Activated partial thromboplastin time and outcome after thrombolytic therapy for acute myocardial infarction: results from the GUSTO-I trial

Long-term returns to local health-care spending

This paper investigates the effects of health-care spending on mortality rates of patients who experienced a heart attack. We relate in-hospital deaths to in-hospital spending and post-discharge deaths to post-discharge health-care spending. In our analysis, we use detailed administrative data on individual personal characteristics including comorbidities, information about the type of medical treatment and information about health-care expenses at the regional level. To account for potential selectivity in the region of health-care treatment we compare local patients with visitors and stayers with recent movers from a different region. We find that in regions with higher health-care spending mortality after heart attacks is substantially lower. From this we conclude that there are long-term returns to local health-care spending.

Italian Association of Hospital Cardiologists Position Paper 'Gender discrepancy: time to implement gender-based clinical management'

It has been well assessed that women have been widely under-represented in cardiovascular clinical trials. Moreover, a significant discrepancy in pharmacological and interventional strategies has been reported. Therefore, poor outcomes and more significant mortality have been shown in many diseases. Pharmacokinetic and pharmacodynamic differences in drug metabolism have also been described so that effectiveness could be different according to sex. However, awareness about the gender gap remains too scarce. Consequently, gender-specific guidelines are lacking, and the need for a sex-specific approach has become more evident in the last few years. This paper aims to evaluate different therapeutic approaches to managing the most common women's diseases.

Risk Factors Associated With Exclusion of Obese Patients Ischemic Stroke With a History of Smoking From Thrombolysis Therapy

The objective of this study is to determine risk factors that may contribute to exclusion decision from recombinant tissue plasminogen activator (rtPA) in patients with acute ischemic stroke (AIS) with a combined current or history of smoking and obesity. This study was conducted on data from 5469 patients with AIS collected from a regional stroke registry. Risk factors associated with inclusion or exclusion from rtPA were determined using multivariate logistic regression analysis. The adjusted odds ratios and 95% confidence interval for each risk factor were used to predict the increasing odds of an association of a specific risk factor with exclusion from rtPA. In the adjusted analysis, obese patients with AIS with a history of smoking (current and previous) excluded from rtPA were more likely to present with carotid artery stenosis (OR = 0.069, 95% CI 0.011-0.442), diabetes (OR = 0.604, 95% CI 0.366-0.997), higher total cholesterol (OR = 0.975, 95% CI 0.956-0.995), and history of alcohol use (OR = 0.438, 95% CI 0.232-0.828). Higher NIHSS score (OR = 1.051, 95% CI 1.017-1.086), higher triglycerides (OR = 1.004, 95% CI 1.001-1.006), and higher high-density lipoprotein (OR = 1.028, 95% CI 1.000-1.057) were associated with the inclusion for rtPA. Our findings reveal specific risk factors that contribute to the exclusion of patients with AIS with a combined effect of smoking and obesity from rtPA. These findings suggest the need to develop management strategies to improve the use of rtPA for obese patients with AIS with a history of smoking.

Sex Differences in Therapies against Myocardial Ischemia-Reperfusion Injury: From Basic Science to Clinical Perspectives

Mortality from myocardial infarction (MI) has declined over recent decades, which could be attributed in large part to improved treatment methods. Early reperfusion is the cornerstone of current MI treatment. However, reoxygenation via restored blood flow induces further damage to the myocardium, leading to ischemia-reperfusion injury (IRI). While experimental studies overwhelmingly demonstrate that females experience greater functional recovery from MI and decreased severity in the underlying pathophysiological mechanisms, the outcomes of MI with subsequent reperfusion therapy, which is the clinical correlate of myocardial IRI, are generally poorer for women compared with men. Distressingly, women are also reported to benefit less from current guideline-based therapies compared with men. These seemingly contradicting outcomes between experimental and clinical studies show a need for further investigation of sex-based differences in disease pathophysiology, treatment response, and a sex-specific approach in the development of novel therapeutic methods against myocardial IRI. In this literature review, we summarize the current knowledge on sex differences in the underlying pathophysiological mechanisms of myocardial IRI, including the roles of sex hormones and sex chromosomes. Furthermore, we address sex differences in pharmacokinetics, pharmacodynamics, and pharmacogenetics of current drugs prescribed to limit myocardial IRI. Lastly, we highlight ongoing clinical trials assessing novel pharmacological treatments against myocardial IRI and sex differences that may underlie the efficacy of these new therapeutic approaches.

Systemic thrombolytics as rescue therapy for COVID-19 patients with acute respiratory distress syndrome: A retrospective observational study

Background

Coronavirus disease 2019 (COVID-19) pneumonia with severe acute respiratory distress syndrome (ARDS) is often associated with a progressive respiratory failure that is refractory to maximal ventilatory support and other ARDS strategies. Studies show evidence of a hypercoagulable state in COVID-19 patients, including capillary thrombosis and alveolar fibrin deposits which impede normal gas exchange. In this context, thrombolysis is considered as a salvage therapy to rescue critically hypoxemic patients.

Methods

In this retrospective observational study, the efficacy of thrombolysis on outcome of COVID-19 ARDS with respiratory failure was analyzed. Patients with severe ARDS and d-dimer levels of 5 μg/ml or above were initiated on alteplase, as a 25 mg bolus followed by a 25 mg infusion over 22 h. Primary outcome was intensive care unit (ICU) mortality and secondary outcomes were change in PaO2/FiO2 24 h after thrombolysis, avoidance of intubation, ventilator free days (VFD), and ICU and hospital length-of-stay (LOS).

Results

Thirteen out of 34 patients with severe COVID ARDS underwent thrombolysis. They had lower ICU mortality than non-thrombolysed patients (23.1% vs. 71.4%, P = 0.006), greater percentage improvement in PaO2/FiO2 (116% vs. 31.5%, P = 0.002), more VFDs (13 days vs. 0 day, P = 0.004), and lesser requirement for intubation (23.1% vs. 76.2%, P = 0.004). ICU and hospital LOS were similar.

