Percutaneous Coronary Intervention

Percutaneous coronary intervention or percutaneous coronary intervention (abbreviation PCI; synonym: percutaneous transluminal coronary angioplasty, PTCA; English : percutaneous transluminal coronary angioplasty) is a therapeutic procedure in cardiology (study of the heart). It serves to widen stenosed (narrowed) or completely blocked coronaries (arteries that surround the heart and supply the heart muscle with blood) (= revascularization). The procedure is the first therapeutic option for acute myocardial infarction and can also be used to treat unstable acute coronary syndrome. Acute coronary syndrome represents the spectrum of life-threatening cardiac diseases from unstable angina pectoris (“chest tightness”; sudden onset of pain in the region of the heart; here: Form of angina whose symptomatology is not constant but changes) to myocardial infarction (heart attack). Although patients with stable coronary syndromes are now regularly treated invasively by PCI, the available studies do not show any clear advantage over drug therapy in this case. When the high-quality studies were included, no advantage for PCI could be identified.

Indications (areas of application)

Chronic coronary artery disease (CAD).

  • Single-vessel disease* – In the presence of identifiable clinical symptoms or diagnostic evidence of ischemia (reduced blood flow), PCI is the method of choice for one or more high-grade stenoses (narrowing) of a coronary vessel (heart vessel) compared with other methods. In the absence of symptoms or the absence of ischemia, PCI should not be used.
  • Multivessel disease* – Even in the absence of symptoms, PCI is applicable if there is stenosis* of at least two coronary vessels. However, PCI is not superior to bypass surgery.
  • Stent stenosis – PCI may be used if stenosis (narrowing) of a stent recurs. The risk of stenosis of a stent is approximately 30%.
  • Venous bypass opening-10% of all PCIs performed are on venous bypass vessels. The risk of stenosis of a bypass vessel is significantly greater than that of a coronary artery.

* In clinically stable patients with coronary 1- or 2-vessel disease with or without RIVA stenosis, PCI is generally assigned a Class 1 recommendation [2018 ESC/EACTS Guidelines]. Note: In stable CAD, percutaneous coronary intervention is warranted only when there is either the highest grade stenosis (>90%) or regional evidence of ischemia (usually by measuring fractional flow reserve, FFR).FFR indicates the ratio of mean blood pressure distal to the stenosis to mean aortic pressure.FFR-guided coronary intervention appears to improve prognosis in stable coronary artery disease (CAD). Acute coronary syndrome

  • NSTEMI (non-ST-segment elevation myocardial infarction; non-ST-segment elevation myocardial infarction) – NSTEMI is the term used to describe a myocardial infarction that does not show typical ST-segment elevation on the ECG. Contrary to earlier opinion, the lethality (mortality) of NSTEMI at one year is almost identical to that of ST-segment elevation myocardial infarction. In NSTEMI patients, eventual invasive treatment is based on initial risk stratification into four risk groups: (NSTE-ACS: Non-ST-Elevated Myocardial Infarction or Non-ST-segment elevation myocardial infarction-acute coronary syndrome (ACS)):
    • Low risk: invasive workup optional.
    • Intermediate risk: transport to a PCI center for invasive treatment (within 72 hours).
    • High risk (troponin changes suspicious for infarction, dynamic ST or T wave changes, “Global Registry of Acute Coronary Events” (GRACE) score > 40) → same-day transport to a PCI center and invasive workup early (< 24 hours).
    • Very high risk (eg.B. continuing chest pain (chest pain) despite medication, life-threatening arrhythmias, acute heart failure (cardiac insufficiency), hemodynamic instability/cardiogenic shock) → transport to a PCI center for immediate invasive treatment (< 2 hours).

    Furthermore, patients with inadequately treatable angina pectoris (“chest tightness”; seizure-like chest pain triggered by reduced blood flow to the heart) should be referred for PCI treatment in the context of emergency treatment, but also if patient instability is present. In patient populations with risk factors for myocardial infarction, PCI should be performed within 72 hours. A narrower time window for initiation of PCI has not been shown to improve prognosis, contrary to expectations.

  • STEMI* (ST-segment elevation myocardial infarction; ST-elevation myocardial infarction) – STEMI represents a myocardial infarction (heart attack) with detectable ST-segment elevation, which should be treated by PCI (acute PCI; acute PTCA) within 90-120 minutes to reduce the risk of lethality (mortality). In addition to interventional care (targeted intervention) by PCI, thrombolysis (drug dissolution of the blood clot) is a therapeutic option. However, up to 12 hours after symptom onset, PCI is superior to drug thrombolysis.
  • Cardiogenic Shock – As a result of myocardial infarction, among other conditions, there is a possibility that the performance of the heart to supply vital organs is not possible. PCI can improve survival in cardiogenic shock due to myocardial infarction even after 36 hours.

