Chronic Stable Coronary Artery Disease Case File

Chronic Stable Coronary Artery Disease Case File

Eugene C. Toy, Md, Michael d . Faulx, Md

Case 4

A 68-year-old man presents to his new primary care provider for an initial patient visit. His sole active complaint is mild retrosternal chest pressure that lie experiences only after significant exertion. and the discomfort resolves within minutes of cessation of the provoking activity. The pattern and severity of his symptoms have not changed significantly over the last 3 years. and he denies any episodes of chest pain at rest. dizziness, syncope, dyspnea, palpitations, or lower extremity edema. He has a history of coronary artery disease requiring percutaneous coronary intervention (PCI) with placement of a bare-metal stent to the right coronary artery 5 years ago. He was told that his other coronary vessels were mildly diseased

and there were no other lesions suitable for PCI. Other pertinent medical his tory includes hypercholesterolemia and longstanding hypertension. His current medications include aspirin 81 mg, metoprolol succinate 25 mg daily, simvastatin 10 mg, and hydrochlorothiazide 12.5 mg daily. He is a lifelong nonsmoker, and does not consume alcohol or use illicit drugs. On examination the patient is comfortable and in no acute distress. The heart rate is 90 bpm and regular, and the blood pressure is 155/85 mmHg in the left arm. There are no murmurs, rubs, gallops, or clicks on cardiac auscultation. and the second heart sound is physiologically split. There are no apparent extra heart sounds. The remainder of the physical examination is unremarkable. Aresting 12-lead electrocardiogram (ECG) is obtained, and is shown hi Figure 4-1.

c What is the most likely diagnosis?

c What is the best next diagnostic step?

c What is the best next step in therapy?

Figure 4-1. Resting 12- lead ECG. (Reproduced, with permission, from Donald Underwood, MD)

Answer to Case 4:

Chronic Stable Coronary Artery Disease

Summary: A 68-year-old man is establishing care with a new primary care provider. He is currently experiencing typical chest pain symptoms with heavy exertion, and these symptoms have been stable for the last 3 years. He denies chest pain at rest, worsening of his angina over the last 3 months, and has no symptoms suggestive of congestive heart failure. He has a known history of coronary artery disease and is on aspirin, a long-acting beta-blocker, simvastatin, and hydrochlorothiazide. His physical examination is unremarkable, and he does not smoke or drink alcohol. The patient has a normal resting ECG and is able to exercise. Importantly, his blood pressure remains elevated, and his resting heart rate does not suggest therapeutic β-adrenergic blockade.

• Most likely diagnosis: Chronic stable coronary artery disease (CAD).

• Next diagnostic step: (1) assess biochemical markers of risk for CAD and MI (total, LDL, and HDL cholesterol, serum creatinine, fasting blood glucose, or hemoglobin A1c) and (2) perform exercise ECG stress testing to evaluate risk for subsequent non fatal MI or death rom cardiovascular causes

• Next step in therapy: Optimize guideline-based medical therapy to reach a target blood pressure of <140/90 mmHg, reduce LDL to a target of ≤100 mg/dL, and reduce angina symptoms by titrating beta-blocker and/or adding a nitrate (sublingual nitroglycerin on an as-needed basis or longer-acting isosorbide mononitrate).

ANALYSIS

Objectives

1. Recognize signs and symptoms of coronary heart disease, and be aware of the usual differential diagnosis for chest pain.
2. Understand the role of risk factor modification in managing patients with stable ischemic heart disease.
3. Appreciate the role of noninvasive stress testing, coronary angiography, optimal medical therapy, and percutaneous or surgical revascularization in chronic stable angina.

Considerations

This 68-year-old man has typical anginal chest pain, and has known coronary artery disease. His angina is stable, and evident only with significant exertion. Importantly, his history and physical findings do not suggest the presence of an acute coronary syndrome (such as unstable angina or acute MI) or significant left ventricular dysfunction. The resting 12-lead ECG is normal, and he is on an appropriate pharmacological regimen for stable coronary heart disease. The first diagnostic step in this case would be to evaluate whether he requires more aggressive risk factor modification by

measuring serum total cholesterol, LDL, HDL, creatinine, and blood glucose levels. The patient’s blood pressure is not currently adequately controlled, and in addition to increasing the doses of his antihypertensive medications, he should be encouraged to adopt lifestyle modifications to reduce his blood pressure to <140/90 mmHg. He is already on a diuretic and a beta-blocker, and a third agent may be necessary to achieve the target blood pressure. An angiotensin-converting enzyme inhibitor (ACEI) or an angiotensin receptor blocker should be introduced preferentially. In addition, the beta-blocker dose can be slowly titrated to target a resting heart rate between 60 and 70 bpm, which may further improve his angina symptoms. Subsequent to this, the patient should be referred for exercise ECG stress testing to establish his risk for future nonfatal myocardial infarction or death rom cardiovascular causes. Several risk indices factor in results from exercise stress testing or other noninvasive modalities, and those patients with high-risk findings should be considered for percutaneous or surgical revascularization if a high-risk epicardial coronary lesion is identified on coronary angiography. Barring features suggestive of high risk for future complications, studies have shown that optimal medical therapy alone is as effective as optimal medical therapy plus percutaneous coronary intervention.

