ACC/AHA/ASNC Guidelines for the Clinical Use of Cardiac Radionuclide Imaging—Executive Summary
2003; Lippincott Williams & Wilkins; Volume: 108; Issue: 11 Linguagem: Inglês
10.1161/01.cir.0000080946.42225.4d
ISSN1524-4539
AutoresFrancis J. Klocke, Michael G. Baird, Beverly H. Lorell, Timothy M. Bateman, Joseph V. Messer, Daniel S. Berman, Patrick T. O’Gara, Blasé A. Carabello, Richard O. Russell, Manuel D. Cerqueira, Martin G. St. John Sutton, Anthony N. DeMaria, James E. Udelson, John W. Kennedy, Mario S. Verani, Kim A. Williams, Elliott M. Antman, Sidney C. Smith, Joseph S. Alpert, Gabriel Gregoratos, Jeffrey L. Anderson, Loren F. Hiratzka, David P. Faxon, Sharon A. Hunt, Valentı́n Fuster, Alice K. Jacobs, Raymond J. Gibbons, Richard O. Russell,
Tópico(s)Radiation Dose and Imaging
ResumoHomeCirculationVol. 108, No. 11ACC/AHA/ASNC Guidelines for the Clinical Use of Cardiac Radionuclide Imaging—Executive Summary Free AccessReview ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessReview ArticlePDF/EPUBACC/AHA/ASNC Guidelines for the Clinical Use of Cardiac Radionuclide Imaging—Executive SummaryA Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASNC Committee to Revise the 1995 Guidelines for the Clinical Use of Cardiac Radionuclide Imaging) Committee Members Francis J. Klocke, Michael G. Baird, Beverly H. Lorell, Timothy M. Bateman, Joseph V. Messer, Daniel S. Berman, Patrick T. O'Gara, Blase A. Carabello, Richard O. RussellJr, Manuel D. Cerqueira, Martin G. St. John Sutton, Anthony N. DeMaria, James E. Udelson, J. Ward Kennedy, Mario S. Verani, Kim Allan Williams, Elliott M. Antman, Sidney C. SmithJr, Joseph S. Alpert, Gabriel Gregoratos, Jeffrey L. Anderson, Loren F. Hiratzka, David P. Faxon, Sharon Ann Hunt, Valentin Fuster, Alice K. Jacobs, Raymond J. Gibbons and Richard O. Russell Committee Members , Francis J. KlockeFrancis J. Klocke , Michael G. BairdMichael G. Baird , Beverly H. LorellBeverly H. Lorell , Timothy M. BatemanTimothy M. Bateman , Joseph V. MesserJoseph V. Messer , Daniel S. BermanDaniel S. Berman , Patrick T. O'GaraPatrick T. O'Gara , Blase A. CarabelloBlase A. Carabello , Richard O. RussellJrRichard O. RussellJr , Manuel D. CerqueiraManuel D. Cerqueira , Martin G. St. John SuttonMartin G. St. John Sutton , Anthony N. DeMariaAnthony N. DeMaria , James E. UdelsonJames E. Udelson , J. Ward KennedyJ. Ward Kennedy , Mario S. VeraniMario S. Verani , Kim Allan WilliamsKim Allan Williams , Elliott M. AntmanElliott M. Antman , Sidney C. SmithJrSidney C. SmithJr , Joseph S. AlpertJoseph S. Alpert , Gabriel GregoratosGabriel Gregoratos , Jeffrey L. AndersonJeffrey L. Anderson , Loren F. HiratzkaLoren F. Hiratzka , David P. FaxonDavid P. Faxon , Sharon Ann HuntSharon Ann Hunt , Valentin FusterValentin Fuster , Alice K. JacobsAlice K. Jacobs , Raymond J. GibbonsRaymond J. Gibbons and Richard O. RussellRichard O. Russell Originally published16 Sep 2003https://doi.org/10.1161/01.CIR.0000080946.42225.4DCirculation. 2003;108:1404–1418I. Introduction 1405II. Acute Syndromes 1406 A. Myocardial Perfusion Imaging in the Assessment of Patients Presenting With Chest Pain to the Emergency Department 1406 B. Detection of AMI When Conventional Measures Are Nondiagnostic 1406 C. Radionuclide Testing in Risk Assessment: Prognosis and Assessment of Therapy After STEMI 1406D. Radionuclide Testing in Risk Assessment: Prognosis and Assessment of Therapy After NSTEMI or UA 1406III. Chronic Syndromes 1407 A. Detection (Diagnosis) of CAD 1407 Sensitivity and Specificity 1407 Effect of Referral Bias 1407 Quantitative Analysis 1408 ECG-Gated SPECT 1408 Attenuation Correction 1408 Positron Emission Tomography 1408 B. Management of Patients With Known or Suspected Chronic CAD: Assessment of Disease Severity, Risk Stratification, Prognosis 1408 Nongated Myocardial Perfusion Imaging 1408 Gated SPECT 1408 Radionuclide Angiography 1408 Cost Effectiveness 1408 Frequency of Testing 1408 Evaluation of the Effects of Medical Therapy 1408 C. Specific Patient Populations 1408 African Americans 1408 Women 1408 Normal Resting ECG, Able to Exercise 1409 Intermediate-Risk Duke Treadmill Score 1409 Normal Resting ECG, Unable to Exercise 1409 LBBB/Pacemakers 1409 Left Ventricular Hypertrophy 1409 Patients With Nonspecific