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Who Needs PCI (Coronary Intervention: for Whom?)1

Soumitra Kumar
The objective of percutaneous coronary intervention (PCI) is to deliver maximum clinical gain at the lowest possible levels of risk. The process involves the interaction of a number of factors:
  • The training and experience of the interventionist
  • Access to equipment and facilities
  • The availability of surgical or other supports
  • Characteristics of the patient
  • Nature of clinical presentation
  • Details of the epicardial coronary anatomy
Unusual or high-risk cases may necessitate the collaboration of other interventionists, clinical cardiologists, internists, surgical and anesthetic colleagues in an institutional ‘HEART TEAM’. Above all, process of informed consent can be refined if patients can be appraised of a case specific assessment of likely gains and potential risks.
The enthusiasm for PCI must be tempered with realization of the following facts:
a. Potential for clinical gain is real but selective: In stable angina, there is no evidence to suggest that PCI confers prognostic advantage in low-risk patients, and confers symptomatic benefit which can be modest and can attenuate over medium-term follow-up. In non-ST elevation acute coronary syndrome (NSTE-ACS), invasive strategy will benefit a significant, but selected subset of patients only, i.e. those at high risk; and to a lesser extent, those at an intermediate risk only. In acute ST-elevation myocardial infarction (STEMI), prompt access to PCI facilities and appropriately trained staff may be required within a specific time frame in the natural history, if benefits are to be realized.
b. Performance of PCI often involves some level of morbidity and mortality: All trials comparing PCI with medical therapy have shown a small albeit higher rate of major adverse cardiac events (MACE) in the intervention group, mostly related to complications at the time of revascularization and these have important complications for the patient's perception of outcome and for the consumption of health-care resources.
c. Recognition of the fact that alternative options exist and may be equally or more effective: Several independent lines of evidence indicate that revascularization will improve prognosis only in high-risk patients with stable angina. Although there are no randomized data 2providing this, it is known from large registries that only patients with documented ischemia involving >10% of the LV myocardium have a lower CV, and all cause mortality, when revascularization is performed. In contrast, revascularization can increase mortality in patients with ischemia involving <10% of the myocardium (Fig. 1).
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FIG. 1: ESC guidelines 2014
Another line of evidence comes from a large prospective angiographic registry that patients with left main stenosis, proximal left anterior descending (LAD) and proximal triple vessel disease, who are known to benefit in terms of prognosis from revascularization had annual death >3% on medical treatment (Fig. 2).
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FIG. 2: Annual mortality with medical therapy
Based on FAME-2 Trial, FFR is considered gold standard for invasive assessment of physiological stenosis significance and an indispensable tool for decision making in coronary revascularization. Use of FFR in true catheterization laboratories accurately identifies which lesions should be revascularized and improves the outcome in most elective clinical and angiographic conditions, as compared with situations where revascularization decisions are simply made on the basis of angiographic appearance of the lesions.
Over the two decades, prior to publication of the five-year outcome of the SYNTAX and FREEDOM trials, approximately 20 trials of PCI versus CABG had been conducted. During that period, PCI evolved from plain old balloon angioplasty (POBA), to the use of Bare-metal stents (BMS) and then to drug-eluting stents (DES). Similarly, overall results of surgery have also improved substantially, with better medical therapy allied to 3improvements in anesthesia and surgical techniques, such as increasing use of arterial grafts and off-pump surgery. The most definitive analysis of CABG vs. PCI to date (Hlatky et al 2007), has been a collaborative analysis of individual patient data from ten randomized trials involving 7812 patients. The overall hazard ratio for death with CABG versus PCI was 0.9 (p=0.12) implying that CABG has no survival benefit over PCI. However, there was a significant reduction in mortality with CABG in patients over 65 years of age (HR=0.82, p=0.02) and in patients with diabetes (HR=0.7, p=0.014).
Despite the availability of internationally recognized guidelines and recommendations for PCI and CABG in differing anatomical patterns of CAD, it is increasingly recognized that individual practitioners still follow personal preferences even when these are not evidence-based and may be overtly “biased” at times. This is particularly so in the scenario of ‘ad-hoc’ PCI, i.e. when stenting is performed immediately after diagnostic angiography and in effect, denying the patient any opportunity to discuss possible surgical options with a cardiac surgeon. This raises questions about the whole consent process and emphasize the need for recommendations for interventions to be overseen by a multidisciplinary “HEART TEAM”, rather than an individual practitioner.