Approach To:

The Patient with Stable Angina

DEFINITIONS

STABLE ANGINA: Typically retrosternal heaviness, pressure, or squeezing pain that occurs with activity and resolves promptly with rest or administration of nitroglycerin.

ACUTE CORONARY SYNDROME (ACS): A spectrum of clinical entities that represent the end result of acute myocardial ischemia, typically the result of acute occlusion of an epicardial coronary artery due to vasospasm or atherogenic plaque rupture and thrombosis.

UNSTABLE ANGINA (UA): Part of the spectrum of the acute coronary syndrome. UA includes recent-onset angina (within 2 months of presentation), rest, crescendo or prolonged angina, and angina not promptly relieved by nitroglycerin.

CLINICAL APPROACH

Etiologies

The differential diagnosis of chest pain consists of clinical entities that can be chronic and relatively benign, or acute and imminently life-threatening. Excluding those diagnoses that present an immediate threat to the life of the patient is the first task of the clinician. The 12-lead ECG is paramount for the diagnosis of an acute coronary syndrome and can direct patient management decisions rapidly. If acute aortic disease is a consideration, chest x-ray or CT imaging, evaluation of peripheral pulses, and blood pressure measurements in both arms should be undertaken. Other diagnoses to be considered include pneumothorax, pericarditis, pulmonary embolus, and esophageal perforation.

*Pain that radiates to the neck or jaws is strongly suggestive of angina.

Clinical Presentation

History The classic presenting complaint in patients with stable coronary heart disease is exertional chest discomfort. This is most frequently described as a retrosternal pressure or squeezing sensation, with occasional radiation to the jaw or the upper extremities. Prompt relief of pain with nitrates or on cessation of exertion supports the diagnosis (Table 4-1). On the basis of the patient’s age and gender, the classification of chest pain as typical, atypical, or noncardiac can predict the likelihood of angiographic coronary stenosis with fair accuracy (Table 4-2). In cases of severe or high-risk CAD, symptoms related to left ventricular dysfunction or conduction system abnormalities may be apparent. These include dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea, lower extremity edema, palpitations, and syncope or near-syncope. Finally, it is critical to note historical features suggestive of an acute coronary syndrome, including crescendo angina, rest angina, and angina not promptly relieved by rest or nitroglycerin.

Physical Examination Often, the cardiac exam is unrevealing, but findings suggestive of left ventricular dysfunction, such as sinus tachycardia, pulmonary rales, elevated jugular venous pulsation, lower extremity edema, and new cardiac murmurs, are significant.

*Angiographically significant stenosis defned as > 50% stenosis. (Adapted from Diamond GA, Forrester JS. N Engl J Med. 1979;300:1350–1358.)

TREATMENT OF CAD

Risk Factor Modification

Identify and treat dyslipidemia, with a goal LDL of <100 mg/dL if coronary disease has been established or if the 10-year risk of coronary heart disease (CHD) is estimated to be >20%, with an optional LDL-C (low-density lipoprotein cholesterol): goal of <70 mg/dL. Aggressively treat elevated blood pressure and hyperglycemia associated with diabetes mellitus, and encourage smoking cessation in those patients who use tobacco.

Improvement of Anginal Symptoms

Optimal medical therapy includes use of beta-blockers, calcium channel blockers, and nitrates. It is important to titrate medications to maximally tolerated dosages. In refractory cases ranolazine and enhanced external counterpulsation (EECP) can be considered. EECP involves hour-long sessions of sequential balloon counterpulsation therapy with large pneumatic cuffs that are placed on the legs. Patients are typically treated 5 days per week for a 7-week session. Adjunctive therapies such as ranolazine and EECP have been shown to reduce symptom frequency, nitroglycerin usage, and the degree of ST segment depression with exercise, but these modalities have not been shown to impact survival or “hard events” such as the rate of myocardial infarction. Patients with refractory symptoms despite optimal medical therapy and coronary anatomy that is not conducive to revascularization may even be referred for spinal cord stimulation to address their chest pains.

Non Invasive Evaluation of Risk and Prognosis

Noninvasive stress testing and advanced imaging can provide additional data concerning risk and prognosis in patients with stable ischemic heart disease. In patients with an interpretable resting electrocardiogram who can exercise, exercise ECG stress testing is considered a class 1 indication according to the joint American College of Cardiology/American Heart Association (ACC/AHA) guidelines. Exercise is generally the preferred stressor because it provides additional information concerning the functional capacity of the patient. The Duke treadmill score (DTS) is commonly used as a risk prediction tool, and has been shown to be a reliable risk index across a large spectrum of patient populations (Table 4-3). Those patients

Note: d TS = (exercise duration in minutes) – 5×(maximal ST deviation in mm) – 4×(treadmill angina

score). Treadmill angina scored as 0 (no angina during testing), 1 (non limiting angina during testing),

or 2 (exercise- limiting angina during testing). (Adapted from Mark DB, Shaw L, Harrell FE Jr,

et al. N Engl J Med. 1991;325(12):849–853.)

with a high-risk score may benefit from invasive assessment to identify lesions that should be revascularized, such as significant left main disease or highly stenotic proximal left anterior descending disease.

