2011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: Executive Summary

HomeCirculationVol. 124, No. 242011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: Executive Summary Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissionsDownload Articles + Supplements ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toSupplementary MaterialsFree AccessResearch ArticlePDF/EPUB2011 ACCF/AHA Guideline for the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: Executive SummaryA Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines Bernard J. Gersh, MB, ChB, DPhil, FACC, FAHA, Barry J. Maron, MD, FACC, Robert O. Bonow, MD, MACC, FAHA, Joseph A. Dearani, MD, FACC, Michael A. Fifer, MD, FACC, FAHA, Mark S. Link, MD, FACC, FHRS, Srihari S. Naidu, MD, FACC, FSCAI, Rick A. Nishimura, MD, FACC, FAHA, Steve R. Ommen, MD, FACC, FAHA, Harry Rakowski, MD, FACC, FASE, Christine E. Seidman, MD, FAHA, Jeffrey A. Towbin, MD, FACC, FAHA, James E. Udelson, MD, FACC, FASNC and Clyde W. Yancy, MD, FACC, FAHA Bernard J. GershBernard J. Gersh Appendix 1 , Barry J. MaronBarry J. Maron Appendix 1 , Robert O. BonowRobert O. Bonow , Joseph A. DearaniJoseph A. Dearani , Michael A. FiferMichael A. Fifer Appendix 1 , Mark S. LinkMark S. Link Appendix 1 , Srihari S. NaiduSrihari S. Naidu Appendix 1 , Rick A. NishimuraRick A. Nishimura , Steve R. OmmenSteve R. Ommen , Harry RakowskiHarry Rakowski , Christine E. SeidmanChristine E. Seidman , Jeffrey A. TowbinJeffrey A. Towbin , James E. UdelsonJames E. Udelson and Clyde W. YancyClyde W. Yancy Originally published8 Nov 2011https://doi.org/10.1161/CIR.0b013e318223e230Circulation. 2011;124:2761–2796Other version(s) of this articleYou are viewing the most recent version of this article. Previous versions: January 1, 2011: Previous Version 1 Table of ContentsPreamble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2763 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2765 1.1. Methodology and Evidence Review . . . . . . . .27651.2. Organization of the Writing Committee . . . . .27651.3. Document Review and Approval . . . . . . . . . .27651.4. Scope of the Guideline . . . . . . . . . . . . . . . . . .2765Recommendations for HCM. . . . . . . . . . . . . . . . . . .2766 2.1. Genetic Testing Strategies/Family Screening—Recommendations . . . . . . . . .2766 2.1.1. Genotype-Positive/Phenotype-Negative Patients—Recommendation . . . . . . . . .27662.2. Electrocardiography—Recommendations . . . .27662.3. Echocardiography—Recommendations . . . . . .27662.4. Stress Testing—Recommendations . . . . . . . . .27672.5. Cardiac Magnetic Resonance—Recommendations. . . . . . . . . . . . . . . . . . . . . .27672.6. Detection of Concomitant Coronary Disease—Recommendations . . . . . . . . . . . . . .27672.7. Asymptomatic Patients—Recommendations .27682.8. Pharmacologic Management—Recommendations . . . . . . . . . . . . . . . . . . . . . .27682.9. Invasive Therapies—Recommendations . . . . .27692.10. Pacing—Recommendations. . . . . . . . . . . . . . .27702.11. Patients With LV Systolic Dysfunction—Recommendations. . . . . . . . . . . . . . . . . . . . . .27702.12. Selection of Patients for Heart Transplantation—Recommendations . . . . . . . .27702.13. SCD Risk Stratification—Recommendations . . .27702.14. Selection of Patients for ICDs—Recommendations. . . . . . . . . . . . . . . . . . . . . .27712.15. Selection of ICD Device Type—Recommendations. . . . . . . . . . . . . . . . . . . . . .27722.16. Participation in Competitive or Recreational Sports and Physical Activity—Recommendations. . . . . . . . . . . . . . . . . . . . . .27722.17. Management of AF—Recommendations. . . . .27722.18. Pregnancy/Delivery—Recommendations. . . . .2773Prevalence/Nomenclature/Differential Diagnosis . .2773 3.1. Prevalence . . . . . . . . . . . . . . . . . . . . . . . . . . .2773 3.1.1. Clinical Definition and Differential Diagnosis . . . . . . . . . . . . . . . . . . . . . . .27733.1.2. Impact of Genetics . . . . . . . . . . . . . . . . . . . . .27743.1.3. HCM Centers . . . . . . . . . . . . . . . . . . . . . . . . .2774Clinical Course and Natural History, Including Absence of Complications . . . . . . . . . . . . . . . . . . . .2774Pathophysiology . . . . . . . . . . . . . . . . . . . . . . . . . . . .2775 5.1. LVOT Obstruction . . . . . . . . . . . . . . . . . . . . .2775Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2775 6.1. Cardiovascular Magnetic Resonance. . . . . . . .2776Concomitant Coronary Disease . . . . . . . . . . . . . . . .2777Choice of Imaging Modality . . . . . . . . . . . . . . . . . .2777 8.1. Invasive Coronary Arteriography . . . . . . . . . .27778.2. Noninvasive CTA. . . . . . . . . . . . . . . . . . . . . .27778.3. Single Photon Emission Computed Tomography Myocardial Perfusion Imaging . . . . .27778.4. Positron Emission Tomography . . . . . . . . . . .27778.5. Stress Echocardiography . . . . . . . . . . . . . . . . .2777Management of HCM. . . . . . . . . . . . . . . . . . . . . . . .2777 9.1. Asymptomatic Patients . . . . . . . . . . . . . . . . . .27779.2. Symptomatic Patients . . . . . . . . . . . . . . . . . . .27789.3. Invasive Therapies . . . . . . . . . . . . . . . . . . . . .2779 9.3.1. Selection of Patients. . . . . . . . . . . . . . .27799.3.2. Results of Invasive Therapy for the Relief of LVOT Obstruction . . . . . . . .27799.3.3. Operator Experience. . . . . . . . . . . . . . .27799.3.4. Surgical Therapy . . . . . . . . . . . . . . . . .2780 9.3.4.1. Outcomes . . . . . . . . . . . . . . . .27809.3.4.2. Complications. . . . . . . . . . . . .27809.3.4.3. Mitral Valve Abnormalities and Other Anatomic Issues. . . . .27809.3.5. Alcohol Septal Ablation. . . . . . . . . . . .2780 9.3.5.1. Selection of Patients. . . . . . . .27819.3.5.2. Results . . . . . . . . . . . . . . . . . .27819.3.5.3. Complications. . . . . . . . . . . . .27819.3.6. DDD Pacing. . . . . . . . . . . . . . . . . . . . .27819.3.7. LV Systolic Dysfunction . . . . . . . . . . .27829.4. Prevention of SCD . . . . . . . . . . . . . . . . . . . . .2782 9.4.1. Established Risk Markers. . . . . . . . . . .2782 9.4.1.1. Prior Personal History of Ventricular Fibrillation, SCD, or Sustained VT . . . . . .27829.4.1.2. Family History of SCD. . . . . .27829.4.1.3. Syncope . . . . . . . . . . . . . . . . .27829.4.1.4. Nonsustained Ventricular Tachycardia . . . . . . . . . . . . . .27829.4.1.5. Maximum LV Wall Thickness .27829.4.1.6. Abnormal Blood Pressure Response During Exercise . .27829.4.2. Other Potential SCD Risk Modifiers .2782 9.4.2.1. LVOT Obstruction . . . . . . . . .27829.4.2.2. LGE on CMR Imaging . . . . . .27829.4.2.3. LV Apical Aneurysm . . . . . . .27839.4.2.4. Genetic Mutations. . . . . . . . . .27839.4.3. Utility of SCD Risk Markers in Clinical Practice . . . . . . . . . . . . . . . . . .27839.5. ICD Therapy in HCM . . . . . . . . . . . . . . . . . .2783 9.5.1. Complications of ICD Therapy in HCM . . . . . . . . . . . . . . . . . . . . . . . .27839.6. Participation in Competitive or Recreational Sports and Physical Activity . . . . . . . . . . . . . .27849.7. Atrial Fibrillation . . . . . . . . . . . . . . . . . . . . . .2784Occupational Considerations . . . . . . . . . . . . . . . . . .2785References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2785Appendix 1. Author Relationships With Industry and Other Entities (Relevant). . . . . . . . . . . . . .2794Appendix 2. Reviewer Relationships With Industry and Other Entities (Relevant) . . . . . . . . . .2795Jacobs Alice K., MD, FACC, FAHAChair, ACCF/AHA Task Force on Practice GuidelinesPreambleIt is essential that the medical profession play a central role in critically evaluating the evidence related to drugs, devices, and procedures for the detection, management, or prevention of disease. Properly applied, rigorous, expert analysis of the available data documenting absolute and relative benefits and risks of these therapies and procedures can improve the effectiveness of care, optimize patient outcomes, and favorably affect the cost of care by focusing resources on the most effective strategies. One important use of such data is the production of clinical practice guidelines that, in turn, can provide a foundation for a variety of other applications such as performance measures, appropriateness use criteria, clinical decision support tools, and quality improvement tools.The American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA) have jointly engaged in the production of guidelines in the area of cardiovascular disease since 1980. The ACCF/AHA Task Force on Practice Guidelines (Task Force) is charged with developing, updating, and revising practice guidelines for cardiovascular diseases and procedures, and the Task Force directs and oversees this effort. Writing committees are charged with assessing the evidence as an independent group of authors to develop, update, or revise recommendations for clinical practice.Experts in the subject under consideration have been selected from both organizations to examine subject-specific data and write guidelines in partnership with representatives from other medical practitioner and specialty groups. Writing committees are specifically charged to perform a formal literature review, weigh the strength of evidence for or against particular tests, treatments, or procedures, and include estimates of expected health outcomes where data exist. Patient-specific modifiers, comorbidities, and issues of patient preference that may influence the choice of tests or therapies are considered. When available, information from studies on cost is considered, but data on efficacy and clinical outcomes constitute the primary