Conclusion

Thrombolysis can be considered as a rescue therapy for nonintubated COVID-19 ARDS patients with severe hypoxemic respiratory failure, who show evidence of a procoagulant state. Larger studies are needed before inclusion into the regular treatment protocol for COVID-19 patients.

Evaluation of the activated partial thromboplastin time and its influential factors in ischemic heart disease patients under heparin treatment

This study aimed to detect the defects of the current methods used to monitor unfractionated heparin (UFH) anticoagulant effect and find possible assistive parameters for activated partial thromboplastin time (aPTT) test to improve treatment performance. The required information was gathered from patients' case records, treatment charts and laboratory reports. Kendall's tau correlation coefficient was calculated for analysing the relationship between variables. The partial least squares (PLS) and the stepwise multiple regression were operated, and the area under the receiver operating characteristic curve (AUC) and the r-squared (r2) were used to show the analytical ability of the models, respectively. Overall, 102 UFH-receiving ischemic heart disease patients participated in this study. The aPTT value varied from 30 to 95 s (mean ± SD = 44 ± 14). Therapeutic aPTT values were observed in 15% of hospitalization days. The aPTT value showed statistically significant correlations with mean UFH infusion (U/kg/h), age, prothrombin time (PT), smoking, international normalized ratio, haemoglobin (Hgb) and blood triglyceride level. Triglyceride level and PT were efficacious predictors of aPTT value (P < 0.001, r2 = 0.336). Moreover, blood urea nitrogen (BUN) and blood creatinine (Cr) levels were the best predictors for mortality. The mean BUN/Cr ratio was 18 ± 5 and 25 ± 12 in nonexpired and expired subjects, respectively. If calibrated institution-specific therapeutic aPTT ranges and updated weight-based UFH nomograms get employed, aPTT test, along with the BUN/Cr ratio and Hgb level, as assistive parameters for predicting haemorrhagic incidents, would be near ideal monitoring method in UFH-receiving patients.

A rare complication of cerebral venous thrombosis during simple percutaneous coronary intervention: A case report

RATIONALE

Cerebrovascular accidents (CVAs) after percutaneous coronary intervention (PCI), although rare, are associated with high in-hospital morbidity and mortality rates. Cerebral venous thrombosis (CVT) is an uncommon cause of CVAs compared with arterial disease but is associated with favorable outcomes in most cases. We present a rare case of CVT following a simple PCI procedure with stent implantation, which has not been previously reported in the literature.

PATIENT CONCERNS

A 78-year-old woman with hypertension, hyperlipidemia, and coronary artery disease received simple PCI with stent implantation. After PCI, she developed a throbbing headache with nausea and vomiting, with her blood pressure increasing to 190/100 mmHg. Drowsiness, disorientation, and neck stiffness were noted. Neurological complication due to the PCI procedure was highly suspected.

DIAGNOSIS

Noncontrast brain computed tomography was performed along with emergency neurological consultation, and the patient was diagnosed as having acute CVT.

INTERVENTIONS

The patient was treated with anti-intracranial pressure therapy and anticoagulation therapy through low-molecular-weight heparin and was subsequently treated with warfarin.

OUTCOMES

After treatment, the patient's symptoms and signs gradually subsided, and her clinical condition improved. She was discharged with full recovery thereafter.

LESSONS

A case of acute CVT, a rare, and atypical manifestation of venous thromboembolism and CVA, complicated simple PCI with stent implantation. During PCI, identifying patients with a high risk of a CVA is critical, and special care should be taken to prevent this devastating complication.

A pilot study documenting increased thrombin generation following abrupt withdrawal of heparin therapy in healthy dogs

OBJECTIVE

To document if a transient hypercoagulable state occurs in healthy dogs following abrupt cessation of unfractionated heparin (UFH) therapy.

DESIGN

Prospective experimental pilot study.

SETTING

University research facility.

ANIMALS

Seven adult random-source male dogs.

INTERVENTION

Thromboelastography (TEG) and thrombin-antithrombin (TAT) complex formation were used to assess coagulation status in healthy dogs. Seven adult research dogs received 200-300 IU/kg subcutaneous UFH every 8 hours for 4 days. A final IV bolus of 100 IU/kg was given on day 4 and the peak measured heparin concentration 1 hour later is defined as the start of heparin withdrawal (time 0). Citrated whole blood samples were collected at baseline (prior to heparin administration) and 3, 6, 12, 30, and 48 hours after UFH withdrawal. At all time points, a kaolin-activated TEG was performed and citrated plasma for measurement of TAT concentration was collected for batch analysis. Fibrinogen concentration, PCV, total plasma proteins, and platelet count were measured at baseline and 48 hours after heparin withdrawal.

MEASUREMENTS AND MAIN RESULTS

Compared to baseline, TAT was increased 12 hours after heparin withdrawal and returned to baseline by 30 hours. TEG clot formation time (K) was decreased 30 and 48 hours after heparin withdrawal.

CONCLUSION

TAT results suggest that a transient increase in thrombin generation developed 12 hours after withdrawal of UFH therapy. Though clot kinetics were rapid compared to baseline beginning 30 hours after heparin withdrawal, a return to baseline was not documented. Future studies are warranted to determine the clinical relevance of these results and to evaluate the effect of UFH withdrawal in critically ill animals.

