Theotokis, Pantazis

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is an important cause of sudden cardiac death associated with heterogeneous phenotypes, but there is no systematic framework for classifying morphology or assessing associated risks. Here, we quantitatively survey genotype-phenotype associations in HCM to derive a data-driven taxonomy of disease expression. METHODS: We enrolled 436 patients with HCM (median age, 60 years; 28.8% women) with clinical, genetic, and imaging data. An independent cohort of 60 patients with HCM from Singapore (median age, 59 years; 11% women) and a reference population from the UK Biobank (n=16 691; mean age, 55 years; 52.5% women) were also recruited. We used machine learning to analyze the 3-dimensional structure of the left ventricle from cardiac magnetic resonance imaging and build a tree-based classification of HCM phenotypes. Genotype and mortality risk distributions were projected on the tree. RESULTS: Carriers of pathogenic or likely pathogenic variants for HCM had lower left ventricular mass, but greater basal septal hypertrophy, with reduced life span (mean follow-up, 9.9 years) compared with genotype negative individuals (hazard ratio, 2.66 [95% CI, 1.42–4.96]; P <0.002). Four main phenotypic branches were identified using unsupervised learning of 3-dimensional shape: (1) nonsarcomeric hypertrophy with coexisting hypertension; (2) diffuse and basal asymmetrical hypertrophy associated with outflow tract obstruction; (3) isolated basal hypertrophy; and (4) milder nonobstructive hypertrophy enriched for familial sarcomeric HCM (odds ratio for pathogenic or likely pathogenic variants, 2.18 [95% CI, 1.93–2.28]; P =0.0001). Polygenic risk for HCM was also associated with different patterns and degrees of disease expression. The model was generalizable to an independent cohort (trustworthiness, M 1 : 0.86–0.88). CONCLUSIONS: We report a data-driven taxonomy of HCM for identifying groups of patients with similar morphology while preserving a continuum of disease severity, genetic risk, and outcomes. This approach will be of value in understanding the causes and consequences of disease diversity.

Background: Acute myocarditis is an inflammatory condition that may herald the onset of dilated cardiomyopathy (DCM) or arrhythmogenic cardiomyopathy (ACM). We investigated the frequency and clinical consequences of DCM and ACM genetic variants in a population-based cohort of patients with acute myocarditis. Methods: This was a population-based cohort of 336 consecutive patients with acute myocarditis enrolled in London and Maastricht. All participants underwent targeted DNA sequencing for well-characterized cardiomyopathy-associated genes with comparison to healthy controls (n=1053) sequenced on the same platform. Case ascertainment in England was assessed against national hospital admission data. The primary outcome was all-cause mortality. Results: Variants that would be considered pathogenic if found in a patient with DCM or ACM were identified in 8% of myocarditis cases compared with <1% of healthy controls ( P =0.0097). In the London cohort (n=230; median age, 33 years; 84% men), patients were representative of national myocarditis admissions (median age, 32 years; 71% men; 66% case ascertainment), and there was enrichment of rare truncating variants (tv) in ACM-associated genes (3.1% of cases versus 0.4% of controls; odds ratio, 8.2; P =0.001). This was driven predominantly by DSP -tv in patients with normal LV ejection fraction and ventricular arrhythmia. In Maastricht (n=106; median age, 54 years; 61% men), there was enrichment of rare truncating variants in DCM-associated genes, particularly TTN -tv, found in 7% (all with left ventricular ejection fraction <50%) compared with 1% in controls (odds ratio, 3.6; P =0.0116). Across both cohorts over a median of 5.0 years (interquartile range, 3.9–7.8 years), all-cause mortality was 5.4%. Two-thirds of deaths were cardiovascular, attributable to worsening heart failure (92%) or sudden cardiac death (8%). The 5-year mortality risk was 3.3% in genotype-negative patients versus 11.1% for genotype-positive patients ( P adjusted =0.08). Conclusions: We identified DCM- or ACM-associated genetic variants in 8% of patients with acute myocarditis. This was dominated by the identification of DSP -tv in those with normal left ventricular ejection fraction and TTN -tv in those with reduced left ventricular ejection fraction. Despite differences between cohorts, these variants have clinical implications for treatment, risk stratification, and family screening. Genetic counseling and testing should be considered in patients with acute myocarditis to help reassure the majority while improving the management of those with an underlying genetic variant.

Background: Myocarditis may predispose to dilated cardiomyopathy (DCM) and sudden cardiac death (SCD). Familial data indicate a potential genetic susceptibility shared with arrhythmogenic cardiomyopathy (ACM). We present the first large-scale genotype-phenotype study of adults with acute myocarditis. Methods: A cohort comprising 336 consecutive patients with acute myocarditis was enrolled in London and Maastricht. All participants underwent targeted DNA sequencing for well-characterised cardiomyopathy-associated genes. The burden of rare protein altering variants (PAV) in ACM genes, DCM genes, and TTN specifically, were compared with local healthy controls sequenced on the same platform (n=1053). Case ascertainment was assessed against national hospital admission data. Results: We identified rare protein-altering variants in 23% of cases compared to 16% in controls (Δ+6.8%; p=0.021), with rare truncating variants (tv) in 6% of cases compared to <1% of controls ((Δ+5%; p=0.0097). In London (n=230; median left ventricular ejection fraction (LVEF) 63%), which was representative of national myocarditis admissions, 4.8% of cases carried rare tv, particularly within ACM genes (3% cases vs 0% controls; odds ratio 8.2; p=0.001). This was predominantly driven by desmoplakin (DSP)-tv in patients with normal LVEF. In Maastricht (n=106; median LVEF 30%), rare tv in DCM genes were enriched, particularly TTN-tv found in 7% (all with LVEF<50%) compared to 1% in controls (OR 3.6; p=0.0116). During a median follow-up of 1.9 years, all-cause mortality was greatest in those with a DCM variant (18% vs 4% with no variant; OR 5.0; p=0.004). Conclusion: We identified enrichment of cardiomyopathy gene variants in acute myocarditis patients, dominated by DSP-tv in those with normal LVEF and TTN-tv in those with reduced LVEF. Incorporation of genetic testing may be beneficial to identify such high-risk individuals and guide family screening in acute myocarditis patients.