basis for recommendations in these guidelines.In analyzing the data and developing the recommendations and supporting text, the writing committee used evidence-based methodologies developed by the Task Force, which are described elsewhere.1 The committee reviewed and ranked evidence supporting current recommendations with the weight of evidence ranked as Level A if the data were derived from multiple randomized clinical trials (RCTs) or meta-analyses. The committee ranked available evidence as Level B when data were derived from a single RCT or nonrandomized studies. Evidence was ranked as Level C when the primary source of the recommendation was consensus opinion, case studies, or standard of care. In the narrative portions of these guidelines, evidence is generally presented in chronological order of development. Studies are identified as observational, retrospective, prospective, or randomized when appropriate. For certain conditions for which inadequate data are available, recommendations are based on expert consensus and clinical experience and ranked as Level C. An example is the use of penicillin for pneumococcal pneumonia, for which there are no RCTs and treatment is based on clinical experience. When recommendations at Level C are supported by historical clinical data, appropriate references (including clinical reviews) are cited if available. For issues where sparse data are available, a survey of current practice among the clinicians on the writing committee was the basis for Level C recommendations and no references are cited. The schema for Classification of Recommendations and Level of Evidence is summarized in Table 1, which also illustrates how the grading system provides an estimate of the size and the certainty of the treatment effect. A new addition to the ACCF/AHA methodology is separation of the Class III recommendations to delineate whether the recommendation is determined to be of “no benefit” or associated with “harm” to the patient. In addition, in view of the increasing number of comparative effectiveness studies, comparator verbs and suggested phrases for writing recommendations for the comparative effectiveness of one treatment/strategy with respect to another for Class of Recommendation I and IIa, Level of Evidence A or B only have been added.Table 1. Applying Classification of Recommendation and Level of EvidenceTable 1. Applying Classification of Recommendation and Level of EvidenceA recommendation with Level of Evidence B or C does not imply that the recommendation is weak. Many important clinical questions addressed in the guidelines do not lend themselves to clinical trials. Although randomized trials are unavailable, there may be a very clear clinical consensus that a particular test or therapy is useful or effective.*Data available from clinical trials or registries about the usefulness/efficacy in different subpopulations, such as sex, age, history of diabetes, history of prior myocardial infarction, history of heart failure, and prior aspirin use.†For comparative effectiveness recommendations (Class I and IIa; Level of Evidence A and B only), studies that support the use of comparator verbs should involve direct comparisons of the treatments or strategies being evaluated.The Task Force makes every effort to avoid actual, potential, or perceived conflicts of interest that may arise as a result of relationships with industry and other entities (RWI) among the writing committee. Specifically, all members of the writing committee, as well as peer reviewers of the document, are required to disclose all relevant relationships and those 12 months prior to initiation of the writing effort. The policies and procedures for RWI for this guideline were those in effect at the initial meeting of this committee (March 28, 2009), which included 50% of the writing committee with no relevant RWI. All guideline recommendations require a confidential vote by the writing committee and must be approved by a consensus of the members voting. Members who were recused from voting are indicated on the title page of this document with detailed information included in Appendix 1. Members must recuse themselves from voting on any recommendations where their RWI apply. If a writing committee member develops a new RWI during his/her tenure, he/she is required to notify guideline staff in writing. These statements are reviewed by the Task Force and all members during each conference call and/or meeting of the writing committee and are updated as changes occur. For detailed information regarding guideline policies and procedures, please refer to the ACCF/AHA methodology and policies manual.1 RWI pertinent to this guideline for authors and peer reviewers are disclosed in Appendixes 1 and 2, respectively. Comprehensive disclosure information for the Task Force