About one in three adults in the United States (approximately 81 million) has some form of cardiovascular disease, including >17 million with coronary heart disease (CHD) and nearly 10 million with angina pectoris. In approximately 50% of patients, angina is the initial manifestation of stable ischemic heart disease (SIHD).

Take-aways Comprehensive guidelines released by the ACCF/AHA Task Force on Practice Guidelines provide a framework to optimally diagnose and manage patients with stable ischemic heart disease (SIHD). The guidelines recommend that patients with SIHD generally receive a “package” of guideline-directed medical therapy (GDMT) that includes lifestyle interventions and medications shown to improve outcomes.

Complicating the situation is the fact that nearly 6 million patients arrive annually in US emergency departments for evaluation of chest pain, at an estimated cost of more than $3 billion annually. Yet, up to 85% of these patients are not experiencing cardiac-related problems. Managing these patients and trying to figure out who needs admission for urgent intervention and who can be treated and safely discharged is a huge problem.

Due to the widespread nature of the problem and the diversity of patients, treatment of chronic stable angina is the subject of some complicated algorithms contained within the ACCF/AHA guidelines.¹ The strategies can be distilled into five primary objectives:

• Identify and treat associated disease that can precipitate angina
• Reduce coronary risk factors
• Make adjustments in lifestyle
• Pharmacological management
• Revascularization by PCI or CABG surgery

Coronary computed tomography angiography (CCTA) has recently emerged as a noninvasive method to image the coronary arteries. CCTA has a negative predictive value of nearly 100% for the detection of coronary artery disease (demonstrated in the trial known as ROMICAT). This approach has been investigated recently as a means of helping sort out which patients presenting to an emergency department with chest pain are safe to treat and then discharge as opposed to treat urgently and then admit. It is a huge challenge.

In a nonurgent setting, the guidelines state CCTA may be reasonable for patients with an intermediate pretest probability of SIHD who have at least moderate physical functioning or no disabling comorbidity. CCTA is reasonable for these same patients with an intermediate pretest probability of SIHD who a) have continued symptoms with prior normal test findings, or b) have inconclusive results from prior exercise or pharmacological stress testing, or c) are unable to undergo stress with nuclear myocardial perfusion imaging or echocardiography.

For patients with a low-to-intermediate pretest probability of obstructive IHD, the guidelines indicate that noncontrast cardiac CT can be considered to determine the individual’s coronary artery calcium score. Overall, the goal in evaluating a patient with SIHD is to systematically and efficiently utilize the multiple modalities that are necessary to maximize the identification of high-risk features without over-testing.

There are four broad categories of risk stratification to be considered:

• Clinical evaluation and assessment of comorbidities
• Functional capacity/stress test
• Ventricular function
• Coronary anatomy

Of course, every patient does not require each of the modalities listed in the accompanying table. (However, it should be noted that the options have been updated considerably since the last iteration of the guidelines, which is why they are detailed below.) Nor do the tests themselves need to be conducted in sequence. A low-risk patient may only require a clinical evaluation and a stress test or electrocardiogram, while a high-risk patient may proceed directly from clinical evaluation to cardiac catheterization.

Invasive Testing

The guidelines note that invasive coronary arteriography should be considered for patients with SIHD whose clinical characteristics and results of noninvasive testing indicate a high likelihood of severe IHD and when the benefits are deemed to exceed risk.

Whether invasive or noninvasive, the general principles of diagnostic imaging demand that consideration be given to three important factors:

• the pretest probability that valuable information will be gleaned from the imaging;
• the diagnostic accuracy of the test in the setting where it is being considered; and
• the post-test probability that results will lead to a change in management and improved outcomes.

The guidelines state that most patients should have a trial of guideline-directed medical therapy (GDMT) before considering revascularization to improve symptoms. That’s not a new drug: patients with SIHD should generally receive a “package” of GDMT. In the setting of SIHD, GDMT includes lifestyle interventions and medications shown to improve outcomes, including (as appropriate):

• diet, weight loss and regular physical activity;
• smoking cessation (if a smoker);
• aspirin 75–162 mg daily;
• a statin medication in moderate dosage;
• antihypertensive medication to achieve a blood pressure level <140/90 mm Hg (if hypertensive); and
• appropriate glycemic control (if diabetic).

The guidelines also note that deferring revascularization is not associated with worse outcomes, so a trial of GDMT is highly recommended as initial therapy for SIHD. Then, prior to revascularization to improve symptoms, coronary anatomy should be correlated with functional studies to ensure lesions responsible for symptoms are targeted. (In short, figure out what the problem is and make sure you go after the right lesion or lesions.)

The guidelines for managing patients with SIHD note that nearly half of the dramatic decline in cardiovascular mortality observed during the past 40 years has been attributable to interventions directed at modifying risk factors. Of this change, 47% can be attributed to treatments, including risk factor reduction after acute MI, other guideline-based treatments for unstable angina and HF, and revascularization for chronic angina. An additional 44% reduction in age-adjusted death is attributed to population-based changes in risk factors.

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References

1. Fihn SD, Gardin JM, Abrams J, et al. J Am Coll Cardiol. 2012;60:e44-e164. http://content.onlinejacc.org/article.aspx?articleid=1391404

To listen to an interview with Stephan D. Fihn, MD, MPH, about stable ischemic heart disease guidelines, visit youtube.cswnews.org. The interview was conducted by Benjamin M. Scirica, MD, MPH.

Keywords: Myocardial Perfusion Imaging, Life Style, Coronary Artery Disease, Cardiac Catheterization, Comorbidity, Risk Factors, Electrocardiography, Coronary Angiography, Tomography, Echocardiography, Exercise Test

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