* Cardiology societies ESC, ACC, and AHA recommend treating only the infarct artery (“culprit lesion”) as part of acute PCI in patients with STEMI. However, several studies describe a survival benefit if a myocardial infarction patient with multivessel disease is immediately treated with extensive coronary repair. This is now also confirmed by a meta-analysis, so routine revascularization even of nonculprit lesions in patients with STEMI “should be considered.” See also “Further guidance” under COMPLETE trial. Note: The CULPRIT-SHOCK trial puts the recommendation into perspective: multivessel PCI is associated with a significant worsening of prognosis compared with revascularization initially limited to the infarct artery (rate for 30-day mortality was 8.2 percentage points higher in absolute terms – compared after complete revascularization. * * According to the 15-year results of a randomized trial, invasive intervention by cardiac catheterization has no prognostic or symptomatic benefit in intermediate-grade coronary stenosis that does not cause ischemia. The guideline on myocardial revascularization of the European Society of Cardiology and the European Association for Cardio-Thoracic Surgery, among others, has established ten revascularization imperatives to help select the best therapy in each case together with the patient [see guidelines below]. Particular attention should be paid to the revascularization commandments cited below:

  • 5 Revascularization imperative: extensive coronary disease and diabetes mellitus indicate that coronary artery bypass graft (CABG) surgery offers a long-term survival benefit.
  • 6 Revascularization imperative: It is advisable to use the SYNTAX score to assess the anatomic complexity of coronary disease.

Contraindications

When indicated, the benefits outweigh the risks, so there are no contraindications if the general condition is adequate.

Before therapy

The measures that should be taken before PCI are performed depend on the specific indication.However, angiographic assessment alone (visualization of the arteries with the aid of a contrast agent) of the coronary vessels (coronary arteries) is usually not sufficient to establish the indication; the hemodynamic relevance of coronary stenoses (narrowing of the coronary arteries) must also be demonstrated. This is possible either by means of noninvasive functional imaging (e.g., stress echocardiography or cardiac magnetic resonance imaging/cardio-MRI with stress testing) or intracoronary hemodynamic assessment using fractional flow reserve (FFR).In the case of chronic coronary artery disease (CAD), the procedure is performed without emergency necessity, which allows better planning and preparation. In addition to information about current symptoms, relevant pre-existing conditions such as diabetes mellitus, an existing pacemaker, and allergies to materials and contrast media, information about upcoming surgeries, a current resting ECG, and various laboratory values such as the myocardial infarction marker troponin should be available. Ideally, the time to PCI should be less than 90 minutes. The decisive factor is the time at which the STEMI diagnosis was made on the basis of the ECG findings. Since approximately 20% of all patients undergoing PCI are thought to be at high risk for bleeding, it is important to identify these high-risk patients to avoid bleeding complications. High bleeding risk is defined as follows: Risk of bleeding (type 3 or 5 by BARC definition) 4 percent or more or risk of intracranial hemorrhage (brain hemorrhage) 1 percent or more in the first year after PCI. In this regard, the ARC-HBR group settled on 14 major and 6 minor criteria for high risk of bleeding in PCI patients. Major criteria are parameters that alone may be associated with an increase in risk, whereas minor criteria alone are not sufficient for an increase in risk.

