Management of Patients with CAD receiving Invasive Interventions PCIPrepared by: Ahmad Khalil Al-Sadi (RN, MSN, CNS)

More than 1 million PCI procedures were performed worldwide in 2000, and more than 62,000 in the UK in 2004. In 2000, more than 500,000 percutaneous coronary interventions (PCIs) were performed in the United States. By 2004, the number exceeded 650,000 in the United States with rapid growth in other developed countries. Worldwide, the number of PCIs continues to increase annually. More than 1 million PCI procedures were performed worldwide in 2000, and more than 62,000 in the UK in 2004.

WHAT IS PCI Percutaneous Coronary Intervention

The term is used to describe various procedures that can be used to mechanically improve myocardial perfusion without resorting to surgery.

1) PTCA 2) Stent implantation 3) Atherectomy

Angioplasty

Angioplasty is the mechanical alteration of a narrowed or totally obstructed vascular lumen, generally caused by atheroma (the lesion of atherosclerosis). The term derives from the roots "Angio" or vessel and "plasticos" fit for molding. The term has come to include all manner of vascular interventions typically performed in a minimally invasive or percutaneous method.

Percutaneous Transluminal Coronary Angioplasty [PTCA]

A long catheter is passed from femoral artery up to the openings of the coronary arteries. Using radioopaque dye and fluoroscopy, areas of stenosis can be identified. A deflated balloon is passed over a guidewire to a site of stenosis, where the balloon is inflated.

GOALS OF PTCA

Improve blood flow to myocardium-cracking the myocardiumatheroma

Several inflations & balloon sizes may be required to achieve desired goal, usually defined as less 1.5 mm)

Pts with lesions >70% stenosis placing large areas of heart At risk for ischemia.

Relative contraindicationsLeft main stenosis or left main equivalent stenosis (Coronary artery bypass graft [CABG] surgery is still the preferred treatment for left main stenosis. However, this area is rapidly evolving toward safe and feasible PCI options.) Chronic total occlusion (CTO) with the following:

No proximal stump visible Extensive bridging collaterals present

Diffusely diseased small-caliber artery or vein graft small Other coronary anatomy not amenable to percutaneous intervention

Once positioned, the balloon is inflated for about 10 to 30 seconds (occluding coronary flow). The balloon is then deflated and withdrawn from the coronary circulation into the guiding catheter. Injection of contrast into the coronary artery during cine acquisition enables assessment of the result.

Stents

Small stainless steel scaffold supports artery and enables blood flow. Delivered over balloon catheter. Half of PTCA procedures now include stenting.

Metallic stents Tiny, cylindrical, expandable tubes of metallic mesh, to overcome the restenosis of balloon angioplasty. Stainless steel or nitinol. Drug-eluting stents Metallic stents coated with pure drug or polymer matrix containing drug. Complications: Thrombosis (antiplatelet agents are required) Restenosis (cell proliferation should be suppressed)

CURRENT INTERVENTIONAL CARDIAC PROCEDURES

Intracoronary Stents

Used to prop or support the arterial wall. Used to keep vessels open. Anticoagulant & antiplatelet meds given to reduce risk for thrombus formation at site

an intracoronary stent (a cylindrical steel mesh) is then deployed. Inflation pressures used for stent deployment are usually higher (1220 atmospheres). After about 1530 seconds, the balloon is deflated and withdrawn into the guiding catheter, leaving the stent mesh pressed firmly against the walls of the coronary artery. Advances in stent design are such that it is now often possible to position a stent across a tight stenosis without pre-dilating the lesion (so-called primary stent implantation).

Broad indications for Stent implantation

Acute or threatened artery closure following balloon angioplasty, resulted in decreased the need for emergency surgery. Elective stent implantation for optimizing the initial and longer-term revascularization result. longer-

Comparing Stents with Balloon Angioplasty

Reduced adverse cardiac events with stents by about 30 % in the 6 mos following the procedure. Decrease risk and need for repeat revascularization of about 50%. Stents decrease restenosis by providing the largest intimal angiographic gain and by preventing early recoil and late vessel constriction. Higher procedural success rate, long term patency, and improved in-hospital clinical outcome with stenting invein grafts.

