[Show abstract][Hide abstract] ABSTRACT: Type 1 long QT syndrome (LQT1) is a common type of cardiac channelopathy associated with loss-of-function mutations of KCNQ1. Currently there is a lack of drugs that target the defected slowly activating delayed rectifier potassium channel (IKs). With LQT1 patient-specific human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs), we tested the effects of a selective IKs activator ML277 on reversing the disease phenotypes.
A LQT1 family with a novel heterozygous exon 7 deletion in the KCNQ1 gene was identified. Dermal fibroblasts from the proband and her healthy father were reprogrammed to hiPSCs and subsequently differentiated into hiPSC-CMs.
Compared with the control, LQT1 patient hiPSC-CMs showed reduced levels of wild type KCNQ1 mRNA accompanied by multiple exon skipping mRNAs and a ~50% reduction of the full length Kv7.1 protein. Patient hiPSC-CMs showed reduced IKs current (tail current density at 30 mV: 0.33 ± 0.02 vs. 0.92 ± 0.21, P < 0.05) and prolonged action potential duration (APD) (APD 50 and APD90: 603.9 ± 39.2 vs. 319.3 ± 13.8 ms, P < 0.005; and 671.0 ± 41.1 vs. 372.9 ± 14.2 ms, P < 0.005). ML277, a small molecule recently identified to selectively activate KV7.1, reversed the decreased IKs and partially restored APDs in patient hiPSC-CMs.
From a LQT1 patient carrying a novel heterozygous exon7 deletion mutation of KCNQ1, we generated hiPSC-CMs that faithfully recapitulated the LQT1 phenotypes that are likely associated with haploinsufficiency and trafficking defect of KCNQ1/Kv7.1. The small molecule ML277 restored IKs function in hiPSC-CMs and could have therapeutic value for LQT1 patients.
[Show abstract][Hide abstract] ABSTRACT: With the advent of affordable and comprehensive sequencing technologies, access to molecular genetics for clinical diagnostics and research applications is increasing. However, variant interpretation remains challenging, and tools that close the gap between data generation and data interpretation are urgently required. Here we present a transferable approach to help address the limitations in variant annotation.
We develop a network of Bayesian logistic regression models that integrate multiple lines of evidence to evaluate the probability that a rare variant is the cause of an individual's disease. We present models for genes causing inherited cardiac conditions, though the framework is transferable to other genes and syndromes.
Our models report a probability of pathogenicity, rather than a categorisation into pathogenic or benign, which captures the inherent uncertainty of the prediction. We find that gene- and syndrome-specific models outperform genome-wide approaches, and that the integration of multiple lines of evidence performs better than individual predictors. The models are adaptable to incorporate new lines of evidence, and results can be combined with familial segregation data in a transparent and quantitative manner to further enhance predictions. Though the probability scale is continuous, and innately interpretable, performance summaries based on thresholds are useful for comparisons. Using a threshold probability of pathogenicity of 0.9, we obtain a positive predictive value of 0.999 and sensitivity of 0.76 for the classification of variants known to cause long QT syndrome over the three most important genes, which represents sufficient accuracy to inform clinical decision-making. A web tool APPRAISE [http://www.cardiodb.org/APPRAISE] provides access to these models and predictions.
Our Bayesian framework provides a transparent, flexible and robust framework for the analysis and interpretation of rare genetic variants. Models tailored to specific genes outperform genome-wide approaches, and can be sufficiently accurate to inform clinical decision-making.
Genome Medicine 12/2015; 7(1):5. DOI:10.1186/s13073-014-0120-4 · 5.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objectives:
This study used high-resolution 3-dimensional cardiac magnetic resonance to define the anatomical and functional left ventricular (LV) properties associated with increasing systolic blood pressure (SBP) in a drug-naïve cohort.
LV hypertrophy and remodeling occur in response to hemodynamic stress but little is known about how these phenotypic changes are initiated in the general population.
In this study, 1,258 volunteers (54% women, mean age 40.6 ± 12.8 years) without self-reported cardiovascular disease underwent 3-dimensional cardiac magnetic resonance combined with computational modeling. The relationship between SBP and wall thickness (WT), relative WT, end-systolic wall stress (WS), and fractional wall thickening were analyzed using 3-dimensional regression models adjusted for body surface area, sex, race, age, and multiple testing. Significantly associated points in the LV model (p < 0.05) were identified and the relationship with SBP reported as mean β coefficients.
