Coexistence of mitral valve prolapse in a consecutive group of 528 patients with hypertrophic cardiomyopathy assessed with echocardiography

Arrhythmogenic Mitral Valve Prolapse: Can We Risk Stratify and Prevent Sudden Cardiac Death?

Ventricular arrhythmias associated with mitral valve prolapse (MVP) and the capacity to cause sudden cardiac death (SCD), referred to as 'malignant MVP', are an increasingly recognised, albeit rare, phenomenon. SCD can occur without significant mitral regurgitation, implying an interaction between mechanical derangements affecting the mitral valve apparatus and left ventricle. Risk stratification of these arrhythmias is an important clinical and public health issue to provide precise and targeted management. Evaluation requires patient and family history, physical examination and electrophysiological and imaging-based modalities. We provide a review of arrhythmogenic MVP, exploring its epidemiology, demographics, clinical presentation, mechanisms linking MVP to SCD, markers of disease severity, testing modalities and management, and discuss the importance of risk stratification. Even with recently improved understanding, it remains challenging how best to weight the prognostic importance of clinical, imaging and electrophysiological data to determine a clear high-risk arrhythmogenic profile in which an ICD should be used for the primary prevention of SCD.

Hypertrophic cardiomyopathy with anteriorly directed mitral regurgitation is a red flag for concomitant pathology: a case report

Background

Hypertrophic cardiomyopathy (HCM) is often linked to systolic anterior motion (SAM) of the mitral valve, typically resulting in a posteriorly directed mitral regurgitation (MR) jet. An anteriorly directed MR jet suggests additional mitral valve pathology that may not be resolved by myectomy alone.

Case summary

A 58-year-old construction worker with no significant medical history experienced a syncopal event and was admitted to the emergency department with acute pulmonary oedema. A systolic murmur was investigated with a trans-thoracic echocardiogram that revealed severe MR with an unusual anteriorly directed MR jet and a possible flail segment of the posterior leaflet. This finding was further characterized with a trans-oesophageal echocardiogram that revealed severe asymmetric septal hypertrophy with SAM of the mitral valve, severe mitral regurgitation into a dilated left atrium with pulmonary vein flow reversal not caused by HCM-associated SAM, and a markedly abnormal mitral valve with flail and prolapse. The patient underwent successful cardiac surgery, including mitral valve repair and septal myectomy. The patient's recovery was uneventful, allowing for a return to work within a month post-surgery.

Discussion

The anteriorly directed MR jet served as a red flag, leading to the discovery of an independent mitral valve pathology that required surgical intervention beyond the expected treatment for SAM-associated HCM. This case highlights the complexity of assessing MR in patients with HCM and underscores the importance of characterizing MR jet direction in diagnosing additional mitral valve diseases.

Contemporary Surgical Management of Hypertrophic Cardiomyopathy

More than half of symptomatic patients with hypertrophic cardiomyopathy (HCM) have left ventricular outflow tract (LVOT) obstruction. Septal reduction therapy by septal myectomy can dramatically relieve exertional dyspnea, chest pain, and presyncope in properly selected patients and is an important management pathway for many patients. The distribution and degree of hypertrophy in patients with obstructive HCM are variable and, as discussed in this review, can influence clinical manifestations of the disease and surgical management. Subaortic septal hypertrophy is the most common phenotype of obstructive HCM associated with LVOT obstruction, but midventricular obstruction and apical hypertrophy may occur in isolation or in conjunction with subaortic septal hypertrophy. In many comprehensive HCM centers, transaortic septal myectomy is the preferred method of septal reduction therapy for symptomatic patients with obstructive HCM. Early surgical approaches aimed at alleviating left LVOT obstruction were hampered by a lack of understanding of the anatomy and pathophysiology of obstructive HCM. With the advent of Doppler echocardiography and, more recently, cardiac magnetic resonance imaging, surgeons can precisely assess the location and degree of obstruction, left ventricular size and function, and morphology and function of the mitral valve. This review discusses the current understanding of the role of septal myectomy in the management of patients with HCM and details contemporary operative methods.

