VA Risk Stratification in Dilated Cardiomyopathy

Definition

Risk stratification for ventricular arrhythmias (VA) and sudden cardiac death (SCD) in non-ischaemic dilated cardiomyopathy (DCM) is the process of identifying which patients are at high enough arrhythmic risk to benefit from implantable cardioverter-defibrillator (ICD) implantation. LVEF ≤35% has been the traditional threshold, but this criterion — derived from ischaemic disease — is increasingly recognized as insufficient for non-ischaemic DCM.

Key Concepts

Annual Event Rate and Baseline Risk

• The crude annual rate of sustained VA (sustained VT, VF, resuscitated SCD, or appropriate ICD discharge) in DCM is approximately 4.5% (meta-analysis, 55 studies, 11,451 patients, mean follow-up 3.7 years). (sources/VA-DCM-Sammani-2020, high)
• This event rate underscores the importance of ICD consideration in this population. (sources/VA-DCM-Sammani-2020, high)

Pooled Risk Predictors (Meta-Analysis Data)

Key pooled hazard ratios from the largest VA-specific DCM meta-analysis (Sammani 2020):

• LGE presence on CMR: HR 5.55 [4.02–7.67] — strongest single predictor (sources/VA-DCM-Sammani-2020, high)
• Prior sustained VA: HR 4.15 [1.32–13.02] — high heterogeneity (I²=93%) (sources/VA-DCM-Sammani-2020, high)
• Hypertension: HR 1.95 [1.26–3.00] (sources/VA-DCM-Sammani-2020, high)
• LVEF per 10% decrease (echocardiography only): HR 1.45 [1.19–1.78] — significant only when measured by echo, not when CMR and echo are pooled (sources/VA-DCM-Sammani-2020, high)
• LV dilatation (LVEDV/LVESV per 10 mL/m²): HR 1.10 for both parameters — small but significant (sources/VA-DCM-Sammani-2020, high)
• Younger age (per 10-year increase): HR 0.82 [0.74–1.00] — younger age confers higher risk (sources/VA-DCM-Sammani-2020, high)

Non-Pooled Predictors (Systematic Review Signal)

• Non-sustained VT: 9 of 14 studies reported significantly increased arrhythmic risk; could not be pooled due to missing HRs. Supported by AMIOVIRT and DEFINITE trial populations. (sources/VA-DCM-Sammani-2020, high)
• T-wave alternans (TWA): HR 6.5 [2.46–17.14]; clinical utility limited by poor standardization. (sources/VA-DCM-Sammani-2020, high)
• Genetic mutations — PLN, LMNA, FLNC: Each independently associated with VA risk in DCM; FLNC truncating variants associated with VA/SCD in 82% of patients in cohort studies. (sources/VA-DCM-Sammani-2020, high)

Non-Significant Predictors

• Male sex (trend only), NYHA class, family history of DCM, AF, LBBB, QRS duration, LVEF <30% or <35% as categorical thresholds, signal-averaged ECG, standard biomarkers (BNP, ANP, eGFR). (sources/VA-DCM-Sammani-2020, high)

Diastolic Dysfunction as LVEF-Independent Arrhythmic Risk Predictor

• Grade III diastolic dysfunction (restrictive pattern) confers HR 3.52 (95% CI 2.00–6.22; P<0.001) for arrhythmic death or RCA in ischaemic and dilated cardiomyopathy, independent of LVEF. (sources/arrhythmia-diastolic-circep-2020, rating: medium)
• This association persists in both LVEF ≤35% (P=0.001) and LVEF >35% (P=0.014) subgroups, with 41% cumulative AD/RCA risk at 8 years in grade III patients with LVEF >35% — identifying a high-risk group missed by standard primary prevention ICD criteria. (sources/arrhythmia-diastolic-circep-2020, rating: medium)
• Cardiomyopathy aetiology (ischaemic vs. dilated) was not a significant confounder — the grade III effect was aetiology-independent. (sources/arrhythmia-diastolic-circep-2020, rating: medium)
• Grade I dysfunction was independently protective (HR 0.41; P=0.002); grade II was neutral. No patient with normal diastolic function died of arrhythmic death over 8 years. (sources/arrhythmia-diastolic-circep-2020, rating: medium)
• Caveat: Pilot study (n=210, single centre); diastolic grading used pre-2016 ASE criteria. Not included in current ESC/AHA VA risk stratification frameworks. See concepts/LV-Diastolic-Function for grading methodology.

