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Braunwald E, Mark DB, Jones RH. Unstable Angina: Diagnosis and Management. Rockville (MD): Agency for Health Care Policy and Research (AHCPR); 1994 May. (AHCPR Clinical Practice Guidelines, No. 10.)

  • This publication is provided for historical reference only and the information may be out of date.

This publication is provided for historical reference only and the information may be out of date.

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Unstable Angina: Diagnosis and Management.

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3Guideline: Outpatient Care

Introduction

Patients with unstable angina who are judged in the initial evaluation and treatment phase to be at low risk for adverse outcomes can, in many cases, be safely evaluated further as outpatients. Typically, these are patients who have experienced new onset or worsening symptoms that may be due to ischemia, but they have not had severe, prolonged, or rest episodes in the preceding 2 weeks. Their followup evaluation should have been scheduled as soon as possible, generally 72 hours after the initial presentation. In addition, patients with symptoms suggestive of unstable angina whose presentations are not considered sufficiently urgent to require ED evaluation may be seen first in an outpatient facility. This chapter addresses care of patients presenting for initial evaluation as well as those patients who had initial evaluation in an ED (usually within the past 72 hours) and now present for more definitive evaluation of possible unstable angina (see Figure 6).

Figure 6: Patient flow: Outpatient care.

Figure

Figure 6: Patient flow: Outpatient care.

Objectives of Care

In patients without known CAD, the three goals of outpatient care are to assess further the cause of the patient's symptoms, evaluate the risk of future adverse cardiac events, and provide adequate symptom relief. In patients with known CAD, the primary concern is whether to intensify medical therapy or consider PTCA or CABG.

Approach to Care Objectives

Diagnostic Assessment

All patients should have a history, physical examination, and ECG. Initial evaluation for patients without prior ED evaluation should proceed as described for low-risk patients in Chapter 2. For patients returning for followup examination of a recent ED visit, the circumstances surrounding the initial presentation and any interval symptoms since the initial examination represent the important features of the history. Evidence of a worsening symptom pattern may necessitate hospital admission for control and further diagnostic workup. This repeat evaluation should also include a further search for factors that might precipitate or exacerbate unstable angina, such as fever, tachyarrhythmias, hyperthyroidism, severe anemia, cocaine use, noncompliance with medical therapy, environmental temperature extremes, severe psychosocial stress, and changes in the level of physical exertion or lifestyle.

Patients who develop pain during the clinic visit should have a careful cardiac examination during the episode (looking for a new S4 or S3, new or worsening MR murmur, rales) and an immediate ECG (looking for transient changes in the ST-segment or T-wave). A therapeutic trial with sublingual NTG can be attempted after these steps if the discomfort is still present. Repeat examination and an ECG should be performed once symptoms are completely resolved.

Risk Stratification and Further Management

Recommendation: Exercise or pharmacologic stress testing generally should be part of the detailed outpatient workup. However, patients found to have high-risk features (see Table 8), such as evidence of significant LV dysfunction, or an interval acceleration or worsening of symptoms while on appropriate levels of medical therapy, should be considered for direct referral to cardiac catheterization. In addition, patients who have symptoms felt very unlikely to be due to CAD or who are felt to be at very low risk for cardiac events can be managed conservatively, with stress testing reserved for recurrent or worsening symptoms (strength of evidence = C).

After detailed clinical assessment, the clinician will have formed an estimate of the likelihood of CAD (see Table 7) and will have made a clinical judgment of the risk of short-term adverse events (see Table 8). Patients found to have high-risk features, especially those with evidence of LV dysfunction or CHF, should be considered for prompt ICU admission for intensive medical care (see Chapter 4). Patients who have a low likelihood of CAD and are at low risk may benefit by further evaluation that may include a trial of nitrates and beta blockers. Use of noninvasive testing in this population should be delayed until the clinical presentation is more clear to avoid the anxiety and cost associated with the false-positive test common in this low-risk population. In general, all intermediate-risk patients and low-risk patients with an intermediate or high likelihood of CAD benefit from noninvasive testing. A more complete discussion of noninvasive testing in this patient group is included in Chapter 6.

Table 7. Likelihood of significant coronary artery disease in patients with symptoms suggesting unstable angina.

Table

Table 7. Likelihood of significant coronary artery disease in patients with symptoms suggesting unstable angina.

Outpatient Treatment of Symptoms

Recommendation: Patients should be instructed in the proper use of sublingual NTG tablets (strength of evidence = C).

Recommendation: Medical therapy for presumed CAD usually begins with sublingual NTG, followed by oral beta blockers. Long-acting topical or oral nitrates may be added, but care should be taken to use regimens that reduce the likelihood of tolerance. In general, for low-risk outpatients, therapy with ASA and one antianginal medication is sufficient initial treatment unless patients have additional indications for multiagent therapy (e.g., hypertension, supraventricular arrhythmia) (strength of evidence = C). Long-acting forms of antianginal drugs are preferable to enhance patient compliance (strength of evidence = C).

