The American body of Cardiology (A...

The American body of Cardiology (ACC)/American Heart Association (AHA) Task Force forward Practice Guidelines in conjunction with the American Society for Nuclear Cardiology (ASNC) newly published a joint executive summary of approveed indications for the use of specific nuclear cardiologic techniques in three broad areas: acute ischemic syndrome chronic syndrome and heart failure. The recommendations appeared in the September 16 2003 issue of Circulation (http://circ.ahajournals.org/cgi/content/full/108/11/1404) and the well stocked [i]or[/i] provided text also can be plant online at http:// www.acc.org, http://www.americanheart.org, and http:// www.asnc.org.

ACC/AHA Classifications

The ACC/AHA classifications are defined as follows:

* Class I: Conditions for which there is evidence and/or general agreement that a given process or treatment is useful and effective.

* Class II: Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness or efficacy of a conduct or treatment.

* Class IIa: Weight of evidence/opinion is in favor of usefulness or efficacy.

* Class IIb: Usefulness or efficacy is les well established by means of evidence/opinion.

* Class III: Conditions for which there is evidence and/or general agreement that the operation or treatment is not useful or effective and in one cases may be harmful.

Acute Syndromes

Patients who not past nor future to the emergency department with chest pain should be placed in risk categories based onward their probability of acute myocardial infarction, unstable angina, or one as well as the other After initial examination of symptoms, electrocardiogram (ECG) and history, repose single-photon emission computed tomography (SPECT) imaging appears to be useful for identifying patients at high risk (those with perfusion lacks who should be admitted) and patients at depressed risk (those with normal scans who, generally, may be discharged). Whether exercise stres imaging for negative resting scans is indicated the same day or at a later date is still beneath investigation.

When conventional measures do not provide a diagnosis, repose myocardial perfusion imaging with technetium Tc 99m tracers has a high sensitivity for the diagnosis of acute myocardial infarction. However, perfusion destitutions do not distinguish among acute ischemia, acute infarction, or previous infarction.

Radionuclide techniques also are useful for determining the carriage and extent of stress-induced myocardial ischemia. Important prognostic management information can be acquired from the acute or late measurement of ejection fraction, infarct size, and myocardium at risk. For patients with several high-risk factors for unstable angina and ST-elevation myocardial infarction and no serious comorbidities, an early invasive strategy is recommended

Chronic Syndromes

Myocardial perfusion imaging is most numerous useful in patients with an intermediate likelihood of angiographically significant coronary artery disease (CAD) based onward age, sex, risk factors, symptoms, and inferences of stress testing, if available.

In the management of known or suspected chronic CAD, nuclear proofs are most useful for determining risk stratification in patients with a clinically intermediate risk of a later cardiac event. Factors that estimate the expanse of left ventricular dysfunction are the best predictors of cardiac mortality, and markers of provocative ischemia are estimable predictors of the subsequent progress to maturity of acute ischemic syndromes.

The following recommendations apply to patients with chronic syndromes:

* Cardiac stres myocardial perfusion SPECT in patients able to exercise: recommendations for diagnosis of patients with an intermediate likelihood of CAD and/or risk stratification of patients with an intermediate or high likelihood of CAD who are able to exercise to at least 85 percent of maximal predicted heart rate.

CLASS I

1 Exercise myocardial perfusion SPECT to identify the expansion severity, and location of ischemia in patients who do not have left pack branch block or an electronically paced ventricular rhyme but do have a baseline ECG abnormality that interferes with the interpretation of exercise-induced ST-segment changes (eg ventricular pre-excitation, left ventricular hypertrophy digoxin therapy, more than 1-mm ST depression).

2 Adenosine or dipyridamole myocardial perfusion SPECT in patients with left bundle up branch block or electronically paced ventricular rhythm

3 Exercise myocardial perfusion SPECT to assess the functional significance of intermediate (25 to 75 percent) coronary lesions.

4 Exercise myocardial perfusion SPECT in patients with intermediate Duke treadmill score.

5 Repeat exercise myocardial perfusion imaging after initial perfusion imaging in patients whose symptoms have changed to redefine the risk for cardiac event

CLASS IIA

1 Exercise myocardial perfusion SPECT at three to five years after revascularization (i.e., percutaneous coronary intervention or coronary artery bypass graft) in pitch uponed high-risk asymptomatic patients.