Hypertrophic cardiomyopathy resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Steven Bellm, M.D. [2]

Hypertrophic cardiomyopathy resident survival guide Microchapters
Overview
Classification
Causes
Diagnosis
Treatment
Do's
Dont's

Overview

Hypertrophic Cardiomyopathy is defined by LV hypertrophy associated with nondilated ventricular chambers without any other cardiac or systemic disease that itself would be capable of producing the magnitude of hypertrophy evident. HCM patients can also develop a LV outflow obstruction, diastolic dysfunction, myocardial ischemia and mitral regurgitation. HCM is usually recognized by maximal LV wall thickness ≥15 mm. Wall thickness of 13 to 14 mm is considered borderline if there are other compelling information (eg, family history of HCM), based on echocardiography. The diagnostic imaging mainly focused on echocardiography, however cardiovascular magnetic resonance (CMR) is used with increasing frequency.The risk of supraventricular and ventricular arrhythmias and for sudden cardiac death is increased.

Classification

Left Ventricular Hypertrophy

Sarcomere Mutation

Without Extracardiac or Metabolic Findings + Genetic Substrate Unresolved

With Extracardiac or Metabolic Findings Associated With or Without Mutant Gene

Hypertrophic Cardiomyopathy

Syndrome with Left Ventricular Hypertrophy

Causes

Common Causes

• Familial
• Gene mutation
• Hypertension

Complete Diagnostic Approach

A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention.

History and symptoms: ❑  Hints for etiology (at least 3 generations of hypertrophic cardiomyopathy or sudden death in family history, and others) ❑  Duration and onset of illness ❑  Severity and triggers of dyspnea and fatigue, presence of chest pain, exercise capacity, physical activity, sexual activity (NYHA?) ❑  Weight loss/weight gain (cachexia/volume overload?) ❑  Palpitations/(pre)syncope/ICD shocks(adverse prognosis) /ventricular tachycardias/cardiac arrest or fibrillation ❑  Symptoms of transient ischemic attack or thromboembolism (anticoagulation necessary?) ❑  Presence of peripheral edema or ascites (volume overload?) ❑  Problems with breathing at night/ sleep ❑  Medical history: ❑  Prior hospitalizations for HF (adverse prognosis?) ❑  Discontinuation of medications (reasons?) ❑  Medications that may exacerbate HF ❑  Diet (restriction of sodium and fluid intake?)

Physical examination: ❑  Vital signs: ❑  Pulse (strength and regularity/may be brisk in upstroke and bifid through midsystolic obstruction) ❑  Blood pressure ❑  Respiratory rate ❑  General appearance: ❑  BMI(weight loss/weight gain) ❑  Peripheral edema ❑  JVD may show a prominent "a" wave ❑  Heart: ❑  Systolic murmur ❑  LVOT obstruction:harsh crescendo-decrescendo systolic murmur, may radiate to the axilla ❑  mitral regurgitation:mid-late systolic murmur at the apex ❑  LVOT obstruction murmur is similar to valvular aortic stenosis and subaortic stenosis,but systolic murmur increases maneuvers that decrease preload ❑  eventually have paradoxic split of S² ❑  eventually forceful LV apical impulse, presystolic apical impulse, systolic thrill at apex ❑  Lungs: ❑  Rales ❑  Pleural effusion ❑  Abdomen: ❑  Hepatomegaly and/or ascites (volume overload) ❑  Extremities: ❑  Temperature of lower extremities

Laboratory findings: ❑  Complete blood count ❑  Chemistry: ❑  Troponin, BNP or NT-proBNP ❑  Serum electrolytes (including calcium and magnesium) ❑  Blood urea nitrogen ❑  Serum creatinine ❑  Glucose ❑  Fasting lipid profile ❑  Liver function tests ❑  Thyroid-stimulating hormone ❑  Consider Screening for hemochromatosis, HIV, rheumatologic diseases, amyloidosis, or pheochromocytoma ❑  Urinalysis