Mitral Valve Prolapse in Obstructive Hypertrophic Cardiomyopathy

Obstructive hypertrophic cardiomyopathy (oHCM) and mitral valve (MV) prolapse (MVP) are the 2 conditions which could cause symptomatic heart failure and sudden cardiac death. The clinical characteristics and surgical outcomes of patients with oHCM and MVP have not been well reported. From April 2012 to February 2018, 84 patients with oHCM (28 patients with MVP and 56 gender- and age-matched patients without MVP) who underwent septal myectomy at our institution were enrolled in this study. Information on clinical characteristics and outcomes was obtained from electronic medical records and follow-up surveys. Compared with those without MVP, patients with MVP were more symptomatic (New York Heart Association class III to IV; 96% vs 77%), more often moderate-to-severe mitral regurgitation (86% vs 48%), atrial fibrillation (39% vs 11%) and higher incidence of nonsustained ventricular tachycardia (44% vs 15%). Twenty (71%) had MV repair and 8 (29%) had MV replacement. Compared with patients without MVP, those with MVP had a longer postoperative hospital stay (10.9 ± 6.4 vs 7.8 ± 2.8 days). None of the 84 study patients died during hospital or follow-up. At the most recent echocardiographic evaluation, left ventricular outflow tract gradient significantly decreased from 69.7 ± 35.4 millimeters of mercury to 7.3 ± 5.1 millimeters of mercury and the degree of mitral valve regurgitation improved from grade 2.43 ± 0.69 to grade 0.5 ± 0.69. In conclusion, MVP occurs rarely in oHCM, and was related to atrial fibrillation, ventricular arrhythmia and mitral regurgitation. Mitral valve surgery in combination with myectomy is effective and safe for patients with oHCM and MVP, relieving substantially left ventricular outflow tract gradients and mitral regurgitation.

Prognostic Implication of Mitral Valve Disease and Its Progression in East Asian Patients With Hypertrophic Cardiomyopathy

Background Hypertrophic cardiomyopathy (HCM) is a genetic disorder affecting not only the myocardium but also the mitral valve (MV) and its apparatus. This study aimed to investigate the prognostic implication of MV disease and its progression in East Asian patients with HCM. Methods and Results We assessed MV structure and function on the indexed echocardiogram of 1185 patients with HCM (mean±SD age, 60±14 years; men, 67%) in a longitudinal HCM registry, and 667 patients who performed follow-up echocardiogram after 3 to 5 years were also analyzed. Progression of mitral regurgitation (MR) was defined as the increase of at least 1 grade. Clinical outcomes were defined as a composite of cardiovascular death, heart failure hospitalization, MV surgery or septal myectomy, and heart transplantation. Most of the entire cohort was nonobstructive type (n=1081 [91.2%]). A total of 278 patients (23.5%) showed at least mild MR on indexed echocardiogram. MR, systolic anterior motion, and mitral annular calcification were more prevalent in patients with obstructive HCM. During 7.0±4.0 years of follow-up, presence of MR was independently associated with poor clinical outcomes (hazard ratio [HR], 1.60 [95% CI, 1.07-2.40]; P=0.023). On follow-up echocardiogram, 67 (10.0%) patients showed MR progression, and it was independently associated with poor prognosis (HR, 2.46 [95% CI, 1.29-4.71]; P=0.007). Conclusions In East Asian patients with HCM whose major type is nonobstructive, MV disease is common. MR, systolic anterior motion, and mitral annular calcification are more prevalent in patients with obstructive HCM. The presence and progression of MR are associated with a poor prognosis in patients with HCM.

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.