There was a continuous relationship between SBP and asymmetric concentric hypertrophic adaptation of the septum and anterior wall that was associated with normalization of wall stress. In the lateral wall an increase in wall stress with rising SBP was not balanced by a commensurate hypertrophic relationship. In normotensives, SBP was positively associated with WT (β = 0.09) and relative WT (β = 0.07) in the septal and anterior walls, and this regional hypertrophic relationship was progressively stronger among pre-hypertensives (β = 0.10) and hypertensives (β = 0.30).
These findings show that the precursors of the hypertensive heart phenotype can be traced to healthy normotensive adults and that an independent and continuous relationship exists between adverse LV remodeling and SBP in a low-risk population. These adaptations show distinct regional variations with concentric hypertrophy of the septum and eccentric hypertrophy of the lateral wall, which challenge conventional classifications of LV remodeling.
[Show abstract][Hide abstract] ABSTRACT: Atlases encode valuable anatomical and functional information from a population. In this work, a bi-ventricular cardiac atlas was built from a unique data set, which consists of high resolution cardiac MR images of 1000+ normal subjects. Based on the atlas, statistical methods were used to study the variation of cardiac shapes and the distribution of cardiac motion across the spatio-temporal domain. We have shown how statistical parametric mapping (SPM) can be combined with a general linear model to study the impact of gender and age on regional myocardial wall thickness. Finally, we have also investigated the influence of the population size on atlas construction and atlas-based analysis. The high resolution atlas, the statistical models and the SPM method will benefit more studies on cardiac anatomy and function analysis in the future.
Medical image analysis 09/2015; 26(1):133-145. DOI:10.1016/j.media.2015.08.009 · 3.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Human mutations that truncate the massive sarcomere protein titin [TTN-truncating variants (TTNtvs)] are the most common genetic cause for dilated cardiomyopathy (DCM), a major cause of heart failure and premature death. Here we show that cardiac microtissues engineered from human induced pluripotent stem (iPS) cells are a powerful system for evaluating the pathogenicity of titin gene variants. We found that certain missense mutations, like TTNtvs, diminish contractile performance and are pathogenic. By combining functional analyses with RNA sequencing, we explain why truncations in the A-band domain of TTN cause DCM, whereas truncations in the I band are better tolerated. Finally, we demonstrate that mutant titin protein in iPS cell–derived cardiomyocytes results in sarcomere insufficiency, impaired responses to mechanical and β-adrenergic stress, and attenuated growth factor and cell signaling activation. Our findings indicate that titin mutations cause DCM by disrupting critical linkages between sarcomerogenesis and adaptive remodeling.
[Show abstract][Hide abstract] ABSTRACT: sec> Introduction As gene sequencing becomes more widespread, the clinical implications of incidental findings in patients’ genomes are becoming more complex. We identified healthy volunteers with mutations known to cause penetrant, Mendelian aortic disease, and examined the association of these mutations with aortic pulse wave velocity (PWV); a key marker of cardiovascular risk and aortic elastic function. Methods We recruited 476 healthy volunteers with no known history of cardiovascular risk factors or disease for aortic phenotyping and gene sequencing. We measured aortic arch pulse wave velocity derived from Cardiovascular MRI (CMR) using ArtFun software and performed whole exome sequencing (Illumina HiSeq 2000). Sequence was alignedto hg19 reference using BWA v0.7.10 and variants were called using GATK and validated using IGV. Variants that are presumed causative for aortic disease were prioritised using HGMD and were further annotated by literature review. A binary variable, "AOV status" reflected the presence or absence of a variant linked with aortopathy by this approach. Statistical analysis was performed using linear regression modelling, Mann-Whitney U tests and bootstrapping in R. For Mann-Whitney U tests, we used age-corrected PWV [=PWV/log (Age)]. Results 17 of our healthy volunteers (3%) had previously reported pathogenic mutations in seven aortopathy genes ( COL1A2 , COL3A1 , FBN1 , MYH11 , MYLK , TGFBR1 and TGFBR2 ; see Table 1). Abstract 175 Table 1 Mutations in our cohort linked with aortic disease in HGMD Gene Base substitution Amino acid substitution Number in cohort Minor Allele Frequency (ExAC,%) Disease association Evidence of pathogenicity COL1A2 c.2123G >A p. Arg708Gln 1 0.06 Marfan Patient + affected father; functional confirmation COL3A1 c.2002C >A p. Pro668Thr 3 0.17 Ehlers Danlos Single case FBN1 c.7379A >G p. Lys2460Arg 1 0.007 Marfan Single case c.6700G >A p. Val2234Met 1 0.079 Marfan Single case c.3422C >T p. Pro1141Leu 1 0.072 Marfan Single case MYH11 c.4604G >A p. Arg1535Gln 2 0.23 FTAA Single case MYLK c.4195G >A p. Glu1399Lys 1 0.044 FTAA Single case c.3637G >A p. Val1213Met 2 0.010 FTAA Single case TGFBR1 c.1433A >G p. Asn478Ser 1 0.028 Loeys Dietz Single case TGFBR2 c.1119G >A p. Met373Ile 1 0.139 Loeys Dietz Single case c.1159G >A p. Val387Met 2 0.116 Loeys Dietz 2 family members; functional confirmation c.1657T >A p. Ser553Thr 1 0.14 Loeys Dietz 2 separate case series found variant Three mutations (in 4 individuals; 0.8% of our cohort) had evidence for pathogenicity (eg family linkage analysis) beyond just a single case report; two in TGFBR2 (3 individuals) and one in COL1A2 . These four subjects had significantly higher aPWVs than control cases (Mann-Whitney U test; U=235, p = 0.01; see Figure 1 ), and than those cases where the evidence for variant pathogenicity was limited (p = 0.02). Abstract 175 Figure 1 Healthy volunteers with confirmed pathogenic variants have higher aPWVs than controls Linear regression modelling of PWV was significantly improved by the addition of AOV status (ANOVA of nested linear models; p = 0.03; F=5.56(1), R2=0.07; multiple R2=0.57; p < 0.001), and this improvement was more evident with bootstrapped linear regression (p < 0.01). Stepwise model selection by AIC prioritised AOV status in the final linear model, which included log (age), gender, MAP, pulse rate, body surface area and fat mass. Discussion It is not unusual to find “disease-causing” variants in an apparently healthy population. Sometimes this is used to argue against the pathogenicity of a particular variant. However, our results imply that some of these “healthy” individuals may have penetrant aortic disease but of limited expressivity. These individuals may have increased risk of cardiovascular events, and so-called “spontaneous” aortic aneurysm and dissection. This finding therefore has implications for genetic counselling, as well as for the conduct of gene sequencing studies. </sec
[Show abstract][Hide abstract] ABSTRACT: sec> Introduction Dilated cardiomyopathy (DCM) is a genetically heterogenous condition with mutations reported in at least 50 associated genes.1 Our consortium has demonstrated the presence of truncating mutations in the giant sarcomeric gene titin (TTN) in up to 27% of DCM2 making this the commonest genetic cause of DCM. Here we conducted a comprehensive analysis of the frequency of rare coding variants in cardiomyopathy genes in DCM patients and ethnically-matched healthy controls. Methods We sequenced 64 cardiomyopathy genes in 651 individuals, comprising 234 patients referred for prospective evaluation of DCM with cardiac MRI (54 ± 14 yrs at scan, 70.5% males), 98 end-stage DCM (39 ± 16 yrs on date of transplant/left-ventricular assist device implantation, 83.7% males), and 319 prospectively recruited adult healthy volunteers (HVOL, 42 ± 14 yrs at scan, 46.1% males), who underwent detailed phenotyping with cardiac MRI. Next-generation targeted exon sequencing was performed on the SOLiD 5500xl platform. Variant calling was performed using Lifescope v2.5.1. Data were mapped to the Hg19 (GRCh37) human genome reference. Caucasian ethnicity was confirmed using Principal Component Analysis. Burden testing for potentially disease-causing variation was performed on each gene. Results DCM patients were enriched for novel protein-altering variants in 28 genes ( Table 1 : top 7 genes), but only 5 achieved nominal significance. Truncating variants in TTN (TTNtv) remained significant after multiple testing correction (12% DCM, 1.9% controls, p = 8.1 × 10–6). Abstract 76 Table 1 Top 7 genes with novel and protein altering variants in DCM compared to controls Gene tested DCM n (%) HVOL n (%) P value 1-tailed TTNtv
TTNns 40 (12.0)
85 (25.6) 6 (1.9)