ST-T-Wave Changes 1409 Elderly 1409 Asymptomatic Patients 1409 Obese Patients 1409 Diabetes 1409 After Coronary Calcium Screening 1410 Before and After Revascularization 1410 Radionuclide Imaging Before Noncardiac Surgery 1410 D. Recommendations 1410IV. Heart Failure 1412 A. Introduction 1412 B. Assessment of LV Function 1413 Assessment of LV Systolic Dysfunction 1413 Assessment of LV Diastolic Dysfunction 1413 C. Assessment of CAD 1413 Importance of Detecting CAD in Heart Failure Patients 1413 Myocardial Perfusion Imaging to Detect CAD in Heart Failure Patients 1413 D. Assessment of Myocardial Viability 1413 Goals of Assessing Myocardial Viability 1413 General Principles of Assessing Myocardial Viability by Radionuclide Techniques 1414 Techniques and Protocols for Assessing Myocardial Viability 1414 Image Interpretation for Myocardial Viability: Quantitative Versus Visual Analysis of Tracer Activities 1414 Comparison of Techniques 1414 E. Etiologies of Heart Failure 1415 Dilated Cardiomyopathy 1415 Dilated Cardiomyopathy Due to Doxorubicin/Anthracycline Cardiotoxicity 1415 Dilated Cardiomyopathy Due to Myocarditis 1415 Posttransplantation Rejection and Allograft Vasculopathy 1415 Chagas Myocarditis and/or Cardiomyopathy 1416 Sarcoid Heart Disease 1416 Cardiac Amyloidosis 1416 RV Dysplasia 1416 Hypertrophic Cardiomyopathy 1416 Hypertensive Heart Disease 1416 Valvular Heart Disease 1416 Adults With Congenital Heart Disease 1417 References 1417I. IntroductionThe American College of Cardiology (ACC)/American Heart Association (AHA) Task Force on Practice Guidelines regularly reviews existing guidelines to determine when an update or full revision is needed. Guidelines for the Clinical Use of Cardiac Radionuclide Imaging were originally published in 1986 and updated in 1995. Important new developments have continued to occur since 1995, particularly in the areas of acute and chronic ischemic syndromes and heart failure. The Task Force therefore believed the topic should be revisited de novo and invited the American Society for Nuclear Cardiology (ASNC) to cosponsor the undertaking, which represents a joint effort of the 3 organizations.The full-text guideline is available on the Internet (www.acc.org, www.americanheart.org, and www.asnc.org). It discusses the usefulness of nuclear cardiological techniques in 3 broad areas: acute ischemic syndromes, chronic syndromes, and heart failure. Utility is considered for diagnosis, severity of disease/risk assessment/prognosis, and assessment of therapy. An appendix provides descriptions of individual techniques. This Executive Summary includes recommended indications for the use of specific techniques and summary evaluations of topics addressed in the full-text document. Additional supporting evidence and a complete reference list are presented in the full-text document.The current guideline overlaps with several previously published ACC/AHA guidelines for patient treatment that potentially involve cardiac radionuclide imaging. These include published guidelines for chronic stable angina (SA; 2002), unstable angina and non–ST-elevation myocardial infarction (UA/NSTEMI; 2002), heart failure (2001), perioperative cardiovascular evaluation for noncardiac surgery (2002), exercise testing (2002), valvular heart disease (1998), and acute myocardial infarction (AMI; 1999). The present report is not intended to include information previously covered in these guidelines or to provide a comprehensive treatment of the topics addressed in these guidelines.The ACC/AHA classifications I, II, and III are used to summarize indications as follows:Class I: Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effectiveClass II: Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment IIa: Weight of evidence/opinion is in favor of usefulness/efficacy IIb: Usefulness/efficacy is less well established by evidence/opinionClass III: Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and in some cases may be harmfulLevels of evidence for individual class assignments are designated as follows:A: Data derived from multiple randomized clinical trialsB: Data derived from a single randomized trial or from nonrandomized studiesC: Consensus opinion of expertsThese guidelines will be reviewed