Aneurysmal and obstructive lesions of the left ventricular outflow: evaluation on multidetector computed tomography angiography

The left ventricular outflow is an anatomically complex region situated between the anterior leaflet of the mitral valve and the left ventricular aspect of the muscular and membranous interventricular septum. It gives rise to the aorta, provides support to the aortic valvular cusps, and houses important components of the conduction system. The left ventricular outflow handles high pressures and pressure variations and is subsequently affected by a variety of aetio-pathological conditions. Diseases involving the left ventricular outflow can be intraluminal, mural, or extramural, and the consequent complications of the lesions can be local, loco-regional, or even systemic. Appropriate evaluation requires comprehensive multimodality imaging with each modality contributing to assessment of different aspects of diagnosis, lesion characterization, local extension, prognostication for systemic complications and mortality, and the decision for the approach and type of intervention and aggressive follow-up in case non-interventional management is decided. In this review, we briefly describe the relevant anatomy and the gamut of structural abnormalities pertaining to the left ventricular outflow on multidetector computed tomography angiography.

SAM and Severe Mitral Regurgitation Post-Acute Type A Aortic Dissection Surgery Treated With MitraClip

Post-operative systolic anterior motion associated with mitral regurgitation can be a challenging combination. We present the case of a 64-year-old male patient managed by MitraClip (Abbott Laboratories, Abbott Park, Illinois) implantation for systolic anterior motion and severe mitral regurgitation in the early post-operative period after aortic dissection surgery. This is the first description of MitraClip use post–aortic dissection. (Level of Difficulty: Intermediate.)

Exploring the Continuum of Hypertrophic Cardiomyopathy-From DNA to Clinical Expression

The concepts underlying hypertrophic cardiomyopathy (HCM) pathogenesis have evolved greatly over the last 60 years since the pioneering work of the British pathologist Donald Teare, presenting the autopsy findings of “asymmetric hypertrophy of the heart in young adults”. Advances in human genome analysis and cardiac imaging techniques have enriched our understanding of the complex architecture of the malady and shaped the way we perceive the illness continuum. Presently, HCM is acknowledged as “a disease of the sarcomere”, where the relationship between genotype and phenotype is not straightforward but subject to various genetic and nongenetic influences. The focus of this review is to discuss key aspects related to molecular mechanisms and imaging aspects that have prompted genotype–phenotype correlations, which will hopefully empower patient-tailored health interventions.

Characteristics of mitral valve leaflet length in patients with pectus excavatum: A single center cross-sectional study

The mitral valve morphology in patients with pectus excavatum (PE) has not been fully investigated. Thirty-five patients with PE, 46 normal controls, and patients with hypertrophic cardiomyopathy (HCM) who underwent 2 leaflet length measurements of Carpentier classification P2 and A2 using a transthoracic echocardiography were retrospectively investigated. The coaptation lengths and depths, papillary muscle tethering length, and mitral annular diameters were also measured. The P2 and A2 lengths were separately compared between 2 groups: older than 16 years and 16 years or younger. Furthermore, the correlations between actual P2 or A2 lengths and Haller computed tomography index, an index of chest deformity, were investigated in patients with PE exclusively. Among subjects older than 16 years, patients with PE had significantly shorter P2, longer A2, shorter copatation depth, and longer papillary muscle tethering length compared with normal controls. Similarly, patients with PE had significantly shorter P2 and shorter coaptation depth even compared with patients with HCM, while no significant difference was found in A2 length and papillary muscle tethering length. The same tendency was noted between 4 normal controls and 7 age- and sex-matched patients with PE ≤ 16 years old. No significant difference regarding A2/P2 ratio was found between patients with PE older and younger than 16 years. No significant correlation between the Haller computed tomography index and actual mitral leaflet lengths in patients with PE older than 16 years was noted; the same was observed for A2/P2 in all patients with PE. In conclusion, the characteristic features of the shorter posterior mitral leaflet, the longer anterior mitral leaflet, the shorter coaptation depth, and the longer papillary muscle tethering length in patients with PE was demonstrated. This finding might provide a clue regarding the etiology of mitral valve prolapse in PE at its possible earliest form.

