Intrinsic mitral valve alterations in hypertrophic cardiomyopathy sarcomere mutation carriers

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

Mitral regurgitation mechanisms related to systolic anterior motion in hypertrophic cardiomyopathy

Background

Systolic anterior motion (SAM) of the mitral valve can result in mitral regurgitation (MR) and adverse outcomes in patients with obstructive hypertrophic cardiomyopathy (HCM). However, the mechanism and characteristics of MR severity mediated by SAM are unresolved. This study aimed to elucidate the anatomic and hemodynamic associations of MR and the impact of septal myectomy on changes in MR severity in patients with HCM.

Methods

We retrospectively reviewed patients who underwent septal myectomy with SAM and interpretable imaging between 2017-2022. Significant MR was defined as moderate or more MR. The mitral valve, papillary muscle, and left ventricular geometry were quantitatively evaluated via echocardiography and cardiac computed tomography.

Results

Out of 34 patients, two groups were identified: those with preoperative significant MR (n=16) and those without significant MR (n=18). Patients with significant preoperative MR exhibited worse heart failure symptoms at baseline than those without. Following myectomy, these patients showed higher residual left ventricular outflow tract (LVOT) gradients at rest and with provocative measures than those without preoperative MR. Multivariate regression analysis revealed a significant association between the tenting area and MR severity. Additionally, the chordal cutting procedure alleviated the tenting area [2.1 (1.8-2.6) vs. 1.4 (1.2-1.6) cm2] compared to those without it.

Conclusions

Our preliminary data suggested that chordal cutting with septal myectomy was associated with an improvement in the tenting area, contributing to MR severity. This procedure may serve as an effective therapy for patients with SAM and significant MR.

Valvular heart disease and cardiomyopathy: reappraisal of their interplay

Cardiomyopathies and valvular heart diseases are typically considered distinct diagnostic categories with dedicated guidelines for their management. However, the interplay between these conditions is increasingly being recognized and they frequently coexist, as in the paradigmatic examples of dilated cardiomyopathy and hypertrophic cardiomyopathy, which are often complicated by the occurrence of mitral regurgitation. Moreover, cardiomyopathies and valvular heart diseases can have a shared aetiology because several genetic or acquired diseases can affect both the cardiac valves and the myocardium. In addition, the association between cardiomyopathies and valvular heart diseases has important prognostic and therapeutic implications. Therefore, a better understanding of their shared pathophysiological mechanisms, as well as of the prevalence and predisposing factors to their association, might lead to a different approach in the risk stratification and management of these diseases. In this Review, we discuss the different scenarios in which valvular heart diseases and cardiomyopathies coexist, highlighting the need for an improved classification and clustering of these diseases with potential repercussions in the clinical management and, particularly, personalized therapeutic approaches.

Systolic anterior motion of the anterior mitral valve leaflet begins in subclinical hypertrophic cardiomyopathy

AIMS

Anterior mitral valve leaflet (AMVL) elongation is detectable in overt and subclinical hypertrophic cardiomyopathy (HCM). We sought to investigate the dynamic motion of the aorto-mitral apparatus to understand the behaviour of the AMVL and the mechanisms of left ventricular outflow tract obstruction (LVOTO) predisposition in HCM.

METHODS AND RESULTS

Cardiovascular magnetic resonance imaging using a 1.5 Tesla scanner was performed on 36 HCM sarcomere gene mutation carriers without left ventricular hypertrophy (G+LVH-), 31 HCM patients with preserved ejection fraction carrying a pathogenic sarcomere gene mutation (G+LVH+), and 53 age-, sex-, and body surface area-matched healthy volunteers. Dynamic excursion of the aorto-mitral apparatus was assessed semi-automatically on breath-held three-chamber cine steady-state free precession images. Four pre-defined regions of interest (ROIs) were tracked: ROIPMVL: hinge point of the posterior mitral valve leaflet; ROITRIG: intertrigonal mitral annulus; ROIAMVL: AMVL tip; and ROIAAO: anterior aortic annulus. Compared with controls, normalized two-dimensional displacement-vs.-time plots in G+LVH- revealed subtle but significant systolic anterior motion (SAM) of the AMVL (P < 0.0001) and reduced longitudinal excursion of ROIAAO (P = 0.014) and ROIPMVL (P = 0.048). In overt and subclinical HCM, excursion of the ROITRIG/AMVL/PMVL was positively associated with the burden of left ventricular fibrosis (P < 0.028). As expected, SAM was observed in G+LVH+ together with reduced longitudinal excursion of ROITRIG (P = 0.049) and ROIAAO (P = 0.008).