Imaging and additional tests: ❑  Noninvasive imaging and tests: ❑  ECG (i.e. repolarization changes/Prominent abnormal Q waves/P wave abnormalities/Deeply inverted T waves/signs ventricular hypertrophy/Left axis deviation) ❑  2D transthoracic Echocardiography with Doppler: ❑  usually asymmetric LV hypertrophy (HCM confirmed in case of unexplained increased LV wall thickness ≥15 mm/ ≥13 mm may be considered as hypertrophy if there is a known family member with HCM) ❑  Systolic anterior motion of the mitral valve (SAM) ❑  LVOT obstruction (high-velocity, late-peaking jet across the left ventricular outflow tract), use provocative maneuvers to identify obstructions ❑  Ambulatory ECG monitoring (for 24 to 48 hours in all patients diagnosed with HCM): ❑  Risk assessment for ventricular arrhythmias and risk for sudden death ❑  Palpitations with unknown etiology ❑  Consider Cardiovascular magnetic resonance: ❑  If further assessment of anatomic structures is needed and diagnosis remains uncertain following echocardiography ❑  myocardial fibrosis can be identified with contrast-enhanced CMR ❑  Invasive imaging and tests: ❑  Cardiac catheterization rarely required, consider if: ❑  further evaluation of LV outflow tract obstruction is needed ❑  Patients with HCM with chest discomfort who have an intermediate to high likelihood of coronary artery disease (CAD) when the identification of concomitant CAD will change management strategies ❑  Endomyocardial biopsy is indicated to exclude non-sarcomeric disease ❑  Before alcohol septal ablation ❑  Family member screening: ❑  periodic screening with echocardiography and serial electrocardiogram (ECG) for first-degree family members (every 5 years)/ annual screening for adolescents with 12 to 18 years of age ❑  Genetic counseling in first degree family members ❑  All patients should be offered instructions for prophylaxis against infective endocarditis and should be advised to avoid dehydration and strenuous exertion

B01

B02

C01

D01

D02

D03

E01

E02

E03

F01

F02

Treatment

Patients with HCM

Treat comorbidities according to guidelines (hypertension, diabetes mellitus,etc)

Obstructive physiology?

Yes

No

Avoid vasodilator therapy and high-dose diuretics

Heart failure symptoms or angina

Heart failure symptoms or angina

Yes

No

No

Yes

Systolic function?

Annual clinical evaluation

Annual clinical evaluation

Beta-blockade/Verapamil/Disopyramide

LV-EF<50 percent

LV-EF≥50 percent

Persistent symptoms

Therapy as described in Heart failure

Beta-blockade

Verapamil

Invasive therapy

Acceptable surgical candidate

Diuretics

ACE inhibitor or ARB

No

Yes

Acceptable candidate for alcohol ablation?

Alcohol ablation

Surgical myectomy

Yes

No

Consider Alcohol ablation

Consider DDD pacing

Based on the ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy.

Other Interventions

Implantation of an automatic defibrillator

Overall assessment of major and minor risk factors for risk of sudden death and coexisting conditions to decide if implantation automatic defibrillator is indicated.

Do's

Dont's

• Septal reduction therapy should not be performed for asymptomatic adult and pediatric patients with HCM with normal effort tolerance regardless of the severity of obstruction
• eptal reduction therapy should not be done unless performed as part of a program dedicated to the longitudinal and multidisciplinary care of patients with HCM
• Mitral valve replacement for relief of LVOT obstruction should not be performed in patients with HCM in whom septal reduction therapy is an option

• In patients with HCM with resting or provocable outflow tract obstruction, regardless of symptom status, pure vasodilators and high-dose diuretics are potentially harmful.
• Alcohol septal ablation should not be done in patients with HCM with concomitant disease that independently warrants surgical correction (eg, coronary artery bypass grafting for CAD, mitral valve repair for ruptured chordae) in whom surgical myectomy can be performed as part of the operation
• Alcohol septal ablation should not be done in patients with HCM who are less than 21 years of age and is discouraged in adults less than 40 years of age if myectomy is a viable option

• Nifedipine or other dihydropyridine calcium channel-blocking drugs are potentially harmful for treatment of symptoms (angina or dyspnea) in patients with HCM who have resting or provocable LVOT obstruction

• Verapamil is potentially harmful in patients with obstructive HCM in the setting of systemic hypotension or severe dyspnea at rest

• Digitalis is potentially harmful in the treatment of dyspnea in patients with HCM and in the absence of AF

• The use of disopyramide alone without beta blockers or verapamil is potentially harmful in the treatment of symptoms (angina or dyspnea) in patients with HCM with AF because disopyramide may enhance atrioventricular conduction and increase the ventricular rate during episodes of AF

• Dopamine, dobutamine, norepinephrine, and other intravenous positive inotropic drugs are potentially harmful for the treatment of acute hypotension in patients with obstructive HCM

For women with advanced heart failure symptoms and HCM, pregnancy is associated with excess morbidity/mortality

References