Introduction of Use Of Thrombectomy Devices In Primary Percutaneous Interventions For ST-Elevation Myocardial Infarction - An Update

Preview

Summary

Primary percutaneous coronary intervention (PPCI) is the optimal treatment strategy for restoring coronary blood flow in the infarct related artery (IRA) and salvaging myocardium in patients with ST elevation myocardial infarction (STEMI).^1,2 Despite this, PPCI fails to restore optimal myocardial perfusion in up to 40 % of patients despite restoring epicardial artery patency as evidenced by failure of ST-segment resolution (STR) and poor myocardial blush grade (MBG).³ This failure of microvascular perfusion is associated with larger infarct size, left ventricular dysfunction and decreased survival in the long term.^{4– 6}

Even though different mechanisms underlie microvascular injury after PPCI, such as generation of reactive oxygen species, cardiomyocyte calcium overload, vasoconstriction, inflammation and cellular and interstitial oedema, distal embolisation appears to play a pivotal role.^7,8 A number of studies have demonstrated that PCI can result in an embolisation rate of up to 15 %.^8,9 Embolisation of large particles, such as plaque debris, can result in occlusion of pre-arterioles and small side branches, whereas microembolisation can result in occlusion of arterioles and capillaries that can impair perfusion of the myocardium at a microscopic level. ^10,11 A high thrombus burden is associated with an increased incidence of distal embolisation and itself has been associated with higher frequency of adverse outcomes (major adverse cardiac events [MACEs] and mortality).¹²

Strategies, such as thrombectomy devices, to help reduce thrombus burden and prevent distal embolisation have been proposed to increase microvascular flow and improve outcomes.^13,14 As this embolisation occurs predominantly at the time of the initial balloon or stent inflation, using a thrombectomy device to reduce thrombus burden before inflation may decrease the likelihood of distal embolisation (see Figure 1). This has led to the development of a number of devices to prevent this problem occurring.¹¹ Currently, a variety of commercially available devices are available with different mechanisms that enable them to either fragment or aspirate the thrombus (see Table 1 and 2). Thrombectomy devices are broadly divided into two groups depending on whether they are motorised (mechanical thrombectomy) or not (manual thrombectomy).