Usefulness of routine unfractionated heparin infusion following primary percutaneous coronary intervention for acute myocardial infarction in patients not receiving glycoprotein IIb/IIIa inhibitors

Postprocedural Anticoagulation After Primary Percutaneous Coronary Intervention for ST-Segment-Elevation Myocardial Infarction: A Multicenter, Randomized, Double-Blind Trial

BACKGROUND

Postprocedural anticoagulation (PPA) is frequently administered after primary percutaneous coronary intervention in ST-segment-elevation myocardial infarction, although no conclusive data support this practice.

METHODS

The RIGHT trial (Comparison of Anticoagulation Prolongation vs no Anticoagulation in STEMI Patients After Primary PCI) was an investigator-initiated, multicenter, randomized, double-blind, placebo-controlled, superiority trial conducted at 53 centers in China. Patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention were randomly assigned by center to receive low-dose PPA or matching placebo for at least 48 hours. Before trial initiation, each center selected 1 of 3 PPA regimens (40 mg of enoxaparin once daily subcutaneously; 10 U·kg·h of unfractionated heparin intravenously, adjusted to maintain activated clotting time between 150 and 220 seconds; or 0.2 mg·kg·h of bivalirudin intravenously). The primary efficacy objective was to demonstrate superiority of PPA to reduce the primary efficacy end point of all-cause death, nonfatal myocardial infarction, nonfatal stroke, stent thrombosis (definite), or urgent revascularization (any vessel) within 30 days. The key secondary objective was to evaluate the effect of each specific anticoagulation regimen (enoxaparin, unfractionated heparin, or bivalirudin) on the primary efficacy end point. The primary safety end point was Bleeding Academic Research Consortium 3 to 5 bleeding at 30 days.

RESULTS

Between January 10, 2019, and September 18, 2021, a total of 2989 patients were randomized. The primary efficacy end point occurred in 37 patients (2.5%) in both the PPA and placebo groups (hazard ratio, 1.00 [95% CI, 0.63 to 1.57]). The incidence of Bleeding Academic Research Consortium 3 to 5 bleeding did not differ between the PPA and placebo groups (8 [0.5%] vs 11 [0.7%] patients; hazard ratio, 0.74 [95% CI, 0.30 to 1.83]).

CONCLUSIONS

Routine PPA after primary percutaneous coronary intervention was safe but did not reduce 30-day ischemic events.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03664180.

Efficacy of postprocedural anticoagulation after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: A post-hoc analysis of the randomized INNOVATION trial

There exists controversy on whether and for how long anticoagulation is necessary after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI).We aimed to study the impact of prolonged (>24 h) or brief (<24 h) postprocedural anticoagulation on infarct size assessed by cardiac magnetic resonance (CMR) after 30 days as well as on left ventricular ejection fraction (LVEF) and left ventricular (LV) remodeling evaluated by 2D-echocardiography after 9 months from the INNOVATION trial (Clinical Trial Registration: NCT02324348).Of the 114 patients (mean age: 59.5 years) enrolled, 76 (66.7%) received prolonged anticoagulation therapy (median duration: 72.6 h) and 38 (33.3%) patients received brief anticoagulation therapy (median duration: 5 h) after primary PCI. There was no significant difference in infarct size (mean size: 15.6% after prolonged anticoagulation versus 19.8% after brief anticoagulation, P = .100) and the incidence of microvascular obstruction (50.7% versus 52.9%, P = .830) between the groups. Even after adjusting, prolonged anticoagulation therapy could not reduce larger infarct (defined as >75 percentile of infarct size; 19.7% versus 35.3%; adjusted odd ratio [OR]: 0.435; 95% confidence interval [CI]: 0.120-1.57; P = .204). Similar results were observed in subanalyses of major high-risk subgroups. Moreover, follow-up LVEF <35% (3.2% versus 7.4%; adjusted OR: 0.383; 95% CI: 0.051-2.884; P = .352) and LV remodeling (defined as >20% increase in LV end-diastolic volume; 37.1% versus 18.5%; adjusted OR: 2.249; 95% CI: 0.593-8.535; P = .234) were similar between groups.These data suggest that prolonged postprocedural anticoagulation may not provide much benefit after successful primary PCI in patients with STEMI. However, further studies are needed.

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.

The Role of Glycoprotein IIb/IIIa Inhibitors- A Promise Not Kept?

For over one decade Glycoproteins IIb/IIIa inhibitors (GPI) have been administered to prevent coronary artery thrombosis. Initially these agents were used for acute coronary syndromes and subsequently as adjunctive pharmacotherapy for percutaneous coronary interventions (PCIs).

Most benefit of GPI emerged from reduction of ischemic events: mostly non-q-wave myocardial infarctions (NQWMIs) during PCI. However, individual randomized clinical trials could not demonstrate that any of these agents could significantly reduce mortality in any clinical subset of patients. Studies of employing prolonged oral GPI administration resulted in excessive death. The non-homogenous statistically-significant reduction of ischemic endpoints was accompanied by an excess of bleeding, vascular complications, and thrombocytopenia. The clinical and ecomomic burden of major bleeding and thrombocytopenia is substantial. The ACUITY trial has initiate a new debate regarding the efficacy and safety of GPI.

