentially associated with aspirin usage (odd ratio 2.54, 95% confidence interval 0.95 to 6.78, p=0.063), itwasmaybe sequential prescription from initial hospital visit. Diffuse coronary

Effect of different anticoagulants on multiple electrode platelet aggregometry after clopidogrel and aspirin administration in patients undergoing coronary stent implantation: A comparison between citrate and hirudin

Outcomes of platelet function tests are highly dependent on the type of blood anticoagulant used. The primary objective of this study was to clinically evaluate the platelet function after dual antiplatelet therapy using two different types of anticoagulant (citrate and hirudin). We compared data obtained from multiple electrode platelet aggregometry (MEA) with reference to light transmission aggregometry (LTA) and VerifyNow (VN) assays. Blood samples were obtained from 119 patients on dual antiplatelet therapy at the time of PCI (PCI) and the following morning (post-PCI). The platelet function tests were performed using two anticoagulated (citrate or hirudin) blood types for MEA as well as citrated blood for LTA and VerifyNow assays. ADP-induced MEA values at PCI for citrated and hirudinated anticoagulants were 36.5 ± 14.3 AUC and 41.4 ± 18.2 AUC (p = 0.021) and post-PCI values were 28.2 ± 11.9 AUC and 28.3 ± 12.8 AUC (p = 0.95). Additionally, AA-induced MEA values at PCI by citrated and hirudinated blood was 13.4 ± 7.3 AUC and 17.6 ± 13.4 AUC (p < 0.01). Post-PCI AA-induced MEA values were 12.0 ± 6.7 AUC and 13.5 ± 8.5 AUC (p = 0.12), respectively. Significant correlations were observed between the two anticoagulants used for MEA and LTA or VN values under ADP-induced platelet stimulation. Citrate tubes are clinically adequate for MEA assays and provide a more economical alternative to hirudin for early and/or delayed phases after clopidogrel-loading doses.

Early administration of aspirin in patients treated with alteplase for acute ischaemic stroke: a randomised controlled trial

Thrombolysis with intravenous alteplase is the only approved treatment for acute ischaemic stroke. After alteplase-induced recanalisation, reocclusion occurs in 14-34% of patients, probably because of platelet activation. Early administration of antiplatelet therapy after alteplase could reduce the risk of reocclusion and improve outcome. We compared the effects of early addition of intravenous aspirin to alteplase with standard alteplase without aspirin. In this multicentre, randomised, open-label trial with blind-endpoint assessment, patients with acute ischaemic stroke treated with alteplase were randomly assigned to 300 mg intravenous aspirin within 90 min after start of alteplase treatment or to no additional treatment. In both groups, oral antiplatelet therapy was started 24 h after alteplase treatment. The primary endpoint was favourable outcome, defined as a score of 0-2 on the modified Rankin scale at 3 months. This trial is registered with the Netherlands Trial Register (NTR822). Between July 29, 2008, and April 20, 2011, 642 patients (322 patients aspirin, 320 patients standard treatment) of the targeted 800 patients were enrolled. At that time, the trial was terminated prematurely because of an excess of symptomatic intracranial haemorrhage (SICH) and no evidence of benefit in the aspirin group. At 3 months, 174 (54·0%) patients in the aspirin group versus 183 (57·2%) patients in the standard treatment group had a favourable outcome (absolute difference -3·2%, 95% CI -10·8 to 4·2; crude relative risk 0·94, 0·82 to 1·09, p=0·42). Adjusted odds ratio was 0·91 (95% CI 0·66-1·26, p=0·58). SICH occurred more often in the aspirin group (14 [4·3%] patients) than in the standard treatment group (five [1·6%]; absolute difference 2·8%, 95% CI 0·2-5·4; p=0·04). SICH was more often the cause of poor outcome in the aspirin group compared with the standard treatment group (11 vs 1, p=0·006). Early administration of intravenous aspirin in patients with acute ischaemic stroke treated with alteplase does not improve outcome at 3 months and increases the risk of SICH. The results of this trial do not support a change of the current guidelines, which advise to start antiplatelet therapy 24 h after alteplase. The Dutch Heart Foundation.

PLATELTE AGGREGATION AFTER VAUVULAR SURGERY EVALUATED BY A LAZER-LITHT SCATTERING METHOD - EFFCTS OF ANTICOAGULANTS

Objectives. Effects of anticoagulants in the early phase of platelet aggregation in patients with artificial heart valves are unclear. Newly developed particle-counting methods that employ light scattering (LS) can be used to quantify changes in the number of platelet aggregates of different sizes after application of an aggregating stimulus. Using the LS method, we studied the effects of coumarin and aspirin administration in patients with artificial heart valves. Materials and Methods. Forty-seven patients undergoing valvular surgery were divided into 2 group, 26 patients treated with coumarin alone (group 1), and 21 patients treated with aspirin (81mg/day) and coumarin (group 2). Blood samples were obtained before surgery for control and on day 21 after surgery. Platelet aggregation after stimulation by 2.0 μg/ml collagen was determined; small (9 to 25 μm), medium (25 to 50 μm), and large (50 to 70 μm) aggregates were counted. Results. In group 1, platelet aggregation was not inhibited in both conventional optical density (OD) and LS methods. In group 2, OD methods demonstrated that aggregation was significantly reduced. In LS method, generation of large aggregates after stimulation were significantly decreased in patients treated with coumarin and aspirin than in the control (P 0.034), while, the quantity of the small aggregates was increased (P 0.0005). Conclusion. 1) Coumarin does not suppress platelet function. 2) Although aspirin suppresses platelet function, it does not affect the first phase of aggregation. Platelet dysfunction caused by aspirin is mainly due to an inhibition in the development of small aggregates into larger aggregates.