annually by the Task Force and will be considered current unless the Task Force revises or withdraws them from distribution.II. Acute SyndromesA. Myocardial Perfusion Imaging in the Assessment of Patients Presenting With Chest Pain to the Emergency DepartmentOptimal decision-making in patients seen in the emergency department with chest pain requires triage into risk categories on the basis of the probability of AMI, UA, or both and the subsequent risk and potential interventional options. Within such an algorithm, radionuclide imaging provides clinically useful information for diagnosis and management. The UA guidelines use 4 risk levels for chest pain: noncardiac, chronic SA, possible acute coronary syndrome (ACS), and definite ACS (http://www.acc.org/clinical/guidelines/unstable/unstable.pdf).1 Radionuclide imaging is most appropriate in patients with possible ACS. After initial triage on the basis of symptoms, ECG, and history, rest single-photon emission CT (SPECT) imaging appears to be useful for identifying patients at high risk (those with perfusion defects), who should be admitted, and patients with low risk (those with normal scans), who in general may be discharged home with a low risk for subsequent ischemic events. Randomized clinical trials2,3 now support several observational studies (see Table 1 in the full-text guideline) indicating a high negative predictive value for excluding ACS. Table 1 lists recommendations for emergency department imaging for suspected ACS. TABLE 1. Recommendations for Emergency Department Imaging for Suspected ACSIndicationTestClassLevel of EvidenceSee Figure 6 of ACC/AHA 2002 Guideline Update for the Management of Patients With Unstable Angina and Non–ST-Segment Elevation Myocardial Infarction at http://www.acc.org/clinical/guidelines/unstable/incorporated/figure6.htm and Figure 1 of ACC/AHA Guidelines for the Management of Patients with Acute Myocardial Infarction at www.acc.org/clinical/guidelines/nov96/1999/jac1716f01.htm.ACS indicates acute coronary syndromes; CAD, coronary artery disease; ECG, electrocardiogram; MPI, myocardial perfusion imaging.1. Assessment of myocardial risk in possible ACS patients with nondiagnostic ECG and initial serum markers and enzymes, if available.Rest MPIIA2. Diagnosis of CAD in possible ACS patients with chest pain with nondiagnostic ECG and negative serum markers and enzymes or normal resting scan.Same day rest/stress perfusion imagingIB3. Routine imaging of patients with myocardial ischemia/necrosis already documented clinically, by ECG and/or serum markers or enzymesRest MPIIIICB. Detection of AMI When Conventional Measures Are NondiagnosticRest myocardial perfusion imaging with 99mTc tracers has a high sensitivity for diagnosing AMI. Because there is minimal redistribution of the radiopharmaceutical over time, imaging can be delayed for a few hours after the injection and still provide accurate information about myocardial perfusion at the time of injection, which reflects the area of myocardium at risk. Perfusion defects, however, do not distinguish among acute ischemia, acute infarction, or previous infarction.C. Radionuclide Testing in Risk Assessment: Prognosis and Assessment of Therapy After STEMIAs discussed in the ACC/AHA Guidelines for the Management of Patients with Acute Myocardial Infarction: 1999 Update4 (http://www.acc.org/clinical/guidelines/nov96/1999/index.htm), the prognosis of STEMI is primarily a function of ejection fraction (EF), infarct size, and residual myocardium at risk. Thus, acute or late measurement of EF, infarct size, and myocardium at risk provides important prognostic management information. Radionuclide techniques are also useful for assessing the presence and extent of stress-induced myocardial ischemia—information that is useful for immediate and long-term patient management.5–9Table 2 lists recommendations for radionuclide testing in diagnosis, risk assessment, prognosis, and assessment of therapy after acute STEMI. TABLE 2. Recommendations for Use of Radionuclide Testing in Diagnosis, Risk Assessment, Prognosis, and Assessment of Therapy After Acute STEMIPatient Subgroup(s)IndicationTestClassLevel of EvidenceECG indicates electrocardiography; FPRNA, first-pass radionuclide