 
CASE SELECTION—A PRACTICAL APPROACH
A structural approach to case selection or risk stratification might consider three elements:
  1. Factors related to nature of clinical presentation:
    1. Acute coronary Syndrome (STEMI, NSTE-ACS, Cardiogenic Shock)
    2. Stable ischemic heart disease
  2. Factors related to clinical characteristics of the patient:
    1. General cardiac status: For example, heart failure, hypotension, cardiogenic shock, arrhythmias. Need for elective ventilation or circulatory support (e.g. Intra-aortic balloon pump) is a marker of adverse outcome. Post-procedural hypotension or severe brady/tachycardia can precipitate subacute vessel closure.
    2. Peripheral and great vessels: Atherosclerotic or other diseases of peripheral vessels, e.g. occlusions, tortuosity, unfolding can deny access for catheter of choice or for additional equipment. Risk of catheter-related emboli release to head or neck or peripheral vessel is real. Complications at the vascular access site can result in embolization, occlusion or bleeding. Co-existing hypertension, obesity or systemic anti-coagulants can confound these problems.
    3. Renal function: Chronic renal failure (CRF) is an established risk factor for coronary artery disease and on the other hand, results of PCI at any individual lesion may be less favorable in patients with established CRF. Another important concern for patients with any degree of renal impairment, is that the nephrotoxicity of radiographic contrast can precipitate acute renal failure. Even with precautionary measure such as fluid administration or elective filtration, the scope and duration of any PCI procedure will be limited by the need to minimize exposure to contrast agents.
    4. 4Diabetes mellitus: The condition is often a marker of more widespread and diffuse coronary artery disease. This pattern of disease is more difficult to manage with PCI, and CABG may provide a better revascularization strategy. This has been evidenced time and again in trials like BARI, ARTS and most recently in FREEDOM trial. The reasons however are not fully established and may extend beyond the simple presence of more extensive disease.
  3. Details of coronary anatomy and characteristics of proposed target lesion(s): Severity of spread of coronary artery disease, i.e. single vs. double vs. triple vessel disease should be the first consideration. Next, location of lesions should be considered; not only because of the territory in jeopardy, but also because plaque or other pathologies in left main stem or right ostium or proximal portions of principal vessels increase the risk of vessel dissection or abrupt closure. Due consideration should also be given to lesion characteristics, e.g. branches, bifurcations, calcification and tortuosity. In certain clinical situations, (e.g. thrombus laden lesions, saphenous vein graft disease or rotational atherectomy), sequelae of embolization of material to distal vascular bed should be considered. Flow limiting lesions or occlusive disease in non-target vessels increase procedural risk. Procedures to a ‘last remaining conduit’ represent one extreme in this continuum.
 
Appropriateness of Coronary Intervention
Currently, two major international guidelines namely European Society of Cardiology (ESC) and European Association for Cardiothoracic Surgery (EACTS) in 2010 and the other by ACCF/SCAI/STS/AATS/AHA/ASNC/HFSA/SCCT in 2011, updated in 2012, are available. The latter will be discussed mainly in this chapter to facilitate understanding and grasp of the subject since it summarizes indications under three simple headings namely, appropriate (A), inappropriate (I) and uncertain (U).
Key variables in appropriateness criteria
Clinical presentation:
Stable Angina
STEMI
Severity of angina:
CCS Class I
CCS Class IV
Non-invasive testing & risk stratification:
None or Low risk
High risk
Medical therapy:
None
Maximum
Anatomic disease:
No significant disease
Left Main/Triple vessel diseases
Inappropriate (I)
Uncertain (U)
Appropriate (A)
(Adapted from Patel et al. JACC 2009;53:530-53)
 
Appropriate Indications for PCI in Chronic Coronary Artery Disease (Table 1)
  1. CCS Class I-IV angina with one or two vessel CAD without involvement of proximal left anterior descending (LAD) and intermediate risk findings on non-invasive testing. Patient should be on a course of maximal anti-ischemic medical therapy.