CONCLUSION

Dyskinesia of the aorto-mitral apparatus, including SAM of the elongated AMVL, is detectable in subclinical HCM before the development of LVH or left atrial enlargement. These data have the potential to improve our understanding of early phenotype development and LVOTO predisposition in HCM.

Septal Myectomy Outcomes in Children and Adolescents With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Little data exist regarding characteristics and outcomes of pediatric patients undergoing septal myectomy. We evaluated this in a large referral population.

METHODS

Septal myectomy was performed in 199 consecutive patients aged ≤18 years with obstructive hypertrophic cardiomyopathy from January 1, 1976, to June 30, 2021.

RESULTS

Median age was 13 years (interquartile range [IQR], 8-15 years). Left ventricular myectomy approaches included transaortic (163 of 198 [82%]), transapical (16 of 198 [8%]), and combined (19 of 198 [10%]). Right ventricular interventions included myectomy (13 of 199 [7%]) and patch reconstruction of the outflow tract (15 of 199 [8%]). Maximum left ventricular outflow tract gradients decreased after myectomy (prebypass: 50 mm Hg [IQR, 31-73 mm Hg] vs postbypass: 4 mm Hg [IQR, 0-9 mm Hg], P < .001), and this was sustained long-term (5 mm Hg [IQR, 5-10 mm Hg] at 10 years). Iatrogenic aortic and mitral valve injuries occurred in 13 of 199 (7%) and 1 of 199 (1%), respectively; however, all were successfully repaired. Operative mortality was 2 of 199 (1%). The cumulative incidence of redo myectomy was low, at 5.8% at 5 and 8.3% at 10 years. Redo myectomy patients had higher maximum left ventricular outflow tract gradients on echocardiography at predischarge and 1 year and were younger at the index operation (8 years [IQR, 2.5-10 years] vs 13 years [IQR, 9-16 years], P < .001). Overall survival at 10 years was 90%, relative to 47% in a previously reported pediatric nonoperative cohort.

CONCLUSIONS

Pediatric septal myectomy provides safe, effective, and durable relief of ventricular outflow tract obstruction. Iatrogenic valve injury remains a low but nonnegligible risk. Recurrent obstruction requiring redo myectomy is infrequent and can be identified early. Long-term survival in this pediatric septal myectomy cohort appears to fare better than pediatric hypertrophic cardiomyopathy cohorts managed nonoperatively.

Apical papillary muscle displacement is a prevalent feature and a phenotypic precursor of apical hypertrophic cardiomyopathy

AIMS

Papillary muscle (PM) abnormalities are considered part of the phenotypic spectrum of hypertrophic cardiomyopathy (HCM). The aim of this study was to evaluate the presence and frequency of PM displacement in different HCM phenotypes.

METHODS AND RESULTS

We retrospectively analysed cardiovascular magnetic resonance (CMR) findings in 156 patients (25% females, median age 57 years). Patients were divided into three groups: septal hypertrophy (Sep-HCM, n = 70, 45%), mixed hypertrophy (Mixed-HCM, n = 48, 31%), and apical hypertrophy (Ap-HCM, n = 38, 24%). Fifty-five healthy subjects were enrolled as controls. Apical PM displacement was observed in 13% of controls and 55% of patients, which was most common in the Ap-HCM group, followed by the Mixed-HCM and Sep-HCM groups (respectively: inferomedial PM 92 vs. 65 vs. 13%, P < 0.001; anterolateral PM 61 vs. 40 vs. 9%, P < 0.001). Significant differences in PM displacement were found when comparing healthy controls with patients with Ap- and Mixed-HCM subtypes but not when comparing them with patients with the Sep-HCM subtype. T-wave inversion in the inferior and lateral leads was more frequent in patients with Ap-HCM (100 and 65%, respectively) when compared with Mixed-HCM (89 and 29%, respectively) and Sep-HCM (57 and 17%, respectively; P < 0.001 for both). Eight patients with Ap-HCM had prior CMR examinations because of T-wave inversion [median interval 7 (3-8) years], and in the first CMR study, none showed apical hypertrophy [median apical wall thickness 8 (7-9) mm], while all of them presented with apical PM displacement.