Mitral valve prolapse and sudden cardiac death: a systematic review and meta-analysis

OBJECTIVES

Mitral valve prolapse (MVP) is commonly observed as a benign finding. However, the literature suggests that it may be associated with sudden cardiac death (SCD). We performed a meta-analysis and systematic review to determine the: (1) prevalence of MVP in the general population; (2) prevalence of MVP in all SCD and unexplained SCD; (3) incidence of SCD in MVP and (4) risk factors for SCD.

METHODS

The English medical literature was searched for: (1) MVP community prevalence; (2) MVP prevalence in SCD cohorts; (3) incidence SCD in MVP and (4) SCD risk factors in MVP. Thirty-four studies were identified for inclusion. This study was registered with PROSPERO (CRD42018089502).

RESULTS

The prevalence of MVP was 1.2% (95% CI 0.5 to 2.0) in community populations. Among SCD victims, the cause of death remained undetermined in 22.1% (95% CI 13.4 to 30.7); of these, MVP was observed in 11.7% (95% CI 5.8 to 19.1). The incidence of SCD in the MVP population was 0.14% (95% CI 0.1 to 0.3) per year. Potential risk factors for SCD include bileaflet prolapse, ventricular fibrosis complex ventricular ectopy and ST-T wave abnormalities.

CONCLUSION

The high prevalence of MVP in cohorts of unexplained SCD despite low population prevalence provides indirect evidence of an association of MVP with SCD. The absolute number of people exposed to the risk of SCD is significant, although the incidence of life-threatening arrhythmic events in the general MVP population remains low. High-risk features include bileaflet prolapse, ventricular fibrosis, ST-T wave abnormalities and frequent complex ventricular ectopy.

TRIAL REGISTRATION

PROSPERO (CRD42018089502).

Coexistence of abnormal systolic motion of mitral valve in a consecutive group of 324 adult Tetralogy of Fallot patients assessed with echocardiography

Background

The presence of mitral valve prolapse (MVP) in congenital heart disease (CHD) patients is not well described. Tetralogy of Fallot (TOF) is the most common cyanotic CHD associated with overall good long-term survival after palliation. Since MVP is more often identified in adults and TOF patients are now surviving longer, we thus sought to perform this cohort study with a case–control design to (1) determine the prevalence of MVP and systolic displacement of mitral leaflets (SDML) in adult TOF patients, and (2) describe their clinical and imaging characteristics.

Methods

Retrospective interrogation of our echocardiography database identified 328 consecutive TOF patients ≥18 years from 1 January 2000 to 31 December 2014. All images were reviewed to identify patients with concomitant MVP (prolapse >2 mm beyond the long-axis annular plane) or SDML (<2 mm beyond the annular plane).

Results

26 (8%) TOF patients fulfilled criteria for systolic mitral valve abnormality (SMVA) (15 MVP; 11 SDML). 2 had moderate to severe mitral regurgitation requiring repair. When compared with 52 TOF patients without SMVA, those with SMVA were more likely to be females (60.7% vs 33.9%, p=0.03), less likely to have transannular patch (52% vs 97.4%, p<0.0001), had lower right ventricular ejection fraction (36.5% vs 43.8%, p=0.03) and a trend towards increased risk of atrial (44% vs 30.4%, p=0.5) and ventricular arrhythmias (32% vs 25.5%, p=0.6). On multivariate logistic regression, SMVA was independently associated with the absence of transannular patch (p=0.002) and atrial arrhythmias (p=0.04).

Conclusions

In this series of adult TOF patients, we describe a novel finding of a high prevalence of systolic mitral valve abnormalities.

Mitral valve disease--morphology and mechanisms

Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

Targeted Mybpc3 Knock-Out Mice with Cardiac Hypertrophy Exhibit Structural Mitral Valve Abnormalities