is also available online at http://www.cardiosource.org/ACC/About-ACC/Leadership/Guidelines-and-Documents-Task-Forces.aspx. The work of the writing committee was supported exclusively by the ACCF and AHA without commercial support. Writing committee members volunteered their time for this effort.The ACCF/AHA practice guidelines address patient populations (and healthcare providers) residing in North America. As such, drugs that are currently unavailable in North America are discussed in the text without a specific class of recommendation. For studies performed in large numbers of subjects outside of North America, each writing group reviews the potential impact of different practice patterns and patient populations on the treatment effect and on the relevance to the ACCF/AHA target population to determine whether the findings should inform a specific recommendation.The ACCF/AHA practice guidelines are intended to assist healthcare providers in clinical decision making by describing a range of generally acceptable approaches for the diagnosis, management, and prevention of specific diseases or conditions. These practice guidelines represent a consensus of expert opinion after a thorough review of the available current scientific evidence and are intended to improve patient care. The guidelines attempt to define practices that meet the needs of most patients in most circumstances. The ultimate judgment regarding care of a particular patient must be made by the healthcare provider and patient in light of all the circumstances presented by that patient. Thus, there are situations in which deviations from these guidelines may be appropriate. Clinical decision making should consider the quality and availability of expertise in the area where care is provided. When these guidelines are used as the basis for regulatory or payer decisions, the goal should be improvement in quality of care. The Task Force recognizes that situations arise for which additional data are needed to better inform patient care; these areas will be identified within each respective guideline when appropriate.Prescribed courses of treatment in accordance with these recommendations are effective only if they are followed. Because lack of patient understanding and adherence may adversely affect outcomes, physicians and other healthcare providers should make every effort to engage the patient's active participation in prescribed medical regimens and lifestyles.The guideline will be reviewed annually by the Task Force and considered current unless it is updated, revised, or withdrawn from distribution. The full-text version1a of the guideline is e-published in the Journal of the American College of Cardiology and Circulation and is posted on the ACC (www.cardiosource.org) and AHA (my.americanheart.org) World Wide Web sites. Guidelines are official policy of both the ACCF and AHA.Alice K. Jacobs, MD, FACC, FAHA Chair, ACCF/AHA Task Force on Practice Guidelines1. Introduction1.1. Methodology and Evidence ReviewThe recommendations listed in this document are, whenever possible, evidence based. An extensive evidence review was conducted through January 2011. Searches were limited to studies, reviews, and other evidence conducted in human subjects and published in English. Key search words included, but were not limited to, hypertrophic cardiomyopathy (HCM), surgical myectomy, ablation, exercise, sudden cardiac death (SCD), athletes, dual-chamber pacing, left ventricular outflow tract (LVOT) obstruction, alcohol septal ablation, automobile driving and implantable cardioverterdefibrillators (ICDs), catheter ablation, defibrillators, genetics, genotype, medical management, magnetic resonance imaging, pacing, permanent pacing, phenotype, pregnancy, risk stratification, sudden death in athletes, surgical septal myectomy, and septal reduction. References selected and published in this document are representative and not all-inclusive.1.2. Organization of the Writing CommitteeThe committee was composed of physicians and cardiac surgeons with expertise in HCM, invasive cardiology, noninvasive testing and imaging, pediatric cardiology, electrophysiology, and genetics. The committee included representatives from the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons.1.3. Document Review and ApprovalThis document was reviewed by 2 outside reviewers nominated by both the ACCF and AHA, as well as 2 reviewers each from the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons. Other content reviewers included members from the ACCF Adult Congenital and Pediatric Cardiology Council, ACCF Surgeons' Scientific Council, and ACCF Interventional Scientific Council. All information on reviewers' RWI was distributed to the writing committee and is published in this document (Appendix 2).This document was approved