angiography; LV, left ventricular; MPI, myocardial perfusion imaging; RNA, radionuclide angiography; RV, right ventricular; SPECT, single-photon emission computed tomography; STEMI, ST-segment elevation myocardial infarction.All1. Rest LV functionRest RNA or ECG-gated SPECTIBThrombolytic therapy without catheterization2. Detection of inducible ischemia and myocardium at riskStress MPI with ECG-gated SPECT whenever possibleIBAcute STEMI3. Assessment of infarct size and residual viable myocardiumMPI at rest or with stress using gated SPECTIB4. Assessment of RV function with suspected RV infarctionEquilibrium or FPRNAIIaBD. Radionuclide Testing in Risk Assessment: Prognosis and Assessment of Therapy After NSTEMI or UAThe ACC/AHA 2002 Guideline Update for the Management of Patients with UA/NSTEMI1 recommends an early invasive strategy in patients with any of several high-risk indicators and no serious comorbidities. High-risk findings on noninvasive stress testing (eg, myocardial perfusion imaging) are one such indication. In the absence of high-risk findings, the guidelines endorse either an early conservative or early invasive strategy in patients without contraindications for revascularization. Myocardial perfusion imaging is particularly useful in the predischarge risk stratification of patients with UA. The presence and extent of reversible perfusion defects on stress testing after the patient is stabilized are highly predictive of future events.10–14Table 3 lists recommendations for radionuclide testing for risk assessment/prognosis in patients with NSTEMI or UA. TABLE 3. Recommendations for Use of Radionuclide Testing for Risk Assessment/Prognosis in Patients With NSTEMI and UAIndicationTestClassLevel of EvidenceECG indicates electrocardiography; LV, left ventricular; MPI, myocardial perfusion imaging; RNA, radionuclide angiography; SPECT, single-photon emission computed tomography.1. Identification of inducible ischemia in the distribution of the "culprit lesion" or in remote areas in patients at intermediate or low risk for major adverse cardiac events.Stress MPI with ECG gating whenever possibleIB2. Identification of the severity/extent of inducible ischemia in patients whose angina is satisfactorily stabilized with medical therapy or in whom diagnosis is uncertain.Stress MPI with ECG gating whenever possibleIA3. Identification of hemodynamic significance of coronary stenosis after coronary arteriography.Stress MPIIB4. Measurement of baseline LV function.RNA or gated SPECTIB5. Identification of the severity/extent of disease in patients with ongoing suspected ischemia symptoms when ECG changes are not diagnostic.Rest MPIIIaBIII. Chronic SyndromesA. Detection (Diagnosis) of Coronary Artery DiseaseA thorough discussion of the concepts of likelihood of coronary artery disease (CAD) is provided in the ACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina15 (http://www.acc.org/clinical/guidelines/stable/stable_clean.pdf), accompanied by a simplified table for estimating pretest probability ranges. Myocardial perfusion imaging is most useful in patients with an intermediate likelihood of angiographically significant CAD on the basis of age, sex, symptoms, risk factors, and the results of stress testing (for patients who have undergone prior stress testing).1. Sensitivity and SpecificityTables 5 and 6 in the full-text guideline summarize studies reporting sensitivities and specificities of exercise and vasodilator stress perfusion SPECT for the detection of angiographically significant (more than 50% stenosis) CAD. Sensitivities (generally uncorrected for referral bias) average 87% and 89%, respectively; specificities (also uncorrected) average 73% and 75%. TABLE 5. Recommendations for the Use of Radionuclide Techniques to Assess Myocardial ViabilityIndicationTestClassLevel of EvidenceFDG indicates flurodeoxyglucose; PET, positron emission tomography; RNA, radionuclide angiography; SPECT, single-photon emission computed tomography; 201Tl, thallium-201.1. Predicting improvement in regional and global LV function after revascularizationStress/redistribution/reinjection 201TlIBRest-redistribution imagingIBPerfusion plus PET FDG imagingIBResting sestamibi imagingIBGated SPECT sestamibi imagingIIaBLate 