Percutaneous Coronary Intervention

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Chapter 20

Percutaneous Coronary Intervention

1. What does the term percutaneous coronary intervention mean?

    Percutaneous coronary intervention (PCI) is a common term used to describe both percutaneous transluminal coronary angioplasty (PTCA), which implies the use of balloon angioplasty but not stenting, and coronary stent placement. The first successful balloon angioplasty procedure in humans was performed by Dr. Andreas Gruentzig in 1977. Since then, there has been tremendous development in the field of interventional cardiology. The development of coronary stents was a major boost to interventional cardiology, addressing many of the complications and limitations associated with balloon angioplasty. Eighty percent of the PCIs performed currently involve stent placement. PCI has become one of the most commonly performed medical procedures in the United States, with more than about 600,000 procedures performed annually. PCI is performed for coronary revascularization in patients with stable coronary disease, as well as those with acute coronary syndromes (ACS) in the appropriate clinical settings.

2. Which patients with chronic stable angina benefit from PCI?

    The goals of treatment in patients with coronary artery disease are to:

Multiple clinical trials of PCI plus medical therapy or medical therapy alone involving patients with chronic stable angina over the last two decades have consistently shown improvement in angina, exercise duration, and quality of life with PCI. However, they have not demonstrated any difference in death and MI between treatment with PCI plus medical therapy compared to medical therapy alone. In contrast, the use of PCI in patients with ACS has been shown to decrease recurrent ischemia, nonfatal MI, and death.

In general, patients with chronic stable angina in whom PCI should be considered are those with symptom-limiting angina, one or more significant coronary arteries stenoses, a high likelihood of technical success, and a low risk of complications.

In patients with 3-vessel coronary artery disease (CAD), particularly if they have complex and/or extensive CAD (reflected in a high SYNTAX score or diabetes), bypass surgery is generally preferred over multivessel PCI. Unprotected left main PCI can be considered in those with a stenosis that has a high likelihood of procedural success and long-term durability, especially in cases in which the patient is at high risk for surgery (reflected by a high Society of Thoracic Surgeons [STS] risk score).

3. Which patients with unstable angina/non–ST elevation myocardial infarction (UA/NSTEMI) should undergo a strategy of early cardiac catheterization and revascularization?

    Two major strategies, conservative (medical therapy without an initial strategy of catheterization and revascularization) and early invasive, are employed in treating patients with UA/NSTEMI. The early invasive approach involves performing diagnostic angiography with intent to perform PCI along with administering the usual antiischemic, antiplatelet, and anticoagulant medications. Evidence from clinical trials suggests that an early invasive approach with UA/NSTEMI leads to a reduction in adverse cardiovascular outcomes, such as death and nonfatal MI, especially in high-risk patients. Several risk-assessment tools are available that assign a score based upon the patient’s clinical characteristics (e.g., TIMI and GRACE scores). Patients who present with UA/NSTEMI should be risk stratified to identify those who would benefit most from an early invasive approach. Patients with the following clinical characteristics indicative of high risk should be taken for early coronary angiography with intent to perform revascularization:

Initially stabilized patients without the above risk factors (low-risk patients) may be treated with an initial conservative (or selective invasive) strategy. An early invasive approach should not be undertaken in patients with extensive comorbidities, organ failure, or advanced cancer, in which the risk of revascularization is greater than the benefit, or in patients who do not consent to the procedure.

4. What are the contraindications to PCI and the predictors of adverse outcomes?

    The only absolute contraindication to PCI is lack of any vascular access or active severe bleeding, which precludes the use of anticoagulation and antiplatelet agents. Relative contraindications include the following:

Patients generally should not undergo PCI if the following conditions are present:

Clinical predictors of poor outcomes include older age, an unstable condition (ACS, acute MI, decompensated CHF, cardiogenic shock), LV dysfunction, multivessel coronary disease, diabetes mellitus, renal insufficiency, small body size, and peripheral artery disease.

Angiographic predictors of poor outcomes include the presence of thrombus, degenerated bypass graft, unprotected left main disease, long lesions (more than 20 mm), excessive tortuosity of proximal segment, extremely angulated lesions (more than 90 degrees), a bifurcation lesion with involvement of major side branches, or chronic total occlusion.

5. What are the major complications related to PCI?

    The incidence of major complications has constantly decreased over the last two decades as a result of the use of activated clotting time to measure degree of anticoagulation, better antithrombotic and antiplatelet agents, advanced device technology, more skilled operators, and superior PCI strategies. These factors have particularly lowered the incidence of MI and the need for emergent CABG. Major complications of PCI include the following:

Death: The overall in-hospital mortality rate is 1.27% ranging from 0.65% in elective PCI to 4.81% in ST elevation myocardial infarction (STEMI) (based on the National Cardiac Data Registry [NCDR] CathPCI database of patients undergoing PCI between 2004 and 2007).

MI: The incidence of PCI-related MI is 0.4% to 4.9%; the incidence varies depending on the acuity of symptoms, lesion morphology, definition of MI, and frequency of measurement of biomarkers.

Stroke: The incidence of PCI-related stroke is 0.22%. In-hospital mortality in patients with PCI-related stroke is 25% to 30% (based on a contemporary analysis from the NCDR).

Emergency CABG: The need to perform emergency CABG in the stent era is extremely low (between 0.1% and 0.4%).

Vascular complications: The incidence of vascular complications ranges from 2% to 6%. These include access-site hematoma, retroperitoneal hematoma, pseudoaneurysm, arteriovenous fistula, and arterial dissection. In randomized trials, closure devices were only beneficial in reducing time to hemostasis but did not reduce the incidence of vascular complications.

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