Recommendation: Patients with established CAD who are already on medical therapy should have their medical regimen reviewed and dosages increased as appropriate and as tolerated (strength of evidence = C).

Recommendation: Patients with established CAD or who are judged to be intermediate or high likelihood for CAD should be maintained on ASA at 160 to 324 mg per day unless contraindications are present (strength of evidence = A, evidence cited in Chapter 2). Patients unable to take ASA because of a history of true hypersensitivity or recent significant GI bleeding may be started on ticlopidine 250 mg twice per day as a substitute (strength of evidence = B, evidence cited in Chapter 4).

The symptomatic therapy of patients with low-risk unstable angina not requiring hospitalization involves the use of sublingual NTG for treatment of individual anginal episodes and prophylactic therapy with an agent from one of the three major classes of antianginal drugs (nitrates, beta blockers, calcium antagonists). In general, it is reasonable to start therapy with one major antianginal, preferably in a long-acting preparation, and proceed to a second agent only if there are recurrent symptoms on optimal doses of the first agent. In addition, ASA should be a standard part of each regimen. The details of these therapies and the evidence for their use are described in Chapter 4.

Recommendation: Patients who continue to report symptoms they consider to reflect cardiac disease and are not reassured that they do not have CAD by appropriate noninvasive tests, counseling, and rehabilitation may be candidates for cardiac catheterization to confirm the absence of CAD (strength of evidence = C).

Some patients who present with symptoms suggestive of unstable angina and are initially categorized as having low likelihood of CAD will continue to report symptoms suggestive of angina despite an antianginal regimen that appears appropriate. The medical provider should first review all diagnoses and management decisions and, if appropriate, obtain or repeat other noninvasive exercise or pharmacologic stress tests. Fear of heart disease or other psychological problems commonly underlies complaints of cardiovascular symptoms which are out of proportion to objective evidence of ischemia. Some patients benefit from more complete and frequent counseling and reassurance. This group of patients will often respond to cardiac rehabilitation in a structured environment with supervised exercise. A trial of simple measures is reasonable in this group of patients, but failure to respond may necessitate the decision to perform a cardiac catheterization with the intention of confirming the absence of coronary artery disease. If this is to be undertaken, patients must be informed of the reason for the procedure when they provide informed consent.

Some patients find sufficient reassurance with angiographic documentation of normal coronary arteries that their symptoms gradually dissipate. Patients who continue to have symptoms they consider to be angina despite normal coronary angiograms may have small-vessel or vasospastic coronary artery disease requiring further evaluation that is not covered by this guideline. Other patients with continued symptoms but no objective evidence of ischemia or CAD may benefit from evaluation and counseling by medical practitioners other than cardiovascular specialists.

Patient Counseling

Patients and their families and advocates should understand the most likely diagnosis at the conclusion of the outpatient evaluation. Discussion should deal directly with clinical and test results that predict risk and possible outcomes. Further evaluation and treatment options should be discussed. Patients should receive a clear explanation of the rationale for use of medicines and suggested dosages, as well as possible side effects from the doctor, nurse, or pharmacist. On return visits, patients should be asked about their reaction and compliance as well as perceived effectiveness of the treatment plan outlined on the prior visit. All patients should be counseled on risk-factor modification.

Medical Record

Information that should be updated or added to the medical record at the conclusion of outpatient management includes:

  • Age and sex.
  • Duration and nature of symptoms prior to presentation.
  • Previous history of CAD; if yes, prior noninvasive test result, cardiac catheterization result, and/or myocardial revascularization procedure (bypass or angioplasty).
  • Medication and drug use.
  • Risk factors (diabetes, smoking, hypercholesterolemia, hypertension).
  • Systemic causes for precipitating or exacerbating ischemia.
  • ECG interpretation.
  • Initial and final assignment of likelihood of CAD (high, intermediate, low) and basis.
  • Initial and final risk assignment (high, intermediate, low) and basis.
  • Summary of other pertinent positive and negative findings.
  • Patient counseling, including assessment of patient response.
  • Disposition for further care.
  • Results of ancillary clinical studies.
  • Final diagnosis.
  • Final disposition.
  • Effectiveness of antianginal medication used.

Duration of Outpatient Phase

Typically, the interval between initial presentation and initiation of comprehensive outpatient evaluation should be no more than 72 hours. Generally, one clinic visit should be sufficient to establish a working diagnosis, assess risk, and develop a management plan. Serial outpatient evaluation and noninvasive testing may be required depending on the patient's specific findings and response to treatment. Patients with specific indications may be referred for outpatient or inpatient cardiac catheterization.

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