Prognostic value of post-procedural aPTT in patients with ST-elevation myocardial infarction treated with primary PCI

Unfractionated heparin is the most commonly used anticoagulant in ST-elevation myocardial infarction (STEMI) and its effect can be monitored with activated partial thromboplastin time (aPTT). However, the optimal aPTT range during heparin therapy after primary percutaneous coronary intervention (PCI) is yet to be defined. A mean aPTT was calculated of all aPTT measurements in the first 24 hours after pPCI in a total of 1,876 STEMI patients. Mean aPTT measurements were stratified into four categories; < 1.5 times the upper limit of normal (ULN), 1.5 – 2.0 times ULN (the therapeutic group), 2.01 – 3.99 times ULN, and ≥ 4 times ULN. Compared to patients with a therapeutic aPTT, patients with aPTTs < 1.5 times ULN had no increase in recurrent ischaemic events and had similar rates of bleeding complications. Patients with a mean aPTT ≥ 4 times ULN had higher rates recurrent ischaemic and haemorrhagic complications. After multivariable analyses, aPTT ratios ≥ 4 times ULN were no longer associated with recurrent ischaemic events, but remained a strong predictor of severe and moderate bleeding (hazard ratio [HR] 4.64, p = 0.016 and HR 2.27, p = 0.052). In conclusion, in 1,876 STEMI patients treated with pPCI, low aPTTs in the first 24 hours after PCI were not associated with an increase in ischaemic events, whereas high aPTT values were associated with more frequent bleeding complications. These results indicate no clear benefit as well as a safety concern with heparin treatment after primary PCI.

Description and Evaluation of the Implementation of a Weight-Based, Nurse-Driven Heparin Nomogram in a Tertiary Academic Medical Center

Weight-based, nurse-driven heparin nomograms are reported in the medical literature to improve the time it takes to reach a minimum threshold for anticoagulation without compromising patient safety in specific indications or patient populations. This is the first report in the literature of an institution-wide protocol implementation and evaluation of effectiveness with simultaneous transition to an electronic health record. The purpose of implementing this practice change at our institution was to standardize practice, improve time to reach therapeutic anticoagulation, and improve patient safety. We conducted a retrospective analysis utilizing a pre/postimplementation design to compare outcomes. The primary end point evaluated was the time to reach minimum threshold value for therapeutic anticoagulation. Additionally, we assessed the percentage of patients who reached minimum threshold therapeutic anticoagulation within 24 hours, the percentage of patients with a critically supratherapeutic activated partial thromboplastin time (aPTT) value (≥120 seconds) during therapy, and a description of heparin titration for the first 4 aPTT results with nomogram use. Overall time to therapeutic anticoagulation decreased from a mean 18.7 to 11.7 hours (hazard ratio [HR] 1.59; 95% confidence interval 1.22-2.08; P < .0005). Percentage of patients receiving therapeutic anticoagulation within 24 hours increased from 74.4 to 88.5 (odds ratio [OR 2.97, P = .002) and the percentage of patients with an aPTT ≥120 seconds remained constant at 49.9 versus 46.8 (OR 0.92, P = .73). This practice change reduced time to therapeutic anticoagulation without an increase in the proportion of patients with a critically supratherapeutic aPTT at our institution.

Is Intravenous Heparin a Contraindication for TPA in Ischemic Stroke?

There are approximately 2 million cardiac catheterizations that occur every year in the United States and with an aging population this number continues to rise. Adverse events due to this procedure occur at low rates and include stroke, arrhythmia, and myocardial infarctions. Due to the high volume of procedures there are a growing number of adverse events. Stroke after cardiac catheterization (SCC) has an incidence between 0.27 and 0.5% and is one of the most debilitating complications leading to high rates of mortality and morbidity. Given the relatively uncommon clinical setting of stroke after cardiac catheterization, treatment protocols regarding the use of IV or IA thrombolysis have not been adequately developed. Herein, we describe a case of a 39-year-old male who developed a stroke following a cardiac catheterization where IV thrombolysis was utilized although the patient was on heparin prior to cardiac catheterization.

Anticoagulation Monitoring

Optimal management of anticoagulant therapy requires an understanding of the laboratory tests often employed to guide therapy. The activated partial thromboplastin time (aPTT) can detect abnormalities in the intrinsic and common clotting pathways. Despite numerous limitations in the aPTT test, it remains the gold standard for monitoring unfractionated heparin and direct thrombin inhibitor therapy. The aPTT can be performed in the central laboratory or at the bedside (point of care [POC] testing). The activated clotting time (ACT) is a POC test that is routinely employed to monitor high-dose heparin during invasive and surgical procedures. The ACT therapeutic range will depend on the specific procedure or surgery being performed. Heparin levels are becoming more routinely available and are used to establish the aPTT therapeutic range for heparin therapy as well as for direct monitoring of heparin and low-molecular-weight heparin therapy. The international normalized ratio (INR) is the gold standard for monitoring warfarin patients. The target INR depends on the indication for anticoagulation. POC monitoring for warfarin is becoming increasingly used. Clinicians should have a thorough understanding of the benefits as well as the limitations of warfarin POC monitoring.

Gender Differences in Cardiovascular Drugs

The different responses of women and men to cardiovascular drugs reflect gender -specific variances in pharmacokinetic profiles and drug sensitivities coupled to inherent differences in the underlying physiology of each sex. Thus, many common cardiovascular drugs exhibit gender -specific therapeutic and adverse effects. For example, the QT interval of the electrocardiogram is longer in women compared to men, and accordingly, drugs that prolong the QT interval are more likely to cause lethal ventricular arrhythmias in female than male patients. As more clinical drug trials include women subjects, our improved knowledge base for assessing the risk/benefit ratio for cardiovascular drugs in women will enable us to consider gender as one factor in prescribing drugs and adjusting drug loading and maintenance dosages. This short review will present evidence for gender- related differences in the responses to common cardiovascular drugs including statins, antiplatelet and antithrombotic agents, β-blockers, digoxin, vasodilator therapies, and drugs associated with the Long QT Syndrome.

