Dilated Cardiomyopathy and Precision Medicine — Heart Failure Reviews 2022

Authors, Journal, Affiliations, Type, DOI

• Nicoletta Orphanou, Efstathios Papatheodorou, Aris Anastasakis
• Heart Failure Reviews (2022) 27:1173–1191
• Unit of Inherited Cardiovascular Diseases, Hippokration General Hospital, University of Athens Medical School, Athens, Greece
• Narrative review / state-of-the-art
• DOI: https://doi.org/10.1007/s10741-021-10139-0

Overview

This review reframes DCM as an "umbrella" term entering a precision-medicine era, transitioning from symptom relief to genotype-directed disease prevention and reversal. The paper provides a clinically structured walk through epidemiology, classification (including HNDC/Pinto 2016), acquisition causes, genetic architecture gene-by-gene, gene-specific ECG patterns, diagnostic criteria for at-risk relatives, risk stratification with gene-specific ICD thresholds, athletic heart differentiation, and early genotype-directed treatment strategies. A comprehensive gene reference table (Table 2, 20+ genes) maps inheritance, phenotype, and ICD indications in one place. Key original contributions over existing reviews are the Pinto 2016 family diagnostic criteria framework, quantitative exercise echocardiography thresholds for DCM vs athletic heart, genotype-specific LVRR data, and the "apparent healing phenomenon" in treated DCM.

Keywords

Dilated cardiomyopathy; Familial dilated cardiomyopathy; Genetics; Precision medicine; Hypokinetic non-dilated cardiomyopathy; Genotype-directed therapy; Left ventricular reverse remodelling; Sudden cardiac death

Key Takeaways

Epidemiology and Classification

• DCM prevalence 1:2500 (0.04%); familial DCM 30–50% of cases; genetic yield 20–37% overall
• SCD 2–4%/year in unselected DCM; DCM found in 10–19% of aborted SCD autopsies
• HNDC (Hypokinetic Non-dilated Cardiomyopathy): Pinto 2016 ESC redefinition — LVEF <45% without LV dilatation fulfils DCM spectrum; managed identically for VA/SCD purposes
• AHA classification (2006): primary vs secondary; ESC (2007): genetic vs non-genetic
• MOGE(S) classification as functional coding system

Acquired (Non-genetic) DCM Causes

• Alcohol: dose-dependent; up to 32% of "idiopathic" DCM in heavy drinkers; TTNtv increases susceptibility (interaction confirmed)
• Anthracyclines: 25% risk at cumulative dose >550 mg/m²; predisposition in TTNtv carriers
• Myocarditis: viral (coxsackievirus B, parvovirus B19, adenovirus, COVID-19) → DCM in ~30% of acute myocarditis cases; viral genome found in myocardium of up to 76% of "idiopathic" LVSD
• Peripartum CMP (PPCM): last month of pregnancy or within 5 months postpartum; TTNtv in ~10%
• Autoimmune: cardiac autoantibodies (anti-β1/anti-α-myosin) predict development in asymptomatic relatives

Genetic DCM Architecture

• TTN: 18–25% of DCM; truncating variants; A-band location highest-risk; peripartum/alcohol/anthracycline interaction; higher LVRR rates under OMT; AD and AR inheritance
• LMNA: ~6% of DCM; highest malignant VA risk; AV block/AF often precede LVSD by years; accelerated disease course; 30% 12-year mortality; onset 30–40 years; near-complete penetrance by age 70; lower LVRR rates
• DES: <1%; AV block/conduction disease + skeletal myopathy; VAs often before overt LVSD
• DMD (Dystrophin): X-linked; inferolateral pseudoinfarction pattern + short PR + RBBB; Duchenne cardiac involvement in 90% by age 18, Becker in 70%; carrier females: DCM in 3rd–5th decade
• FLNC: 0–3%; 97% penetrance >40 years; VAs in 82%; SCD in 12/28 families (frequent); left-dominant arrhythmogenic + DCM; low QRS voltage; ICD Class IIa when LVEF <45%
• RBM20: unknown frequency; malignant VAs; high SCD risk; biventricular involvement
• BAG3: unknown frequency; high penetrance >40 years; worse prognosis with nonsense variants; male sex/↓LVEF/↑LVEDD = worse prognosis; may coexist with skeletal myopathy
• PLN (Phospholamban): 0–12%; founder mutation in Netherlands (R14del); low QRS amplitude, RBBB, loss of inferior R-waves; significant posterolateral free-wall fibrosis in R14del; high SCD risk; ICD Class IIa when NSVT + LVEF <45%
• SCN5A: 0–2%; sinus bradycardia/AF/AV block preceding LVSD; coexists with BrS and/or LQT3; GOF pR222Q variant → severe arrhythmic DCM, responsive to Na-channel blockers not standard HF therapy
• DSP: 1–13%; low QRS voltage; extensive fibrosis may precede LVSD; episodic myocardial injury; cardiocutaneous syndrome (Carvajal AD/AR)
• TMEM43: <1%; founder variant p.S358L in Newfoundland; poor R-wave progression; ICD benefit confirmed; male worse prognosis (4× hospitalization; younger death)
• MYH7: 4%; AV conduction defects + myopathy; early onset
• MYH6: 4%; AV conduction defects + sick sinus syndrome
• TAZ (Tafazzin): X-linked; Barth syndrome — DCM + myopathy + neutropenia + short stature
• Desmosomal genes (DSG2 4–15%, DSC2 unknown, PKP2, JUP): up to 13% of DCM; frequent LV involvement; overlap with ARVC
• ACTC1: <1%; p.Gly247Asp → atrial septal defect + late-onset DCM; p.H175R/Y220H → severe childhood DCM
• LDB3: <1%; associated with LVNC phenotypes

