An 85-year-old man with a history of tobacco use, hypertension, paroxysmal atrial fibrillation, insulin-dependent diabetes mellitus, prior cerebrovascular accident, previous myocardial infarction (MI), coronary artery disease (CAD), and ischemic cardiomyopathy presented with high-risk non–ST-segment elevation myocardial infarction (NSTEMI) associated with heart failure symptoms (New York Heart Association [NYHA] class IV). Cardiac exam revealed bibasilar rales, a laterally displaced point of maximal impulse, a regular rhythm with normal heart sounds, and trace bilateral lower extremity pitting edema. His electrocardiogram revealed normal sinus rhythm and left axis deviation, along with ST depressions and T-wave inversions in the lateral leads suggestive of ischemia. Chest x-ray showed diffuse pulmonary edema and an enlarged cardiac silhouette. Laboratory values were notable for an initial serum troponin T of 0.08 ng/mL that peaked at 0.13 ng/mL, a serum brain natriuretic peptide level of 1700 pg/mL, and serum creatinine level of 0.7 mg/mL. Echocardiography showed severely reduced left ventricular systolic function with severe global hypokinesis, severe mitral regurgitation, and a left ventricular ejection fraction (EF) of 20% to 25%. Of note, 6 months prior to this admission, his left ventricular systolic EF was 45%. He was initially treated with aspirin and ticagrelor and anticoagulated with unfractionated heparin. Coronary angiography revealed a 99% heavily calcified bifurcation lesion in the proximal left anterior descending (LAD) coronary artery involving the origin of a large first diagonal branch, with Thrombolysis in Myocardial Infarction (TIMI) 1 flow. The Medina classification of the lesion was 1,1,1 (Figure 18-1). The left circumflex coronary artery was a diffusely diseased vessel with a moderate lesion in the distal segment. The right coronary artery (RCA) was a dominant vessel with a severe, long, diffuse, eccentric, and heavily calcified lesion in the mid segment and a second calcified, focal lesion in the posterolateral branch. There was extensive collateral circulation from the RCA to the distal LAD via septal branches (Figure 18-2). The calculated Society of Thoracic Surgery predicted risk of mortality was 11.7%. The case was discussed among the multidisciplinary heart team, including cardiothoracic surgeons and interventional and noninvasive cardiologists. Based on his age and comorbidities, the patient was deemed to be a poor candidate for coronary artery bypass graft surgery (CABG) and was therefore referred for high-risk percutaneous coronary intervention (HR-PCI).

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  Coronary heart disease (CHD) is a major cause of disability and death in the developed world.

  
  
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  The prevalence in the adult population of the United States is 15.5 million.

  
  
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  In the United States, CHD is the leading cause of death, claiming one third of all deaths in adults over 35 years of age.

  
  
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  It is estimated that 635,000 Americans will have a new coronary event (either first hospitalized MI or CHD death) within this coming year and that 300,000 will have a recurrent coronary event.¹

Based on the clinical presentation, multiple cardiovascular risk factors, diffuse coronary anatomy, and low EF, the patient in the case was considered a high-risk candidate for revascularization, and required careful risk-benefit analysis prior to deciding which revascularization strategy to use (CABG vs. PCI) and how that strategy would be executed. As a matter of fact, the decision to revascularize at all remains contentious. Numerous observational and randomized clinical trials have demonstrated a benefit with revascularization in high-risk patients with extensive and severe CAD.² However, there remains a treatment-risk paradox, as studies have also shown that this subgroup of high-risk patients are less likely to be offered revascularization.^3-5 This may be due to the perception that extensive comorbid conditions will dampen the clinical benefit of successful revascularization or that the extent and severity of CAD are simply too far advanced to confer clinical benefit or due to operator concerns that the technical challenge may preclude procedural success. Various hypotheses have been proposed for why revascularization is not offered: (1) the perceived low likelihood of technical success due to the high complexity of disease, or (2) doubt in the likelihood of clinical benefit due to advanced and irreversible disease processes, or (3) numerous and extensive comorbid and competing conditions that may dampen the clinical benefit. Although certain comorbid conditions and risk factors may confer high or prohibitive surgical risk, inventions and technical advances in interventional cardiology have made revascularization in this high-risk subgroup safer and more likely to succeed.⁶ Careful identification and selection of the HR-PCI patient are paramount and lie at the intersection of 3 important spheres, as depicted in Figure 18-3: (1) clinical presentation, risk factors, and comorbidities; (2) CAD complexity; and (3) hemodynamic compromise with severely decreased left ventricular function.⁷