201Tl redistribution imaging (after stress)IIbBDobutamine RNAIIbCPostexercise RNAIIbCPostnitroglycerin RNAIIbC2. Predicting improvement in heart failure symptoms after revascularization.Perfusion plus PET FDG imagingIIaB3. Predicting improvement in natural history after revascularization201Tl imaging (rest-redistribution and stress/redistribution/reinjection)IBPerfusion plus PET FDG imagingIBTABLE 6. Recommendations for the Use of Radionuclide Imaging to Diagnose Specific Causes of Dilated CardiomyopathyIndicationTestClassLevel of Evidence67Ga indicates gallium-67; 99mTc-pyrophosphate, Tc-99m-pyrophosphate; 111In, indium-111; CAD, coronary artery disease; LV, left ventricular; RNA, radionuclide angiography; RV, right ventricular.1. Baseline and serial monitoring of LV function during therapy with cardiotoxic drugs (eg, doxorubicin)Rest RNAIA2. RV dysplasiaRest RNAIIaB3. Assessment of posttransplant obstructive CADExercise perfusion imagingIIbB4. Diagnosis and serial monitoring of Chagas diseaseExercise perfusion imagingIIbB5. Diagnosis of amyloid heart disease99mTc-pyrophosphate imagingIIbB6. Diagnosis and serial monitoring of sarcoidRest perfusion imagingIIbBheart diseaseRest 67Ga imagingIIbB7. Detection of myocarditisRest 67Ga imagingIIbB111In antimyosin antibody imagingIIbC2. Effect of Referral BiasIn estimating the true sensitivity and specificity of noninvasive testing, referral or work-up bias needs to be taken into account. Table 7 in the full-text guideline summarizes studies in which effects of referral bias have been estimated. Because of the profound impact of referral bias on specificity, the concept of the normalcy rate has been developed. The term normalcy rate is used to describe the frequency of normal test results in patients with a low likelihood of CAD, to differentiate it from specificity. TABLE 7. Recommendations for the Use of Radionuclide Imaging to Evaluate Hypertrophic Heart DiseaseIndicationTestClassLevel of EvidenceCAD indicates coronary artery disease; RNA, radionuclide angiography.1. Diagnosis of CAD in hypertrophic cardiomyopathyRest and exercise perfusion imagingIIbB2. Diagnosis and serial monitoring of hypertensive hypertrophic heart diseaseRest RNAIIbB3. Diagnosis and serial monitoring of hypertrophic cardiomyopathy, with and without outflow obstructionRest RNAIIIB3. Quantitative AnalysisQuantitative analysis of myocardial perfusion SPECT has been developed using a variety of approaches and, in general, has similar sensitivities and specificities compared with those of expert visual analysis.4. ECG-Gated SPECTThe current state of the art is ECG-gated myocardial perfusion SPECT (gated SPECT). The ability to observe myocardial contraction in segments with apparent fixed perfusion defects permits the nuclear test reader to discern attenuation artifacts from true perfusion abnormalities. The ability of gated SPECT to provide measurement of left ventricular (LV) EF (LVEF), segmental wall motion, and absolute LV volumes also adds to the prognostic information that can be derived from a SPECT study.5. Attenuation CorrectionThe field of attenuation correction continues to evolve rapidly, with some available systems having undergone more detailed and successful clinical validation than others. On the basis of current information and the rate of technology improvement, the Society of Nuclear Medicine and the American Society of Nuclear Cardiology have concluded that attenuation correction has become a method for which the weight of evidence/opinion is in favor of its usefulness.166. Positron Emission TomographyStudies involving several hundred patients (see Table 10 in the full-text guideline) indicate that perfusion imaging with positron emission tomography (PET) using dipyridamole and either 82Rb or 13N ammonia is also a sensitive and specific clinical means to diagnose CAD.B. Management of Patients With Known or Suspected Chronic CAD: Assessment of Disease Severity, Risk Stratification, PrognosisNuclear tests are best applied for risk stratification in patients with a clinically intermediate risk of a subsequent cardiac event, analogous to the optimal diagnostic application of nuclear testing to patients with an intermediate likelihood of having CAD. Many of the