Systematic Analysis of Adverse Event Reports for Sex Differences in Adverse Drug Events

Increasing evidence has shown that sex differences exist in Adverse Drug Events (ADEs). Identifying those sex differences in ADEs could reduce the experience of ADEs for patients and could be conducive to the development of personalized medicine. In this study, we analyzed a normalized US Food and Drug Administration Adverse Event Reporting System (FAERS). Chi-squared test was conducted to discover which treatment regimens or drugs had sex differences in adverse events. Moreover, reporting odds ratio (ROR) and P value were calculated to quantify the signals of sex differences for specific drug-event combinations. Logistic regression was applied to remove the confounding effect from the baseline sex difference of the events. We detected among 668 drugs of the most frequent 20 treatment regimens in the United States, 307 drugs have sex differences in ADEs. In addition, we identified 736 unique drug-event combinations with significant sex differences. After removing the confounding effect from the baseline sex difference of the events, there are 266 combinations remained. Drug labels or previous studies verified some of them while others warrant further investigation.

Influence of chronic kidney disease on anticoagulation levels and bleeding after primary percutaneous coronary intervention in patients treated with unfractionated heparin

Unfractionated heparin (UFH) plasma protein binding and elimination might be impaired in patients with chronic kidney disease (CKD-defined as creatinine clearance <60 ml/min). It is currently unknown at which UFH bolus dose persistent prolongation of activated partial thromboplastin time (aPTT) occurs in ST-segment elevation myocardial infarction (STEMI) patients with CKD. We investigated the effect of different UFH bolus doses on the first aPTT measured within 6 and 12 h after PPCI in 1071 STEMI patients with and without CKD undergoing primary percutaneous coronary intervention (PPCI) between 1-1-2003 and 31-07-2008. In the first 6 h after PPCI, aPTT ratio was 5.1 for patients with CKD versus 3.4 for those without (p < 0.001). The proportion of patients with markedly high aPTTs (aPTT ratio ≥ 4 times control) increased with increasing heparin bolus and beyond 130 IU/kg there was a marked difference between patients with and without CKD (74.1 and 42.3 % respectively, p < 0.001). By multivariable analysis, CKD was associated with an increased risk of markedly high aPTTs (odds ratio (OR) 2.04; 95 % confidence interval (CI) 1.27-3.27), driven largely by an increased risk of aPTT prolongation in patients treated with UFH boluses ≥130 IU/kg (OR 3.69; 95 % CI 1.85-7.36; p for interaction = 0.009). In conclusion, CKD is associated with severe persistent aPTT prolongation in STEMI patients undergoing PPCI, possibly due to impaired plasma protein binding and reduced UFH elimination. A lower heparin bolus dose might result in lower aPTTs and less bleeding complications in patients with CKD undergoing PPCI.

Sex-based differences in cardiac ischaemic injury and protection: therapeutic implications

Ischaemic heart disease (IHD) is the most frequent cause of mortality among men and women. Many epidemiological studies have demonstrated that premenopausal women have a reduced risk for IHD compared with their male counterparts. The incidence of IHD in women increases after menopause, suggesting that IHD is related to declining oestrogen levels. Experimental observations have confirmed the results of epidemiological studies investigating sex-specific differences in cardiac tolerance to ischaemia. Female sex appears also to favourably influence cardiac remodelling after ischaemia/reperfusion injury. Furthermore, sex-related differences in ischaemic tolerance of the adult myocardium can be influenced by interventions during the early phases of ontogenetic development. Detailed mechanisms of these sex-related differences remain unknown; however, they involve the genomic and non-genomic effects of sex steroid hormones, particularly the oestrogens, which have been the most extensively studied. Although the protective effects of oestrogen have many potential therapeutic implications, clinical trials have shown that oestrogen replacement in postmenopausal women may actually increase the incidence of IHD. The results of these trials have illustrated the complexity underlying the mechanisms involved in sex-related differences in cardiac tolerance to ischaemia. Sex-related differences in cardiac sensitivity to ischaemia/reperfusion injury may also influence therapeutic strategies in women with acute coronary syndrome. Women undergo coronary intervention less frequently and a lower proportion of women receive evidence-based therapy compared with men. Although our understanding of this important topic has increased in recent years, there is an urgent need for intensive experimental and clinical research to develop female-specific therapeutic strategies. Only then we will be able to offer patients better evidence-based treatment, a better quality of life and lower mortality.

Self-titrating anticoagulant nanocomplexes that restore homeostatic regulation of the coagulation cascade

Antithrombotic therapy is a critical portion of the treatment regime for a number of life-threatening conditions, including cardiovascular disease, stroke, and cancer; yet, proper clinical management of anticoagulation remains a challenge because existing agents increase the propensity for bleeding in patients. Here, we describe the development of a bioresponsive peptide-polysaccharide nanocomplex that utilizes a negative feedback mechanism to self-titrate the release of anticoagulant in response to varying levels of coagulation activity. This nanoscale self-titrating activatable therapeutic, or nanoSTAT, consists of a cationic thrombin-cleavable peptide and heparin, an anionic polysaccharide and widely used clinical anticoagulant. Under nonthrombotic conditions, nanoSTATs circulate inactively, neither releasing anticoagulant nor significantly prolonging bleeding time. However, in response to life-threatening pulmonary embolism, nanoSTATs locally release their drug payload and prevent thrombosis. This autonomous negative feedback regulator may improve antithrombotic therapy by increasing the therapeutic window and decreasing the bleeding risk of anticoagulants.

Gender differences in cardiovascular therapy: focus on antithrombotic therapy and percutaneous coronary intervention

The epidemiology of coronary artery disease (CAD) differs between women and men: female cardiac patients are older and have poorer risk profiles than their male counterparts. This results in a preferential exclusion of women from participation in clinical trials, reducing their power to detect differences in performance of cardiovascular therapies in women. In general, all the antiplatelet and anticoagulant medications used in cardiac patients are equally effective in men and women, although women tend to experience a higher relative benefit due to their poorer risk profile. In particular, women with CAD benefit the most from interventional treatment combined with modern antithrombotic drugs. No gender-related differences in the reduction of thromboembolic risk with more potent antithrombotic drugs have been reported. On the other hand, a clear trend to a higher incidence of bleeding complications has been consistently reported in women, which might be related to a more frequent over-dosage of antithrombotic treatment in women than in men. Women are therefore one of the subgroups that might benefit the most from careful dose adjustment of available antithrombotic drugs. However, the development of a gender-based dosage guideline remains an unmet need in cardiology.

