Overview/Definition
Definition:
• Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder characterized by left ventricular hypertrophy without underlying cause, affecting 1 in 500 individuals
Most common cause of sudden cardiac death in young athletes and competitive sports participants
Autosomal dominant inheritance pattern with variable penetrance and expression.
Epidemiology:
• Prevalence of 1:500 in general population with higher detection rates in athletic populations due to screening programs
Accounts for 36-50% of sudden cardiac deaths in athletes <35 years
Male predominance in symptomatic cases (3:1 ratio)
Geographic variations noted with higher rates in certain populations and families.
Age Distribution:
• Clinical manifestations typically develop during adolescence and early adulthood (12-30 years) coinciding with periods of rapid growth and athletic participation
Sudden cardiac death risk peaks during adolescence and young adulthood
Family screening often identifies asymptomatic children requiring long-term monitoring.
Clinical Significance:
• Critical high-yield topic for DNB Pediatrics and NEET SS focusing on genetic counseling, sports participation guidelines, and sudden death prevention
Essential for understanding inherited cardiomyopathy, pre-participation screening protocols, and activity restriction recommendations
Major public health concern in competitive athletics.
Age-Specific Considerations
Newborn:
• HCM rarely manifests in neonatal period except in severe forms associated with metabolic disorders (Noonan syndrome, glycogen storage disease)
Newborns of affected parents require baseline echocardiography and genetic counseling
Early severe forms may present with heart failure requiring immediate intervention.
Infant:
• Infantile HCM may present with failure to thrive, feeding difficulties, or heart failure symptoms
Often associated with metabolic disorders or storage diseases requiring comprehensive evaluation
Family history screening important for identifying genetic forms
Growth and developmental monitoring essential.
Child:
• School-age children may remain asymptomatic or develop exercise intolerance, chest pain, or syncope with exertion
Pre-participation sports screening becomes important at this age
Family screening of siblings and parents crucial for genetic counseling
Activity modification may be necessary based on severity.
Adolescent:
• Peak age for clinical manifestation and sudden cardiac death risk in HCM patients
Participation in competitive sports requires careful evaluation and often restriction
Genetic counseling important for family planning
Transition to adult cardiology care planning begins
Psychological support for activity restrictions may be needed.
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Clinical Presentation
Symptoms:
• Many patients asymptomatic, discovered during routine screening or family evaluation
Symptomatic patients may experience exertional dyspnea, chest pain (typical or atypical), syncope or presyncope with exercise, palpitations, fatigue with exertion
Family history of sudden cardiac death, cardiomyopathy, or syncope important red flags.
Physical Signs:
• Harsh systolic ejection murmur at left sternal border intensified with Valsalva maneuver and standing, decreased with squatting and handgrip
Bifid carotid pulse, prominent S4 heart sound, displaced PMI
Signs may be absent in non-obstructive forms
Blood pressure typically normal unless associated conditions present.
Severity Assessment:
• Asymptomatic with normal exercise tolerance: lower risk but still requires monitoring
Symptomatic with exertional symptoms: higher risk requiring activity restriction
High-risk features: family history sudden cardiac death, syncope, non-sustained VT, severe LVH (wall thickness ≥30mm), abnormal exercise response.
Differential Diagnosis:
• Athletic heart syndrome (physiologic LVH in athletes), infiltrative cardiomyopathies (amyloidosis, sarcoidosis), storage diseases (Fabry disease, glycogen storage disease), hypertensive heart disease, aortic stenosis, other genetic cardiomyopathies
Differentiation requires comprehensive evaluation including genetics.
Diagnostic Approach
History Taking:
• Detailed family history of cardiomyopathy, sudden cardiac death, or syncope through three generations
Personal history of chest pain, syncope, shortness of breath, or exercise intolerance
Detailed sports participation history and performance changes
Medication and substance use history including performance-enhancing drugs.
Investigations:
• Transthoracic echocardiography gold standard showing asymmetric septal hypertrophy (ASH), systolic anterior motion (SAM), mitral regurgitation, LVOT obstruction
ECG may show LVH, T wave inversions, deep Q waves
24-48 hour Holter monitoring for arrhythmias
Exercise stress testing for risk stratification
Genetic testing when indicated.
Normal Values:
• Normal LV wall thickness <12mm in adults, <10mm in children
Septal-to-posterior wall ratio <1.3:1 normal
Normal LVOT gradient <30mmHg at rest, <50mmHg with provocation
Normal exercise response shows appropriate blood pressure rise and absence of complex arrhythmias.
Interpretation:
• HCM diagnosis: LV wall thickness ≥15mm in adults (≥13mm with family history), ≥2 SD above mean for age in children
Asymmetric pattern typical but concentric hypertrophy possible
LVOT gradient ≥30mmHg at rest defines obstructive HCM
Risk stratification requires comprehensive evaluation of clinical and imaging parameters.
Management/Treatment
Acute Management:
• Acute presentations rare but may include heart failure (diuretics, avoid inotropes), syncope (immediate activity restriction, urgent cardiology referral), chest pain evaluation (rule out ischemia, avoid vasodilators), arrhythmias (antiarrhythmics, avoid digoxin)
Avoid dehydration and excessive preload reduction.
Chronic Management:
• Medical therapy: beta-blockers first-line (metoprolol, propranolol), calcium channel blockers (verapamil) for symptomatic patients
Disopyramide for refractory symptoms
Avoid vasodilators, inotropes, and nitrates
ICD placement for high-risk patients
Surgical myectomy for refractory obstructive HCM.
