**5.1. Protected PCI**

**4. Adverse events**

186 Interventional Cardiology

by fluoroscopy from an RAO (right anterior oblique) angle.

support for CS.

occurred [6].

Potential adverse events following Impella® implantation or hemodynamic support with Impella® include hemolysis, functional mitral stenosis, pump displacement, malfunction and vascular site complications including bleeding and limb ischemia. Furthermore, thromboembolic events including stroke and myocardial infarction as well as acute kidney dysfunction or failure might occur. Overall incidence rate is low, seems to differ according to the indication for hemodynamic support, and is also most likely related to the duration of Impella® support. Highest rates for adverse events may accordingly be found in patients undergoing Impella®

**Figure 3.** Correct position of the Impella 2.5 in the left ventricle with the outlet portion above the aortic valve demonstrated

In 120 patients with AMI complicated by CS, The EUROSHOCK trial found major bleeding at the vascular access site in 28.6%, hemolysis in 7.5%, and pericardial tamponade in 1.7% [3]. In another study including 40 patients with end-stage heart failure and implantation of an Impella® 5.0 as bridge to transplant or bridge to left ventricular assist device (LVAD), bleeding requiring transfusion occurred in 28.0%, hemolysis in 8.0%, device malfunction in 10.0%, and limb ischemia in 3.0% [4]. Highest rates of adverse events were generally found for major bleeding at the access site and hemolysis, two complications that may usually be managed

In patients undergoing protected PCI, the frequency of adverse events is usually lower. The PROTECT trial, designed to examine the efficacy and safety of Impella® 2.5 in protected PCI, found mild, transient hemolysis in 10.0% of patients with no other major adverse events [5]. In a further study including 19 patients undergoing protected PCI, no complications

successfully while patients may remain on Impella® support.

Poor outcome in patients undergoing PCI is associated with depressed left ventricular function, higher complexity of lesions, multi-vessels disease, and poor pre-interventional status [9]. In these patients, even limited episodes of myocardial ischemia caused by intracoronary application of contrast medium, inflation of balloons, implantation of stents, or more sophisticated maneuvers like rotablation may provoke hypotension resulting in a vicious cycle of impaired coronary perfusion, malignant cardiac arrhythmias, and cardiac arrest. The preinterventional implantation of an Impella® device, referred to as protected PCI, may provide hemodynamic support in case of hemodynamic compromise and augment intracoronary blood flow.

The PROTECT I trial (A Prospective Feasibility trial Investigating the Use of the IMPELLA RECOVER LP 2.5 System in Patients Undergoing High Risk PCI) was the first trial designed to evaluate the safety and feasibility of the Impella® 2.5 system in patients undergoing protected PCI [5]. Including 20 patients in a prospective, multi-center fashion, this study demonstrated that the Impella® 2.5 is safe and easy to implant with only two patients showing signs of mild hemolysis. All patients included had a poor left ventricular function and underwent PCI of an unprotected left main coronary artery or last patent coronary conduit. None of the patients developed hemodynamic compromise during PCI.

The PROTECT II trial represents the second landmark study for protected PCI via Impella® 2.5, comparing the Impella® device with intra-aortic balloon pump (IABP) in a randomized, controlled design [10]. Although the study was terminated early on grounds of futility (the study was underpowered for the primary endpoint of superiority of Impella® 2.5 compared to IABP in terms of MACCE), trends for improved outcomes were observed for Impella® 2.5-supported patients at 90 days.

Besides the mentioned trials, multiple individual experiences with the device and protected PCI, case studies, and case reports have been published [6, 11–16]. In general, the concept has been described as safe and feasible, resulting in hemodynamic improvement. Data from the USpella registry have further demonstrated the feasibility of protected PCI through Impella® 2.5 in a real-world setting [17].