Relationship between mean platelet volume and low-grade systemic coagulation with vitamin D deficiency in primary ovarian insufficiency

OBJECTIVE

Premature menopause in young women is associated with an increased incidence of cardiovascular disease. The present study was designed to determine vitamin D (vit D) and the coagulation parameters such as activated partial thromboplastin time (APTT), PT, D-dimer, white blood cell (WBC), and mean platelet volume (MPV) levels, in primary ovarian insufficiency (POI) patients and control women with a normal menstrual cycle.

MATERIALS AND METHODS

A total of 43 patients with non-diabetic POI were studied in order to evaluate and compare with the control group comprising 33 women with a normal menstrual cycle.

RESULTS

There was no significant difference between the groups for age and body mass index (BMI). D-dimer, WBC, MPV, PT, total cholesterol, and LDL cholesterol were higher in women with POI. APTT levels were also increased but missed the significance in POI group. Women with POI had significantly lower serum vit D levels compared with healthy control group. FSH level was positively correlated with D-dimer, WBC, MPV, and negatively correlated to vit D and serum D vit level was inversely correlated with MPV, APTT, D-dimer, FSH levels in individual women.

CONCLUSIONS

The obtained results seem to indicate that POI patients had low-grade systemic coagulation and fibrinolytic activation as evidenced by elevated D-dimer, WBC, MPV, PT values potentially be used as indicators of risk factor for thrombosis and atherosclerosis in POI women. All of our patients with POI were deficient in vit D. These results also suggest that vit D deficiency plays important roles of POI women and associated with coagulation, independently from age and BMI.

Women and the management of acute coronary syndrome

Coronary heart disease (CHD) is the leading cause of morbidity and mortality in both men and women in the developed countries. Despite this fact, females are still under-represented in the majority of clinical trials. At the present time, only limited evidence is available with respect to the female-specific aspects of pathogenesis, management, and outcomes in acute coronary syndrome (ACS). Women less frequently undergo coronary intervention, and a lower proportion of women receive evidence-based pharmacotherapy, compared with men. It has been shown that women benefit from an invasive approach and coronary intervention in ACS as much as men, despite their advanced age and higher rate of bleeding complications. Also, administration of beta-blockers, ACE-inhibitors, and intensive statin therapy is associated with a comparable reduction of cardiovascular event rates in women and men. On the other hand, women may profit less than men from fibrinolytic or glycoprotein IIb/IIIa inhibitor therapy. Both sexes benefit equally from aspirin therapy, whereas contradictory data are available on the efficacy of clopidogrel in women. There is an urgent need for intensive research in the development of female-specific therapeutic strategy in ACS, even though the detailed mechanisms of sex differences are still unknown.

Antifactor Xa levels versus activated partial thromboplastin time for monitoring unfractionated heparin

Intravenous unfractionated heparin (UFH) remains an important therapeutic agent, particularly in the inpatient setting, for anticoagulation. Historically, the activated partial thromboplastin time (aPTT) has been the primary laboratory test used to monitor and adjust UFH. The aPTT test has evolved since the 1950s, and the historical goal range of 1.5-2.5 times the control aPTT, which first gained favor in the 1970s, has fallen out of favor due to a high degree of variability in aPTT readings from one laboratory to another, and even from one reagent to another. As a result, it is now recommended that the aPTT goal range be based on a corresponding heparin concentration of 0.2-0.4 unit/ml by protamine titration or 0.3-0.7 unit/ml by antifactor Xa assay. Given that several biologic factors can influence the aPTT independent of the effects of UFH, many institutions have transitioned to monitoring heparin with antifactor Xa levels, rather than the aPTT. Clinical data from the last 10-20 years have begun to show that a conversion from aPTT to antifactor Xa monitoring may offer a smoother dose-response curve, such that levels remain more stable, requiring fewer blood samples and dosage adjustments. Given the minimal increased acquisition cost of the antifactor Xa reagents, it can be argued that the antifactor Xa is a cost-effective method for monitoring UFH. In this review, we discuss the relative advantages and disadvantages of the aPTT, antifactor Xa, and protamine titration tests, and provide a clinical framework to guide practitioners who are seeking to optimize UFH monitoring within their own institutions.

Activated partial thromboplastin time measurement is not associated with clinical outcomes in patients with high-risk non-ST-segment elevation acute coronary syndromes treated with unfractionated heparin

Our objective was to determine the association of activated partial thromboplastin time (aPTT) with recurrent ischemic events and non-coronary artery bypass surgery-related thrombolysis in myocardial infarction major bleeding. We studied 4,985 patients with high-risk non-ST-segment elevation acute coronary syndromes (NSTE ACS) participating in SYNERGY, a prospective, randomized, international trial designed to emulate contemporary practice wherein unfractionated heparin (UFH) is given intravenously and titrated according to a weight-adjusted dosing nomogram to a target aPTT of 1.5-2 times the upper limit of normal (approximately 50-70 s). Aspirin was administered to 95% of patients, clopidogrel to 63%, and glycoprotein IIb/IIIa receptor inhibitors to 58%. More than 90% of patients underwent early coronary angiography, and 69% were revascularized. Used as a time-dependent covariate, aPTT was evaluated as a predictor of time to ischemic or major hemorrhagic events in proportional hazards regression models. Using discrete variable analysis, aPTT was categorized as persistently below a lower threshold of anticoagulation (<50 vs. ≥50 s) for recurrent ischemic events and above an upper threshold (>70 vs. ≤70 s) for major hemorrhagic events. UFH treatment lasted a median of 42 (30, 78) h. At >6-12 (n = 3,021), >12-24 (n = 3,406), and >24-48 (n = 2,497) h, 34, 41, and 46% of patients achieved the target aPTT range, respectively. Both before and after adjusting for baseline predictors of anticoagulant response and risk score (age, hypertension, diabetes, smoking, ST depression, and renal function), no significant relationship between aPTT values and recurrent ischemic events or major bleeding was found. No relationship was observed between clinical outcomes and aPTT values persistently above or below the designated thresholds. Measurements of aPTT were not associated with clinical outcomes among patients with NSTE ACS treated with UFH. The required intensity of anticoagulation for benefit may be relatively modest when UFH is administered concomitantly with dual or triple platelet-directed therapy, particularly in patients undergoing early coronary revascularization.