MYBPC3 mutations cause hypertrophic cardiomyopathy, which is frequently associated with mitral valve (MV) pathology. We reasoned that increased MV size is caused by localized growth factors with paracrine effects. We used high-resolution echocardiography to compare Mybpc3-null, heterozygous, and wild-type mice (n = 84, aged 3–6 months) and micro-CT for MV volume (n = 6, age 6 months). Mybpc3-null mice showed left ventricular hypertrophy, dilation, and systolic dysfunction compared to heterozygous and wild-type mice, but no systolic anterior motion of the MV or left ventricular outflow obstruction. Compared to wild-type mice, echocardiographic anterior leaflet length (adjusted for left ventricular size) was greatest in Mybpc3-null mice (1.92 ± 0.08 vs. 1.72 ± 0.08 mm, p < 0.001), as was combined leaflet thickness (0.23 ± 0.04 vs. 0.15 ± 0.02 mm, p < 0.001). Micro-CT analyses of Mybpc3-null mice demonstrated increased MV volume (0.47 ± 0.06 vs. 0.15 ± 0.06 mm³, p = 0.018) and thickness (0.35 ± 0.04 vs. 0.12 ± 0.04 mm, p = 0.002), coincident with increased markers of TGFβ activity compared to heterozygous and wild-type littermates. Similarly, excised MV from a patient with MYBPC3 mutation showed increased TGFβ activity. We conclude that MYBPC3 deficiency causes hypertrophic cardiomyopathy with increased MV leaflet length and thickness despite the absence of left ventricular outflow-tract obstruction, in parallel with increased TGFβ activity. MV changes in hypertrophic cardiomyopathy may be due to paracrine effects, which represent targets for therapeutic studies.

Determining the role of fibrosis in hypertrophic cardiomyopathy

Fibroblast activity within the heart may be considered a basically constructive process. Hyperactivity of fibroblasts, however, may result in the accumulation of extracellular matrix proteins with adverse effects on cardiac structure and function including electrical instability and increased risk of arrhythmogenic cardiac death. The detection of cardiac fibrosis by dedicated imaging techniques, mainly gadolinium-enhanced MRI, holds promise to refine patient management in a variety of cardiac conditions. This review aims to summarize the current knowledge regarding fibrosis in hypertrophic cardiomyopathy.

Relation of mitral valve prolapse to basal left ventricular hypertrophy as determined by cardiac magnetic resonance imaging

We aimed to characterize the extent and distribution of focal basal left ventricular (LV) hypertrophy in patients with mitral valve prolapse (MVP). Sixty-three patients (mean age: 58 ± 14 years) with MVP and 20 age-matched normal volunteers (mean age: 53 ± 11 years) were assessed using cardiac magnetic resonance imaging. We compared the ratio of basal to mid end-diastolic wall thickness in both groups and correlated it with clinical and imaging parameters. Of the 63 patients, 44 (70%) had posterior leaflet prolapse, 2 (3%) had anterior leaflet prolapse, and 17 (27%) had bileaflet prolapse. There was a significantly increased ratio of basal to mid-ventricular end-diastolic wall thickness in all segments of the left ventricle in those with MVP compared to the controls. The inferolateral (2.1 vs 1.0, p <0.01) and anterolateral (2.1 vs 1.1) ratios (p <0.01) were the greatest compared to the other myocardial segments. The degree of mitral annular excursion had a strong positive correlation with the degree of hypertrophy (r(2) = 0.81, p <0.01) and was an independent predictor in adjusted multivariate analysis (p <0.0001). Age, body mass index, LV end-diastolic volume index, LV end -systolic volume index, LV stroke volume index, degree of prolapse, and mitral regurgitation volume did not have any significant correlation with the degree of hypertrophy. In conclusion, MVP is associated with concentric basal LV hypertrophy and good correlation between the excursion of the mitral valve annulus and the degree of relative LV hypertrophy suggests that locally increased myocardial function could be responsible for this remodeling.

