News:Clot retrieval from the coronary arteries during primary angioplasty improves myocardial perfusion and clinical outcomes

February 8, 2008 By Vijayalakshmi Kunadian MBBS MD MRCP [mailto:vkunadian@perfuse.org]

When it can be performed quickly by expert operators, primary percutaneous coronary intervention (PPCI) is the optimal strategy for the management of patients with acute myocardial infarction. Clinical outcomes for these patients can be significantly improved by opening the occluded arteries as quickly as possible, i.e., by reducing the door-to-balloon times.

Potential clot embolization during PPCI represents a major challenge faced by interventional cardiologists. Over the last few years, advances in pharmacotherapy, including potent antiplatelet and antithrombotic agents, have been supplemented by a number of new adjunct mechanical devices that have emerged from recent randomized clinical trials. These devices fall into 3 broad categories: (1) thrombus extraction devices, (2) proximal protection devices, and (3) distal protection devices. While distal protection has displayed benefits in saphenous vein graft trials, it has not demonstrated similar benefits in native coronary artery interventions because the placement of the distal embolic protection device may cause embolization. As a result, recently there has been a greater emphasis on proximal protection strategies.

In the latest issue of the New England Journal of Medicine, Svilaas and colleagues performed a study using a thrombus extraction device during PPCI called the TAPAS study (Thrombus Aspiration in Percutaneous coronary intervention following Acute myocardial infarction Study). In this single center study the 1071 patients with acute myocardial infarction underwent coronary angiography and then were randomized to thrombus extraction (535 patients) or conventional PPCI (536 patients). 93.4% of the patients in the thrombus extraction group and 89.9% in the conventional PPCI group received glycoprotein IIb/IIIa inhibitor therapy.

The investigators were able to aspirate thrombus in 72.9% of the cases, which were confirmed by histopathological examinations. The major component of the aspirated debris consisted of platelets in 67.7% of cases and of erythrocytes in 15.1% of patients. Patients randomized to the thrombus extraction group demonstrated significant improvement in their myocardial blush grades (Grade 0/1 17.1% versus 26.3%, p<0.001) and ST segment resolution (complete ST segment resolution in 56.6% versus 44.2%, p<0.001) when compared to patients randomized to the conventional PPCI group.

Patients with impaired myocardial blush (Grade 0 or 1) demonstrated worse outcomes (14.1%) than those with Grade 2 blush (8.8%) or Grade 3 blush (4.2%, p<0.001). In keeping with the association of impaired blush with worse outcomes, aspiration was associated with favorable trends with respect to the clinical outcomes such as death (p=0.07), reinfarction (p=0.11), and major adverse cardiac events (p=0.12).

This study adds data to a growing literature linking impaired perfusion with worse clinical outcomes. It also demonstrates that aspiration may be a clinically beneficial strategy.