Cardiomyopathies
Background information
1a. Definition
Cardiomyopathies are a heterogeneous group of myocardial diseases associated with mechanical and/or electrical dysfunction, which usually exhibit inappropriate ventricular hypertrophy or dilatation. They are due to a variety of causes, frequently genetic, and are either confined to the heart or part of generalised systemic disorders.
The WHO/ESC classification distinguishes primary (predominantly involving the myocardium) from secondary cardiomyopathies (myocardial involvement as part of systemic disease).
1b. Clinical classification
| Type | Morphology / physiology | Key notes |
|---|---|---|
| Dilated (DCM) | Dilated LV (or biventricular); impaired systolic function (HFrEF) | Most common; EF typically <40%; AF and thrombus common |
| Hypertrophic (HCM) | Asymmetric LVH without secondary cause; diastolic dysfunction ± LVOTO | AD inheritance; leading cause of SCD in young; dynamic obstruction |
| Restrictive (RCM) | Non-compliant, stiff myocardium; impaired filling; normal or near-normal EF | Rarest; amyloid most common cause in UK; poor prognosis |
| Arrhythmogenic (ARVC) | RV (± LV) fibrofatty replacement; RV dysfunction; arrhythmias | Desmosomal gene mutations; exercise worsens; SCD risk in athletes |
| Peripartum (PPCM) | DCM pattern; last month of pregnancy to 5 months postpartum | ~50% recover; recurrence risk in future pregnancies is high |
| Takotsubo | Transient apical ballooning; precipitated by emotional/physical stress | Predominantly post-menopausal women; usually fully reversible |
1c. Etiopathophysiology
HCM
- Autosomal dominant; sarcomere protein mutations (MYH7, MYBPC3 most common)
- Asymmetric septal hypertrophy → LVOTO and diastolic dysfunction
- Myocyte disarray + fibrosis → arrhythmia substrate
DCM
- ~35% familial (TTN, LMNA gene mutations commonest)
- Acquired: alcohol, viral (Coxsackie B), anthracyclines, peripartum, tachycardia-induced, haemochromatosis, thyroid, selenium deficiency
- Ventricular remodelling → neurohormonal activation → progressive dysfunction
RCM
- Amyloidosis (AL or ATTR), sarcoidosis, haemochromatosis, post-radiation
- Interstitial infiltration or fibrosis → stiff, non-compliant walls
- Impaired ventricular filling → elevated filling pressures
ARVC
- Desmosomal gene mutations (PKP2, DSP, DSG2)
- Fibrofatty replacement of RV myocardium
- Exercise accelerates progression; triggers ventricular arrhythmias
Assessment
2a. Clinical presentation
| Type | Symptoms | Signs | AKT pearls |
|---|---|---|---|
| HCM | Exertional dyspnoea, angina, palpitations, exertional syncope, sudden death | Ejection systolic murmur (LLSE); jerky pulse; double apical impulse; S4 | Murmur ↑ with Valsalva/standing; ↓ with squatting/leg raise. Dynamic = key distinguisher from AS |
| DCM | Progressive dyspnoea, orthopnoea, PND, fatigue, oedema, palpitations | Displaced apex; S3; bibasal creps; JVP↑; peripheral oedema | Can be incidental (CXR, ECG). Exclude reversible causes. AF in ~25% |
| RCM | Dyspnoea, fatigue, oedema, ascites; symptoms of systemic disease | Kussmaul sign; elevated JVP; signs of amyloid (periorbital purpura, macroglossia) | Differentiate from constrictive pericarditis — may need CT/MRI/biopsy |
| ARVC | Palpitations, syncope, SCD; often triggered by exercise in young adults | May be normal; RV heave if advanced | Epsilon wave on ECG is pathognomonic. LBBB-morphology VT. Naxos/Carvajal if palmoplantar keratoderma |
| PPCM | Dyspnoea, oedema, orthopnoea in late pregnancy / postpartum | Signs of HF; tachycardia | Diagnosis of exclusion in peripartum period. Bromocriptine increasingly used |
Red flags warranting urgent assessment:
- Syncope or presyncope during exertion
- Family history of unexplained sudden cardiac death <40 yrs
- Sustained palpitations or documented VT/VF
- New HF symptoms with haemodynamic compromise
2b. Investigations
All suspected cardiomyopathy
- ECG: LVH, Q waves, repolarisation changes, epsilon wave (ARVC), low voltage + thick walls (amyloid)
- CXR: cardiomegaly, pulmonary oedema, pleural effusions
- Echocardiogram: first-line structural assessment — EF, wall thickness, LVOTO, diastolic function
- Bloods: FBC, U&E, LFT, TFT, ferritin/iron studies, HbA1c, BNP/NT-proBNP
- Cardiac MRI: gold standard for tissue characterisation (fibrosis on LGE), ARVC, amyloid
Targeted by type
- HCM: 48h Holter (NSVT = SCD risk); exercise stress test (BP response); genetic testing
- DCM: Coronary angiography / CTCA to exclude IHD; genetic panel; viral serology if clinically indicated
- RCM/amyloid: Serum/urine electrophoresis (AL); Tc-DPD bone scintigraphy (ATTR); fat pad/BM biopsy; SAP scan
- ARVC: Signal-averaged ECG; CMR; exercise-provoked VT; genetic testing (desmosomal panel)
- PPCM: Echo (EF typically <45%); troponin; BNP
BNP / NT-proBNP in primary care: Use to rule out HF if Echo not immediately available. Raised BNP (>100 pg/mL) warrants urgent echocardiography. Normal BNP has high negative predictive value.