Optimal Medical Therapy Versus Revascularization

According to data from several randomized clinical trials, optimal medical therapy is as efficacious as PCI plus optimal medical therapy in reducing the risk of nonfatal myocardial infarction, other cardiovascular events, and death in patients with stable ischemic heart disease. Optimal medical therapy alone is therefore considered an effective initial management strategy barring any evidence of high risk based on clinical features and results from noninvasive stress testing (Figure 4-2).

Figure 4-2. Algorithm for the management of stable coronary artery disease (ACS, acute coronary syndrome; ECG, electrocardiogram; OMT, optimal medical therapy ).

CASE CORRELATION

• See also Case 1 (acute coronary syndrome/STEMI) and Case 2 (acute coronary syndrome/NSTEMI).

COMPREHENSION QUESTIONS

Match the following intervention or diagnostic study (A–D) to the clinical situation (questions 4.1 through 4.3):

A. Refer for coronary angiography

B. Perform exercise ECG stress testing

C. Perform exercise stress testing in conjunction with echocardiography or nuclear perfusion imaging

D. Refer or coronary artery bypass surgery

4.1 A 65-year-old physically active woman with stable angina and a normal resting

ECG is establishing care with a new provider.

4.2 A 78-year-old man recently underwent exercise ECG stress testing and was found to be at high risk on the basis of the reported Duke treadmill score.

4.3 A 55-year-old man with coronary artery disease, hypertension, and hyperlipidemia seeks medical attention because of stable exertional chest pain. His electrocardiogram demonstrates left ventricular hypertrophy with repolarization abnormality, and he is able to exercise.

4.4 Which of the following statements regarding stable coronary artery disease is most accurate?

A. Percutaneous coronary intervention is associated with improved survival compared with optimal medical therapy in patients with stable angina.

B. Ranolazine therapy is associated with a decreased risk for myocardial infarction in patients with stable angina.

C. All patients with abnormal stress test results should be referred for coronary angiography to assess for obstructive epicardial coronary disease.

D. Beta-blockers, calcium channel antagonists, and nitrates are considered first-line antianginal medications.

E. The elements that constitute the Duke treadmill score (DTS) include exercise duration, degree of ST segment deviation, and the number of abnormal left ventricular segments seen on myocardial imaging.

ANSWERS

4.1 B. The patient is able to exercise and has an interpretable resting ECG, and should undergo exercise stress testing to determine her risk for future adverse events.

4.2 A. Coronary angiography should be performed to determine whether there are high-risk coronary artery stenoses, such as significant obstruction of the left main coronary artery.

4.3 C. This patient should undergo noninvasive stress testing for risk assessment, but because the resting ECG will complicate interpretation of the stress test, echocardiography or nuclear perfusion imaging should be utilized in conjunction. Importantly, exercise should be utilized as a stressor whenever possible because of the additional prognostic information that it provides.

4.4 D. Beta-blockers, calcium channel antagonists, and nitrates are all considered first-line agents for the treatment of angina. Survival is unaffected by PCI in patients with stable angina who are treated with appropriate medical therapy, although survival is improved by PCI in subjects with acute coronary syndromes. Ranolazine is a second-line agent for the treatment of angina, and its use is not associated with any improvement in death rate or the risk for infarction. Coronary angiography is not immediately indicated in patients with stable angina and abnormal, low-risk stress test findings. The Duke treadmill score is based on exercise duration, degree of ST segment deviation, and the presence or absence of symptoms.

CLINICAL PEARLS

C Optimal medical therapy alone is an accepted initial management strategy in chronic stable angina without high-risk features on noninvasive testing.

C Exercise ECG stress testing is the preferred testing modality if the resting ECG is interpretable an the patient is able to exercise.

C Optimal medical therapy alone is an accepted initial management strategy in chronic stable angina without high-risk features on noninvasive testing.

C Exercise ECG stress testing is the preferred testing modality if the resting ECG is interpretable and the patient is able to exercise.

C Evaluate the patient with stable angina for signs and symptoms of left ventricular dysfunction, as this may suggest the presence of a high-risk epicardial coronary artery obstruction.

C Titrate beta-blockers, nitrates. and calcium channel antagonists to the maximally tolerated dosages to alleviate anginal symptoms during exertion.

References

Boden WE, O’Rourke RA, Teo KK, et al. Optimal medical therapy with or without PCI or stable coronary disease. N Engl J Med. 2007;356:1503. 

Fihn SD, Gardin JM, Abrams J, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline or the diagnosis and management o patients with stable ischemic heart disease: A report o the American College o Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, and the American College o Physicians, American Association or Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society or Cardiovascular Angiography and Interventions, and Society o Thoracic Surgeons. J Am Coll Cardiol. 2012;60:e44–e164.

HomeCase FilesChronic Stable Coronary Artery Disease Case File