major determinants of prognosis in CAD can be assessed by measurements of stress-induced perfusion and function. Studies including large patient samples have now demonstrated that factors estimating the extent of LV dysfunction (LVEF, the extent of infarcted myocardium, transient ischemic dilation of the LV, and increased lung uptake) are excellent predictors of cardiac mortality. In contrast, markers of provocative ischemia (exertional symptoms, electrocardiographic changes, the extent of reversible perfusion defects, and stress-induced ventricular dyssynergy) are better predictors of the subsequent development of acute ischemic syndromes.171. Nongated Myocardial Perfusion ImagingNot withstanding the now well-demonstrated advantages of gated imaging, nongated perfusion scintigraphy has played a major role in risk stratification of CAD patients. The full-text guideline summarizes studies of stress myocardial perfusion imaging in definite or suspected CAD (see Table 12 in the full-text guideline). Normal stress perfusion SPECT results are consistently predictive of a less than 1% annual risk of cardiac death or myocardial infarction.2. Gated SPECTThe information contained in the combined assessment of perfusion and function with gated myocardial perfusion SPECT is likely to enhance its prognostic and diagnostic content. The most common current approach combines poststress and/or rest LV function by gated SPECT with rest/stress perfusion measurements.3. Radionuclide AngiographyRest LVEF is universally recognized as one of the most important determinants of long-term prognosis in patients with chronic stable CAD. Radionuclide angiography (RNA) can also be helpful in evaluating dyspnea by establishing the state of right ventricular (RV) and LV performance. LV function during exercise reflects disease severity and provides prognostic information.4. Cost EffectivenessAs indicated in the ACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina,15 cardiac imaging can serve as a gatekeeper to cardiac catheterization to minimize the rate of normal catheterizations and to enrich the angiographic population with a greater proportion of patients with significant, yet treatable, disease.5. Frequency of TestingConsiderations for follow-up testing are also summarized in the ACC/AHA 2002 Guideline Update for the Management of Patients With Chronic Stable Angina.15 If patients develop new signs or symptoms suggesting a worsened clinical state, repeat testing at the time of worsening would be appropriate. In the absence of a change in clinical state, the estimated patient risk after initial testing (high, intermediate, or low, as defined earlier) should play an important role in individual recommendations.186. Evaluation of the Effects of Medical TherapyAlthough the available evidence suggests that the efficacy of therapy can be assessed with repeat SPECT procedures while the patient is under the effects of the medical treatment, information about the effects of medical therapy on outcomes is limited.C. Specific Patient Populations1. African AmericansThe role of noninvasive imaging has been studied infrequently in African Americans or other minorities. Normal rest and stress SPECT perfusion studies have been associated with higher rates of AMI and/or cardiac death in African Americans than in other populations,19,20 but included higher than usual cardiac risk patients and did not account for the incidence of LV hypertrophy (LVH).212. WomenAs discussed in the ACC/AHA 2002 Guideline Update for Exercise Testing22 (http://www.acc.org/clinical/guidelines/exercise/exercise_clean.pdf), the use of radionuclide testing in women is influenced importantly by the later presentation of CAD in women than in men and by sex-related limitations in exercise stress testing. These issues have provoked interest in the potential additive benefit of stress perfusion imaging in women, particularly those with at least an intermediate likelihood of coronary disease.23–263. Normal Resting ECG, Able to ExercisePatients with a normal resting ECG constitute a large and important subgroup. Most patients who present with multiple risk factors with or without cardiac symptoms have a normal resting ECG. Such patients are likely to have normal LV