Problems with Stenting

Neointimal hyperplasia Healing process Cellular proliferation Thrombosis Blood clotting Response to foreign body Restenosis Re-narrowing of the vessel

DrugDrug-eluting stent

multiple types of DESs are available, with the 2 most commonly used in the United States being the sirolimus (Cypher) stent (SES) and the paclitaxel (Taxus) stent (PES). These stents comprise a metal stent with a polymer that elutes hyperplasia. a drug that reduces neointimal hyperplasia. Newer stent platforms are evolving with more uniform drug delivery systems and with the ability for some stents to store different drugs for local intracoronary delivery. SES and PES have both been extensively tested in a wide spectrum of coronary lesions, all of which have demonstrated significant reductions in restenosis and target lesion revascularization (TLR) rates when compared with bare metal stents.

RAVEL: 1-Year survival free of MI or repeat revascularization Controlled release of cell growth inhibitors from stents has shown promise in preventing restenosis. Most experience has accrued with sirolimus. The Randomized Study with the Sirolimus-Coated Bx Velocity Balloon-Expandable Stent in the Treatment of Patients with de Nova Native Coronary Artery Lesions (RAVEL) evaluated a stent coated with a 5-mm thick layer of a sirolimuspolymer matrix. The stent releases active drug over a period of 30 days following placement.

1-year data in 238 patients with stable/unstable angina or silent ischemia, a single primary target lesion in a native coronary vessel of 2.5 to 3.5 mm in diameter, stenosis of 51% to 99% of luminal diameter, and a TIMI flow rate >1. Study subjects were randomized to receive the sirolimus-eluting stent or an uncoated stent. The estimate of survival free from MI and repeat revascularization. The difference between the two groups was entirely due to greater need for repeat revascularization in the uncoated-stent group ( 22.8%) versus the sirolimus-eluting stent group (0%). None of the sirolimus-eluting stent group had acute, subacute, or late thrombosis, which suggested to the RAVEL investigators that re-endothelialization had occurred.

TAXUS I: Results at 6 and 12 months Encouraging preliminary results on preventing restenosis have been reported with a paclitaxel-eluting stent in the TAXUS I trial. To evaluate a stent coated with a paclitaxel-polymer matrix that releases active drug over 10 days, the study enrolled 61 patients with lesions of 50% to 99% luminal diameter in a native coronary vessel of 3.0 mm to 3.5 mm in diameter. Subjects were randomized to the paclitaxel-eluting stent or an uncoated stent.

TAXUS I: Results at 6 and 12 monthsAs shown, at 6 months there was a significant improvement in the paclitaxel eluting stent compared with the uncoated stent with regard to diameter stenosis within the stented area, with no differences at the proximal and distal edges. At 12 months, the rate of target-lesion PCI was 10% in the control group and 0% in the paclitaxel-eluting stent group.

Comparison of Therapy

Hospital Stay: CABG 4-7 days

Angioplasty 1-2 days Stent 1-2 days

Restenosis: CABG 5-6%, usually after 5 years Angioplasty 25-45%, usually within 6 months 25 Stent 15-20%, usually within 6 months 15-

Comparison of Therapy Cost CABG $35,000 Angioplasty $17,000 Stent $19,000 Cost-effectiveness Cost Additive procedures: Within 5 years, 20-40% of patients have second PTCA, 25% 20have CABG Additive costs: 0 years: per patient costs of PTCA 30-50% those of CABG 30 1 year: 50-60% 50 3 years: 60-80% 60 >3 years: >80%

PCI COMPLICATIONS

Allergic reactions to contrast dye and contrast nephropathy

Allergic reactions related to iodine-based contrast agents for angiographic imaging are classified as minor (hives, rash), moderate (urticaria, bronchoconstriction), or severe (anaphylactoid reaction [as opposed to anaphylactic reaction] with hemodynamic collapse). In patients with a history of contrast reaction, the risk for repeated anaphylactoid reaction is generally reported to range from 17% to 35%. Previous adverse reactions to shellfish or seafood in general are believed to be associated with future anaphylactoid reaction to iodine-based contrast.