CONCLUSION

Apical PM displacement is part of the phenotypic Ap-HCM spectrum and may precede the development of hypertrophy. These observations suggest a potential pathogenetic, mechanical link between apical PM displacement and Ap-HCM.

Histopathology of the Mitral Valve Residual Leaflet in Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Mitral valve (MV) elongation is a primary hypertrophic cardiomyopathy (HCM) phenotype and contributes to obstruction. The residual MV leaflet that protrudes past the coaptation point is especially susceptible to flow-drag and systolic anterior motion. Histopathological features of MVs in obstructive hypertrophic cardiomyopathy (OHCM), and of residual leaflets specifically, are unknown.

OBJECTIVES

The purpose of this study was to characterize gross, structural, and cellular histopathologic features of MV residual leaflets in OHCM. On a cellular-level, we assessed for developmental dysregulation of epicardium-derived cell (EPDC) differentiation, adaptive endocardial-to-mesenchymal transition and valvular interstitial cell proliferation, and genetically-driven persistence of cardiomyocytes in the valve.

METHODS

Structural and immunohistochemical staining were performed on 22 residual leaflets excised as ancillary procedures during myectomy, and compared with 11 control leaflets from deceased patients with normal hearts. Structural components were assessed with hematoxylin and eosin, trichrome, and elastic stains. We stained for EPDCs, EPDC paracrine signaling, valvular interstitial cells, endocardial-to-mesenchymal transition, and cardiomyocytes.

RESULTS

The residual leaflet was always at A2 segment and attached by slack, elongated and curlicued, myxoid chords. MV residual leaflets in OHCM were structurally disorganized, with expanded spongiosa and increased, fragmented elastic fibers compared with control leading edges. The internal collagenous fibrosa was attenuated and there was collagenous tissue overlying valve surfaces in HCM, with an overall trend toward decreased leaflet thickness (1.09 vs 1.47 mm, P = 0.08). No markers of primary cellular processes were identified.

CONCLUSIONS

MV residual leaflets in HCM were characterized by histologic findings that were likely secondary to chronic hemodynamic stress and may further increase susceptibility to systolic anterior motion.

Cardiac Multimodality Imaging in Hypertrophic Cardiomyopathy: What to Look for and When to Image

Hypertrophic cardiomyopathy (HCM), now recognized as a common cardiomyopathy of complex genomics and pathophysiology, is defined by the presence of left ventricular hypertrophy of various morphologies and severity, significant hemodynamic consequences, and diverse phenotypic, both structural and clinical, profiles. Advancements in cardiac multimodality imaging, including echocardiography, cardiac magnetic resonance imaging, and cardiac computed tomography, with and without angiography have greatly improved the diagnosis of HCM, and enable precise measurements of cardiac mass, volume, wall thickness, function, and physiology. Multimodality imaging provides comprehensive and complementary information and hasemerged as the bedrock for the diagnosis, clinical assessment, serial monitoring, and sudden cardiac death risk stratification of patients with HCM. This review highlights the role of cardiac multimodality imaging in the modern diagnosis and management of HCM.

Is anterior mitral valve leaflet length important in outcome of septal myectomy for obstructive hypertrophic cardiomyopathy?

OBJECTIVES

Elongation of mitral valve leaflets is a phenotypic feature of hypertrophic cardiomyopathy, and some surgeons advocate plication of the anterior leaflet at the time of septal myectomy. The present study investigates mitral valve leaflet length and outcomes of patients undergoing septal myectomy for obstructive hypertrophic cardiomyopathy.

METHODS

We reviewed the records and echocardiograms of 564 patients who underwent transaortic septal myectomy for obstructive hypertrophic cardiomyopathy between February 2015 and April 2018. Extended septal myectomy without plication of the anterior leaflet was the standard procedure. From intraoperative prebypass transesophageal echocardiograms, we measured anterior and posterior mitral valve leaflets and their coaptation length. For comparison, we performed these mitral valve leaflet measurements in 90 patients who underwent isolated coronary artery bypass grafting and 92 patients undergoing aortic valve replacement in the same period. Among patients with hypertrophic cardiomyopathy undergoing septal myectomy, we assessed left ventricular outflow tract gradient relief and 1-year survival in relation to leaflet length.

