Editor's Note: Commentary based on Task Force Members, Montalescot G, Sechtem U, Achenbach S, et al. 2013 ESC guidelines on the management of stable coronary artery disease: the Task Force on the management of stable coronary artery disease of the European Society of Cardiology. Eur Heart J 2013;34:2949-3003.

Background

Stable coronary artery disease (SCAD) is a highly prevalent condition with major public health implications.^1-2 For patients with chest pain, the assessment of the likelihood that symptoms indicate CAD is the first step in evaluation. The verification of the diagnosis of CAD can be obtained from non-invasive testing with the selective use of cardiac imaging when indicated. Assessment of the risk for future events such as MI or cardiac death can initially be derived from an understanding of the nature and severity of symptoms, patient clinical attributes, and the results of non-invasive testing. Management is based on the use of optimal medical therapy (OMT) and revascularization when indicated to relieve symptoms, improve quality of life, and extend longevity.

Methods and Summary of the Guidelines

The 2013 ESC SCAD guidelines provide a step-by-step approach to the evaluation and management of patients with chest pain. Important elements include: 1) establishing the diagnosis of CAD based on pre-test probability (PTP) of disease and the results of non-invasive testing, 2) assessing the risk for future clinical events, 3) initiating guideline-directed or OMT and 4) determining the need for invasive coronary angiography (ICA) and revascularization. The guidelines highlight the importance of utilizing an estimate of the PTP of CAD to frame the assessment of a patient with stable chest pain. Estimates of PTP of disease in the guideline rely heavily on the risk-prediction tool proposed by Genders et al.³ Components of the tool include age, gender, and quality of chest pain. The tool assigns patients into 1 of 4 likelihood categories: low-likelihood (PTP < 15%), low-intermediate likelihood (PTP 15-65%), high-intermediate likelihood (PTP 65-85%), and high-likelihood (PTP > 85%). These likelihood categories dictate the need for further testing to verify the diagnosis. Low-likelihood patients are not recommended for further testing and are thus removed from the diagnostic algorithm and presumed not to have SCAD, whereas high likelihood patients are assumed to have SCAD without need for further non-invasive testing. Accordingly, it is the intermediate likelihood categories for which non-invasive testing is most discriminatory. Step-wise recommendations for the non-invasive assessment of patients with intermediate-likelihood of CAD are provided. The presence of a positive non-invasive study in this population is diagnostic of SCAD (see guidelines figure 2).

Once the diagnosis of SCAD has been verified, a prognostic risk assessment is performed to insure that the intensity of therapy is appropriately matched to both the severity of symptoms and the perceived risk for an untoward event. This risk can be estimated from the results of non-invasive testing; patients are considered either low-risk (<1% mortality/year), intermediate-risk (mortality ≥1% but ≤3%/year), or high-risk (>3% mortality/year). All patients with SCAD regardless of risk should receive OMT, including primary and secondary prevention therapies as appropriate. Intensification of treatment, including revascularization, is targeted to ischemic burden, symptoms and risk.

Perspective

The 2013 ESC SCAD guidelines provide a logical and stepwise approach to diagnosis and treatment. The guidelines include clear recommendations for OMT and enumerate current indications for revascularization, recognizing the limitations of invasive therapy in this SCAD cohort, particularly among low-risk patients with limited symptoms.

While the use of PTP to determine the likelihood of CAD is helpful, the differentiation of patients with low-intermediate likelihood (15-50% PTP) from those with high-intermediate likelihood of CAD (50-85% PTP) as a means to direct downstream testing may be difficult in practice. For the former group, the writing committee suggests that patients could be referred directly to coronary computed tomographic angiography (CCTA) to assess for the presence of CAD. By comparison, the ACC/AHA 2012 Stable Ischemic Heart Disease (SIHD) guidelines limit a recommendation for the use of CCTA to patients who have contraindications to standard stress testing.⁴

The 2013 ESC SCAD guidelines also include recommendations for the assessment of asymptomatic patients with intermediate likelihood of CAD. In contrast to the ACC/AHA SIHD guidelines, which do not include mention of testing for carotid intima media thickness (IMT) and ankle-brachial index (ABI) to search for atherosclerosis in other arterial beds, and provide a Class IIb recommendation for the use of coronary calcium scoring in such patients⁴, the ESC SCAD guidelines assign a Class IIa recommendation to the use of these modalities for the assessment of asymptomatic individuals with intermediate likelihood of CAD.