Lifestyle Modifications:
• Activity restriction crucial: avoid competitive sports, high-intensity exercise
Recreational activity allowed with limitations based on risk assessment
Adequate hydration maintenance, avoid extreme heat
Genetic counseling for affected families
Regular cardiology follow-up with serial imaging and risk reassessment.
Follow Up:
• Annual comprehensive evaluation including history, physical examination, ECG, echocardiography, and Holter monitoring
Exercise stress testing every 2-3 years for risk stratification
Genetic counseling and family screening
Sports participation clearance requires specialized evaluation and often lifelong restriction from competitive athletics.
Age-Specific Dosing
Medications:
• Metoprolol: Children 1-2mg/kg BID (max 100mg BID), Adolescents 25-50mg BID initially, titrate to maximum tolerated dose
Propranolol: 0.5-1mg/kg BID-TID in children, 40-80mg BID in adolescents
Verapamil: contraindicated <1 year, 4-8mg/kg/day divided TID in older children/adolescents.
Formulations:
• Metoprolol available as 25mg, 50mg, 100mg tablets and extended-release formulations
Propranolol 10mg, 20mg, 40mg tablets and 4mg/mL oral solution for pediatric dosing
Verapamil 80mg, 120mg tablets and sustained-release preparations
Disopyramide 100mg, 150mg capsules for specialized use.
Safety Considerations:
• Beta-blocker monitoring for bradycardia, hypotension, bronchospasm (avoid in asthma), and exercise intolerance
Verapamil monitoring for heart block, hypotension, and negative inotropic effects
Avoid abrupt discontinuation of cardiac medications
Monitor for drug interactions, especially with calcium channel blockers.
Monitoring:
• Regular vital signs including heart rate and blood pressure monitoring on cardiac medications
ECG monitoring for conduction abnormalities and arrhythmias
Holter monitoring annually or with symptom changes
Exercise testing for functional capacity assessment and arrhythmia detection
Electrolyte monitoring with diuretic therapy.
Prevention & Follow-up
Prevention Strategies:
• Primary prevention through family screening and genetic counseling to identify at-risk individuals before symptom development
Secondary prevention focuses on sudden cardiac death prevention through risk stratification, activity restriction, and ICD placement when indicated
Pre-participation athletic screening programs.
Vaccination Considerations:
• Standard immunization schedule appropriate unless specific contraindications exist
COVID-19 vaccination recommended with awareness of potential myocarditis risk requiring temporary activity restriction post-vaccination
Influenza vaccine recommended annually, especially for patients with heart failure symptoms.
Follow Up Schedule:
• Newly diagnosed: every 3-6 months initially for medication titration and symptom assessment
Stable patients: annual comprehensive evaluation with imaging and risk assessment
High-risk patients: more frequent monitoring every 3-6 months
Emergency protocols for new symptoms, syncope, or concerning arrhythmias.
Monitoring Parameters:
• Symptom assessment including exercise tolerance, chest pain, syncope, palpitations
Physical examination for murmur changes, heart failure signs
Echocardiographic monitoring for progression of hypertrophy, obstruction, and systolic function
ECG and Holter monitoring for arrhythmias and conduction abnormalities.
Complications
Acute Complications:
• Sudden cardiac death most feared complication, occurring in 0.5-1% annually in high-risk patients
Ventricular arrhythmias (VT/VF) most common mechanism
Atrial fibrillation with rapid ventricular response can cause hemodynamic compromise
Heart failure exacerbations may require hospitalization and optimization of medical therapy.
Chronic Complications:
• Progressive heart failure in 10-15% of patients due to diastolic dysfunction and eventual systolic dysfunction
Atrial fibrillation in 20-25% of patients increasing stroke risk
Infective endocarditis risk requires prophylaxis for certain procedures
Progressive mitral regurgitation from SAM requiring surgical intervention.
Warning Signs:
• Red flag symptoms requiring immediate evaluation: syncope or near-syncope, chest pain especially with exertion, severe shortness of breath, palpitations with hemodynamic symptoms, new or worsening exercise intolerance
Family history of sudden cardiac death raises risk significantly.
Emergency Referral:
• Immediate referral for: syncope in HCM patient, sustained ventricular arrhythmias, heart failure symptoms, chest pain with ECG changes
New diagnosis of HCM requires urgent cardiology referral for risk stratification and activity restriction
Family members of sudden cardiac death victims need emergency screening.
Parent Education Points
Counseling Points:
• Explain genetic nature of HCM with 50% transmission risk to offspring requiring family screening
Discuss variable expression meaning affected family members may have different symptoms or severity
Emphasize excellent prognosis with appropriate management and activity modification
Address psychological impact of sports restriction.
Home Care:
• Monitor for symptoms of worsening condition including increased shortness of breath, chest pain, dizziness, or palpitations
Maintain adequate hydration especially in hot weather
Avoid extreme physical exertion and competitive sports
Ensure compliance with prescribed medications and follow-up appointments.
Medication Administration:
• Give cardiac medications consistently at same times daily with attention to heart rate and blood pressure effects
Monitor for side effects including fatigue, dizziness, or breathing difficulties
Never discontinue medications abruptly without medical supervision
Use precise measuring for liquid formulations.
When To Seek Help:
• Seek immediate medical attention for: loss of consciousness or fainting episodes, severe chest pain especially with activity, severe shortness of breath or difficulty breathing, fast or irregular heartbeat with symptoms
Contact cardiologist promptly for: new or worsening symptoms, medication side effects, or concerns about activity levels.