Management — UK NICE CKS / NICE guidelines
3a. Emergency care
Call 999 / admit immediately if:
- Acute decompensated HF (severe dyspnoea, SpO₂ <90%, pulmonary oedema)
- Sustained VT or VF, or ICD shock
- Exertional syncope in known or suspected HCM/ARVC — do not allow to drive
- Haemodynamic instability (SBP <90 mmHg, cold peripheries, oliguria)
- New onset HF in peripartum period
- Acute HF: IV loop diuretics (furosemide 40–80 mg IV); IV nitrates if SBP >110 mmHg; oxygen if SpO₂ <94%; consider CPAP/BiPAP
- VT/VF: follow ALS algorithm; correct electrolytes; amiodarone IV; urgent cardiology input
- HCM + LVOTO obstruction: avoid vasodilators (nitrates, ACEi), diuretics (worsen obstruction); cautious IV fluids; beta-blocker or phenylephrine
- Cardiac amyloid: extreme sensitivity to diuretics and vasodilators — cautious use
3b. Referral
Urgent (same-day / within days)
- Any suspected new cardiomyopathy with haemodynamic compromise
- Syncope or sustained VT in known cardiomyopathy
- New PPCM
- ICD shock or device malfunction
Routine / semi-urgent
- Newly diagnosed or suspected cardiomyopathy (echo changes, elevated BNP) → cardiologist
- Known HCM / ARVC → inherited cardiac conditions (ICC) clinic
- First-degree relatives of index cases → ICC clinic for cascade screening
- Pregnancy planning in known cardiomyopathy → joint obstetric cardiology clinic
- Refractory symptoms despite optimised therapy → HF specialist / transplant centre
NICE NG106 (Hypertrophic cardiomyopathy): Refer all patients with newly diagnosed HCM to a specialist HCM centre or ICC clinic. Offer genetic testing when a pathogenic variant has been identified; offer cascade testing to first-degree relatives.
3c. Primary care management
DCM / HFrEF — four pillars (NICE NG106 & NG172)
1stACEi / ARB
- Ramipril or enalapril; titrate to max tolerated dose
- ARB (candesartan) if ACEi-intolerant
- ARNI (sacubitril/valsartan) if EF ≤35% on optimised therapy — replaces ACEi/ARB
2ndBeta-blocker
- Bisoprolol, carvedilol, or nebivolol (licensed for HFrEF)
- Start low, titrate slowly; avoid abrupt withdrawal
3rdMRA
- Spironolactone or eplerenone
- Monitor K⁺ and renal function closely
- Avoid if K⁺ >5.0 or eGFR <30
4thSGLT2i
- Dapagliflozin 10 mg or empagliflozin 10 mg
- NICE-approved regardless of diabetes status (EF ≤40%)
- Reduce HF hospitalisation and CV death
HCM — primary care role
- Beta-blocker (bisoprolol/propranolol) or verapamil — first line for symptoms (dyspnoea, angina, palpitations)
- Disopyramide — add if LVOTO symptoms persist (negative inotrope)
- Mavacamten (myosin inhibitor, NICE TA 2024) — for symptomatic obstructive HCM; specialist initiation
- Avoid: nitrates, dihydropyridine CCBs, digoxin, loop diuretics (worsen LVOTO)
- Anticoagulate if AF present (DOAC preferred)
- Advise against competitive sport; personalised exercise guidance via ICC clinic
Cardiac amyloid (ATTR) — GP awareness
- Tafamidis (NICE TA 2022) — licensed for wild-type and hereditary ATTR-CM; specialist initiation; reduces mortality and HF hospitalisation
- Avoid digoxin (binds amyloid fibrils — unpredictable toxicity); extreme diuretic sensitivity
- Refer for patisiran/inotersen if hereditary ATTR with polyneuropathy
General primary care responsibilities
- Annual review: symptoms, weight, BP, renal function, electrolytes, BNP, device check if ICD/CRT
- Medication optimisation: titrate to maximum tolerated doses; monitor for side effects
- Diuretic self-management: educate on flexible furosemide dosing (weight monitoring)
- AF management: anticoagulation (CHA₂DS₂-VASc ≥2 in men, ≥3 in women), rate/rhythm control
- DVLA: Patients must inform DVLA. ICD → Group 1 licence: 6-month driving restriction after appropriate shock. Group 2 (HGV/bus): bar if ICD in situ or HCM diagnosis
- Vaccinations: Influenza and pneumococcal (all HF patients per NICE)
- Lifestyle: alcohol cessation (DCM), sodium restriction, fluid management, cardiac rehab referral
- Cascade screening: identify and refer first-degree relatives of HCM, DCM, ARVC probands
- Contraception / pregnancy: seek specialist input; many cardiomyopathies carry significant obstetric risk
ICD indications to know for AKT: EF ≤35% on optimised HFrEF therapy (≥3 months); HCM with ≥1 major SCD risk factor; ARVC with sustained VT or high-risk features; secondary prevention post-VF/VT arrest.
CRT indications (NICE NG106): LBBB + QRS ≥130 ms + EF ≤35% + symptomatic HF on optimised therapy. QRS 120–149 ms without LBBB — individualised decision.
Sources informing these notes
NICE NG106 — Hypertrophic cardiomyopathyNICE NG172 — Chronic heart failureNICE TA 2022 — Tafamidis (ATTR-CM)NICE TA 2024 — MavacamtenNICE CKS — Heart failureBMJ Best Practice — CardiomyopathiesESC 2023 Cardiomyopathy GuidelinesStatPearls — CardiomyopathyDVLA: Assessing fitness to drive 2024