Gender differences in anticoagulation and antithrombotic therapy

Cardiovascular disease is the main cause of mortality and morbidity worldwide. The rate of thromboembolic events has increased in women but not in men. Large clinical studies support the use of a variety of antithrombotic drugs for the treatment of patients with different cardiovascular diseases. The heterogeneous patient population included in these trials affects the attempt to generalize the study results to subgroups, which are not sufficiently represented in the study population, such as women and other minorities. Gender-related differences in the clinical presentation and outcome seem to relate to differences in platelet biology and coagulation reactions, resulting in different rates of thromboembolic and bleeding events. The effectiveness of antithrombotic therapies and the occurrence of adverse events define the clinical benefit of the treatment for each patient. This chapter gives an overview of the currently available data on gender-differences in anticoagulation and antithrombotic therapy.

Critical values in the coagulation laboratory: results of a survey of the North American Specialized Coagulation Laboratory Association

Critical values are vital to safe clinical and laboratory practice. To address the lack of information on critical values in coagulation, pattern-of-practice surveys were distributed to members of the North American Specialized Coagulation Laboratory Association. More than 70% of respondents had critical values for commonly performed tests. Median values were as follows: prothrombin time, more than 37 seconds; international normalized ratio, more than 5; activated partial thromboplastin time, more than 100 seconds; and fibrinogen level, less than 100 mg/dL. Critical value reporting generated a significant workload, with up to 15% of these tests yielding critical results. The median time to report critical values was 7 minutes for inpatients. Despite the lack of guidelines surrounding critical values in coagulation, this survey confirms that laboratories have reasonable and uniform practices. It also provides critical value medians and ranges for a wide range of tests. Laboratories without critical values or in the process of reviewing their values may find this survey of their peers useful.

Race, Bleeding, and Outcomes in STEMI Patients Treated with Fibrinolytic Therapy

BACKGROUND

studies have shown higher bleeding and mortality rates among African Americans who receive fibrinolytic therapy for ST-segment elevation myocardial infarction (STEMI) compared with whites; however, the relationship of bleeding risk to mortality has not been evaluated.

METHODS

we studied data from 32,260 STEMI patients receiving fibrinolysis enrolled in the US in 5 clinical trials. Bleeding was defined according to criteria from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries study. Main outcome measure was adjusted 1-year mortality.

RESULTS

despite younger age (median: 57 years vs 61 years) and fewer comorbidities, moderate or severe bleeding occurred more frequently among African-Americans than whites (16.3% vs 14.1%; P=.0147, adjusted OR 1.36; 95% confidence interval [CI], 1.14-1.62; P=.0006) as did 1-year mortality (11.5% vs 9.4%). African-American race and moderate or severe bleeding were independently related to 1-year mortality (χ(2) 9.02, P=.0003 and 148.58, P<.0001, respectively). Mortality was highest among African Americans with bleeding (hazard ratio [HR] 2.83; 95% CI, 2.08-3.86) followed by whites with bleeding (HR 1.99; 95% CI, 1.78-2.22) and African Americans without bleeding (HR 1.33; 95% CI, 1.02-1.73) (referent whites without bleeding).

CONCLUSIONS

in STEMI patients receiving fibrinolysis, moderate or severe bleeding and mortality were significantly higher in African Americans compared with whites. Bleeding was associated with similarly increased mortality risk in both groups.

Upstream treatment of acute coronary syndrome in the ED

Rapid risk stratification, selection of downstream management options, and institution of initial pharmacotherapy are essential to ensure that patients admitted to the emergency department with acute coronary syndromes receive optimal care. A broad range of antiplatelet and antithrombotic medications is available that permits tailoring of initial pharmacotherapy to each patient's risk status. In the urgent setting, thienopyridines (clopidogrel and prasugrel) carry limitations including response variability and increased risk for bleeding in patients requiring subsequent coronary artery bypass graft surgery. Glycoprotein IIb-IIIa receptor inhibitors, although they are highly effective in preventing ischemic events, must be used with care to reduce bleeding risk. Bivalirudin, a relatively new direct thrombin inhibitor, represents another upstream option but is costly and does not have approval for this indication. Simplified institutional management paradigms can streamline the process of selecting appropriate pharmacotherapy and aid in care delivery that will optimize patient outcomes.

Aptamers: the emerging class of future anticoagulation for vascular disease

Anticoagulation is an important therapeutic strategy to treat and prevent recurrent thrombotic events in patients after acute myocardial infarction and ischemic stroke. However, available anticoagulants have numerous shortcomings including hemorrhage risks, limited clinical application including heparin-induced thrombocytopenia and modest therapeutic benefit. Each component of the coagulation cascade is a potential target for new drug developments. Representing an attractive new therapeutic class, aptamers are nucleic acid ligand with a high affinity and specificity for proteins involved in the clot growth. Potential antidote control of aptamer activity offers an important advance in anticoagulant safety. Aptamers are a promising class of compounds, both for target validation and therapy. As designer drugs, they exhibit high specificity, high affinity and modifiable bioavailability. The ability to generate inhibitors with such properties against a variety of target proteins will be valuable as the human genome and proteome are deciphered. This article summarizes current knowledge of aptamers developed against coagulation proteins, focusing on the biology, pharmacology, preclinical and early clinical experience with this novel class of anticoagulants.

