Revascularization Approaches

Shared Decision-Making

Current guidelines recommend the use of a multidisciplinary heart team to facilitate decisions regarding coronary revascularization, percutaneous aortic valve replacement, and other high-risk cardiac procedures. This decision-making process is best shared across a wide variety of individuals including the patient, the patient’s family, the interventional cardiologist, the cardiac surgeon, the general cardiologist, and the primary care physician. It has been demonstrated that this clinical care paradigm is not only feasible but also appealing. Physicians who have known the patient over a prolonged period of time, often the general cardiologist and/or primary care physician, should play an important role in recommending therapies regarding coronary revascularization, whether it be CABG or PCI. Ideally the risk-benefit discussion during these heart team meetings would be provided by both the interventional cardiologist and the cardiac surgeon, who are best suited to provide an individualized risk-benefit assessment.

Coronary Revascularization: General Comments

Coronary revascularization procedures are common and costly, associated with an annual cost of $3.2 billion to Medicare. The rates of coronary revascularization procedures in the United States are decreasing. Between 2001 and 2008 there was a 14% decrease in the annual rate of coronary revascularization procedures, which was principally driven by a 28%, reduction in CABG procedures and an unchanged PCI rate. After 2008, PCI rates in the United States decreased by 28%, and much of this decline was in patients with SIHD ( Fig. 23.1 ).

Following publication of US national rates of “appropriate” coronary revascularization, data from the Washington State Clinical Outcomes Assessment Program between 2010 and 2013 showed that the number of PCI procedures decreased substantially, which was driven by a 43% decline in the number of PCI procedures performed for elective indications. The majority of this decline occurred following the onset of state-wide measurement of PCI appropriateness.

An estimated 500,000 PCI procedures are performed annually in the United States, and an equal number is performed in the rest of the world. The safety and efficiency of procedural techniques have evolved over the past 40 years. PCI is now considered a mature medical procedure. The physician-reported success rates are 99%, and the observed morbidity and mortality rates are approximately 1% to 2%. The complication rates for PCI procedures remain low despite an increasing complexity of lesions and higher-risk clinical demographics.

In 2010, 1488 facilities in the United States were enrolled in the American College of Cardiology National Cardiovascular Data Registry (ACC NCDR) CathPCI Registry, which captured approximately 85% of the PCI procedures performed. A 2012 analysis from this registry includes 1.1 million PCI patients and provides a cross-sectional description of the current state of coronary angiography and PCI in the United States. Institutional and operator volumes for PCI procedures are often used as proxies for PCI quality. Both vary considerably across institutions, with approximately half of all ACC NCDR institutions performing fewer than 400 PCI procedures and 13% performing more than 1000 PCI procedures annually. Currently, 40% of patients are older than age 65 and 12% are older than 80, 80% of patients are overweight, 45% are obese, and 36% have a history of diabetes mellitus. Approximately half the patients underwent a preprocedural stress test, with myocardial perfusion imaging being most commonly performed. Fig. 23.2 shows the percent of patients by indications for diagnostic coronary angiography and PCI. Approximately 18% of patients underwent PCI for stable angina symptoms, while an additional 9% were asymptomatic. Radial artery access in the 2010 report was used in approximately 7% of PCI procedures. This percentage has steadily increased over the last 7 years, with transradial access rates now approaching 20% in the United States (but higher in many parts of the world). The observed in-hospital mortality rate was 0.72%, and in-hospital stroke rate was 0.17%. The most common noncardiac complication continues to be periprocedural bleeding. With the emergence of third- and fourth-generation drug-eluting stents (DESs), target vessel revascularization rates are low at 5% to 7%, and stent thrombosis rates are measurably lower with newer-generation DES platforms.

