Percutaneous coronary intervention overview

# Overview
Percutaneous coronary intervention (PCI), commonly known as coronary angioplasty, is an invasive cardiologic therapeutic procedure to treat the stenotic (narrowed) coronary arteries of the heart. These stenotic segments are due to the build up of cholesterol-laden plaques that form due to atherosclerosis in coronary heart disease. PCI is usually performed by an interventional cardiologist. Percutaneous coronary intervention can be performed to reduce or eliminate the symptoms of coronary artery disease, including angina (chest pain), dyspnea (shortness of breath) on exertion, and congestive heart failure. PCI is also used to abort an acute myocardial infarction, and in some specific cases it may reduce mortality.

# Risks stratification and benefits of PCI
There are several risk assessment scores which can help in determining a patient's risk for death, myocardial infarction and recurrent cardiac events.

# Preparation of the patient for PCI
There are several steps involved in preparing the patient for PCI, which include the use of premedications and the use of a Heart Team approach. Attention should be given to possible adverse reactions to contrast, possible anaphylactoid reactions, the use of statins, bleeding risk in the patient, and the presence of on-site surgical back-up services.

# PCI equipment

## Guiding catheter selection
Diagnostic catheters used for coronary arteriography are usually constructed from polyethylene or polyurethane with a fine wire braid within the wall to allow advancement and directional control (torquability) and to prevent kinking. The outer diameter size of the catheters ranges from 4 to 8F, but 5 and 6F catheters are used most commonly for diagnostic arteriography.

## Guidewire selection
Angioplasty guidewires are small, soft, flexible, lubricated, wires that act as a rail over which equipment such as an angioplasty balloon, a stent, or an intravascular ultrasound device can be delivered over into the coronary artery. Angioplasty guide wires were introduced in 1982 by doctors Simpson and Roberts. The introduction of coronary guidewires was a major advance as it allowed the angioplasty balloon to be a traumatically steered to the proper location.

# Pharmacotherapy to Support PCI
2011 AHA guidelines recommend the use of antiplatelet therapy aspirin (Level of Evidence: B) and P2Y12 receptor inhibitor (clopidogrel, prasugrel and ticagrelor) (Level of Evidence: A) to support PCI in patients with ACS. Few randomised trials have been conducted showing comparison of clopidogrel with aspirin and other P2Y12 inhibitors (prasugrel and ticagrelor) in terms of clinical benefit and risk of bleeding when given in patients undergoing PCI. However, there is limited data comparing new P2Y12 receptor inhibitors (prasugrel and ticagrelor) for downstream and upstream therapy in patients undergoing PCI with non ST elevation MI in terms of clinical benefit and adverse effects. Hence, a new large scale randomised open label trial called DUBIUS is in process in Italy comparing two new P2Y12 inhibitors prasugrel and ticagrelor for pretreatment in patients with non ST elevation MI undergoing PCI.

# Vascular Closure Devices
At the very heart of any successful endovascular procedure is successful arterial entry and exit. The first successful cardiac catheterization, according to Andre Cournand, was performed on an equine patient in 1844 utilizing a retrograde approach through both the jugular vein and carotid artery. Human retrograde left heart catheterization was first reported by Zimmerman and Limon-Lason in 1950. Shortly thereafter in 1953, Seldinger developed the percutaneous technique and this technique was quickly adapted to left heart cardiac catheterizations. With the growth of Interventional Cardiology in the years following Gruntzigs introduction of coronary angioplasty in 1977, the percutaneous approach became, and today remains, by far the most common method of performing catheterization, angiography and endovascular intervention. Within the realm of percutaneous approaches, the majority of the procedures are performed from the femoral approach, with a minority being done from a radial approach. Brachial and axillary are also used in a minority of procedures. Reasons for the continued preference of the femoral route for access includes the vessel size, operator training and equipment, radiation exposure (operator), and the advent of vascular closure devices. Studies have suggested that between 8-10% of all patients selected for a transradial approach will convert to a transfemoral route

# Recommendations for Perioperative ManagementTiming of Elective Noncardiac Surgery in Patients Treated With PCI and DAPT
Elective noncardiac surgery should be delayed 30 days after BMS implantation and optimally 6 months after DES implantation(Level of Evidence: B-NR). When noncardiac surgery is required in patients currently taking a P2Y12 inhibitor, a consensus decision among treating clinicians as to the relative risks of surgery and discontinuation or continuation of antiplatelet therapy can be useful.(Level of Evidence: C-EO)". Elective noncardiac surgery after DES implantation in patients for whom P2Y12 inhibitor therapy will need to be discontinued may be considered after 3 months if the risk of further delay of surgery is greater than the expected risks of stent thrombosis(Level of Evidence: C-EO)". " Prasugrel should not be administered to patients with a prior history of stroke or TIA(Level of Evidence: B-R)