Gene-Specific ECG Patterns for Directed Diagnosis

• LMNA / SCN5A: sinus node dysfunction, AV block — conduction defects precede cardiomyopathy
• DMD / DES: conduction abnormalities
• FLNC / PLN / DSP: low QRS voltage on surface ECG
• DMD: posterolateral Q-wave "pseudonecrosis" pattern (inferolateral pseudoinfarction) — key clue for muscular dystrophy
• TMEM43: poor R-wave progression in precordial leads (predominantly males)
• PLN R14del: RBBB + loss of inferior R-waves + low QRS amplitude

Diagnosis — Pinto 2016 Criteria for At-Risk Relatives

First-degree relatives of DCM index patient should be screened with ECG + echocardiogram starting in childhood, annually through adolescence, every 2–3 years in adults.

Major criteria:

• LVEF 45–50% (borderline-reduced) OR
• LVEDD >2 standard deviations above normal + ≥5 mm below classic DCM threshold

Minor criteria (≥2 Minor = Probable; requires exclusion of non-genetic causes):

• LBBB or AV conduction block
• VAs >100/24h or NSVT ≥120 bpm
• Regional wall motion abnormality
• LGE on CMR
• Endomyocardial biopsy: ultrastructural or inflammatory abnormalities
• Positive cardiac autoantibodies

Diagnostic categories for relatives:

• Definite: Classic DCM criteria (LVEF <45% + LVEDD >2SD+5mm)
• Probable: LVEF 45–50% alone, or ≥2 minor criteria
• Possible: 1 major OR 1 minor criterion — warrants closer follow-up

Diagnosis — DCM vs Athletic Heart Syndrome

• LV dilatation + low-normal LVEF (<55%) in 10–15% of competitive endurance athletes
• Combined ECG + BNP + 24h-Holter + CMR fails to diagnose >30% of mild DCM in athletes
• Exercise echocardiography is superior: inability to increase LVEF >11% OR peak LVEF >63% = >80% sensitivity, >90% specificity for DCM (Millar et al.)
• Practical algorithm (Fig. 3): history (FHx SCD, symptoms) → ECG → exercise echo LVEF response → genetic testing if pathogenic variant found in DCM gene

Risk Stratification — Gene-Specific ICD Indications

• General DCM: ICD for LVEF ≤35% + NYHA II–III after ≥3 months OMT (standard threshold)
• LMNA: ≥2 of (NSVT, LVEF <45%, male sex, non-missense mutation) → Class IIa ICD (validated in n=269 cohort; lmna-risk-vta.fr calculator)
• FLNC: LVEF <45% → Class IIa ICD (12/28 families experienced SCA, mean LVEF 39.6%)
• BAG3: High penetrance >40 years; male sex + ↓LVEF + ↑LVEDD = risk factors; 8/18 carriers reached transplant or death
• PLN R14del: NSVT + LVEF <45% → Class IIa ICD; dual DCM and ARVC phenotype
• TMEM43 p.S358L: ICD demonstrated better survival vs conventional management; males worse
• Non-invasive risk parameters (PVCs, NSVT, late potentials, QTc prolongation) may be relevant in DCM but further studies warranted

Sports Participation — 2020 ESC Sports Cardiology Criteria

• Low-to-moderate intensity recreational exercise: reasonable in all DCM patients regardless of LVEF (in absence of limiting symptoms or exercise-induced VAs)
• LMNA or FLNC genotype: high-intensity exercise PROHIBITED even in phenotype-negative (gene+/phenotype−) individuals — Class III (ESC 2020)
• High-intensity/competitive sports may be considered in asymptomatic individuals IF ALL of the following:
  • LVEF 45–50%
  • No frequent or complex VAs on Holter or exercise testing
  • Absence of LGE on CMR
  • Ability to increase LVEF by 10–15% during exercise
  • No high-risk genotype (LMNA or FLNC)