for publication by the governing bodies of the ACCF and the AHA and endorsed by the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons.1.4. Scope of the GuidelineAlthough there are reports of this disease dating back to the 1800s, the first modern pathologic description was provided over 50 years ago by Teare2 and the most important early clinical report by Braunwald et al in 1964.3The impetus for the guidelines is based on an appreciation of the frequency of this clinical entity and a realization that many aspects of clinical management, including the use of diagnostic modalities and genetic testing, lack consensus. Moreover, the emergence of 2 different approaches to septal reduction therapy (septal myectomy and alcohol septal ablation) in addition to the ICD has created considerable controversy. The discussion and recommendations about the various diagnostic modalities apply to patients with established HCM and to a variable extent to patients with a high index of suspicion of the disease.Although the Task Force was aware of the lack of high levels of evidence regarding HCM provided by clinical trials, it was believed that a guideline document based on expert consensus that outlines the most important diagnostic and management strategies would be helpful.To facilitate ease of use, it was decided that recommendations in the pediatric and adolescent age groups would not appear as a separate section but instead would be integrated into the overall content of the guideline where relevant.2. Recommendations for HCM2.1. Genetic Testing Strategies/Family Screening—RecommendationsClass IEvaluation of familial inheritance and genetic counseling is recommended as part of the assessment of patients with HCM.4–9(Level of Evidence: B)Patients who undergo genetic testing should also undergo counseling by someone knowledgeable in the genetics of cardiovascular disease so that results and their clinical significance can be appropriately reviewed with the patient.10–14(Level of Evidence: B)Screening (clinical, with or without genetic testing) is recommended in first-degree relatives of patients with HCM.4–7,9,15,16(Level of Evidence: B)Genetic testing for HCM and other genetic causes of unexplained cardiac hypertrophy is recommended in patients with an atypical clinical presentation of HCM or when another genetic condition is suspected to be the cause.17–19(Level of Evidence: B)Class IIaGenetic testing is reasonable in the index patient to facilitate the identification of first-degree family members at risk for developing HCM.5,8,15(Level of Evidence: B)Class IIbThe usefulness of genetic testing in the assessment of risk of SCD in HCM is uncertain.20,21(Level of Evidence: B)Class III: No BenefitGenetic testing is not indicated in relatives when the index patient does not have a definitive pathogenic mutation.4–9,22(Level of Evidence: B)Ongoing clinical screening is not indicated in genotype-negative relatives in families with HCM.22–25(Level of Evidence: B)See Data Supplement 1 for additional data regarding genetic testing strategies/family screening.2.1.1. Genotype-Positive/Phenotype-Negative Patients—RecommendationClass IIn individuals with pathogenic mutations who do not express the HCM phenotype, it is recommended to perform serial electrocardiogram (ECG), transthoracic echocardiogram (TTE), and clinical assessment at periodic intervals (12 to 18 months in children and adolescents and about every 5 years in adults), based on the patient's age and change in clinical status.26–29(Level of Evidence: B)2.2. Electrocardiography—RecommendationsClass IA 12-lead ECG is recommended in the initial evaluation of patients with HCM. (Level of Evidence: C)Twenty-four–hour ambulatory (Holter) electrocardiographic monitoring is recommended in the initial evaluation of patients with HCM to detect ventricular tachycardia (VT) and identify patients who may be candidates for ICD therapy.30–33(Level of Evidence: B)Twenty-four–hour ambulatory (Holter) electrocardiographic monitoring or event recording is recommended in patients with HCM who develop palpitations or lightheadedness.30–32(Level of Evidence: B)A repeat ECG is recommended for patients with HCM when there is worsening of symptoms. (Level of Evidence: C)A 12-lead ECG is recommended every 12 to 18 months as a component of the screening algorithm for adolescent first-degree relatives of patients with HCM who have no evidence of hypertrophy on echocardiography. (Level of Evidence: C)A 12-lead ECG is recommended as a component of the screening algorithm for first-degree relatives of patients with HCM. (Level of Evidence: C)Class IIaTwenty-four–hour ambulatory (Holter) electrocardiographic monitoring, repeated every 1 to 2 years, is reasonable in patients with HCM who have no previous evidence of VT to identify patients who may be