Percutaneous coronary intervention (PCI) is one of the most frequently performed therapeutic procedures in medicine.1 PCI is a costly procedure with mean Medicare payments to hospitals and physicians totaling more than $15,000 per procedure.2 Although PCI's indication as an emergency intervention in patients with acute coronary syndrome (ACS) is well established, recommended indications for PCI in patients with stable ischemic heart disease (SIHD) are very limited (Table 1).3 Current guidelines for the management of SIHD include guideline-directed medical therapy (GDMT) for all patients.3 Several landmark studies have shown no increased survival benefit in patients with SIHD who undergo PCI compared with those treated with GDMT alone. However, review of current practices shows that despite the procedural risk and lack of benefit, clinicians continue to recommend and proceed with PCI in patients with SIHD, sometimes in patients who are asymptomatic.4
Initial evaluation of patients presenting with chest pain must include differentiation between stable and unstable disease (Table 2). Patients with SIHD experience stable angina with chest pain occurring at a predictable level of exertion; symptoms are relieved with rest.3 Some patients with SIHD may even be asymptomatic. In contrast, patients with new-onset angina (within 2 months of initial presentation), angina occurring at rest, or angina that increases in intensity or frequency are considered to have unstable angina and warrant evaluation for potential ACS.3
Patients with suspected SIHD who have had no previous evaluation for ischemic heart disease, or those with known SIHD who have had a change in their clinical status warrant further investigation.3 If a patient's symptoms, risk factors, existing comorbidities, or current cardiac disease raise the likelihood of a high-risk coronary lesion, obtain cardiac stress testing.3 All patients with evidence of ischemia on stress testing should be started on GDMT. If stress testing suggests a high-risk coronary lesion, and revascularization is the patient's preference, pursue coronary angiography with the intent to revascularize.3 If stress testing does not indicate a high-risk coronary lesion, the patient should be maximized on GDMT and symptoms reassessed in follow-up.
Guidelines recommend that noninvasive cardiac stress testing be performed before diagnostic cardiac catheterization or PCI in patients with SIHD.3 However, a 2004 analysis of more than 20,000 Medicare records revealed that fewer than 50% of patients had undergone stress testing before PCI.5 In 2012, a review of a cardiac catheterization laboratory registry of nearly 1 million US patients showed that only 52% of patients with SIHD had some type of stress testing before PCI.6
The American College of Cardiology (ACC)/American Heart Association (AHA) Task Force recommend GDMT for all patients with ischemic heart disease. The goals of GDMT are to reduce death, prevent myocardial infarction (MI), reduce or eliminate ischemic symptoms, and provide an acceptable quality of life.3
The Class I recommendations from the ACC/AHA Task Force on Practice Guidelines for SIHD are outlined in Table 3. Most noteworthy among the guidelines are those with Level A evidence demonstrating efficacy in multiple populations and randomized clinical trials or meta-analyses.
Based on current guidelines, patients should be maximized on GDMT before being referred for PCI to treat unacceptable symptoms of angina. However, one review of patients with SIHD who were admitted for elective cardiac catheterization, with potential for revascularization, revealed that 30% of patients were not on an aspirin, beta-blocker, and statin.7 Just under 30% of the patients referred for PCI were on maximal antianginal therapy.7
PERCUTANEOUS CORONARY INTERVENTION
PCI is recommended in most patients with ACS (Table 1). Conversely, situations that necessitate PCI in patients with SIHD are limited. PCI may be an alternative to coronary artery bypass grafting (CABG) to improve survival in patients with an unprotected left main coronary artery stenosis greater than 50%.3 In this case, PCI would only be preferred to CABG if the coronary lesion was not significantly complex (for example, a lesion that does not involve a vessel bifurcation), if a long-term benefit were anticipated, and if the patient was not a surgical candidate.3
For patients with unacceptable ischemic symptoms, guidelines recommend PCI if the coronary artery stenosis is significant—that is, greater than 70% diameter narrowing (Table 1). More recently, fractional flow reserve (FFR) has been used in determining the indication for revascularization. FFR is the ratio of maximal achievable blood flow through a stenosed coronary artery to the hypothetical maximal achievable blood flow through the same artery without the stenosis.8 Current guidelines consider an FFR less than or equal to 0.8 as indicative of a significant stenosis.3 The ACC/AHA Task Force on Practical Guidelines has recommended the use of CABG or PCI in patients with one or more significant coronary artery stenoses and unacceptable ischemic symptoms despite GDMT.3
COMPARISON TO MEDICAL THERAPY ALONE
Guidelines from the ACC/AHA Task Force, which do not recommend PCI to improve survival or reduce MI risk in patients with SIHD, are based on convincing research trials, three of which are considered here.
The Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) Trial
Study patients in this large trial (N = 2,287) had SIHD with at least one 70% stenosis in a coronary artery and noninvasive testing demonstrating cardiac ischemia.9 All patients received GDMT and half underwent PCI of at least one coronary artery.9 After nearly 5 years of observation, the study end points of death or non-fatal MI were virtually identical in the two groups.9
The Bypass Angioplasty Revascularization Investigation in Type 2 Diabetes (BARI 2D) Study
This study was noteworthy for the inclusion of patients with SIHD, all of whom also had type 2 diabetes.10 Inclusion criteria included a coronary artery stenosis greater than 50% as well as a positive stress test.10 If stress testing was unavailable, patients were required to have at least a 70% stenosis and symptoms of classic stable angina.10 Half of the 2,368 study patients underwent cardiac catheterization and revascularization by PCI or CABG (whichever was deemed more appropriate), and half were randomized to GDMT alone. Follow-up over 5 years showed no difference in major cardiovascular events or survival.10
The Fractional Flow Reserve Versus Angiography for Multivessel Evaluation 2 (FAME 2) Trial
All patients with SIHD in this study had FFR measured for every coronary artery stenosis.11 Unlike the COURAGE and BARI 2D trials, patients in FAME 2 who underwent PCI received second-generation drug-eluting stents rather than bare-metal stents. Patients with FFR less than or equal to 0.8 received either GDMT alone or GDMT plus PCI. No significant difference in mortality or rate of MI was found between the two groups.11 A significantly higher rate of urgent revascularization was found in the GDMT group (16.3%) compared with the PCI group (4%).11 The prevalence of angina at 2-year follow-up was lower in the PCI group, but by the 5-year follow-up, no significant difference in angina prevalence was found between the two groups.11,12
One other important observation emerged in this trial. FFR measurement yielded a cohort with FFR greater than 0.8, inferring no critical coronary lesion. This cohort received only GDMT and its outcome was similar to the group with an FFR less than or equal to 0.8 who were treated with GDMT and PCI.11
These three trials demonstrate that for patients with SIHD, PCI plus GDMT provides no survival benefit over GDMT alone. Also, characterizing angiographic stenoses using FFR is advantageous to identify patients with functionally critical lesions, and to treat these with PCI to avoid later need for revascularization.
Two of the three trials reviewed were performed in years when the stents used were bare metal. The outcomes of death or nonfatal MI were not different with bare-metal stents compared with drug-eluting stents, but patients with bare-metal stents had a 3% greater need for revascularization.13 Another important difference is that dual antiplatelet therapy is required for only 1 month in patients with bare-metal stents, and typically for a year in those with drug-eluting stents.14 For patients judged to be at high risk for bleeding, or those who require surgery in the near future, bare-metal stents often are preferred.
RISKS OF PCI
A data registry of nearly 1 million people who underwent PCI reported that complications occurred in 4.5% of the patients who did not present with ST-segment elevation myocardial infarction (STEMI), and 12.4% in patients with STEMI.6 The most common complication was access site bleeding within 72 hours of PCI; additional complications included cardiogenic shock, heart failure, stroke, pericardial tamponade, and renal failure.6
Because the vast majority of PCIs are performed with drug-eluting stents, most patients are prescribed 1 year of dual antiplatelet therapy. A study following 8,500 patients for 2 years after PCI found that 6.2% of patients experienced postdischarge bleeding.15 The major site of bleeding was gastrointestinal. The patients who had bleeding complications were older, had lower baseline hemoglobin, and were more likely to be taking oral anticoagulants.15
KEEPING PATIENTS INFORMED
Both the AHA/ACC Task Force and the European Society of Cardiology Task Force on the management of SIHD include in their guidelines the importance of an informed patient and stress that decisions about treatment should be a shared process between patient and clinician.3,16 The clinician is expected to explain all risks, perceived benefits, and costs to the patient.
Perceived benefits of PCI
The beliefs of patients with SIHD and their cardiologists about PCI were studied in an informative trial.17 Patients and their cardiologists were sent surveys with questions about the expectations of PCI in patients with SIHD. Results revealed that most patients believed that PCI would reduce their risk of MI, as well as reduce their risk of fatal MI.17 Of the cardiologists surveyed, fewer than 20% believed PCI would reduce the risk of MI or fatal MI.17 This study shows a surprising discrepancy between patient and clinician beliefs.
PCI often is performed for patients with unacceptable angina. Although angina is reduced more quickly with PCI than with GDMT alone, this benefit appears short-lived. In the FAME2 trial, at 5-year follow-ups no significant difference was found between the presence of angina in the PCI group compared with the GDMT group.12 Data also suggest that PCI may have a placebo effect. A double-blind randomized controlled trial was performed in patients with SIHD who were experiencing angina and had at least one coronary stenosis of 70% or greater.18 The control group underwent insertion of a coronary catheter without the performance of PCI and the treatment group underwent PCI. At 6-week follow-up, no significant difference was found in the rate of improvement in class of angina between the groups.18
Based on current guidelines, GDMT is the initial strategy to treat patients with SIHD. Initial investigation of SIHD should include noninvasive testing for ischemia before consideration of cardiac catheterization and potential PCI. Studies comparing management of SIHD with PCI and GDMT alone to date have shown no survival benefit in those who undergo PCI, although there likely is a decrease in the need for urgent revascularization in patients who undergo PCI based on the FFR of a lesion. PCI has been shown to provide more immediate relief of angina compared with GDMT alone; however, this benefit appears short-lived.12 Despite current guidelines and evidence from trials, some cardiologists continue to perform PCI in patients with SIHD as an initial strategy in management before a trial of GDMT and without objective evidence of ischemia based on noninvasive testing.5,6 Care of patients with SIHD should be according to current guidelines and evidence-based medicine. Patients need to be well informed of the actual benefits of PCI in SIHD as well as the potential risks involved. Well-informed patients are more likely to choose GDMT alone over PCI if they do not perceive clear benefits from the procedure. If unnecessary PCI in patients with SIHD is avoided, needless complications would be eliminated and there would be a substantial reduction in costs in the management of heart disease.
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