# Post PCI management
After PCI, use of aspirin should be continued indefinitely. In patients receiving a stent (bare metal stent (BMS) or drug eluting stent (DES)) during PCI for ACS, P2Y12 inhibitor therapy should be given for at least 12 months. Options include clopidogrel 75 mg daily, prasugrel 10 mg daily , and ticagrelor 90 mg twice daily. (Level of Evidence: B). In patients receiving drug eluting stent (DES) for a non-ACS indication, clopidogrel 75 mg daily should be given for at least 12 months if the patient is not at high risk of bleeding. Continuation of clopidogrel, prasugrel or ticagrelor beyond 12 months may be considered in patients undergoing placement of drug eluting stent (DES). (Level of Evidence: C)".  Proton pump inhibitors should be used in patients with a history of prior gastrointestinal bleeding who require dual antiplatelet therapy (DAPT).  When a patient predisposed to inadequate platelet inhibition with clopidogrel is identified by genetic testing, treatment with an alternate P2Y12 inhibitor (e.g., prasugrel or ticagrelor) might be considered. Routine periodic stress testing of asymptomatic patients after PCI without specific clinical indications should not be performed.  Medically supervised exercise programs (cardiac rehabilitation) should be recommended to patients after PCI, particularly for moderate- to high-risk patients for whom supervised exercise training is warranted.

# Risk reduction after PCI
Status of tobacco use should be asked about at every visit (Level of Evidence: B). Every tobacco user and family members who smoke should be advised to quit at every visit. (Level of Evidence: B). The tobacco user should be assisted by counseling and developing a plan for quitting. (Level of Evidence: B)". Follow-up, referral to special programs, or pharmacotherapy (including nicotine replacement and pharmacological treatment) should be arranged. (Level of Evidence: B)". Blood pressure goal is less than 140/90 mm Hg or less than 130/80 mm Hg if patient has diabetes or chronic kidney disease. Starting dietary therapy is recommended. Reduce intake of saturated fats (to less than 7% of total calories), trans fatty acids, and cholesterol (to less than 200 mg per day) (Level of Evidence: B)".  LDL-C should be less than 100 mg per dL. (Level of Evidence: B).  If triglycerides are greater than or equal to 150 mg per dL or HDL-C is less than 40 mg per dL, weight management, physical activity, and smoking cessation should be emphasized. (Level of Evidence: B). Adding plant stanol/sterols (2 g per day) and/or viscous fiber (greater than 10 g per day) is reasonable to further lower LDL-C. (Level of Evidence: A)". A fasting lipid profile should be assessed in all patients and within 24 hours of hospitalization for those with an acute cardiovascular or coronary event. For hospitalized patients, initiation of lipid-lowering medication is indicated. It may be reasonable to encourage increased consumption of omega-3 fatty acids in the form of fish or in capsules (1 g per day) for risk reduction. For treatment of elevated triglycerides, higher doses are usually necessary for risk reduction. (Level of Evidence: B)". Physical activity goal is 30 minutes 5 days per week; optimal daily. Advising medically supervised programs (cardiac rehabilitation) for high-risk patients (e.g., recent acute coronary syndrome or revascularization, heart failure) is recommended. (Level of Evidence: B)". For all patients, it is recommended that risk be assessed with a physical activity history and/or an exercise test to guide prescription. (Level of Evidence: B)".  For all patients, encouraging 30 to 60 minutes of moderate-intensity aerobic activity is recommended, such as brisk walking on mostpreferably alldays of the week, supplemented by an increase in daily lifestyle activities (e.g., walking breaks at work, gardening, and household work). (Level of Evidence: B)"

# Post PCI Follow-up
According to AHA guidelines, routine periodic stress testing of asymptomatic patients after PCI without specific clinical indications should not be performed. However, there has been a conflicting evidence on benefits of coronary angiography versus clinical follow up to detect major complications such as restenosis and its impact on survival outcome. In the recent ReACT trial 2016, it is demonstrated that there is no difference in clinical benefit when coronary angiography is compared to regular clinical follow up after PCI. Study results demonstrated that there was increased incidence of coronary revascularization with the corornary angiography after one year following PCI but there was no difference in the primary endpoint which included composite of death, MI, stroke, or emergency hospitalizations for acute coronary syndrome or heart failure when compared to regular clinical follow up after 5 years.

# Hybrid coronary revascularization
Hybrid coronary bypass is a relatively new procedure and alternative to traditional bypass surgery that is defined by the performance of coronary bypass surgery and coronary stenting during the same operation. A much smaller incision (made through the rib cage as opposed to cutting the sternum and opening the rib cage) than with traditional bypass surgery.

# PCI Complications
Complications of PCI include , vessel perforation, dissection, distal embolization, no-reflow, coronary vasospasm, abrupt closure, access site complications, peri-procedure bleeding, restenosis, renal failure, thrombocytopenia, late acquired stent malapposition and loss of side branch.

## Factors associated with complications
Factors associated with complications can be taken into account using various risk score systems. These systems take into account clinical variables, age, cardiovascular history, comorbities, anatomical variables. Mayo clinic risk score and the CADILLAC risk score are two common examples.