Selective “patient-tailored” use of GPI limited to moderate-high risk PCI patients with low bleeding propensity is suggested. Research of new algorithms emphasizing abbreviated GPI administration, careful access site and bleeding surveillance, in conjunction with lower doses of unfractionated heparin or new and safer anti-thrombins may further enhance patient safety.

Thrombocytopenia following percutaneous coronary intervention

BACKGROUND

Thrombocytopenia following percutaneous coronary intervention (PCI) is an underappreciated condition that is often clinically challenging. There are no guidelines on the management of patients with this condition.

OBJECTIVE

To review recent data in etiologies, risk factors, prevention, management, and prognostic implications of thrombocytopenia following PCI.

EVIDENCE ACQUISITION

Search of MEDLINE, EMBASE, the Cochrane Database, and Google Scholar using the term thrombocytopenia + PCI and other relevant keywords to identify systematic reviews, clinical trials, cohort studies, case series, and case reports. The review was limited to English-language articles published between January 1980 and June 2009. Articles on patients with baseline thrombocytopenia prior to PCI were excluded.

EVIDENCE SYNTHESIS

Thrombocytopenia is not infrequent following PCI. The typical patient with post-PCI thrombocytopenia is on multiple therapies that can potentially cause a decrease in the platelet count. Identification of the cause is critical because management of the condition varies significantly based on the etiology. The severity of the thrombocytopenia also determines the clinical management of the patient. Several observational studies have demonstrated the adverse prognostic impact of the complication on clinical outcomes and have identified risk factors.

CONCLUSIONS

Judicious use of therapies that can cause thrombocytopenia, efficient detection of the cause of the decrease in platelet count, and appropriate management of the condition can potentially improve the quality of care and outcomes following PCI. Further research into risk factors that predispose post-PCI patients to developing thrombocytopenia is warranted.

The Harmonizing Outcomes with RevasculariZatiON and Stents in Acute Myocardial Infarction (HORIZONS-AMI) Trial: study design and rationale

BACKGROUND

Advances in coronary angioplasty and adjunct pharmacology have improved patient outcomes after primary percutaneous coronary intervention (PCI) in acute myocardial infarction (AMI). However, several areas for improvement remain. Hemorrhagic complications, which are common in patients receiving intense anticoagulant and antiplatelet agents during primary PCI to suppress ischemia, have been strongly associated with early and late mortality. Moreover, restenosis after bare-metal stents (BMSs) frequently results in symptom recurrence and the need for repeat rehospitalization and revascularization procedures. Newer pharmacologic agents and drug-eluting stents may address both of these issues.

STUDY DESIGN

In the HORIZONS-AMI trial, 3,602 patients with AMI undergoing primary PCI were prospectively randomized to unfractionated heparin plus routine use of glycoprotein (GP) IIb/IIIa inhibitors versus the direct thrombin inhibitor bivalirudin plus provisional use of GP IIb/IIIa inhibitors reserved for predefined thrombotic complications. In a second randomization, 3,011 eligible patients were randomly assigned to either a polymer-based paclitaxel-eluting stent or to an otherwise identical BMS. The study was powered for the assessment of sequential safety and efficacy end points for each specific randomization, with clinical end points assessed at 30 days, 1 year, and then annually for 5 years.

SUMMARY

The ongoing HORIZONS-AMI trial will determine whether bivalirudin monotherapy reduces bleeding complications and improves overall event-free survival compared with unfractionated heparin plus the routine use of GP IIb/IIIa inhibitors in patients undergoing primary PCI for AMI. Furthermore, this study will determine whether paclitaxel-eluting stents safely reduce rates of ischemic target lesion revascularization compared with BMSs in the setting of primary PCI.

Glycoprotein IIb/IIIa inhibitors: questioning indications and treatment algorithms

Glycoprotein inhibitors (GPI) are viewed as beneficial adjunctive pharmacotherapy agents for percutaneous coronary interventions (PCIs). The major benefit of GPI is derived from the reduction of ischemic events (mostly non-Q-wave myocardial infarctions) during PCI. There is no single randomized clinical trial demonstrating that any of these agents significantly reduces mortality in any clinical subset of patients. Studies of sustained oral GPI resulted in excessive death and myocardial infarctions. Reduction of ischemic end points was counteracted by excessive bleeding, vascular complications, and thrombocytopenia. These complications bear considerable medical and economic impact. The Acute Catheterization and Early Intervention Triage Strategy trial demonstrated that GPI, when added to heparin, enoxaparine, or bivalirudin, do not reduce mortality or ischemic events but significantly increase bleeding complications. Major bleeding resulted in threefold mortality at 1 year. In view of available data, the use of GPI should be limited to moderate-risk to high-risk PCI patients with low bleeding propensity. Protocols of abbreviated GPI administration and careful bleeding surveillance, in conjunction with lower doses of unfractionated heparin or new and possibly safer antithrombins, can potentially improve patient safety.