Dilated cardiomyopathy

Definition: left ventricular or biventricular dilatation with systolic dysfunction not explained by abnormal loading conditions or coronary artery disease.

Epidemiology: Pathy's notes that idiopathic dilated cardiomyopathy is relatively more prevalent in developing countries and Arabic populations than in the West, and that non-ischaemic causes of heart failure (rheumatic disease, Chagas disease, hypertension) dominate outside high-income settings — directly relevant to Indian practice.

Aetiology: idiopathic/familial (titin truncating variants, lamin A/C — the latter associated with conduction disease and requiring early ICD), alcohol, anthracyclines and trastuzumab, viral myocarditis, tachycardia-induced, peripartum, thyrotoxicosis and hypothyroidism, iron overload, thiamine deficiency, and HIV.

Pathophysiology: myocyte loss and interstitial fibrosis → reduced contractility → neurohormonal activation (sympathetic, RAAS, natriuretic peptides) → progressive remodelling with eccentric hypertrophy, annular dilatation causing functional mitral regurgitation, stasis with mural thrombus, and re-entrant ventricular arrhythmia.

Clinical features: congestive heart failure with a displaced diffuse apex, S3 gallop, pansystolic murmur of functional mitral regurgitation, raised JVP, hepatomegaly and oedema; also arrhythmia, thromboembolism and sudden death.

ECG: sinus tachycardia, atrial fibrillation, left bundle branch block, poor R-wave progression, ventricular ectopy, non-sustained ventricular tachycardia.

Echocardiography is the key test: dilated chambers, globally reduced ejection fraction, functional mitral regurgitation, sometimes apical thrombus. Cardiac MRI with late gadolinium enhancement distinguishes ischaemic (subendocardial) from non-ischaemic (mid-wall) patterns and refines arrhythmic risk.

Additional work-up: coronary angiography or CT coronary angiography to exclude ischaemic cardiomyopathy; thyroid function, iron studies, HIV serology, alcohol history; genetic testing and family screening in familial disease.

Treatment: remove the cause (alcohol abstinence, rate control of incessant tachycardia, correct thyroid or iron abnormality); full four-pillar HFrEF therapy — ARNI or ACE inhibitor/ARB, beta blocker, mineralocorticoid receptor antagonist and SGLT2 inhibitor — plus diuretics for congestion, ivabradine if heart rate remains >70 in sinus rhythm, anticoagulation for atrial fibrillation or documented thrombus, CRT for conduction delay, and ICD in selected patients with a reasonable life expectancy.

Prognosis and geriatric caveat: some patients show substantial recovery of ejection fraction with optimal therapy ("heart failure with improved ejection fraction"), and therapy should not be withdrawn once function recovers (TRED-HF). In very frail elders, tolerability, symptom control and quality of life take precedence over full-dose uptitration and device therapy. Latest Updates and Current Practice Update (concise) SGLT2 inhibitors are now a first-line pillar in dilated cardiomyopathy with reduced ejection fraction (DAPA-HF, EMPEROR-Reduced); the textbooks list them only as an emerging possibility. STRONG-HF supports rapid, protocol-driven uptitration of all four pillars within weeks of decompensation, with close biochemical and clinical review — replacing the traditional slow month-by-month titration. 2023 ESC Cardiomyopathy Guideline makes genetic testing and cascade family screening standard in dilated cardiomyopathy, and highlights lamin A/C and filamin C variants as indications for earlier ICD implantation irrespective of ejection fraction thresholds.