The mitral valve in hypertrophic cardiomyopathy: old versus new concepts

Elongation and pathological thickening of the mitral valve (MV) is commonly seen in hypertrophic cardiomyopathy (HCM), and its pathogenic basis is poorly understood. Associated features include mal-positioning of the papillary muscles and MV, as well as systolic anterior motion (SAM) of the MV leaflets, which can worsen the turbulence and dynamic left ventricular outflow tract (LVOT) gradient. Coaptation of the MV leaflets depends on both anterior and posterior leaflet length and position, and failure of either to optimally adapt in this setting can result in mitral regurgitation or worsened LVOT obstruction. The cause of MV enlargement in HCM is not currently understood, and several different hypotheses may be relevant. The lack of correlation between MV size and the severity of left ventricular hypertrophy, as well as the early findings in genetically predisposed individuals with sarcomere mutations, suggest that it may be an intrinsic aspect of HCM in certain individuals. Other evidence points to a reactive process in the setting of excess production of paracrine growth factors in diseased myocardium that may influence valve overgrowth. Improved understanding of the responsible adaptive mechanisms will pave the way for studies targeted on the prevention and treatment of MV disease in HCM.

Novel hypertrophic cardiomyopathy phenotype: segmental hypertrophy isolated to the posterobasal left ventricular free wall

Few other diseases show the degree of phenotypic heterogeneity expressed by HC. The two novel patients reported here with isolated posterobasal LV free wall hypertrophy (and mitral valve prolapse) extend this morphologic diversity even farther, now 3 decades after the introduction of contemporary 2-dimensional imaging.

Hypertrophic obstructive cardiomyopathy complicated by ruptured chordae tendinea to the posterior mitral leaflet and severe congestive heart failure

A 63-year-old woman with hypertrophic obstructive cardiomyopathy developed rapidly progressive fatigue, shortness of breath and congestive heart failure. A transesophageal echocardiogram demonstrated ruptured chordae to the posterior mitral valve leaflet with severe mitral regurgitation. Mitral valve replacement eliminated the outflow gradient. Acute or subacute hemodynamic deterioration in a patient with hypertrophic obstructive cardiomyopathy should lead to a search for associated lesions.

Surgery Insight: septal myectomy for obstructive hypertrophic cardiomyopathy—the Mayo Clinic experience

Septal myectomy has been the gold standard treatment for the relief left ventricular outflow tract obstruction and cardiac symptoms in both adults and children with obstructive hypertrophic cardiomyopathy. In almost all circumstances, abnormalities of the mitral valve and subvalvar mitral apparatus can be managed without the need for mitral valve replacement, and other cardiac lesions can be repaired simultaneously. In the current era, the operative mortality for isolated septal myectomy at an experienced center is low in both children and adults (approximately 1%). Excellent late results with myectomy are gratifying: 90% of patients improve by at least one NYHA class, and improvements persist in most individuals on late follow-up. Late survival in patients with obstructive hypertrophic cardiomyopathy who undergo myectomy exceeds that of patients who do not receive surgical treatment and, in addition, myectomy may be associated with reduced long-term risk of sudden cardiac death. These results should serve as a basis for comparison with newer nonsurgical treatment regimens.

Total relief of severe left ventricular outflow obstruction after spontaneous rupture of chordae tendineae in a patient with hypertrophic cardiomyopathy

In hypertrophic cardiomyopathy (HCM), rupture of mitral chordae tendineae is infrequent and causes acute haemodynamic deterioration. A 38 year old male patient had chordae rupture leading to prolapse of both mitral leaflets and severe regurgitation, without change in symptomatic status. One year before, he had had mild mitral regurgitation and a resting left ventricle outflow tract of 105 mm Hg that disappeared in the present evaluation. In this unique case, worsening of mitral regurgitation was counterbalanced by total relief of the severe obstruction. This case report highlights the role of the mitral valve apparatus in the genesis of obstruction in HCM, further stimulating surgical techniques in which mitral repair can be the main procedure.

Septal myectomy for obstructive hypertrophic cardiomyopathy

Septal myectomy effectively relieves left ventricular outflow tract obstruction (LVOTO) and cardiac symptoms in both adults and children with obstructive hypertrophic cardiomyopathy (HCM). Abnormal attachments of the papillary muscles and chordae and other cardiac lesions can be repaired at the same time. Early mortality for isolated septal myectomy in both children and adults is low (0% to 2.5%). Median echocardiographic LVOT gradients at rest on late follow-up have been as low as 0 to 5 mm Hg. Symptomatic improvements after myectomy occurs in the majority; 90% of patients improve by at least one functional class, and most remain improved on late follow-up. Late survivorship compares very favorably with the natural history of nonoperated patients with symptomatic obstructive HCM. These results serve as a basis for comparison with newer nonsurgical alternatives.