function and an excellent prognosis. For these reasons, a stepwise strategy is generally recommended in which an exercise ECG, and not a stress imaging procedure, is performed as the initial test in patients with an intermediate pretest likelihood of CAD who are not taking digoxin, have a normal resting ECG, and are able to exercise. A stress imaging technique should be used for patients with widespread rest ST depression (more than 1 mm), complete left bundle-branch block (LBBB), ventricular-paced rhythm, pre-excitation, or LVH with repolarization changes.154. Intermediate-Risk Duke Treadmill ScoreThe Duke treadmill score combines various forms of information from stress testing and provides a simple way to calculate risk.27 Annual mortality rates according to risk groups are presented in the ACC/AHA 2002 Chronic Stable Angina Guideline Update.15 The score has been reported to work well for both inpatients and outpatients and equally well for men and women. Only a small number of elderly patients, however, have been studied. Several studies have demonstrated value of myocardial perfusion scintigraphy in further risk assessment of patients with an intermediate score associated with an intermediate risk of cardiac death.28–305. Normal Resting ECG, Unable to ExerciseIn patients with an intermediate to high likelihood of CAD who have a normal resting ECG but are unable to exercise, pharmacologic myocardial perfusion SPECT with adenosine or dipyridamole has been shown to be highly effective in diagnosis and risk stratification.6. LBBB/PacemakersPharmacologic stress perfusion imaging is preferable to exercise perfusion imaging for purposes of both diagnosis and risk stratification.31,32 Several studies have observed an increased prevalence of myocardial perfusion defects during exercise imaging, in the absence of angiographic coronary disease, in patients with LBBB. Given that ECG testing is nondiagnostic in patients with ventricular pacing in a manner similar to that observed with LBBB, it is likely that the considerations with regard to the use of radionuclide techniques for diagnostic and risk stratification purposes in patients with ventricular pacemakers are the same as those applied to patients with LBBB.7. Left Ventricular HypertrophyIn patients with LVH, with or without resting ST-segment abnormality, ST depression during exercise is frequently present in the absence of significant CAD. In these patients, stress nuclear techniques have similar diagnostic sensitivity and specificity to those observed in patients without LVH. The diagnostic value of myocardial perfusion SPECT is not generally degraded by the presence of hypertension without evidence of LVH,33 although an increased frequency of false-positive studies has been reported in athletes.34 Similarly, although the number of reports is small, the prognostic value of myocardial perfusion SPECT in patients with LVH appears to be equal to that observed in patients without LVH.358. Patients With Nonspecific ST-T-Wave ChangesPatients with nonspecific ST-T-wave changes, such as might occur with digoxin, Wolff-Parkinson-White syndrome (WPW), or other conditions, are considered to have nondiagnostic stress ECG responses with regard to ST-segment depression. Although there are limited data on the diagnostic and prognostic information for myocardial perfusion SPECT in these patients, those with intermediate to high likelihood of coronary disease can perhaps be effectively assessed for detection and risk stratification with myocardial perfusion SPECT.9. ElderlyPrognostic value of perfusion scintigraphy in elderly patients has been reported.3610. Asymptomatic PatientsThe relatively low prevalence of CAD and risk of future events will affect the performance of any diagnostic test in a manner predictable by Bayesian principles (ie, positive predictive value will usually be low). It is not clear that detecting asymptomatic preclinical CAD will lead to therapeutic intervention that will reduce risk beyond that indicated by risk factor profiling and currently recommended strategies to reduce risk.37Persons whose occupations may affect public safety (eg, airline pilots, truckers, bus drivers) or who are professional or high-profile athletes co
Referência(s)