Genotype-Directed Treatment (Emerging)

• SCN5A pR222Q GOF: Standard HF therapy relatively ineffective; dramatic improvement with sodium-channel-blocking drugs (class 1A/1C agents) — reversal of the arrhythmic DCM phenotype
• LMNA: p38 MAPK inhibitor ARRY-371797 in phase 3 RCT (NCT03439514, REALM-DCM); first genotype-specific RCT in any cardiomyopathy — (Note: subsequent Lancet 2023 data [DCM-Lancet-2023] showed this trial failed to demonstrate benefit)
• TTN: Metabolic alterations (↑cardiac metabolism → sarcomere dysfunction); targeting TTNtv-induced metabolic changes as potential gene-directed prevention strategy
• DMD: CRISPR/Cas9 in vivo genome editing showing dystrophin restoration and cardiac function improvement in dystrophic mice (preclinical)
• iPSC-CM modelling validated for LMNA, DES, TNNT2, PLN, RBM20, TTN, BAG3: disrupted sarcomeres, ↓contractile force, dysfunctional Ca²⁺ regulation; β-blockers and Ca²⁺ antagonists attenuated phenotype in vivo; PLN R14del iPSC-CM studies showed full phenotype reversion with targeted gene correction

Prognostic Markers — Genotype and LVRR

• ~40% of DCM patients achieve significant LVRR with adequate pharmacological and device treatment
• LVRR process requires 6 months–2 years; strongly related to long-term prognosis
• TTN pathogenic variants: associated with increased likelihood of LVRR (Verdonshot et al.; confirmed by dal Ferro et al. — higher LVRR under OMT)
• LMNA mutations: strongly associated with lower LVRR rate
• FLNC, DES, DMD, and cytoskeletal/Z-disk genes: low LVRR rates (dal Ferro et al.)
• Right ventricular dysfunction, functional MR, and LBBB at diagnosis predict prognosis and LVRR likelihood
• "Apparent healing phenomenon": ~15% of DCM patients normalise LV size and function after OMT; most maintain normal function at 10-year follow-up; however, 5% deteriorate again at 15 years (progressive HF, transplantation, or ICD requirement) → lifelong follow-up and medical therapy required even after apparent normalisation

Disease-Modifying Factors and Complex Genetic Architecture

• Large phenotypic heterogeneity driven by: multiple variants in same individual, modifier genes, age, ethnicity, sex, lifestyle
• TTN truncating variants more likely to manifest as DCM phenotype in Europeans vs African-Americans
• Multi-parametric scoring combining genotype + disease-modifying factors represents ideal clinical tool but requires substantial further research

Limitations of the Document

• Narrative review without systematic search methodology or GRADE-level evidence assessment
• Gene frequency data for several genes listed as "unknown" — reflects 2021 state of evidence
• LMNA p38 MAPK trial results were not yet available at time of writing (NCT03439514 was ongoing); subsequent Lancet 2023 data showed the trial failed
• Gene list in Table 2 reflects 2021 position papers; ClinGen reclassifications since then (notably PKP2 disputed for DCM, MYBPC3 limited evidence) are not captured
• Limited representation of ancestry-diverse populations in cited studies

Key Concepts Mentioned

• concepts/Arrhythmogenic-Cardiomyopathy — overlap phenotype (DSP, FLNC, PLN, DSG2)
• concepts/Sports-Cardiology-SDM — 2020 ESC criteria for DCM sports eligibility
• concepts/Genetic-Testing-in-Cardiomyopathy — panel testing, family screening protocols
• concepts/Cascade-Family-Screening — Pinto 2016 relative diagnostic criteria
• concepts/VA-Risk-Stratification-DCM — gene-specific ICD thresholds
• concepts/Late-Gadolinium-Enhancement — LGE as diagnostic and prognostic marker
• concepts/ClinGen-Gene-Disease-Validity — gene-disease validity curation referenced

Key Entities Mentioned

• entities/DCM — primary subject; Pinto criteria, LVRR data, gene table, exercise echo, sports criteria
• entities/LMNA — accelerated disease, AV block, LVRR data, p38 MAPK trial, sports prohibition
• entities/TTN — most common; higher LVRR rates; metabolic targeting
• entities/PLN — R14del ICD threshold; DCM+ARVC overlap; low QRS
• entities/FLNC — ICD Class IIa at LVEF <45%; high-intensity sports prohibition even gene+/phenotype−
• entities/SCN5A — pR222Q GOF → Na-channel blocker response

Wiki Pages Updated

• wiki/sources/dcm-precision-hfreview-2022 — created
• wiki/sourceindex.md — entry added
• entities/DCM — source_count updated; Pinto 2016 relative diagnostic criteria; exercise echo LVEF >11% thresholds; genotype-specific LVRR + apparent healing; sports criteria for high-intensity eligibility