PCI with left ventricular hemodynamic support

Key points

Complex percutaneous coronary intervention (PCI) procedures have become more common as techniques for chronic total occlusions (CTOs), bifurcation, and left main lesions have been developed with improved outcomes.
Complex PCI can create significant acute risk for hemodynamic collapse in the Cath lab and the placement of prophylactic left ventricular (LV) support can minimize the risk of such an event.
Multiple percutaneous options for LV support are now available, but they differ in their ease of use, potential complications, and hemodynamic effects.
Clinical data mainly support the use of the Impella device to support complex PCI.

The performance of percutaneous coronary intervention (PCI) to improve myocardial blood flow to decrease symptoms of angina and potentially improve left ventricular (LV) function has been well established. There exists a large spectrum of potential discussion on this topic from “simple” PCI procedures involving singular lesions of lesser complexity to multivessel PCI, which includes lesions that are chronically occluded or in patients with severely depressed LV function. Regardless, the performance of PCI results in an acute period of myocardial ischemia while balloon inflation impedes forward blood flow in the artery being addressed. Before balloon angioplasty, it was demonstrated in animal models that acute ischemia rapidly decreased the maximum pressure that could be generated in the LV in a given time (the derivative of pressure over time [dP/dT]), that decreased systolic force generated by the ischemic myocardium, that the effects become apparent within seconds of the occlusion of the vessel, and that these changes recurred with reocclusion (i.e., subsequent balloon inflation).

Putting it together, patients with preserved LV function and relatively simple PCI will still have some short-term effects from the procedure within the LV wall, but this is not sufficient to result in prolonged hypotension, impaired cardiac output, or ventricular rhythm disturbances. Patients with impaired function and/or undergoing a PCI procedure to multiple arteries, which potentially increases the amount of acute ischemia that the ventricle is exposed to, may not be able to tolerate the short-term dysfunction within the myocardium—a subset now referred to as “complex PCI” ( Fig. 10.1 ). Thus, to perform PCI on these patients, the LV requires “support” to maintain hemodynamic stability throughout the procedure.

Patient selection

Presently, selection of patients in whom hemodynamic support is used during PCI remains institution dependent. Nevertheless, there are some similar guiding principles that can be found to help with preprocedural planning. The first of these is that these procedures are not recommended to be done on an “ad hoc” basis and there should be a formal Heart Team discussion that is documented within the medical record that goes through the relative merits of this procedure and gains support from the collective team of surgeons and interventional cardiologists. Although these procedures have a higher complication rate than those of standard PCI, they are also potentially associated with greater benefit for the patient, and it is recommended that the goals to be achieved by taking on a supported PCI procedure be defined before the procedure and agreed upon by the Heart Team and the patient.

Currently, there is a single randomized controlled trial (RCT) that has investigated supported PCI: PROTECT II. The findings of this trial will be discussed later in this chapter, but the enrollment criteria can provide information on the types of patients who should be considered ( Table 10.1 ). A suggested algorithm ( Fig. 10.2 ) for decision making in supported PCI procedures illustrates many critical issues. After a Heart Team recommendation on pursuing the procedure, using historical clinical data, understanding the implications of the planned PCI procedure itself (e.g., hemodynamic insult of atherectomy), and assessing invasive hemodynamics has been recommended in an attempt to predict the potential for hemodynamic collapse during the procedure. Typically, baseline LV function has been used as a significant and common element when considering using LV support. When it is felt that alterations to hemodynamics are likely, the prophylactic implantation of an LV support device before performing a PCI is achieved. Operators experienced at these devices also have the ability to implant them relatively quickly when hemodynamic collapse occurs unexpectedly.

Table 10.1

Inclusion Criteria for Patients to Be Considered for PROTECT II

Patient’s EF	Angiographic Disease
EF ≤ 35%	Unprotected left main or last patent vessel
EF ≤ 30%	Three-vessel disease

EF , Ejection fraction.

$Figure 10.2, Key factors to consider when planning a complex percutaneous coronary intervention (PCI) as to when implementing a left ventricular (LV) support device preprocedure would be most beneficial. The patient’s LV ejection fraction remains a key determinate, and anatomic features, patient comorbidities, and invasive hemodynamic findings significantly increase the need for support.$

Lesion subsets frequently requiring consideration for support during PCI include left main intervention and patients who have previously undergone bypass surgery with multiple failed grafts. In patients with left main disease, Fig. 10.3 illustrates some of the critical elements involved with successful PCI. Because most lesions involve the distal left main, these interventions frequently involve bifurcation techniques. Thus should the patient have an impaired baseline ejection fraction (EF) or heart failure (e.g., pulmonary capillary wedge pressure [PCWP] > 20 mm Hg), multiple balloon inflations resulting in decreased perfusion to the left coronary system will potentially result in significant hypotension, ventricular dysrhythmias, or loss of pulsatilla of the ventricle, and pre-PCI placement of LV support would be indicated. Patients with prior bypass grafts that have failed often have complex disease within the native vessels that requires multiple stents and sometimes prolonged atherectomy procedures to prepare the vessel, which may also result in similar untoward hemodynamic results as left pain PCI.