The 2013 ESC SCAD guidelines provide clear recommendations for the use of ICA and revascularization in appropriate patients. Prior iterations of ACC/AHA guidelines for managing SIHD patients recommended that "at any point, on the basis of coronary anatomy, severity of angina symptoms, and patient preferences, it is reasonable to consider evaluation for coronary revascularization".⁵ This approach to revascularization continued to be highlighted^6,7 until recent randomized controlled trials such as the Optimal Medical Therapy with or without PCI for Stable Coronary Disease (COURAGE) study demonstrated no differences in cumulative rates of clinical events or measurable improvement in quality of life for patients treated with OMT plus percutaneous coronary intervention (PCI) versus those managed with OMT alone.^8,9

The 2013 ESC SCAD guidelines espouse a more cautious approach to the use of coronary revascularization for patients with SCAD. Once the diagnosis of SCAD is established, the guidelines provide a comprehensive set of recommendations for initiation of OMT and emphasize the need for coronary revascularization only in the presence of poorly controlled symptoms despite OMT or when findings on noninvasive testing indicate a high-risk of future clinical events (> 10% of myocardium demonstrating ischemia).¹⁰ Additionally, the 2013 ESC SCAD guidelines stress the importance of using fractional flow reserve (FFR) to determine the need for intervention in patients with intermediate severity coronary stenoses and no prior objective evidence of ischemia.

For patients at moderate to high risk for future clinical events, a more nuanced approach is proposed in which the decision to pursue revascularization is based on the burden of coronary disease, the severity and extent of ischemia, and the expected clinical and prognostic benefit. As delineated in figure 5 in the guidelines, patients considered for revascularization should meet three criteria: 1) have significant obstructive CAD; 2) demonstrate a large burden of ischemia (>10% myocardium involved); and 3) have attempted OMT. If these criteria are fulfilled and revascularization is technically feasible, the approach to revascularization is dictated by clinical (e.g., diabetes), anatomical (e.g., left main, multi-vessel disease, bifurcation, tortuosity), LV functional (e.g., EF), operator/center expertise, and patient preferences/values. Table 32 in the guideline lists recommendations for revascularization and displays whether they are targeted to an improvement in prognosis versus amelioration of symptoms. For patients with >50% left-main or proximal left-anterior descending (LAD) disease , 2-3 vessel disease with impaired LV function, any single vessel stenosis of > 50% with documented FFR of < 0.80, or a large area of ischemia (>10% of myocardium) in the same distribution of the stenosed artery, revascularization to improve both prognosis and symptoms is assigned a Class I recommendation. The guidelines also provide a class I recommendation for revascularization to improve symptoms for any significant stenosis in patients with limiting symptoms who are unresponsive or unable to tolerate OMT.

Recommendations for revascularization are based on the outcomes reported from several clinical trials (see guideline Table 33).^8,11-17 The COURAGE trial did not show a difference in the rate of the primary composite endpoint of death or non-fatal MI between patients undergoing PCI plus OMT versus those managed with OMT alone (median follow-up 4.6 years). On the other hand, the Swiss Interventional Study on Silent Ischemia Type II (SWISS II),¹¹ which enrolled patients following a recent MI who had evidence of silent ischemia on stress testing, demonstrated a reduction in a primary composite endpoint of death, MI, or symptom-driven revascularization with PCI plus OMT versus OMT alone. This study was performed more than 20 years ago. The use of FFR to select patients for revascularization was evaluated in the Fractional Flow Reserve-Guided PCI versus Medical Therapy in Stable Coronary Disease (FAME-2) study.¹² FAME-2 enrolled stable CAD patients with one-, two-, or three-vessel disease amenable to PCI. Patients with at least one stenosis in a major vessel with an FFR < 0.80 were randomized to PCI plus OMT or OMT alone. The trial was halted prematurely due to a significant reduction in the primary composite endpoint of death, MI, or urgent revascularization with PCI plus OMT versus OMT alone. The ongoing International Study of Comparative Health Effectiveness With Medical and Invasive Approaches (ISCHEMIA) Trial, which is designed to assess whether, in patients with moderate or severe ischemia, a routine invasive strategy with coronary angiography and revascularization plus OMT is superior to a conservative strategy of OMT alone,¹⁸ will perhaps provide further insight into the optimal management strategy for this patient population.

Conclusion

The 2013 ESC SCAD guidelines are concise, pragmatic, and well grounded in the current evidence base. Utilization of PTP estimates of disease should help focus performance of non-invasive testing. An integrated risk assessment will identify patients for whom revascularization, in addition to OMT, will be most efficacious.

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References

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Keywords: Cardiac Imaging Techniques, Chest Pain, Coronary Artery Disease, Coronary Disease, Public Health, Quality of Life

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