    5
    Table 1   Appropriate indications for PCI in chronic coronary artery disease
    High-risk findings on non-invasive study
    CCS class III or IV angina
    Symptoms Med. Rx.
    Stress Test Med. Rx.
    Class III or IV Max Rx.
    A
    A
    A
    A
    A
    High Risk Max Rx.
    A
    A
    A
    A
    A
    Class I or II Max Rx.
    A
    A
    A
    A
    A
    High Risk No/min Rx.
    A
    A
    A
    A
    A
    Asymptomatic Max Rx.
    U
    A
    A
    A
    A
    Int. Risk Max Rx.
    A
    A
    A
    A
    A
    Class III or IV No/min Rx.
    A
    A
    A
    A
    A
    Int. Risk No/min Rx.
    U
    U
    A
    A
    A
    Class I or II No/min Rx.
    U
    A
    A
    A
    A
    Low Risk Max Rx.
    U
    A
    A
    A
    A
    Asymptomatic No/min Rx.
    U
    U
    A
    A
    A
    Low Risk No/min Rx.
    I
    U
    A
    A
    A
    Intermediate-risk findings on non-invasive study
    CCS class I or II angina
    Symptoms Med. Rx.
    Stress Test Med. Rx.
    Class III or IV Max Rx.
    A
    A
    A
    A
    A
    High Risk Max Rx.
    A
    A
    A
    A
    A
    Class I or II Max Rx.
    U
    A
    A
    A
    A
    High Risk No/min Rx.
    U
    A
    A
    A
    A
    6
    Asymptomatic Max Rx.
    U
    U
    U
    U
    A
    Int. Risk Max Rx.
    U
    A
    A
    A
    A
    Class III or IV No/min Rx.
    U
    U
    A
    A
    A
    Int. Risk No/min Rx.
    U
    U
    U
    A
    A
    Class I or II No/min Rx.
    U
    U
    U
    A
    A
    Low Risk Max Rx.
    U
    U
    A
    A
    A
    Asymptomatic No/min Rx.
    I
    I
    U
    U
    A
    Low Risk No/min Rx.
    I
    I
    U
    U
    U
    Low-risk findings on non-invasive study
    Asymptomatic
    Symptoms Med. Rx.
    Stress Test Med. Rx.
    Class III or IV Max Rx.
    U
    A
    A
    A
    A
    High Risk Max Rx.
    U
    A
    A
    A
    A
    Class I or II Max Rx.
    U
    U
    A
    A
    A
    High Risk No/min Rx.
    U
    U
    A
    A
    A
    Asymptomatic Max Rx.
    I
    I
    U
    U
    U
    Int. Risk Max Rx.
    U
    U
    U
    U
    A
    Class III or IV No/min Rx.
    I
    U
    A
    A
    A
    Int. Risk No/min Rx.
    I
    I
    U
    U
    A
    Class I or II No/min Rx.
    I
    I
    U
    U
    U
    Low Risk Max Rx.
    I
    I
    U
    U
    U
    Asymptomatic No/min Rx.
    I
    I
    U
    U
    U
    Low Risk No/min Rx.
    I
    I
    U
    U
    U
    Coronary Anatomy
    CTO of 1 vz.; no other dise­ase
    1–2 vz. Dise­ase; no Prox. LAD
    1 vz. Dise­ase of Prox. LAD
    2 vz. Dise­ase with Prox LAD
    3 vz. Disease; no Left Main
    Coronary Anatomy
    CTO of 1 vz.; no other dise­ase
    1–2 vz. Dise­ase; no Prox. LAD
    1 vz. Dise­ase of Prox. LAD
    2 vz. Dise­ase with Prox LAD
    3 vz. Dise­se; no Left Main
    Source: ACCF/SCAI/STS/AATS/AHA/ASNC/HFSA/SCCT 2012 Appropriate Use Criteria for Coronary Revascularization Focused Update, http://content.onlinejacc.org/article.aspx?articleid=1201161
  2. 7CCS Class I-IV angina with one or two vessel CAD without involvement of proximal LAD and high-risk findings on non-invasive testing. Patient receiving no or minimal anti-ischemic medical therapy.
  3. Asymptomatic or CCS Class I-IV angina with one or two vessel CAD without involvement of proximal LAD and high-risk findings on non-invasive testing. Patient receiving a course of maximal anti-ischemic medical therapy.