RESULTS

Median patient age (interquartile range) was 60.3 (50.2-67.7) years, and 54.1% were male. Concomitant mitral valve repair was performed in 36 patients (6.4%), and mitral valve replacement was performed in 8 patients (1.4%), primarily for intrinsic mitral valve disease. Patients in the hypertrophic cardiomyopathy cohort had significantly longer mitral valve leaflet measurements compared with patients undergoing coronary artery bypass grafting or aortic valve replacement (P < .001 for all 3 measurements). Preoperative resting left ventricular outflow tract gradients were not related to leaflet length (<30 mm, median 49 [21, 81.5] mm Hg vs ≥30 mm, 50.5 [21, 77] mm Hg; P = .76). Further, gradient reduction after myectomy was not related to leaflet length; patients with less than 30 mm anterior leaflet length had a median gradient reduction of 33 (69, 6) mm Hg compared with 36.5 (62, 6) mm Hg for patients with leaflet length 30 mm or more (P = .36). Anterior mitral valve leaflet length was not associated with increased 1-year mortality (P = .758).

CONCLUSIONS

Our study confirms previous findings that patients with hypertrophic cardiomyopathy have slight (5 mm) elongation of mitral valve leaflets. In contrast to other reports, increased anterior mitral valve leaflet length was not associated with higher left ventricular outflow tract gradients. Importantly, we found no significant relationship between anterior mitral valve leaflet length and postoperative left ventricular outflow tract resting gradients or gradient relief. Thus, in the absence of intrinsic mitral valve disease, transaortic septal myectomy with focus on extending the excision beyond the point of septal contact is sufficient for almost all patients.

[Mitral valve replacement in patients with obstructive hypertrophic cardiomyopathy]

OBJECTIVE

To analyze the incidence and causes of mitral valve replacement in patients with obstructive hypertrophic cardiomyopathy (HCM).

MATERIAL AND METHODS

There were 172 patients (98 women and 74 men) with obstructive HCM and severe mitral valve insufficiency between November 2017 and May 2023. All patients complained of chronic heart failure NYHA class III. Surgical correction of left ventricular outflow tract (LVOT) obstruction and mitral valve repair with elimination of systolic anterior motion were technically successful in 160 (93.0%) patients.

RESULTS

The need for mitral valve replacement was noted in 12 (7.0%) patients. Mean cardiopulmonary bypass time was 83.5±19.2 min (94; 127), aortic cross-clamping - 62.8±14.3 min (70; 102). In 5 cases, primary mitral valve replacement was scheduled due to obvious organic lesion of the mitral valve (tearing of chords, rheumatic lesion with leaflet restriction). In 7 patients, valve replacement was forced after ineffective primary septal myectomy (LVOT pressure gradient, severe mitral insufficiency).

CONCLUSION

Mitral valve replacement is an involuntary strategy after ineffective myectomy with severe mitral insufficiency and high LVOT pressure gradient.

Different mechanisms of mitral regurgitation in hypertrophic cardiomyopathy: A clinical case and literature review

Background

Abnormalities of the mitral valve (MV) apparatus are typical features of hypertrophic cardiomyopathy (HCM). These abnormalities include leaflet elongation, thick leaflets, displacement of papillary muscle, and systolic anterior motion (SAM) of the MV anterior leaflet. Mitral valve chordal rupture associated with HCM is a rare but serious issue capable of change the clinical apparence and the prognosis of the patient.

Case summary

A 57-year-old lady with a history of diabetes, dyslipidemia, and a previous single episode of atrial fibrillation (treated with pharmacological cardioversion), presented to the Emergency Department for worsening dyspnea (New York Heart Association Classification class IV). A trans-thoracic echocardiogram (TTE) showed a significant, septal, and asymmetric left ventricular hypertrophy (basal anteroseptal wall diastolic thickness of 19 mm) with normal left ventricle systolic function. A SAM of AML was evident together with a left ventricular outflow tract gradient of 56 mmHg at rest, rising to 136 mmHg during the Valsalva maneuver. In addition, there was evidence of moderate to severe mitral regurgitation (MR) with an anteriorly directed jet, not very typical of MR related to SAM. A 2D-3D trans-esophageal echocardiogram (2D-3D TEE) revealed a combined MR mechanism based on PML degenerative prolapse with P2-flail from ruptured chordae with related eccentric anteriorly directed regurgitant jet, together with a second regurgitant posteriorly directed jet, related to SAM of AML. The patient underwent MV repair together with septal myectomy, with a good final outcome.