82 (25.7) 1.26 × 10–7 * 0.55 LMNA 8 (2.4) 0 0.004 DSP 12 (3.6) 4 (1.3) 0.04 RBM20 13 (3.9) 5 (1.6) 0.05 PKP2 10 (3) 3 (0.9) 0.05 MYH7 12 (3.6) 5 (1.6) 0.08 TNNT2 4 (1.2) 0 0.06 * Significant after multiple testing correction, p < 0.0008 Rare variation in SCN5A and MYH6, previously reported to play a key role in DCM, were not enriched in DCM (SCN5A – 2.1% DCM, 2.8% controls, p = 0.80; MYH6 –0.9% DCM, 2.2% controls, p = 0.95) and nor were non-synonymous SNPs in TTN (TTNns, 25.6% DCM, 25.7% controls, p = 0.55). Importantly, an additive effect of variation in multiple DCM genes on DCM risk was identified using logistic regression models (p = 5.7 × 10 x -4), demonstrating a multi-genic basis for DCM in some cases. Conclusions To the best of our knowledge, this is the first comprehensive study of the genetic architecture of DCM compared to an ethnically-matched healthy control cohort. The majority of genes reported to contain rare variants in DCM have similar burdens of variation in controls. Some variants may contribute to disease, but excluding TTNtv the majority of such variants are uninterpretable in the absence of functional or segregation data. References
Mestroni L, Taylor MR. Genetics and genetic testing of dilated cardiomyopathy: a new perspective. Discov Med. 2013;15(80):43-9
Herman DS, Lam L, Taylor MR, Wang L, Teekakirikul P, Christodoulou D, et al . Truncations of titin causing dilated cardiomyopathy. N Engl J Med. 2012;366(7):619-28 </sec
[Show abstract][Hide abstract] ABSTRACT: sec> Introduction TTN truncating variants (TTNtv) cause severe dilated cardiomyopathy (DCM), but sometimes occur in healthy individuals, posing significant challenges for the interpretation of these variants in an era of accessible genome sequencing. The mechanism by which TTNtv impact clinical outcomes is poorly understood. Methods Here, we integrated the power of quantitative cardiac MRI and capacity of next generation sequencing to assess the relationship between TTN genotype and cardiac phenotype. We sequenced TTN in 4,440 subjects including 308 healthy volunteers, 3,603 Framingham Heart Study (FHS) and Jackson Heart Study (JHS) participants, 374 prospective, unselected DCM cases and 155 end-stage retrospective DCM cases including 84 for whom left ventricular (LV) tissue was available for RNA and protein studies. Results TTNtv were identified in 1.4% of controls (healthy volunteers, FHS and JHS participants), in 13% of unselected and 22% of end-stage DCM cases (OR 16.6, P = 4.8 × 10–45, DCM vs controls). More than 45% of controls have at least one rare TTN non-synonymous SNP (nsSNP). Rare and novel TTN nsSNPs were not enriched in DCM, either alone or in combination with a TTNtv ( P = 0 .8 (38.85% in DCM vs 38.24% in controls) suggesting that TTN nsSNPs are not an important cause of DCM. To improve TTN transcript annotations, we determined average cardiac TTN exon usage de novo from RNA-sequencing. TTNtv in DCM cases were enriched in highly utilised exons and isoforms (P = 2.5 × 10–4) compared to controls. We estimate that TTNtv in highly utilised exons have >93% probability of pathogenicity (likelihood ratio 14) in DCM cases. TTNtv-positive DCM patients had more depressed LV ejection fraction (LVEF:P = 0.02), thinner LV walls (P < 0.02), and a higher incidence of sustained ventricular tachycardia (P = 0.001). C-terminus TTNtv were associated with lower LVEF vs N-terminus (β = -18 ± 7%, p = 0.006) and were more common in end-stage disease. No change was detected in total TTN mRNA or protein levels in TTNtv-positive hearts. Conclusion TTNtv are the most common cause of DCM. TTN nsSNPs are not an important cause of DCM in the absence of other discriminating features. Incorporation of variant position and exon-specific expression improves interpretation of TTNtv. Most individuals with TTNtv do not develop DCM, but TTNtv in highly utilised, particularly distal exons commonly cause DCM with severely impaired LV function and life-threatening ventricular arrhythmias, likely through dominant-negative mechanisms. In DCM patients, presence and position of TTNtv may aid prognostication and management. Abstract C Figure 1 TTNtv and survival in DCM. Outcomes in unselected DCM patients with (red) and without (blue) TTNtv. (Left) Age censored at adverse event (death, cardiac transplant or left-ventricular assist device (LVAD)) or at age 70 years. (Right) Adverse events after enrollment, to control for ascertainment (interval censored from time of enrollment to age 70 years or adverse event). Event free survival is reduced in TTNtv-positive DCM ( P = 0.015) as a result of faster disease progression. A trend to younger presentation (Table 2), and worse outcomes after enrollment ( P = 0.05) combine to give reduced survival overall </sec