LVEF Limitations

• The standard ICD threshold of LVEF ≤35% was established by SCD-HeFT (Bardy et al., NEJM 2005; n=2,521; 48% non-ischaemic; LVEF ≤35%; median 45.5 months): ICD HR 0.77 (P=0.007) with no aetiology interaction (P=0.68), confirming primary prevention benefit applies equally to non-ischaemic HF. However, the subsequent DANISH trial (n=1,116; LVEF ≤35%; median 67.6 months; enrolled 2008–2014, after ARNi availability) showed no all-cause mortality benefit in NICM (HR 0.87; P=0.28), despite halving SCD (HR 0.50; P=0.005); benefit was age-dependent (HR 0.64 in age <68 subgroup, P=0.01). The discordance between SCD-HeFT (ACEi + BB background only) and DANISH (partial ARNi era) may reflect progressive GDMT improvements independently reducing arrhythmic substrate. (sources/icd-hfref-scdheft-nejm-2005, sources/icd-nicm-danish-nejm-2016, sources/VA-SCD-ESC-2022, sources/VA-DCM-Sammani-2020, high)
• LVEF as a continuous echocardiographic variable predicts VA (HR 1.45 per 10%), but categorical cutoffs (LVEF <30% or <35%) are non-significant in pooled analysis, suggesting LVEF should not be the sole criterion. (sources/VA-DCM-Sammani-2020, high)
• Genotype-specific ICD criteria now extended to LVEF 35–50% range for high-risk genotypes (PLN, LMNA, FLNC, RBM20) with additional risk factors. (sources/VA-SCD-ESC-2022)

Multi-Parameter Risk Stratification (Current Guidelines)

• ESC 2022 multi-risk-factor ICD threshold (Class IIa): ICD in DCM/HNDCM with LVEF <50% AND ≥2 of: syncope, LGE on CMR, inducible SMVT at PES, pathogenic mutation in LMNA/PLN/FLNC/RBM20. (sources/VA-SCD-ESC-2022)
• ESC CMP 2023: Genotype-guided ICD considered in PLN, LMNA, FLNC, RBM20, DES, TMEM43 carriers with LVEF >35% and additional risk factors (NSVT, syncope, LGE). (sources/esc-cmp-2023)
• Genotype-specific calculators: LMNA risk-VTA calculator (lmna-risk-vta.fr); PLN p.Arg14del risk calculator endorsed for ICD decisions in respective mutation carriers. (sources/esc-cmp-2023)

Future Directions

• A dedicated DCM-VA risk calculator analogous to HCM Risk-SCD and the ARVC risk model is needed.
• Such a model should incorporate: younger age, hypertension, prior (non-)sustained VA, LVEF (echo), LV dilatation, LGE, genetic mutations (PLN, LMNA, FLNC), and sex.
• Competing risk analysis (VA vs. HF-related outcomes) is essential for accurate real-world risk estimation. (sources/VA-DCM-Sammani-2020, high)

Contradictions / Open Questions

• LVEF echo vs. CMR discordance: LVEF predicts VA only when measured by echocardiography (HR 1.45 significant), but not when CMR and echo are pooled (HR 1.30 non-significant). The modality-specific difference may reflect population-selection differences or systematic underestimation of LVEF by echo in DCM. This has practical implications for how LVEF thresholds are applied in ICD guidelines. (sources/VA-DCM-Sammani-2020, high)
• ESC 2022 dual ICD thresholds: Two Class IIa criteria (standard LVEF ≤35% and multi-factor LVEF <50%) coexist without guidance on which applies when a patient qualifies under both. (sources/VA-SCD-ESC-2022)
• Quality of evidence is moderate: Crude (unadjusted) HRs are pooled; confounder adjustment was limited in most primary studies. The true independent contribution of each risk factor remains uncertain. (sources/VA-DCM-Sammani-2020, high)
• Competing risks not modelled: DCM patients face both arrhythmic death and HF-related death/transplantation. Competing risks modelling may change individual risk estimates substantially. (sources/VA-DCM-Sammani-2020, high)
• Diastolic grade III as an additional ICD selection criterion (LVEF >35%): Current multi-parameter frameworks (LGE, genotype, LVEF, NSVT, syncope) do not incorporate diastolic grading. The Pezawas pilot study (n=210) found 41% cumulative AD/RCA risk in LVEF >35% patients with grade III dysfunction — comparable to conventional high-risk cohorts. The data are insufficient for guideline incorporation, and the pre-2016 diastolic grading criteria limit direct translation. Prospective validation in large cohorts using contemporary ASE diastolic grading is needed. (sources/arrhythmia-diastolic-circep-2020, rating: medium)

Connections

• Related to entities/DCM
• Related to entities/LMNA
• Related to entities/PLN
• Related to entities/FLNC
• Related to entities/NDLVC
• Related to concepts/Late-Gadolinium-Enhancement
• Related to concepts/Sudden-Cardiac-Death
• Related to concepts/HCM-Risk-SCD
• Related to concepts/Cascade-Family-Screening
• Related to concepts/LV-Diastolic-Function — grade III diastolic dysfunction as LVEF-independent arrhythmic predictor

Sources

• sources/VA-DCM-Sammani-2020
• sources/VA-SCD-ESC-2022
• sources/esc-cmp-2023
• sources/arrhythmia-diastolic-circep-2020
• sources/icd-nicm-danish-nejm-2016
• sources/icd-hfref-scdheft-nejm-2005