Conclusion

Pre-operative echocardiography (both TTE and 2D-3D TEE) is an essential tool in order to detect different MV abnormalities in patients with HCM. These types of patients should never be treated by septal reduction alone. Surgical MV repair or replacement, together with septal myectomy, may be the preferred approach.

Systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy: a narrative review

Background and Objective

The prevalence of hypertrophic cardiomyopathy (HCM) is estimated to be 1 in 200 to 500 individuals, with systolic anterior motion (SAM) of the mitral valve (MV) and left ventricular outflow tract (LVOT) obstruction present in 60% to 70%. In this narrative review, we aim to elucidate the pathophysiology of SAM-septal contact and LVOT obstruction in HCM by presenting a detailed review on the anatomy of the MV apparatus in HCM, examining the various existing theories pertaining to the SAM phenomenon as supported by cardiac imaging, and providing a critical assessment of management strategies for SAM in HCM.

Methods

A literature review was performed using PubMed, EMBASE, Ovid, and the Cochrane Library, of all scientific articles published through December 2021. A focus was placed on descriptive studies, reports correlating echocardiographic findings with pathologic diagnosis, and outcomes studies.

Key Content and Findings

The pathophysiology of SAM involves the complex interplay between HCM morphology, MV apparatus anatomic abnormalities, and labile hemodynamic derangements. Echocardiography and cardiac magnetic resonance (CMR) vector flow mapping have identified drag forces, as opposed to the "Venturi effect", as the main hydraulic forces responsible for SAM. The degree of mitral regurgitation with SAM is variable, and its severity is correlated with degree of LVOT obstruction and outcomes. First line therapy for the amelioration of SAM and LVOT obstruction is medical therapy with beta-blockers, non-dihydropyridine calcium-channel blockers, and disopyramide, in conjunction with lifestyle modifications. In refractory cases septal reduction therapy is performed, which may be combined with a 'resect-plicate-release' procedure, anterior mitral leaflet extension, surgical edge-to-edge MV repair, anterior mitral leaflet retention plasty, or secondary chordal cutting.

Conclusions

Recent scientific advances in the field of HCM have allowed for a maturation of our understanding of the SAM phenomenon. Cardiac imaging plays a critical role in its diagnosis, treatment, and surveillance, and in our ability to apply the appropriate therapeutic regimens. The increasing prevalence of HCM places an emphasis on continued basic and clinical research to further improve outcomes for this challenging population.

Anterior mitral valve leaflet length in cats with hypertrophic cardiomyopathy

INTRODUCTION

Anterior mitral valve leaflet (AMVL) elongation is a recognised feature of hypertrophic cardiomyopathy (HCM). However, whether AMVL elongation precedes left ventricular hypertrophy in cats is currently unknown. The aim of this study was to explore the risk of developing an HCM phenotype in cats with an elongated AMVL.

ANIMALS

FIFTY-FIVE APPARENTLY HEALTHY CATS WITH A NORMAL BASELINE ECHOCARDIOGRAM AND A FOLLOW-UP ECHOCARDIOGRAM AT >ONE YEAR.

MATERIALS AND METHODS

This was a retrospective longitudinal study. Cats at the baseline were grouped based on whether or not they developed an HCM phenotype at follow-up. AMVL length and left atrial and left ventricular dimensions were measured from two-dimensional images.

RESULTS

The median follow-up period of the study population was 5.4 years (25th and 75th quartile, 2.7-6.7 years). During this time, 17 cats (30.9%) developed an HCM phenotype. At the baseline, cats that subsequently developed an HCM phenotype had greater AMVL length (9.4 mm [25th and 75th quartile, 9.0-10.6 mm] vs. 8.5 mm [25th and 75th quartile, 7.6-9.1 mm], P < 0.0001) and maximal left ventricular wall thickness (4.5 mm [25th and 75th quartile, 4.1-4.7 mm] vs. 4.0 mm [25th and 75th quartile, 3.7-4.6 mm], P = 0.007) than those that did not. Multiple logistic regression analysis confirmed that both baseline variables were independent predictors for development of an HCM phenotype.

