STEMI Patients with Large Thrombus Benefit from Low-dose Thrombolysis

Download this article's Factoid (PDF & PPT for Gold Subscribers)

Intracoronary administration of low-dose thrombolysis is safe and reduces thrombus burden in patients with ST-segment elevation myocardial infarction (STEMI) who maintain a large thrombus burden even after manual aspiration, according to a registry study published online March 17, 2014, ahead of print in European Heart Journal: Acute Cardiovascular Care.

Beatriz Vaquerizo, MD, of the Hospital Sant Pau (Barcelona, Spain), and colleagues enrolled 30 STEMI patients with a large thrombus burden (TIMI thrombus grade 3 or 4) and failed manual aspiration thrombectomy at multiple centers from April 2006 to July 2012. All patients were treated with local, low-dose, intracoronary thrombolysis (tenecteplase 27% and alteplase 73%) followed by PCI. Most procedures were performed radially (53.3%), and repeat manual thrombectomy was performed with more than 1 device in 30% of patients.

After treatment, both epicardial flow and myocardial reperfusion improved. Post-lysis thrombus grade 4-5 remained in only 1 patient, and TIMI flow grade improved from 0/1 at baseline to 2 or higher in the majority of patients (97%). In most patients a myocardial blush grade 2-3 (85%) was obtained after reperfusion therapy. Similarly, ST-segment resolution of more than 50% was observed in 82% of patients.

In-hospital mortality was 10% including 3 patients with cardiogenic shock. There were no major bleeding events, and at a median follow-up of 14.4 months only 1 new clinical event was reported (TLR).

Confirming the ‘Real Problem’

In this patient population, low-dose intracoronary thrombolysis leads to “improvements in epicardial flow and improved tissue-level perfusion by dissolving thrombi at the microvascular level,” Dr. Vaquerizo and colleagues write. “Moreover, with correct patient selection, this is a safe strategy, without major bleeding complications.”

The study confirms that the problem of massive intracoronary thrombosis is infrequent among primary PCI cases for STEMI, they note. The “real problem,” the investigators observe, arises in “cases of a large thrombus burden in which, even in the current era, after administration of potent antiplatelet and anticoagulant regimens and [use of] manual aspiration, residual thrombus persists.”

The authors suggest that the lack of bleeding events seen in this study can be explained by several factors:

• Careful monitoring of anticoagulation
• Use of radial access in more than half of patients
• Low baseline bleeding risk
• Local administration of thrombolysis, permitting use of lower drug dose

Study limitations include the retrospective nature and small sample size, according to Dr. Vaquerizo and colleagues. They add that imaging follow-up was not available to “confirm that the satisfying procedural results translated into preserved cardiac function.”

However, the authors conclude, the study “provides important data to aid our everyday clinical practice, because the optimal management of cases in which there remains a large thrombus burden despite mechanical thrombectomy is unknown, and the risk of poor procedural results and associated adverse events at follow-up is high.”

Study Details

Mean age was 61.4 years and more than three-quarters were men (78.6%). Few patients had a history of prior MI (14.3%) or PCI (7.1%). The most frequent traditional coronary risk factors were dyslipidemia (57.1%) and hypertension (46.4%). More than 80% of patients received dual antiplatelet therapy before undergoing the interventional procedure and 70% were pretreated with a bolus of unfractionated heparin in the ER.

The most frequent infarct location was inferior (57%), and the right coronary artery was the most often treated (53.6%). One-third of patients were admitted to the hospital within 12 hours of symptom onset, and baseline TIMI flow grade was 0/1 in 93% of patients.

Source:

Boscarelli D, Vaquerizo B, Miranda-Guardiola F, et al. Intracoronary thrombolysis in patients with ST-segment elevation myocardial infarction presenting with massive intraluminal thrombus and failed aspiration. Eur Heart J: Acute Cardiovasc Care. 2014;Epub ahead of print.

Related Stories

• FAST-MI Registry: Fibrinolysis, Primary PCI Yield Similar 5-Year Survival in STEMI Patients
• Thrombolysis with Immediate Transfer for PCI Safe for Rural STEMI Patients
• PCI-Backed Thrombolysis as Good as Primary PCI for STEMI