candidates for ICD therapy.33(Level of Evidence: C)Annual 12-lead ECGs are reasonable in patients with known HCM who are clinically stable to evaluate for asymptomatic changes in conduction or rhythm (ie, atrial fibrillation [AF]). (Level of Evidence: C)Class IIbTwenty-four–hour ambulatory (Holter) electrocardiographic monitoring might be considered in adults with HCM to assess for asymptomatic paroxysmal AF/atrial flutter. (Level of Evidence: C)2.3. Echocardiography—RecommendationsClass IA TTE is recommended in the initial evaluation of all patients with suspected HCM.34–41(Level of Evidence: B)A TTE is recommended as a component of the screening algorithm for family members of patients with HCM unless the family member is genotype negative in a family with known definitive mutations.42–45(Level of Evidence: B)Periodic (12 to 18 months) TTE screening is recommended for children of patients with HCM, starting by age 12 years or earlier if a growth spurt or signs of puberty are evident and/or when there are plans for engaging in intense competitive sports or there is a family history of SCD.45,46(Level of Evidence: C)Repeat TTE is recommended for the evaluation of patients with HCM with a change in clinical status or new cardiovascular event.47–53(Level of Evidence: B)A transesophageal echocardiogram (TEE) is recommended for the intraoperative guidance of surgical myectomy.54–56(Level of Evidence: B)TTE or TEE with intracoronary contrast injection of the candidate's septal perforator(s) is recommended for the intraprocedural guidance of alcohol septal ablation.57–60(Level of Evidence: B)TTE should be used to evaluate the effects of surgical myectomy or alcohol septal ablation for obstructive HCM.60–66(Level of Evidence: C)Class IIaTTE studies performed every 1 to 2 years can be useful in the serial evaluation of symptomatically stable patients with HCM to assess the degree of myocardial hypertrophy, dynamic obstruction, and myocardial function.35,37,41(Level of Evidence: C)Exercise TTE can be useful in the detection and quantification of dynamic LVOT obstruction in the absence of resting outflow tract obstruction in patients with HCM.48,51,53,67,68(Level of Evidence: B)TEE can be useful if TTE is inconclusive for clinical decision making about medical therapy and in situations such as planning for myectomy, exclusion of subaortic membrane or mitral regurgitation secondary to structural abnormalities of the mitral valve apparatus, or in assessment for the feasibility of alcohol septal ablation.54–56(Level of Evidence: C)TTE combined with the injection of an intravenous contrast agent is reasonable if the diagnosis of apical HCM or apical infarction or severity of hypertrophy is in doubt, particularly when other imaging modalities such as cardiovascular magnetic resonance (CMR) are not readily available, not diagnostic, or are contraindicated. (Level of Evidence: C)Serial TTE studies are reasonable for clinically unaffected patients who have a first-degree relative with HCM when genetic status is unknown. Such follow-up may be considered every 12 to 18 months for children or adolescents from high-risk families and every 5 years for adult family members.43–46(Level of Evidence: C)Class III: No BenefitTTE studies should not be performed more frequently than every 12 months in patients with HCM when it is unlikely that any changes have occurred that would have an impact on clinical decision making. (Level of Evidence: C)Routine TEE and/or contrast echocardiography is not recommended when TTE images are diagnostic of HCM and/or there is no suspicion of fixed obstruction or intrinsic mitral valve pathology. (Level of Evidence: C)2.4. Stress Testing—RecommendationsClass IIaTreadmill exercise testing is reasonable to determine functional capacity and response to therapy in patients with HCM. (Level of Evidence: C)Treadmill testing with monitoring of an ECG and blood pressure is reasonable for SCD risk stratification in patients with HCM.69–71(Level of Evidence: B)In patients with HCM who do not have a resting peak instantaneous gradient of greater than or equal to 50 mm Hg, exercise echocardiography is reasonable for the detection and quantification of exercise-induced dynamic LVOT obstruction.67,70–72(Level of Evidence: B)2.5. Cardiac Magnetic Resonance—RecommendationsClass ICMR imaging is indicated in patients with suspected HCM when echocardiography is inconclusive for diagnosis.73,74(Level of Evidence: B)CMR imaging is indicated in patients with known HCM when additional information that may have an impact on management or decision making regarding invasive management, such as magnitude and distribution of hypertrophy or anatomy of the mitral valve apparatus or papillary muscles, is not adequately defined with echocardiography.73–77(Level of Evidence: B)Class IIa