CONCLUSIONS

The AMVL length was greater in cats that subsequently developed left ventricular hypertrophy. Further studies investigating the clinical application of AMVL in the natural history of feline HCM are warranted.

Genetic determinants of clinical phenotype in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disease that affects approximately one in 500 people. HCM is a recognized genetic disorder most often caused by mutations involving myosin-binding protein C (MYBPC3) and β-myosin heavy chain (MYH7) which are responsible for approximately three-quarters of the identified mutations.

METHODS

As a part of the international multidisciplinary SILICOFCM project ( www.silicofcm.eu ) the present study evaluated the association between underlying genetic mutations and clinical phenotype in patients with HCM. Only patients with confirmed single pathogenic mutations in either MYBPC3 or MYH7 genes were included in the study and divided into two groups accordingly. The MYBPC3 group was comprised of 48 patients (76%), while the MYH7 group included 15 patients (24%). Each patient underwent clinical examination and echocardiography.

RESULTS

The most prevalent symptom in patients with MYBPC3 was dyspnea (44%), whereas in patients with MYH7 it was palpitations (33%). The MYBPC3 group had a significantly higher number of patients with a positive family history of HCM (46% vs. 7%; p = 0.014). There was a numerically higher prevalence of atrial fibrillation in the MYH7 group (60% vs. 35%, p = 0.085). Laboratory analyses revealed normal levels of creatinine (85.5 ± 18.3 vs. 81.3 ± 16.4 µmol/l; p = 0.487) and blood urea nitrogen (10.2 ± 15.6 vs. 6.9 ± 3.9 mmol/l; p = 0.472) which were similar in both groups. The systolic anterior motion presence was significantly more frequent in patients carrying MYH7 mutation (33% vs. 10%; p = 0.025), as well as mitral leaflet abnormalities (40% vs. 19%; p = 0.039). Calcifications of mitral annulus were registered only in MYH7 patients (20% vs. 0%; p = 0.001). The difference in diastolic function, i.e. E/e' ratio between the two groups was also noted (MYBPC3 8.8 ± 3.3, MYH7 13.9 ± 6.9, p = 0.079).

CONCLUSIONS

Major findings of the present study corroborate the notion that MYH7 gene mutation patients are presented with more pronounced disease severity than those with MYBPC3.

Management of the mitral valve in patients with obstructive hypertrophic cardiomyopathy

Septal myectomy is the gold standard treatment option for patients with obstructive hypertrophic cardiomyopathy whose symptoms do not respond to medical therapy. This operation reliably relieves left ventricular outflow tract gradients, systolic anterior motion of the mitral valve, and associated mitral valve regurgitation. However, there remains controversy regarding the necessity of mitral valve intervention at the time of septal myectomy. While some clinicians advocate for concomitant mitral valve procedures, others strongly believe that the mitral valve should only be operated on if there is intrinsic mitral valve disease. At Mayo Clinic, we have performed septal myectomy on more than 3000 patients with obstructive hypertrophic cardiomyopathy, and in our experience, mitral valve operation is rarely necessary for patients who do not have intrinsic mitral valve disease such as leaflet prolapse or severe calcific stenosis. In this paper, we review anatomical considerations, imaging, and surgical approaches in the management of the mitral valve in hypertrophic cardiomyopathy.

The Role of Mitral Valve in Hypertrophic Obstructive Cardiomyopathy: An Updated Review

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease and the most common cause of sudden cardiac death in young population, especially in athletes under 35 years old. Mutations occur primarily in the β-myosin heavy chain gene and involve the cardiac myosin-binding protein C gene. In this review we would like to focus on the importance of the examination of mitral valve apparatus and the mitral valve abnormalities in patients with HCM. Abnormalities in mitral valve (elongated mitral leaflets, displacement of papillary muscles, and systolic anterior motion) may be the primary pathognomonic elements, even in the absence of hypertrophy. Echocardiography is the gold standard for the diagnosis of HCM. Magnetic resonance imaging emerges as one of the most important imaging modalities for precise diagnosis, assisting in risk stratification and treatment strategy. Mitral valve abnormalities take part fundamentally in the formation of systolic anterior motion of the mitral valve and, they have substantially been repaired surgically. Although myectomy addresses the septum reduction, obstruction relief should be maximally achieved with a potential combination of myectomy and mitral valve repair.