  4. Chronic total occlusion of one vessel only, with CCS Class III or IV angina on maximal medical therapy and intermediate risk findings on non-invasive study or CCS Class I or II angina with maximal medical therapy and high-risk findings on stress testing.
  5. One vessel disease involving proximal LAD with CCS Class I-II angina on maximal medical therapy or Class III-IV angina with no or minimal medical therapy and patient having intermediate risk findings on non-invasive testing.
  6. One vessel disease involving proximal LAD with CCS Class I-II angina on maximal medical therapy and high-risk findings on stress testing.
  7. Two vessel disease including proximal LAD with CCS Class I-IV angina irrespective of intensity of medical therapy and intermediate risk findings on non-invasive study.
  8. Two vessel disease including proximal LAD with CCS Class I-II angina irrespective of intensity of medical therapy along with high or intermediate risk findings on non-invasive study, or if on maximal medical therapy, then with low-risk findings on stress testing.
  9. Three vessel disease (without Left Main Disease) with high or intermediate risk findings on non-invasive study either with symptoms (CCS Class I-IV angina) or asymptomatic, irrespective of intensity of medical therapy. Patients with low risk findings on stress testing, can be considered appropriate if on maximal medical therapy.
 
Methods of Revascularization of Advanced CAD
CABG
PCI
1.
Two vessel CAD with Proximal LAD
A
A
2.
Three vessel CAD with low CAD burden (i.e. three focal stenosis, low SYNTAX score)
A
A
3.
Three vessel CAD with intermediate to high CAD burden (i.e. multiple diffuse lesions, presence of CTO or high SYNTAX score)
A
U
4.
Isolated Left Main Stenosis
A
U
5.
Left Main Stenosis and additional CAD with low CAD burden (i.e. 1-2 vessel additional involvement, low SYNTAX score)
A
U
6.
Left Main Stenosis and additional CAD with intermediate to high CAD burden (i.e. three vessel involvement, presence of CTO or high SYNTAX score)
A
I
Inappropriate (I)
Uncertain (U)
Appropriate (A)
8 Proposed Scoring system to select patients with chronic Coronary Artery Disease for PCI
Angina Class
Pattern of CAD
None
0
LMCA
+++++
CCS Class I or II
+
TVD
+++
CCS Class III or IV
++
DVD
++
Post MI
+++
SVD
++
Symptoms despite
Proximal LAD
+ (additional)
max medical therapy
+ (additional)
Exercise Test
Co-morbidity
Negative
–
Mild
0
Mild +ve
0
Moderate
–
Strong +ve
++
Severe
--
Post MI +ve
++ (additional)
Ischemic VT/VF
++
[+] = Positive score
LV Function
[-] = Negative score
≥ ++++ = Essential indication
LVEF > 40%
0
+++ = Appropriate indication
LVEF < 40%
+
≤ ++ = Inappropriate indication
 
Appropriateness of PCI in ACS Setting
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SUGGESTED READING
  1. Chan PS, Brindis RG, Cohen DJ. Concordance of physician rating with appropriate use criteria for coronary revascularization. J Am Coll Cardiol. 2011; 57: 1546-53.
  1. Kappetein AP, Mohr FW, Feldman TF. Comparison of coronary bypass surgery with drug eluting stenting for treatment of left main and/or three vessel disease: 3-year follow-up of the SYNTAX trial. Eur. Heart J. 2011; 17: 2125-34.
  1. Ko DT, Guo H, Wijeysundera HC, et al. Assessing the association of appropriateness of coronary revascularization and clinical outcomes for patients with stable coronary artery disease. J Am Coll Cardiol. 2012; 60: 1876-84.
  1. Patel MR, Dehmen GJ, Hirshfeld JW et al. ACCF/SCAI/STS/AATS/AHA/ASNC/HFSA/SCCT. Appropriate use of criteria for coronary revascularization focused update. J Am Coll Cardiol. 2012; 59(9): 857-81.
  1. Sanchez CE, Marroquin O, Lee J, et al. The revascularization Heart Team approach complements appropriate use criteria for coronary revascularization. J Am Coll Cardiol 2014; 63: 12-5.