Procedure

Percutaneous coronary intervention is used to dilate stenosed (narrowed) or completely occluded coronaries (coronary arteries). To perform the procedure, a catheter is inserted through either the femoral artery (inguinal artery) or the radial artery (forearm artery; first-choice access), through which a balloon catheter can be advanced. A meta-analysis showed the advantages of transradial access: both the rate of major adverse cardiac events (MACE) (relative risk reduction 16%) and all-cause mortality (all-cause mortality) in the radial access group (1.55% vs. 2.22%, OR =0.71, p = 0.001) were significantly lower than in the femoral group. The European Society of Cardiology (ESC) guideline on the management of acute ST-elevation myocardial infarction (STEMI) recommended the radial artery as the preferred vascular access route for primary PCI (class 1 recommendation). The balloon can be expanded (dilated) in a present stenosis (vasoconstriction) so that the stenosis is widened and improvement in blood flow can be achieved. As the stenosis expands, the calcium deposits in the area of deposition are forced into the elastic wall of the coronary vessels (coronary arteries) and can remain there. To prevent restenosis (renewed narrowing of the vessel), a stent (vascular support) is usually implanted. Modern stents can release drugs called “drug eluting stents” (DES), which are designed to make restenosis less likely. Drug-eluting stents (DES) have received a stronger class 1 recommendation (instead of IIa previously) in the current ESC guideline on the management of acute ST-elevation myocardial infarction (STEMI) and are now considered a superior alternative to bare metal stents (BMS). Bare metal stents are considered obsolete according to current European guidelines on myocardial revascularization. Stents with “ultrathin” stent struts (strut thickness <70 μm) appear to reduce the risk of myocardial infarction (myocardial infarction; 20% lower risk; RR=0.80; 95% CI 0.65-0.99) and stent thrombosis (RR=0.97; 95% CI 0.77-1.22) compared with DES. A drug-coated balloon (DCB) catheter may be considered in the future as an alternative to stent implantation for stenosis of the small coronary vessels (narrowing of the small coronary arteries): The primary study endpoint (cardiac mortality, nonfatal myocardial infarction (heart attack), target vessel revascularization) showed no relevant difference between balloon and stent treatment 12 months after initial treatment (7.5 versus 7, 3%). Implantation of coronary stents in the case of very heavily calcified plaques can be optimized by calcium fragmentation with intracoronary lithotripsy (IVL, intravascular lithotripsy). Post-stent dilation was thus achieved in almost all patients (99%). The 30-day rate for cardiac events was 7.8%, with periprocedural myocardial infarctions (heart attacks) accounting for the majority. Revascularization of noninfarct arteries in patients with STEMI and multivessel disease “may be considered.”Thus, not only the “culprit” infarct artery (culprit lesion) but also other narrowed coronary arteries (non culprit vessel) are revascularized. Note: In myocardial infarction patients with existing multivessel coronary disease and cardiogenic shock, revascularization should initially focus only on the “culprit” infarct-related coronary lesion (culprit lesion). If more vessels are treated, mortality (death rate) increases. Note: The strategy of manual catheter thrombus aspiration in STEMI has received a downgrade (class III recommendation (no benefit)).

After Therapy

After coronary stent implantation (insertion of vascular stents into coronary arteries; bare metal stents, BMS) and indication for oral anticoagulation, dual therapy of oral anticoagulation and an antiplatelet agent is recommended. In cases of high ischemic risk, acetylsalicylic acid (ASA) may also be considered in triple therapy. According to a randomized trial, dual antiplatelet therapy can be shortened to 3 months in patients at high risk of bleeding. Continuation of therapy as monotherapy with ticagrelor reduced the rate of bleeding without an increase in coronary events (combination of death, myocardial infarction, or stroke). (combination of death, myocardial infarction, or apoplexy) occurred.In patients scheduled to receive PCI for NSTEMI, prasugrel should be given preference over ticagrelor [Guidelines: ESC Guidelines, 2020]. Other drug therapy options and precautions must be discussed individually between patient and physician. The basis of follow-up treatment should be optimal reduction of coronary risk factors (eg, smoking, blood pressure, diabetes mellitus, cholesterol, triglycerides).

Potential complications

  • Plaque Rupture – An existing stenosis or plaques in the coronaries can rupture (tear) and subsequently thrombose (lead to occlusion of the vessel) during percutaneous coronary intervention. To contain the extent of the complication, therapy consists of immediate stent implantation into the ruptured site. Depending on the risk profile and the extent of the complication, the administration of additional anticoagulants (anticoagulant drugs) is essential.
  • Coronary spasm – Coronary spasm is a spontaneous contraction of the smooth muscle of the coronary vessels (coronary arteries) that can usually occur during percutaneous coronary intervention. Patients with coronary artery disease are at increased risk for coronary spasm.
  • Dissection – a tear of the inner vessel wall with subsequent hemorrhage results in separation of the wall layers of the coronary artery.
  • Closure of the stenosis – However, intervention also carries the risk of completely closing a narrowing. Rapid intervention is necessary to correct the acute cessation of blood flow to the vessel.
  • Stent fractures (fractures of vascular stents; 12.3% in drug-eluting stents (DES); in the study, all-cause mortality (all-cause mortality) and cardiac mortality (cardiac-related mortality) were not significantly different in the groups with and without stent fractures).
  • Stent thrombosis (acute thrombotic occlusion of an artery within an implanted stent) – in patients with drug-eluting stents (DES; drug-eluting stents/vascular bridges), early stent thrombosis within the next 30 days after percutaneous coronary intervention is associated with a mortality (death rate) of 38, 5%.Note: Bioresorbable coronary stent thrombosis is referred to as scaffold thrombosis.
  • Thromboembolism – During intervention, an existing thrombus (blood clot) may detach and be carried away. Depending on the location of the thrombus, the occlusion by thromboembolism (occlusion of a blood vessel by detached thrombus) can affect different parts of the blood supply to the heart.
  • Atrial fibrillation (VHF), postoperative (0.1%).