Identification of known and unknown genes associated with mitral valve prolapse using an exome slice methodology

PURPOSE

Although a familial distribution has been documented, the genetic aetiology of mitral valve prolapse (MVP) is largely unknown, with only four genes identified so far: FLNA, DCHS1, DZIP1 and PLD1. The aim of this study was to evaluate the genetic yield in known causative genes and to identify possible novel genes associated with MVP using a heart gene panel based on exome sequencing.

METHODS

Patients with MVP were referred for genetic counselling when a positive family history for MVP was reported and/or Barlow's disease was diagnosed. In total, 101 probands were included to identify potentially pathogenic variants in a set of 522 genes associated with cardiac development and/or diseases.

RESULTS

97 (96%) probands were classified as Barlow's disease and 4 (4%) as fibroelastic deficiency. Only one patient (1%) had a likely pathogenic variant in the known causative genes (DCHS1). However, an interesting finding was that 10 probands (11%) had a variant that was classified as likely pathogenic in six different, mostly cardiomyopathy genes: DSP (1×), HCN4 (1×), MYH6 (1×), TMEM67 (1×), TRPS1 (1×) and TTN (5×).

CONCLUSION

Exome slice sequencing analysis performed in MVP probands reveals a low genetic yield in known causative genes but may expand the cardiac phenotype of other genes. This study suggests for the first time that also genes related to cardiomyopathy may be associated with MVP. This highlights the importance to screen these patients and their family for the presence of arrhythmias and of 'disproportionate' LV remodelling as compared with the severity of mitral regurgitation, unravelling a possible coexistent cardiomyopathy.

The year 2018 in the European Heart Journal-Cardiovascular Imaging: Part II

European Heart Journal - Cardiovascular Imaging was launched in 2012 as a multimodality cardiovascular imaging journal. It has gained an impressive impact factor during its first 5 years and is now established as one of the top cardiovascular journals and has become the most important cardiovascular imaging journal in Europe. The most important studies from 2018 will be highlighted in two reports. Part I of the review has focused on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on cardiomyopathies, congenital heart diseases, valvular heart diseases, and heart failure.

Genetic relevance and determinants of mitral leaflet size in hypertrophic cardiomyopathy

BACKGROUND

Whether mitral leaflet elongation is a primary phenotype of hypertrophic cardiomyopathy (HCM) is controversial. We investigated the genetic relevance and determinants of mitral leaflet size by performing extensive gene analyses in patients with HCM.

METHODS

Anterior mitral leaflet (AML) lengths were measured in HCM patients (n = 211) and age- and sex-matched controls (n = 30) using echocardiography with hemodynamic and chamber geometric assessments. We analyzed 82 nuclear DNA (8 sarcomeric genes, 74 other HCM-associated genes) and mitochondrial DNA. Cardiac magnetic resonance imaging (CMR) was performed in the 132 HCM patients.

RESULTS

Average indexed AML was significantly longer for HCM than for controls (17.2 ± 2.3 vs. 13.3 ± 1.6 mm/m², P <  0.001). Average AML length correlated with body surface area (BSA), left ventricular (LV) end-systolic volume (P <  0.001) and LV mass by CMR (P < 0.001). Average indexed AML by BSA of pure-apical HCM was significantly shorter than other typed HCM (16.6 ± 2.0 vs. 17.4 ± 2.4 mm/m², P = 0.025). Indexed AML was independently correlated with left atrial wall stress. The thin filament mutation group showed larger average AML (31.9 ± 3.8 vs. 29.6 ± 3.8 mm, P = 0.045), but this was not significant with the indexed value. No difference in AML size among subgroups was observed based on the presence of sarcomere protein or mitochondria-related gene variants (P > 0.05).

CONCLUSION

AML elongation was a unique finding of HCM. However, the leaflet size was more related to chamber geometry and hypertrophy pattern rather than genetic factors within overt HCM.