In patients with complex multivessel and/or unprotected left main disease or intermediate to high Synergy Between PCI With Taxus and Cardiac Surgery (SYNTAX) scores, CABG has demonstrated superiority over PCI in the need for subsequent revascularization but has shown no immediate short-term mortality benefit.⁸ Further, the presence and cumulative effect of certain comorbidities increase immediate surgical risk and begin to define the HR-PCI patient. Clinical factors that have been shown to increase the risk of CABG include advanced age, frailty, renal failure, peripheral artery disease, prior stroke, chronic lung disease, pulmonary hypertension, depressed left ventricular systolic function, and clinical heart failure. When patients are deemed at extreme risk or inoperable or the mortality risk is estimated to exceed 5% as predicted by risk assessment models, such as the Society of Thoracic Surgery (STS) score or the EuroSCORE, percutaneous revascularization is a consideration as an alternative to surgery.^9-11 Additional factors that may make patients poor candidates for surgical revascularization include hostile mediastinum, severely calcified (porcelain) aorta, and poor distal targets. In our case, the patient’s advanced age, frailty, multiple comorbidities, and severely reduced left ventricular systolic function were key factors in making our patient a poor surgical candidate.

Historically, percutaneous treatment of complex and extensive anatomic lesions that jeopardize larger territories of myocardium in high-risk patients has been associated with increased risk of complications, ischemia, and hemodynamic collapse. Coronary anatomy characterized by unprotected left main disease, complex 3-vessel disease, or last patent conduit compromises large territories of myocardium, and bifurcation and/or heavily calcified lesions and/or chronic total occlusions increase the degree of procedural difficulty and risk of complications. Thus, we define HR-CAD based on the presence of either unprotected left main disease and/or 3-vessel disease and/or high scores according to an angiographic grading system such as the Balloon Pump–Assisted Coronary Intervention Study (BCIS-1) jeopardy score or the SYNTAX score.^12,13 With advancements in technologies and techniques and inception of percutaneous left ventricular assist devices, complete revascularization through PCI can now be achieved in patients who otherwise might not have had the opportunity to receive treatment in the past. Figures 18-1 and 18-2 demonstrate severe 2-vessel CAD involving long and heavily calcified lesions, 1 of which involves a bifurcation lesion in the proximal LAD that supplies a large territory of myocardium. Evidenced by the multitude of collaterals, the RCA provides flow to not only the right ventricle, inferior wall, and lateral wall, but also to myocardium supplied by the diseased proximal LAD, namely the anterior, anteroseptal, anterolateral, and apical walls. Thus, the lesion in the RCA is of “double” importance. In our case, the anatomic lesions comprised an intermediate-risk SYNTAX score of 24, and given the anatomic features (long, heavily calcified, bifurcation lesions), PCI would require aggressive tools and advanced techniques to achieve complete revascularization, conferring higher risk to the patient.

The last consideration, but no less critical, is the assessment of procedural risk based on the left ventricular systolic function and/or hemodynamic status. Severe left ventricular systolic dysfunction, severe valvular lesions, and elevated filling pressures and/or decompensated heart failure may all increase periprocedural risk. Medical therapy should be optimized prior to the procedure in order to decrease filling pressures, minimize symptoms, and improve renal function to decrease the risk of contrast-induced kidney injury. Severe ventricular dysfunction and/or severe valvular lesions decrease physiologic reserve and, when coupled with prolonged ischemic time, can lead to hemodynamic collapse. To mitigate this risk, careful consideration must be given to the use of mechanical circulatory support (MCS).

The transient interruption of coronary blood flow during PCI can lead to ischemia, decreased myocardial contractility, and cardiovascular collapse in patients with depressed left ventricular function and high-risk coronary anatomy. The mechanisms whereby coronary blood flow is transiently interrupted include repetitive contrast dye injections, balloon inflations, atherectomy passes, and stenting, all of which may cause hemodynamic compromise and collapse, which may be counterbalanced with the use of MCS.⁷

MEDICAL THERAPY

Guideline-Directed Medical Therapy (GDMT)

Medical therapy is the foundation of the treatment of CAD, and via GDMT, it both improves outcomes and alleviates symptoms. Antiplatelet agents, statins, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and β-blockers seek to stabilize atherosclerosis and prevent disease progression, thereby decreasing recurrent events and improving overall survival. On the other hand, anginal relief is achieved by decreasing oxygen demand and/or improving hemodynamics with calcium channel blockers, β-blockers, nitrates, and ranolazine.¹⁴ Despite continued advances in medical therapy, patients continue to present with either acute coronary syndrome or prognostically important high-risk coronary anatomy, 2 important scenarios in which revascularization (in addition to GDMT) would improve symptoms and decrease adverse coronary events.