[Show abstract][Hide abstract] ABSTRACT: sec> The titingene ( TTN ) is a major determinant of myocardial function, its importance in both familial and ‘idiopathic’ Dilated Cardiomyopathy (DCM) has recently been ascertained. In some instances a second genetic mutation or a physiological perturbation (e.g. pregnancy) may reveal otherwise latent TTN mutation effects. We hypothesise that patients with pronounced LV dysfunction following MI, when controlling for infarct parameters and coronary anatomy, may have a high burden of TTN truncating variants (TTNtvs). We studied a large cohort of post-MI patients prospectively recruited at the Royal Brompton and Harefield NHS Foundation Trust. Gadolinium-enhanced Cardiac Magnetic Resonance was used to characterise cardiac dimensions, function and tissue properties. The size and thickness of MI, wall motion and number of hibernating segments were quantified by two experts blinded to genotype using a standard 17-segment model. Targeted re-sequencing of TTN and other key DCM genes was performed. Genetic variation in DCM genes in 530ethnically matchedhealthy volunteers along with public repositories was used for variant annotation and comparison. Our initial analyses show that out of the 336 post-MI patients, nine (2.7%) had a TTNtv. As hypothesised, TTNtv were significantly enriched in patients with LV ejection fraction (LVEF) <35% (4.6% vs 1.4%, p = 0.01). Patients with a TTNtv had a significantly lower LVEF than those without (31.2 ± 13.9% vs 41.2 ± 14.7%; p = 0.026) Regression models taking into account cardiac, non-cardiac and genetic covariates are in process. These data identify a novel role of large effect size for TTNtv , in post-MI systolic dysfunction. Based on these findings it will be important to explore if genetic stratification of the post-MI patient can inform medical or revascularisation strategies. </sec
[Show abstract][Hide abstract] ABSTRACT: Introduction TTN truncating variants (TTNtv) cause severe dilated cardiomyopathy (DCM), but sometimes occur in healthy individuals, posing significant challenges for the interpretation of these variants in an era of accessible genome sequencing. The mechanism by which TTNtv impact clinical outcomes is poorly understood.
Methods Here, we integrated the power of quantitative cardiac MRI and capacity of next generation sequencing to assess the relationship between TTN genotype and cardiac phenotype. We sequenced TTN in 4,440 subjects including 308 healthy volunteers, 3,603 Framingham Heart Study (FHS) and Jackson Heart Study (JHS) participants, 374 prospective, unselected DCM cases and 155 end-stage retrospective DCM cases including 84 for whom left ventricular (LV) tissue was available for RNA and protein studies.
Results TTNtv were identified in 1.4% of controls (healthy volunteers, FHS and JHS participants), in 13% of unselected and 22% of end-stage DCM cases (OR 16.6, P = 4.8 × 10–45, DCM vs controls). More than 45% of controls have at least one rare TTN non-synonymous SNP (nsSNP). Rare and novel TTN nsSNPs were not enriched in DCM, either alone or in combination with a TTNtv (P = 0.8 (38.85% in DCM vs 38.24% in controls) suggesting that TTN nsSNPs are not an important cause of DCM. To improve TTN transcript annotations, we determined average cardiac TTN exon usage de novo from RNA-sequencing. TTNtv in DCM cases were enriched in highly utilised exons and isoforms (P = 2.5 × 10–4) compared to controls. We estimate that TTNtv in highly utilised exons have >93% probability of pathogenicity (likelihood ratio 14) in DCM cases. TTNtv-positive DCM patients had more depressed LV ejection fraction (LVEF: P = 0.02), thinner LV walls (P < 0.02), and a higher incidence of sustained ventricular tachycardia (P = 0.001). C-terminus TTNtv were associated with lower LVEF vs N-terminus (β=–18 ± 7%, p = 0.006) and were more common in end-stage disease. No change was detected in total TTN mRNA or protein levels in TTNtv-positive hearts.
Conclusion TTNtv are the most common cause of DCM. TTN nsSNPs are not an important cause of DCM in the absence of other discriminating features. Incorporation of variant position and exon-specific expression improves interpretation of TTNtv. Most individuals with TTNtv do not develop DCM, but TTNtv in highly utilised, particularly distal exons commonly cause DCM with severely impaired LV function and life-threatening ventricular arrhythmias, likely through dominant-negative mechanisms. In DCM patients, presence and position of TTNtv may aid prognostication and management.
