An update on the use of anticoagulant therapy in ST-segment elevation myocardial infarction

Introduction: Together with antiplatelet therapy, anticoagulants are vital to improve outcomes in patients presenting with ST-segment elevation myocardial infarction.

Challenges lie in finding the optimal balance between the risk of bleeding and preventing thrombotic complications such as reinfarction or stent thrombosis. During the last decade, bivalirudin was introduced as a valid alternative to heparin for patients undergoing primary percutaneous coronary intervention. Several trials have been conducted to identify the agent with the best antithrombotic results at the lowest bleeding complication rate. In a rapidly evolving field with changes in vascular access, available P2Y₁₂ inhibitors, and indications for glycoprotein IIb/IIIa inhibitor administration, conflicting evidence became available.

Areas covered: This paper mainly focuses on the evidence above and gives brief discussion to the recent literature on anticoagulation in fibrinolytic therapy and advances in antiplatelet therapy.

Expert opinion: To date, no robust evidence is available challenging unfractionated heparin as the primary choice for anticoagulation in patients presenting with ST-segment elevation myocardial infarction. Further research should include efforts to refine anticoagulation strategies on an individual patient level. For patients undergoing primary percutaneous coronary intervention, bivalirudin could be used as an alternative to unfractionated heparin, while enoxaparin or fondaparinux is an alternative agent for patients treated with fibrinolytic therapy.     

Incidence and clinical significance of distal embolization during primary angioplasty for acute myocardial infarction.

AIMS: Although recognized as an important feature of atherosclerotic coronary disease, little is known about the frequency and prognostic importance of distal embolization during primary angioplasty for acute myocardial infarction. METHODS AND RESULTS: As part of a randomized trial of thrombolysis vs primary angioplasty, 178 patients with acute myocardial infarction were treated with primary angioplasty. In these patients the occurrence of distal embolization after angioplasty was assessed. Embolization was defined as a distal filling defect with an abrupt 'cutoff' in one of the peripheral coronary artery branches of the infarct-related vessel, distal to the site of angioplasty. We analysed myocardial blush grade, ST-T segment elevation resolution, enzymatic infarct size and left ventricular ejection fraction in patients with and without distal embolization. Clinical information was collected for a mean of 5 years. Distal embolization was present in 27 patients (15.2%). Mean age and gender were not different from patients without distal embolization. Angiographic success (thrombolyis in myocardial infarction flow grade 3 and residual stenosis <50%) after primary angioplasty was less frequently observed in patients with distal embolization (70% vs 90%, P<0.01). Myocardial blush and ST-T segment elevation resolution after angioplasty were reduced when distal embolization was present. Patients with distal embolization had a larger enzymatic infarct size (mean cumulative lactate dehydrogenase measured over 72 h, 1612 vs 847, P<0.05) and a lower left ventricle ejection fraction at discharge (42% vs 51%, P<0.01). Long-term mortality was higher in patients with distal embolization (44% vs 9%, P<0.001). CONCLUSION: Distal embolization in patients treated with primary angioplasty is visible on the coronary angiogram in 15.2% of patients. It is related to reduced myocardial reperfusion, more extensive myocardial damage and a poor prognosis. Additional pharmacological interventions and/ or mechanical devices should be studied to prevent and/or treat distal embolization.     

Left ventricular thrombus formation after acute myocardial infarction as assessed by cardiovascular magnetic resonance imaging

Introduction

Left ventricular (LV) thrombus formation is a feared complication of myocardial infarction (MI). We assessed the prevalence of LV thrombus in ST-segment elevated MI patients treated with percutaneous coronary intervention (PCI) and compared the diagnostic accuracy of transthoracic echocardiography (TTE) to cardiovascular magnetic resonance imaging (CMR). Also, we evaluated the course of LV thrombi in the modern era of primary PCI.

Methods

200 patients with primary PCI underwent TTE and CMR, at baseline and at 4 months follow-up. Studies were analyzed by two blinded examiners. Patients were seen at 1, 4, 12, and 24 months for assessment of clinical status and adverse events.

Results

On CMR at baseline, a thrombus was found in 17 of 194 (8.8%) patients. LV thrombus resolution occurred in 15 patients. Two patients had persistence of LV thrombus on follow-up CMR. On CMR at four months, a thrombus was found in an additional 12 patients. In multivariate analysis, thrombus formation on baseline CMR was independently associated with, baseline infarct size (g) (B = 0.02, SE = 0.02, p < 0.001). Routine TTE had a sensitivity of 21–24% and a specificity of 95–98% compared to CMR for the detection of LV thrombi. Intra- and interobserver variation for detection of LV thrombus were lower for CMR (κ = 0.91 and κ = 0.96) compared to TTE (κ = 0.74 and κ = 0.53).

Conclusion

LV thrombus still occurs in a substantial amount of patients after PCI-treated MI, especially in larger infarct sizes. Routine TTE had a low sensitivity for the detection of LV thrombi and the interobserver variation of TTE was large.     

The Effect of Ergotamine on Prostaglandin Formation in Guinea Pig''s Ear Slices

SYNOPSIS
We have studied the effect of ergotamine tartrate (10⁻⁷ and 10⁻⁵ M) on prostaglandin (PG) formation in guinea pig's ear slices because of the suggested role of PGs in the pathophysiology of the migraine attack. The ear slices were incubated with arachidonic acid (AA) and the amount of different PGs (6-keto-F_1a, F_2a, E₂, D₂ and A₂) in the incubation medium was determined. The results indicate that ergotamine is an inhibitor of PG synthesis and that it probably affects either the phospholipase A₂ or the cyclo-oxygenase activity.     

Predicting Early Mortality Among Implantable Defibrillator Patients Treated With Cardiac Resynchronization Therapy

BackgroundThe beneficial effects of a cardiac resynchronization defibrillator (CRT-D) in patients with heart failure, low left ventricular ejection fraction (LVEF), and wide QRS have clearly been established. Nevertheless, mortality remains high in some patients. The aim of this study was to develop and validate a risk score to identify patients at high risk for early mortality who are implanted with a CRT-D.Methods and ResultsFor predictive modelling, 1282 consecutive patients from 5 centers (74% male; median age 66 years; median LVEF 25%; New York Heart Association class III–IV 60%; median QRS-width 160 ms) were randomly divided into a derivation and validation cohort. The primary endpoint is mortality at 3 years. Model development was performed using multivariate logistic regression by checking log likelihood, Akaike information criterion, and Bayesian information criterion. Model performance was validated using C statistics and calibration plots. The risk score included 7 independent mortality predictors, including myocardial infarction, LVEF, QRS duration, chronic obstructive pulmonary disease, chronic kidney disease, hyponatremia, and anemia. Calibration-in-the-large was suboptimal, reflected by a lower observed mortality (44%) than predicted (50%). The validated C statistic was 0.71 indicating modest performance.ConclusionA risk score based on routine, readily available clinical variables can assist in identifying patients at high risk for early mortality within 3 years after CRT-D implantation.