Most recent studies have defined contrast nephropathy as an increase in serum creatinine concentration of 25% or an absolute increase of 44 mol/L (0.5 mg/dL). Contrast nephropathy usually first manifests as an elevation in creatinine concentration 24 to 48 hours after the procedure that peaks 3 to 5 days after the procedure. Patient-related factors associated with an increased risk for contrast nephropathy include diabetes; preexisting renal insufficiency; and, possibly, reduced intravascular volume status.

In-stent restenosis (ISR) Pooled data from six trials indicate that the rate of instent restenosis steadily increases over the first year, regardless of how restenosis is defined. At 12 months, 12% of patients require target lesion revascularization, almost double the rate at 6 months. At 12 months, 15.8% of patients have target vessel failure. These findings underscore the importance of at least 12-month follow-up when assessing strategies for reducing in-stent restenosis.

Restenosis is the process by which a treated arterial narrowing recurs over time. The restenosis process is now believed to occur because of negative arterial remodeling (arterial constriction) and intimal hyperplasia, combined with other complex processes. Factors associated with an increased risk for restenosis include diabetes; unstable or severe angina at the time of PCI; lesions in the left anterior descending artery or in a saphenous vein graft; total length of the lesion treated; chronically occluded arteries; previously treated lesions; and factors related to technical aspects of the procedure itself, most notably minimum luminal diameter immediately afterward. The restenotic process occurs over the first 1 to 6 to 8 months after PCI.

The presenting symptom for most patients with restenosis is exertional angina (25% to 85%); fewer patients (11% to 41%) present with unstable angina, and presentation with acute MI is rare (1% to 6%). Stents have been demonstrated to decrease restenosis rates in saphenous vein bypass grafts, in chronically occluded arteries, and in patients treated with primary angioplasty for acute MI. Drug-eluting stents dramatically reduces the rates of restenosis compared with bare-metal stents.

Stent Thrombosis

A catastrophic complication, associated with 30-day mortality rates in recent series of 20.8% to 26%. Most frequently occurs in the first days to weeks after stent implantation. Patients usually present with severe chest pain and often present with ST-segment elevation. Patients treated with bare-metal (non drug-eluting) stents should receive 4 weeks of clopidogrel in addition to aspirin to prevent stent thrombosis. Because of concern that late stent thrombosis may develop in patients who are treated with drug-eluting stents, most recent trials have extended clopidogrel treatment to 3 to 6 months after PCI, in addition to aspirin therapy.

Stent infection

Foreign body implantation predisposes to the development of infections by damaging or invading epithelial or mucosal barriers, by supporting growth of micro-organisms and by impairing host defense mechanisms. Manifested within the first four weeks after stent implantation with fever being the clinical hallmark, chest pain, and positive blood cultures. Stent infection should be suspected and blood cultures should be withdrawn in all patients presenting with fever within the first weeks after coronary stent implantation even in the absence of chest pain, ECG abnormalities or elevation of cardiac enzymes.

verification of the local infection by cardiac imaging modalities, including transthoracic and transoesophageal echocardiography, coronary angiography, computed tomography, and magnetic resonance imaging. Compliance with current standards for the prevention of infections during cardiac catheterisation are measures to prevent infection include the removal of hair from the puncture site, application of antiseptic to the skin, and the use of sterile drapes. Operators should perform appropriate hand washing, wear a sterile gown and sterile gloves and a generally sterile environment should be maintained during the procedure. Rapid institution of antibiotic treatment represents the mainstay of therapy, and surgical drainage of the infective focus including stent removal may be necessary.