The use and limitations of unfractionated heparin

Despite the development of newer anticoagulants, unfractionated heparin remains an indispensible agent in the treatment of thrombotic disorders. Heparin exerts its major effect via antithrombin, converting antithrombin to a more efficient inhibitor of circulating thrombin (factor IIa), factor Xa, factor IXa, factor XIIa, and kallikrein. However, due to the multiple anticoagulant mechanisms of heparin, differential molecular weight-based clearance, issues of heparin resistance, and patient-specific characteristics (age, weight, gender, and tobacco), attaining therapeutic anticoagulation is complicated. As a result, a minority of patients in major clinical trials achieve an activated partial thromboplastin time within the target window in an appropriate time-frame despite the use of weight-based titration nomograms. The resultant under- or over-therapeutic anticoagulation is associated with increased risks of ischemic and bleeding complications, suggesting the importance of maintaining heparin anticoagulation within a relatively narrow therapeutic range. In this review we discuss the mechanisms of heparin action, clinical ramifications of incorrect dosing in major trials, and attempts to improve the achievement of therapeutic anticoagulation.

Effect of body mass index on bleeding frequency and activated partial thromboplastin time in weight-based dosing of unfractionated heparin: a retrospective cohort study

OBJECTIVE

To assess bleeding and activated partial thromboplastin time (APTT) in relation to body mass index (BMI) in patients prescribed weight-based dosing of intravenous unfractionated heparin (UFH) for cardiac indications without a maximum (dose-capped) initial bolus or capped initial infusion rate.

PATIENTS AND METHODS

Consecutive patients admitted to an academic medical center from February 1, 2002, through November 31, 2003, who were treated with a UFH nomogram consisting of a 60-U/kg intravenous bolus plus an initial continuous intravenous infusion of 12 U/kg hourly and titrated to a goal APTT range corresponding to thromboplastin-adjusted target heparin levels of 0.3 to 0.7 U/mL by anti-Xa assay were evaluated for this retrospective cohort study. Patients were excluded if they concomitantly received a fibrinolytic, glycoprotein IIb/IIIa inhibitor, or any other antithrombotic agent (except warfarin). Study patients were divided into quartiles by BMI.

RESULTS

Of the 1054 patients included in the study, 807 (76.6%) had an initial bolus dose higher than 4000 U, and 477 (45.3%) had an initial infusion rate higher than 1000 U/h. Despite a significant difference among BMI quartiles in proportion of supratherapeutic first APTT values (P<.001), no statistically significant difference was found in bleeding frequency (P=.26) or frequency of first APTT within the goal range (P=.27). Logistic regression analyses revealed that BMI was not a significant predictor of bleeding or first APTT within the goal range.

CONCLUSION

We did not find any difference in the proportion of first APTT values in the goal range or an increased risk of bleeding in obese patients treated with UFH without a capped initial dose. Our data demonstrate the safe use of weight-based UFH without a capped initial bolus dose or capped initial infusion rate in patients with medical cardiac conditions.

Acute coronary syndromes: Diagnosis and management, part II

At the most severe end of the spectrum of acute coronary syndromes is ST-segment elevation myocardial infarction (STEMI), which usually occurs when a fibrin-rich thrombus completely occludes an epicardial coronary artery. The diagnosis of STEMI is based on clinical characteristics and persistent ST-segment elevation as demonstrated by 12-lead electrocardiography. Patients with STEMI should undergo rapid assessment for reperfusion therapy, and a reperfusion strategy should be implemented promptly after the patient's contact with the health care system. Two methods are currently available for establishing timely coronary reperfusion: primary percutaneous coronary intervention and fibrinolytic therapy. Percutaneous coronary intervention is the preferred method but is not always available. Antiplatelet agents and anticoagulants are critical adjuncts to reperfusion. This article summarizes the current evidence-based guidelines for the diagnosis and management of STEMI. This summary is followed by a brief discussion of the role of noninvasive stress testing in the assessment of patients with acute coronary syndrome and their selection for coronary revascularization.

Prolonged anticoagulation therapy adjunctive to aspirin after successful fibrinolysis: from early reduction in reocclusion to improved long-term clinical outcome

BACKGROUND

Long-term addition of antithrombotics (clopidogrel, anticoagulants) to aspirin has improved outcome after acute coronary syndromes. Data on the impact after fibrinolysis are scarce. In Antithrombotics in the Prevention of Reocclusion In COronary Thrombolysis-2 (APRICOT-2), adjunctive moderate-intensity coumarin (median international normalized ratio 2.6) conferred a marked reduction in 3-month reocclusion and ischemic events. Given the association between reocclusion and long-term outcome, we performed long-term clinical follow-up.

METHODS

Patients with thrombolysis in myocardial infarction (TIMI) 3 flow <48 hours after fibrinolysis for ST-elevation myocardial infarction were randomized to aspirin plus coumarin, with prolonged heparinization until the target international normalized ratio (2-3) was reached, or aspirin with standard heparinization. Three-month follow-up angiography (reocclusion rates 15% vs 28%) and long-term clinical follow-up (median 7.3 years, interquartile range 5.9-8.6 years) were performed.

RESULTS

Patients randomized to adjunctive anticoagulation (n = 123) received coumarin for a median of 280 days (113-387 days). Survival was 94% versus 88% in patients on aspirin alone (n = 128, P = .12). Infarct-free survival was 86% versus 71% (P = .01). Thrombolysis in myocardial infarction bleeding was 4% in both groups. Patients with reocclusion had impaired survival: 80% versus 94% (P < .01). In a multivariable model without reocclusion, combination therapy independently predicted survival (hazard ratio [HR] 0.36, 95% confidence interval [CI] 0.13-1.00) and infarct-free survival (HR 0.51, 95% CI 0.28-0.95). When adjusted for reocclusion, combination therapy did not predict outcome. Reocclusion independently predicted death (HR 2.56, 95% CI 1.02-6.43) and reinfarction.