Prehospital Administration of Aspirin in Patients With Unstable Angina and Acute Myocardial Infarction

Both experimental and clinical studies suggest that the prehospital administration of aspirin may be beneficial in patients with unstable angina and acute myocardial infarction. Experimental studies indicate that within 1 hour of aspirin administration, serum levels peak and significant inhibition of platelet aggregation occurs. Clinical studies demonstrate that early treatment with aspirin reduces mortality and reinfarction rates in patients with unstable angina and acute myocardial infarction. However, these same studies also indicate that prolonged delays often occur before in-hospital therapy with aspirin is initiated. Since the potential benefits are great and the risks and costs are low, physicians should encourage the prehospital administration of aspirin in patients with symptoms suggestive of unstable angina or acute myocardial infarction.

Prehospital administration of aspirin in patients with unstable angina and acute myocardial infarction

Prehospital administration of aspirin in patients with unstable angina and acute myocardial infarction

Absorption Kinetics of Low Dose Aspirin in Patients with Evolving Acute Myocardial Infarction

Administration of aspirin in patients with evolving acute myocardial infarction (AMI) has been associated with reduced short and long term mortality. Neither the mechanism of the beneficial effect of aspirin nor the kinetics of its absorption in these patients have been determined. We studied the pharmacokinetics of rapid release aspirin (100mg) in 20 patients with evolving AMI. The peak creatine kinase (CK) level was 2452 ±416 (SEM) IU/L. Thrombolytic therapy was utilised in 16 patients. Aspirin was administered 5.8 ±0.8 hours after onset of pain (range 1.5 to 11 hours). The peak aspirin concentration was 939 ±137 μg/L, occurring 0.71 ±0.11 hours (range 0.3 to 2.0 hours) after aspirin ingestion. There was considerable interindividual variability in aspirin absorption, which was not significantly correlated with age, sex, bodyweight, time after onset of pain, thrombolytic therapy, infarct site or peak CK level. However, the maximal aspirin concentration was lower and time to peak concentration greater than that observed in a previous analogous study in normal subjects.

Pre-hospital opiate and aspirin administration in patients with suspected myocardial infarction

The benefit of immediate oral aspirin in the treatment of acute myocardial infarction is now established, having an equivalent impact to that of intravenous thrombolytic therapy in reducing early mortality.*RF 1-3* Though practical problems still exist with pre-hospital thrombolysis, aspirin can easily be given in this setting. Pain relief is a fundamental component and opiate analgesia is thought to be the most effective treatment. It is accepted that the route of administration should be intravenous rather than intramuscular, which can result in erratic absorption,4 haematoma formation, and a spurious increase in creatine kinase activity.5 The aim of this study was to assess the frequency with which aspirin was given acutely in patients suspected of acute …

Implications of preoperative administration of aspirin in patients undergoing coronary artery bypass grafting

The perioperative consequences of preoperative aspirin administration were assessed in a large prospective cooperative study of 772 patients undergoing coronary artery bypass grafting. The 772 patients were randomized to receive either aspirin (325 mg once a day), aspirin (325 mg three times a day), aspirin plus dipyridamole (325 and 75 mg together three times a day) (aspirin group), sulfinpyrazone (267 mg three times a day) or placebo (nonaspirin group). The therapy, except in the aspirin group, was started 48 h before the operation. In all aspirin subgroups, one 325 mg aspirin dose was given 12 h before surgery and maintained thereafter according to the assigned regimen.Patients in the aspirin group had significantly more postoperative bleeding and received more packed blood cells and blood products than did patients in the nonaspirin group. Although total operative duration and cardiopulmonary bypass duration were not different, the interval between completion of cardiopulmonary bypass and wound closure was significantly longer (p = 0.035) in the aspirin group. Thirty-one (6.6%) of 471 patients in the aspirin group and 5 (1.7%) of 301 patients in the nonaspirin group also required reoperation for control of postoperative bleeding (p = 0.002). The site of bleeding found at reoperation was not different between the two groups. There was no difference in operative mortality rates, incidence of other bleeding complications or occurrence of other postoperative complications between the two groups.Thus, antiplatelet regimens involving preoperative initiation of aspirin therapy, which has been shown to improve graft patency, increase the risk of abnormal postoperative bleeding and the need for reoperation. These observations prompted a prospective clinical trial to compare the benefits and risks of preoperative versus early postoperative administration of aspirin. Until the results of the new trial are known, the data from the current study should be taken into consideration for risk assessment of patients undergoing coronary artery bypass grafting.