The case for surgery in obstructive hypertrophic cardiomyopathy

Relief of left ventricular (LV) outflow obstruction in patients with hypertrophic cardiomyopathy (HCM) and disabling symptoms refractory to maximum medical management has historically been a surgical problem. Surgical septal myectomy permanently abolishes systolic anterior motion of the mitral valve and mitral regurgitation, while normalizing LV pressures and wall stress. Also, these salutary goals are achieved without encumbering patients with post-procedural devices (e.g., pacemakers or defibrillators) or creating potentially arrhythmogenic substrates, as may occur with alcohol septal ablation. Procedural morbidity and mortality risk with myectomy is similar to, and in some institutions less than those for alcohol septal ablation. Over four decades, reports from numerous centers worldwide have consistently and unequivocably documented the benefits of surgery on hemodynamic and functional state, restoring normal and acceptable quality of life to patients of all ages by largely reversing the complications of heart failure. Long-term survival after myectomy is similar to that of the general population and superior to non-operated patients with obstruction. The LV outflow tract morphology in HCM is heterogeneous and not uncommonly includes congenital anomalies of the mitral valve apparatus for which the surgeon has the flexibility to adapt the repair, often employing an extended myectomy. In the current atmosphere of increasing and perhaps excessive enthusiasm for newer catheter-based interventions, it is a critical time to promote and re-emphasize that surgery is the time-honored (and presently the most effective) treatment strategy for relieving heart failure-related disability resulting from dynamic LV outflow obstruction in HCM, and is the primary treatment option for this subgroup of severely symptomatic drug-refractory patients.

Clinical significance of atrial fibrillation in hypertrophic cardiomyopathy

Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with hypertrophic cardiomyopathy (HCM), and it bears numerous pathophysiologic consequences that potentially affect patient outcome and symptoms. However, studies regarding the impact of AF on the long-term prognosis of HCM patients have been limited in number, with sometimes conflicting results. Recently, studies on community-based patient populations showed that AF is associated with long-term clinical deterioration, embolic complications, and increased cardiovascular mortality due to heart failure and stroke. The consequences of AF on the long-term prognosis of HCM patients are not uniformly unfavorable, however, and in about one third of patients the arrhythmia is compatible with an uneventful course.

Mitral regurgitation in hypertrophic obstructive cardiomyopathy: relationship to obstruction and relief with myectomy

OBJECTIVES

This study examined: 1) the impact of myectomy on postoperative mitral regurgitation (MR) and 2) the association between the severity of MR and the left ventricular outflow tract (LVOT) gradient.

BACKGROUND

For patients with hypertrophic obstructive cardiomyopathy (HOCM) and MR, controversy exists as to whether myectomy alone is sufficient in eliminating MR. Furthermore, the relationship between the degree of MR and the LVOT peak gradient has not been well defined.

METHODS

We performed pre- and postoperative transthoracic as well as intraoperative transesophageal studies in 104 consecutive patients with HOCM undergoing septal myectomy. Left ventricular outflow tract gradient and the nature of MR were assessed.

RESULTS

In the 93 patients without independent mitral valve disease, a relationship was observed between MR severity and the LVOT gradient. Left ventricular outflow tract gradient (mean +/- standard deviation) for trivial, mild, moderate and severe MR were: 23.2+/-19.1, 43.8+/-25.4, 70.1+/-21.0 and 104+/-21.0 mm Hg (p < 0.001). Early postoperative, MR was absent or trivial in 80%, mild in 19% and moderate in 1%. None of these patients required additional mitral valve surgery. For patients with independent mitral valve disease (n = 11), five required mitral valve surgery as well as myectomy. The remainder had significant reductions in the degree of MR with myectomy alone.

