Cardiovascular Disorders

Cardiomyopathies

Clinical overview and exam mastery guide for dilated, hypertrophic, and restrictive cardiomyopathy with high-yield pharmacology and ICD risk strategy.

DCM
Dilation and reduced EF
HCM
Hypertrophy and LVOT risk
RCM
Stiff ventricle, preserved EF
Sudden Death Prevention
ICD in high-risk patients

Classification Snapshot

DCM Dilated Low EF HCM Hypertrophy LVOT obstruction RCM Stiff ventricle Preserved EF Key Exam Axis: hemodynamics + sudden death risk DCM -> HF therapy | HCM -> rate/contractility control | RCM -> underlying cause focus

Different morphology patterns drive different treatment priorities.

1. What Are Cardiomyopathies?

Cardiomyopathies are diseases of cardiac muscle that impair pump function and/or ventricular filling. Core categories include dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), and restrictive cardiomyopathy (RCM).

Dilated cardiomyopathy Hypertrophic cardiomyopathy Restrictive cardiomyopathy

2. Dilated Cardiomyopathy (DCM)

Pathophysiology and Causes

  • Ventricular dilation with reduced systolic function
  • Decreased ejection fraction and HFrEF progression
  • Common causes: idiopathic, viral myocarditis, alcohol, anthracyclines, genetics

Clinical Features

  • Dyspnea
  • Fatigue
  • Peripheral edema
  • Signs of heart failure
Core DCM Therapy MOA Major Side Effects Contraindications / Cautions
ARNI / ACE inhibitor / ARB RAAS pathway suppression and/or neprilysin modulation to reduce afterload/remodeling Hypotension, hyperkalemia, renal dysfunction, cough (ACE inhibitor) Pregnancy; angioedema history for ARNI/ACE inhibitor contexts
Evidence-based beta blockers Reduce adrenergic drive, lower HR, improve remodeling over time Bradycardia, fatigue, hypotension Cardiogenic shock, severe bradycardia, unstable decompensation at initiation
MRA (spironolactone/eplerenone) Aldosterone receptor blockade, reduced fibrosis/remodeling Hyperkalemia, renal dysfunction, gynecomastia (spironolactone) Severe renal impairment, significant hyperkalemia
SGLT2 inhibitors Renal sodium-glucose transport inhibition with cardiorenal benefit Volume depletion, genital infections, rare euglycemic DKA Severe renal dysfunction (agent specific), type 1 diabetes
Loop diuretics (symptom control) Na-K-2Cl inhibition in loop of Henle to reduce congestion Hypokalemia, hypotension, dehydration Use with electrolyte and renal monitoring
Treat DCM as HFrEF. In severely reduced EF with high arrhythmic risk, evaluate for ICD.

3. Hypertrophic Cardiomyopathy (HCM)

Pathophysiology and Risk

  • Asymmetric septal hypertrophy
  • Dynamic LV outflow tract obstruction (obstructive subtype)
  • Diastolic dysfunction
  • Sudden cardiac death risk, especially in young athletes

Symptoms

  • Syncope
  • Dyspnea
  • Chest pain
HCM Therapy MOA Major Side Effects Contraindications / Cautions
Beta blockers (first-line) Lower HR and contractility, improve diastolic filling, reduce LVOT obstruction Bradycardia, fatigue Severe bradycardia, cardiogenic shock
Non-DHP CCB (verapamil) Lower contractility and improve diastolic relaxation Bradycardia, hypotension, constipation Avoid in severe obstruction with hypotension
Disopyramide (obstructive HCM add-on) Class IA sodium channel blockade with negative inotropic effect Anticholinergic effects, QT prolongation Baseline prolonged QT or major proarrhythmic risk
High-yield trap: avoid preload-reducing drugs in severe obstructive HCM (nitrates, aggressive diuresis, and vasodilators such as ACE inhibitors in severe obstruction) because obstruction can worsen.

4. Restrictive Cardiomyopathy (RCM)

Pathophysiology and Causes

  • Stiff ventricles with impaired diastolic filling
  • Ejection fraction often preserved
  • Common causes: amyloidosis, hemochromatosis, sarcoidosis

Clinical Pattern and Strategy

  • Right-sided heart failure features, fatigue, edema
  • Treat underlying disease
  • Use diuretics cautiously for symptoms
  • Manage arrhythmias as needed
There is no universal curative pharmacotherapy for RCM; treatment is cause-specific plus symptom control.

5. Sudden Cardiac Death Risk

In HCM and severe DCM, evaluate for high-risk markers and ICD candidacy.

Family history of sudden death Severe LV hypertrophy Syncope Ventricular arrhythmias
ICD therapy is a key prevention strategy in high-risk cardiomyopathy patients.

Management Recap Drill

DCM: treat as HFrEF with full guideline-directed therapy.
DCM severe EF reduction: assess ICD indications.
HCM: beta blocker first-line, then verapamil/disopyramide when indicated.
HCM: avoid strong preload reduction in severe obstructive disease.
RCM: treat underlying cause and control symptoms cautiously.

Visual Algorithm Placeholder

[Insert Cardiomyopathy Classification and Management Flowchart Here During UI Integration]

Guideline References (Management)

ACC/AHA Guideline for Hypertrophic Cardiomyopathy

https://www.acc.org/guidelines

ACC/AHA Heart Failure Guidelines (DCM Framework)

https://www.acc.org/guidelines

6. Common Exam Traps

HCM with severe obstruction: avoid aggressive preload reduction.
DCM management follows HFrEF treatment principles.
RCM often presents with preserved EF despite severe filling abnormality.
Young athlete sudden death pattern should raise concern for HCM.
ICD decisions are central in high-risk cardiomyopathy.

7. Quick Revision Summary

Must Remember

  • DCM = dilation with reduced EF
  • HCM = hypertrophy with possible dynamic LVOT obstruction
  • RCM = stiff ventricle with impaired filling
  • HCM core drug: beta blocker
  • DCM requires comprehensive HF therapy

Practice Questions Placeholder

  • Topic: Cardiomyopathies
  • Subtopics: dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, ICD indications, sudden death risk