Further notes

  • FITT-STEMI project (approximately 20,000 patients): in patients with acute myocardial infarction (STEMI), reopening of the occluded vessel by cardiac catheterization within 90 minutes of initial medical contact was shown to reduce mortality (mortality) by two-thirds compared with longer time intervals. In resuscitated infarct patients mortality could be halved
  • One study examined the percentage of men and women, respectively, who had persistent symptoms despite stent implantation:
    • Year 1: 16.3% of women and 10.5% of men.
    • 2nd year: 17.2% vs. 11.1

    The overall rates for clinical events for myocardial infarction, coronary revascularization (reopening of vessels), and death were approximately the same (14, 8% versus 14, 2%).

  • COMPLETE trial: preventive complete coronary (coronary artery) repair in patients with STEMI significantly reduced the rate of reinfarction (7.8% versus 10.5%) or cardiovascular death (8.9% versus 16.7%) compared with the group in which only stenosis vasoconstriction) was treated; there was also no increase in bleeding and increased renal damage (due to contrast administration).
  • With permanent oral anticoagulation, more complications (+50%) should be expected after PCI. Long-term mortality increased by 36% (compared with patients not receiving oral anticoagulation).
  • Surgery after stenting: current European Society of Cardiology (ESC) guidelines recommend:
    • elective (schedulable) surgery:
      • Bare-metal stent: after at least 4 weeks.
      • Drug-eluting stent (DES): after 6 months, better even 12 months after percutaneous coronary intervention (PCI).

    A study based on the Danish National Patient Registry demonstrated that Beyond the first month, there was already no difference in risk compared with surgery performed at 9 to 12 months after PCI.

  • Biostents (polymer stents made of lactic acid) have been withdrawn from the market again in 2017, because of intrusions of the stent scaffold into the interior of the vessel, at a time when they have not yet fully grown into the vessel wall. This can lead to subsequent thrombosis or myocardial infarction.
  • Note: CHD patients with 1-vessel coronary disease (stenosis grade >70%) and stable coronary artery disease received PCI or placebo PCI after randomization. The following results could be demonstrated:
    • Exercise time improved significantly only in the PCI group (28.4 vs. 11.8 seconds)
    • No relevant difference in the increase in exercise time was demonstrated between the PCI and placebo-PCI groups (and this despite documented markedly improved coronary hemodynamics, demonstrated by FFR determination)
  • EXCEL study: 5-year data showed that stenting and bypass surgery were equally beneficial in the patients studied. The primary endpoint of the study was a composite of death from any cause, myocardial infarction (heart attack), and apoplexy (stroke): the endpoint outcome at 5 years was 22% versus 19, 2%, although this was not statistically significant. However, the hard endpoint all-cause mortality (all-cause death rate) at 5 years was 13.0% (PCI) versus 9.9% (surgery).
  • According to a meta-analysis, the following patient groups benefit from percutaneous coronary intervention:
    • All-cause mortality (all-cause mortality rate): patients with non-ST-segment elevation acute coronary syndrome (NSTEACS) who received either additional invasive therapy or conservative therapy alone benefited significantly: decrease in risk of death after PCI (RR 0.84; 95% CI 0.72-0.97; p = 0.02)
    • Cardiovascular mortality (mortality from cardiovascular disease): patients with STEMI and multivessel coronary disease as significant (RR 0.68; 95% CI 0.47-0.98; p = 0.04).Ardiovascular mortality: patients with STEMI and multivessel coronary disease as significant (RR 0.68; 95% CI 0.47-0.98; p = 0.04).
    • Myocardial infarctions (MIs): patients with unstable coronary artery disease (CAD benefited with a significant 26% relative risk reduction with PCI (RR 0.74; 95% CI 0.62-0.90; p = 0.002); furthermore, STEMI patients with multivessel disease (RR 0.66; 95% CI 0.54-0.80; p < 0.001)
  • ISCHEMIA trial: in patients with stable coronary artery disease, no reduction in cardiovascular events was demonstrated by an additional strategy of invasive coronary angiography plus revascularization by cardiac catheterization (or bypass surgery, if necessary): After a median follow-up duration of 3.3 years, the rates for the primary end point were not significantly different at 13.3% (invasive strategy) and 15.5% (optimal medical therapy) (hazard ratio [HR] 0.93; 95% confidence interval [CI] 0.80-1.08).The primary composite end point was defined as follows: cardiovascular death, nonfatal myocardial infarction (heart attack), resuscitation after cardiac arrest, hospital admissions for unstable angina (present when symptoms increased in intensity or duration compared with previous angina attacks), or heart failure (cardiac insufficiency).