CONCLUSIONS

For patients with HOCM and MR not due to independent mitral valve disease, myectomy significantly reduced the degree of MR, without requirement for additional mitral valve surgery. In these patients the severity of MR was directly related to the magnitude of the LVOT gradient.

Mechanism of mitral regurgitation in hypertrophic cardiomyopathy: mismatch of posterior to anterior leaflet length and mobility

BACKGROUND

In hypertrophic cardiomyopathy, a spectrum of mitral leaflet abnormalities has been related to the mechanism of mitral systolic anterior motion (SAM), which causes both subaortic obstruction and mitral regurgitation. In the individual patient, SAM and regurgitation vary in parallel; clinically, however, great interindividual differences in mitral regurgitation can occur for comparable degrees of SAM. We hypothesized that these differences relate to variations in posterior leaflet length and mobility, restricting its ability to follow the anterior leaflet (participate in SAM) and coapt effectively.

METHODS AND RESULTS

Different mitral geometries produced surgically in porcine valves were studied in vitro. Comparable degrees of SAM resulted in more severe mitral regurgitation for geometries characterized by limited posterior leaflet excursion. Mitral geometry was also analyzed in 23 patients with hypertrophic cardiomyopathy by intraoperative transesophageal echocardiography. All had typical anterior leaflet SAM with significant outflow tract gradients but considerably more variable mitral regurgitation; therefore, regurgitation did not correlate with obstruction. In contrast, mitral regurgitation correlated inversely with the length over which the leaflets coapted (r= -0.89), the most severe regurgitation occurring with a visible gap. Regurgitation increased with increasing mismatch of anterior to posterior leaflet length (r=0.77) and decreasing posterior leaflet mobility (r= -0.79).

CONCLUSIONS

SAM produces greater mitral regurgitation if the posterior leaflet is limited in its ability to move anteriorly, participate in SAM, and coapt effectively. This can explain interindividual differences in regurgitation for comparable degrees of SAM. Thus, the spectrum of leaflet length and mobility that affects subaortic obstruction also influences mitral regurgitation in patients with SAM.

Hypertrophic cardiomyopathy with obstruction: important diagnostic clue provided by the direction of the mitral regurgitation jet

We present an unusual case of hypertrophic cardiomyopathy complicated by mitral regurgitation resulting from chordal rupture with flail posterior mitral leaflet. The diagnosis was suggested by the presence of an anteriorly directed mitral regurgitation jet on transthoracic color flow imaging, in addition to the typical posterolateral-lateral jet caused by systolic anterior mitral motion. The flail posterior leaflet was confirmed by transesophageal echocardiography, and the patient underwent mitral valve repair in addition to myectomy. This combination of hypertrophic cardiomyopathy and flail mitral leaflet usually requires surgical intervention, and prompt diagnosis is important. The presence of an anteriorly directed mitral regurgitant jet should always raise suspicion of posterior mitral leaflet abnormality.

New diagnostic options in hypertrophic cardiomyopathy

The pathophysiologic features and clinical manifestations of HCM have been elucidated by the introduction of several new diagnostic options. Knowledge of the molecular defects of HCM has advanced rapidly, and genetic screening studies have reemphasized the value of the standard electrocardiogram as an initial screening tool. Analysis of heart rate variability, late potentials, and QT dispersion were not found to be reliable prognostic markers in HCM. However, measurement of dispersion of conduction is probably a sensitive technique in identifying a high risk for sudden cardiac death. Significant developments include transthoracic and transesophageal echocardiography and their role in studying the mitral valve, early detection of left ventricular chamber dilatation, analysis of coronary flow, and intraoperative echocardiography. Finally, advances in the application of magnetic resonance imaging and positron-emission tomography are underway.

Hypertrophic cardiomyopathy. Clinical spectrum and treatment

HCM is a heterogeneous disease genotypically, phenotypically, pathophysiologically, clinically, and therapeutically. In decisions on the management of these patients, it is important to recognize this heterogeneity and to direct therapy at the predominant abnormalities.