CONCLUSIONS

Moderate-intensity oral anticoagulation added to aspirin improved 8-year clinical outcome after successful fibrinolysis. The beneficial effect was largely attributed to a reduction in reocclusion, which independently predicted death and reinfarction. This study provides a mechanistic rationale for prolonged adjunctive anticoagulation after fibrinolysis.

Anticoagulants in coronary artery disease

Anticoagulant therapy for acute coronary syndromes is becoming more complex as newer agents are added to unfractionated heparin and warfarin. The anticoagulants used in current clinical practice are low molecular weight heparins, direct thrombin inhibitors, and heparinoids. Properties of and recent clinical trial data regarding these newer anticoagulants are reviewed in reference to current American College of Cardiology/American Heart Association guidelines.

The impact of fibrinolytic therapy for ST-segment-elevation acute myocardial infarction

As privileged witnesses of the initiation and widespread use of reperfusion therapy the authors review the history of fibrinolytic therapy and of tissue-plasminogen activator (t-PA) more particularly and the current indications for its use in the era of mechanical reperfusion.

Major bleeding: management and risk reduction in acute coronary syndromes

BACKGROUND

Guidelines for the management of high-risk non ST-segment elevation acute coronary syndrome (NSTE ACS) recommend antithrombotic and antiplatelet therapy combined with an early invasive strategy. While this strategy reduces ischemic complications, it places patients at risk for bleeding complications.

OBJECTIVE

We sought to provide a narrative review of the risk factors for bleeding, risks associated with bleeding and strategies to prevent bleeding complications.

METHODS

A comprehensive literature review was performed to identify relevant evidence.

RESULTS/CONCLUSIONS

Bleeding complications in NSTE ACS are associated with adverse events and higher mortality. Prevention of bleeding complications can be achieved through judicious dosing of medications, the use of antithrombotic agents associated with a lower bleeding risk and use of the radial artery approach in patients requiring coronary intervention. Future work should focus on delineating the mechanisms underlying the bleeding-mortality relationship and developing a better understanding of the tradeoff between efficacy and safety.

Excess heparin dosing among fibrinolytic-treated patients with ST-segment elevation myocardial infarction

BACKGROUND

Although the use of heparin with fibrinolytics is associated with more rapid ST-segment resolution and increased infarct-related artery patency among patients with ST-segment elevation myocardial infarction (STEMI), its associated increase in bleeding risk is well documented and might be augmented by excess heparin dosing.

METHODS

We sought to characterize the incidence and associated bleeding risk of excess heparin dosing among patients with STEMI treated with fibrinolysis who were enrolled in the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the American College of Cardiology/American Heart Association Guidelines initiative. Excess dosing was defined as a bolus more than 60 U/kg or an infusion more than 12 U/kg/h per American College of Cardiology/American Heart Association guidelines and was further stratified into major and mild excess (major defined as a bolus>70 U/kg or infusion >15 U/kg/h).

RESULTS

Among 964 fibrinolytic-treated patients with STEMI, 758 (79%) received adjunctive unfractionated heparin therapy. Of these, 368 patients (49%) received excess dosing of unfractionated heparin and 137 patients (18%) received major excess heparin dosing. Factors significantly associated with excess dosing included low body weight and female sex. Patients who received major excess dosing had higher unadjusted rates of major bleeding (19.2% vs 12.4%, P=.004) and transfusion (13.5% vs 4.7%, P=.0002) than patients without excess dosing. After adjustment, a trend persisted for the association with higher transfusion risk (odds ratio 1.39 [0.61-3.14]).

CONCLUSION

Approximately half of fibrinolytic-treated patients with STEMI in contemporary practice received an excess dose of unfractionated heparin. Careful attention to dosing is needed to limit the compounded bleeding risk when heparin is added to fibrinolytic therapy.

Unfractionated heparin dosing and risk of major bleeding in non-ST-segment elevation acute coronary syndromes

BACKGROUND

Unfractionated heparin (UFH) is a mainstay of treatment for patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS), but the practice of weight-adjusted bolus and infusion dosing has not been carefully evaluated.

METHODS

Using data from 31,445 high-risk patients with NSTE ACS enrolled at 420 hospitals in the CRUSADE initiative, we evaluated initial UFH dosing relative to guideline recommendations and determined factors associated with excess weight-adjusted dosing and major bleeding, overall and among subgroups. Excess dose was defined as >70 U/kg for bolus or >15 U/kg per hour for infusion.

RESULTS

The most frequent bolus dose was 5,000 U (42.7%) and infusion dose was 1,000 U/h (46%). An excess weight-adjusted UFH bolus or infusion dose was administered 35% of the time. Factors strongly associated with excess weight-adjusted dosing were age (per 10-year increase) (odds ratio [OR] 1.11, 95% CI 1.08-1.15) and female sex (OR 1.45, 95% CI 1.33-1.59). Rate of major bleeding increased proportionally in relation to dose of UFH for both bolus and infusion, specifically when dose was above the recommended weight-adjusted range (>70 U/kg for bolus or >15 U/kg per hour for infusion). Both excess bolus (OR 1.03, 95% CI 1.00-1.06) and infusion (OR 1.16, 95% CI 1.05-1.28) were individually associated with increased bleeding. The relationship between weight-adjusted UFH dose and major bleeding did not vary independently by sex or age.

CONCLUSIONS

In high-risk patients with NSTE ACS, initial UFH bolus and infusion dosing were frequently higher than recommended weight-adjusted ranges, particularly in patients with lower body weight. Excess bolus and infusion rate dosing was associated with more bleeding and was common among elderly and females. Attention to dosing by weight rather than standard bolus and infusion dosing should lead to improved safety in the use of UFH.