Abrupt vessel closureMay occur in as many as 5% of balloon angioplasty cases and typically develops when compression of the true lumen by a large dissection flap occurs, thrombus formation, superimposed coronary vasospasm, or a combination of these processes. The presence of large coronary dissections immediately after balloon angioplasty is associated with a 5-fold increase in the 5risk of abrupt closure. The use of intracoronary stents and new antiplatelet drugs has decreased the incidence of abrupt closure significantly (to 90% stenosis, Stenosis length 2 or more luminal diameters, Stenosis at branch point, Stenosis on bend ( 45). 45 Right coronary artery stenosis. Postprocedure: Intimal dissection >10 mm Residual stenosis >50% Transient in-lab closure inResidual transstenotic gradient 20 mm Hg

Myocardial Infarction

can occur during PCI because of coronary dissection, abrupt vessel closure, thrombotic occlusion of the epicardial vessel, distal embolization of thrombus or atheromatous material to the microcirculation, side branch occlusion, coronary spasm, or a combination of events. The incidence of MI, defined primarily as CK-MB concentrations elevated to more than two to three times the upper limit of normal, generally ranges between 5% and 30%. Serial CK and CK-MB measurements (6 to 8 and 16 to 24 hours after the procedure) should be obtained in patients with suspected ischemia during PCI.

Emergency Coronary Bypass Surgery and DeathRecent data demonstrate that the need for emergency CABG has decreased since the introduction of coronary stents and that CABG rates are currently less than 1%. Death is similarly rare, most recent registries and clinical trials report mortality rates of less than 1%. Factors associated with increased mortality rates during PCI include advanced age, female sex, diabetes, previous MI, multivessel disease, left main or equivalent coronary disease, a large area of myocardium at risk, preexisting left ventricular function, and preexisting renal insufficiency.

Factors associated with increased mortality for angioplasty

Clinical Factors: Female gender, Age >65 years, Unstable angina, Congestive heart failure, Chronic renal failure. Angiographic Factors: Left main coronary disease, Three-vessel disease, Left Threeventricular ejection fraction < 0.30. Risk index: Myocardial jeopardy score, Proximal right coronary stenosis, Collaterals originate from dilated vessel.

Vascular Complications

overt bleeding with a decrease in hemoglobin level of at least 30 to 50 g/L (3 to 5 g/dL), need for blood transfusion, or retroperitoneal bleeding. In current clinical practice, as evidenced by results of recent interventional trials, rates of major bleeding complications are low (0.7% to 1.7%). Insertion of vascular sheaths may produce groin or retroperitoneal hematomas. Groin hematomas may present with localized pain, lowerextremity edema due to femoral vein compression, or neurologic symptoms due to compression of the femoral nerve, palpation of localized swelling or tenderness in the area, or loss of sensory or motor function.

Retroperitoneal hematoma should be suspected in patients with unexplained hypotension and/or a marked decrease in hematocrit, may experience flank, abdominal, or back pain. Most retroperitoneal hematomas can be treated conservatively with discontinuation or reversal of anticoagulation and antiplatelet therapy and with blood transfusions alone when necessary; only 16% of patients require surgery. Indications for surgical intervention include persistent hypotension, decreasing hematocrit despite transfusion, or femoral neuropathy (due to nerve compression).

A femoral pseudoaneurysm is a communication between the femoral artery and the overlying fibromuscular tissue, resulting in a bloodfilled cavity. The reported incidence ranges from 0.5% to 6.3%. Groin tenderness, a palpable pulsatile mass, and/or new bruit in the groin area should prompt examination by Doppler flow imaging. Can be treated with ultrasound-guided compression, ultrasound-guided thrombin injection, or surgical repair.

Arterial pseudoaneurysm

An arteriovenous (AV) fistula can result from sheath mediated communication between the femoral artery and femoral vein, may be suggested by the presence of a systolic and diastolic bruit and confirmed by Doppler ultrasonography. Reported incidence ranges from 0.2% to 2.1%. Can be treated with conservative therapy (careful observation) in most patients or with ultrasoundguided compression, surgical repair, or percutaneous implantation of covered stents if necessary.

Characteristics of type A, B, and C lesions

Type A lesions (minimally complex) : Discrete (length 3 mo old and/or bridging collaterals. Inability to protect major side branches Degenerated vein grafts with friable lesions Although the risk of abrupt vessel closure may be moderately high with Type B lesions, the likelihood of a major complication may be low in certain instances such as in the dilation of total occlusions