[Show abstract][Hide abstract] ABSTRACT: The extent of translational control of gene expression in mammalian tissues remains largely unknown. Here we perform genome-wide RNA sequencing and ribosome profiling in heart and liver tissues to investigate strain-specific translational regulation in the spontaneously hypertensive rat (SHR/Ola). For the most part, transcriptional variation is equally apparent at the translational level and there is limited evidence of translational buffering. Remarkably, we observe hundreds of strain-specific differences in translation, almost doubling the number of differentially expressed genes. The integration of genetic, transcriptional and translational data sets reveals distinct signatures in 3′UTR variation, RNA-binding protein motifs and miRNA expression associated with translational regulation of gene expression. We show that a large number of genes associated with heart and liver traits in human genome-wide association studies are primarily translationally regulated. Capturing interindividual differences in the translated genome will lead to new insights into the genes and regulatory pathways underlying disease phenotypes.
[Show abstract][Hide abstract] ABSTRACT: Rationale:
To maintain cardiac mechanical and structural integrity after an ischemic insult, profound alterations occur within the extracellular matrix. Osteoglycin is a small leucine-rich proteoglycan previously described as a marker of cardiac hypertrophy.
To establish whether osteoglycin may play a role in cardiac integrity and function after myocardial infarction (MI).
Methods and results:
Osteoglycin expression is associated with collagen deposition and scar formation in mouse and human MI. Absence of osteoglycin in mice resulted in significantly increased rupture-related mortality with tissue disruption, intramyocardial bleeding, and increased cardiac dysfunction, despite equal infarct sizes. Surviving osteoglycin null mice had greater infarct expansion in comparison with wild-type mice because of impaired collagen fibrillogenesis and maturation in the infarcts as revealed by electron microscopy and collagen polarization. Absence of osteoglycin did not affect cardiomyocyte hypertrophy in the remodeling remote myocardium. In cultured fibroblasts, osteoglycin knockdown or supplementation did not alter transforming growth factor-β signaling. Adenoviral overexpression of osteoglycin in wild-type mice significantly improved collagen quality, thereby blunting cardiac dilatation and dysfunction after MI. In osteoglycin null mice, adenoviral overexpression of osteoglycin was unable to prevent rupture-related mortality because of insufficiently restoring osteoglycin protein levels in the heart. Finally, circulating osteoglycin levels in patients with heart failure were significantly increased in the patients with a previous history of MI compared with those with nonischemic heart failure and correlated with survival, left ventricular volumes, and other markers of fibrosis.
Increased osteoglycin expression in the infarct scar promotes proper collagen maturation and protects against cardiac disruption and adverse remodeling after MI. In human heart failure, osteoglycin is a promising biomarker for ischemic heart failure.
Circulation Research 12/2014; 116(3). DOI:10.1161/CIRCRESAHA.116.304599 · 11.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective Myocardial fibrosis identified by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in patients with hypertrophic cardiomyopathy (HCM) is associated with adverse cardiovascular events, but its value as an independent risk factor for sudden cardiac death (SCD) is unknown. We investigated the role of LGE-CMR in the risk stratification of HCM.
Methods We conducted a prospective cohort study in a tertiary referral centre. Consecutive patients with HCM (n=711, median age 56.3 years, IQR 46.7–66.6; 70.0% male) underwent LGE-CMR and were followed for a median 3.5 years. The primary end point was SCD or aborted SCD.
Results Overall, 471 patients (66.2%) had myocardial fibrosis (median 5.9% of left ventricular mass, IQR: 2.2–13.3). Twenty-two (3.1%) reached the primary end point. The extent but not the presence of fibrosis was a significant univariable predictor of the primary end point (HR per 5% LGE: 1.24, 95% CI 1.06 to 1.45; p=0.007 and HR for LGE: 2.69, 95% CI 0.91 to 7.97; p=0.073, respectively). However, on multivariable analysis, only LV-EF remained statistically significant (HR: 0.92, 95% CI 0.89 to 0.95; p<0.001). For the secondary outcome of cardiovascular mortality/aborted SCD, the presence and the amount of fibrosis were significant predictors on univariable but not multivariable analysis after adjusting for LV-EF and non-sustained ventricular tachycardia.
Conclusions The amount of myocardial fibrosis was a strong univariable predictor of SCD risk. However, this effect was not maintained after adjusting for LV-EF. Further work is required to elucidate the interrelationship between fibrosis and traditional predictors of outcome in HCM.