Lesion progression is a well-recognized factor accounting for future cardiovascular risk following PCI. Approximately 20% of patients undergo repeat PCI within 3 years of the index PCI because of nonculprit lesion progression. Similarly, the Providing Regional Observations to Study Predictors of Events in the Coronary Tree (PROSPECT) trial demonstrated that 50% of all major adverse cardiovascular events at 3 years occur solely as a function of nonculprit lesion progression. Current PCI practices are designed to identify and effectively treat culprit lesions. Because of this, optimal medical therapy for secondary prevention is requisite among patients undergoing PCI.

Two major limitations of PCI remain: a higher than desirable frequency of incomplete revascularization related to complex disease and residual cardiovascular risk related to morbid and mortal events due to disease progression.

CABG is also very common and now performed approximately 400,000 times annually in the United States. There has, however, been a steady decline in the frequency of CABG procedures performed in the United States. Until recently this decline has been associated with an increase in percutaneous coronary revascularization procedures. The most commonly used conduits are the left internal mammary artery (LIMA) and the greater saphenous veins. The use of the LIMA is now considered a quality indicator for CABG and has long been linked to higher long-term patency than saphenous venous grafts. Moreover clinical outcomes are improved with use of the LIMA. Other arterial conduits such as the radial artery, the right internal mammary artery, and the gastroepiploic artery have been used and demonstrate improved patency rates compared with the saphenous venous grafts but are not routinely used in clinical practice.

In general, a CABG procedure takes 3 to 4 hours, and the patient remains hospitalized for 5 to 7 days and recuperates for 6 to 12 weeks following discharge. The risk for perioperative morbidity and mortality has decreased over time. There is now nearly universal participation of CABG centers in the Society of Thoracic Surgeons National Adult Cardiac Surgery Database. Although the predicted risk of mortality has not changed over time, there has been a measurable reduction in the adjusted mortality rates in the last 10 years ( Fig. 23.3 ). This has been similarly true for perioperative stroke rates.

Stroke remains a serious complication following CABG. Risk factors include increasing age, concomitant peripheral or cerebrovascular disease, diabetes, and aortic atherosclerosis. Neurocognitive decline has also been described in the post-CABG population and specifically linked to cardiopulmonary bypass. These studies have not been randomized controlled trials and the results are heterogeneous. Thus the link between CABG and cognitive decline remains uncertain. The current belief is that neurocognitive dysfunction is related to a number of factors including the impact of major surgery coupled with long-term effects in patients with cardiovascular risk factors and concomitant coronary artery and cerebrovascular disease.

There remains a risk for native disease progression and bypass graft failure following CABG. Thus it is vitally important that clinicians ensure patients remain on appropriate medical therapy. A 2016 American Heart Association (AHA) scientific statement clarifies appropriate secondary prevention therapy following CABG ( Box 23.1 ). In addition to these recommendations, studies have suggested that P2Y12 receptor inhibition following CABG may be associated with improved graft patency.

There has been significant interest in maintaining the benefits of CABG with the use of less-invasive approaches. These techniques require specialized training and are limited in that complete revascularization is achieved less often. The sustainability of these techniques remains uncertain. Off-pump surgery has also been studied; however, the results have been inconsistent with no clear advantage over on-pump surgery. Hybrid surgical and percutaneous revascularization strategies have been explored in recent years. With this strategy patients undergo minimally invasive surgery with a LIMA usually to the left anterior descending artery and then subsequently undergo PCI to either the left circumflex or right coronary artery. Long-term data comparing this hybrid approach to conventional CABG are lacking, but this approach makes sound clinical sense in specific patient populations. Common appropriate use criteria for PCI and CABG for patients with multivessel disease are shown in Table 23.1 .

Indications for Coronary Revascularization in Patients with Stable Ischemic Heart Disease

The goals of coronary revascularization, whether PCI or CABG, are to relieve symptoms, improve QoL, and mitigate the risk of future complications related to atherosclerotic CAD such as cardiovascular mortality and nonfatal MI. These goals have not changed over the last several decades. However, the evidence base for coronary revascularization and medical therapy has greatly expanded over the past decade. These newer data provide clinicians with additional insights when recommending therapy to patients with chronic stable heart disease.