Sustained Improvement After Combined Anterior Mitral Leaflet Extension and Myectomy in Hypertrophic Obstructive Cardiomyopathy

MYH7 mutation is associated with mitral valve leaflet elongation in patients with obstructive hypertrophic cardiomyopathy

Mitral valve (MV) leaflet elongation is recognized as a primary phenotypic expression of hypertrophic cardiomyopathy (HCM) that contributes to obstruction. This study investigates the correlation between MV length and genotype mutations in the two predominant genes, myosin-binding protein C (MYBPC3), and the β-myosin heavy chain (MYH7) in patients with obstructive HCM (OHCM). Among the 402 OHCM patients, there were likely pathogenic or pathogenic variations in MYH7 (n = 94) and MYBPC3 (n = 76), along with a mutation-negative group (n = 212). Compared to genotype-negative patients, genotype-positive individuals exhibited elongated MV length, thicker interventricular septum, and increased instances of late gadolinium enhancement. Notably, MYH7 mutations were associated with a more severe disease trajectory than MYBPC3 mutations. After adjusting for potential confounders, multivariate linear regression analysis revealed that MYH7 gene mutations and left ventricular volume were independently associated with MV leaflet elongation. The study indicates that mutations in MYH7 and hemodynamics factors are significant risk factors for elongated MV leaflet. Consequently, regular assessment of MV length, especially in patients with MYH7 mutation and enlarged LV volume, is crucial for timely preoperative strategic planning and improved prognosis.

Mitral Valve Interventions for Hypertrophic Obstructive Cardiomyopathy

The mitral valve (MV) plays an important role in the pathophysiology of hypertrophic obstructive cardiomyopathy (HOCM). Dynamic left ventricular outflow tract (LVOT) obstruction, caused by systolic anterior motion (SAM), is a common occurrence in most patients with hypertrophic cardiomyopathy and is directly associated with the MV apparatus. First line therapy for HOCM patients is pharmacological, and surgical intervention is often indicated for patients who do not respond to medical therapy. Emerging research on mitral disease in HOCM, specifically mitral regurgitation (MR), demonstrates that these patients frequently do not respond to standard therapeutic options, and can benefit from MV interventions. In this review, we describe the involvement of the MV in the pathogenesis of HOCM, discuss medical therapy, and explore available mitral procedures. Surgical myectomy, often combined with various modifications to the MV apparatus, is frequently necessary to achieve a durable resolution of LVOT obstruction and SAM-related MR. Alcohol septal ablation, an alternative to surgical myectomy, will be briefly mentioned. We also emphasize the role of transcatheter edge-to-edge repair (TEER) as a promising and novel therapeutic option for HOCM patients. Over time, TEER has established itself as an effective and safe procedure, demonstrating success across a spectrum of anatomical variations. The leaflet modification and movement restriction achieved through TEER help reduce SAM and, consequently, have the potential to alleviate LVOT obstruction and SAM-related MR. Furthermore, we propose a treatment algorithm for cases where TEER is a potential course of action for patients who are at high risk for other interventions.

Extended septal myectomy for obstructive hypertrophic cardiomyopathy and its impact on mitral valve function

AIMS

Septal myectomy is the treatment of choice for hypertrophic obstructive cardiomyopathy (HOCM). Around 30-60% of patients with HOCM have a secondary mitral valve regurgitation due to systolic anterior motion (SAM). We report our experience with extended septal myectomy and its impact on the incidence of concomitant mitral valve procedures.

METHODS

This is a retrospective study on 84 patients who underwent SM from January 2008 to February 2022. Surgical procedure was performed according to the concept of 'extended myectomy' described by Messmer in 1994. Follow-up outcomes in terms of survival, hospital admissions for heart failure or MV disease, cardiac reoperations, and pacemaker (PMK) implantation were recorded.

RESULTS

Mean age was 61 ± 15 years. Mitral valve surgery was performed in seven cases (8%); particularly only one patient without degenerative mitral valve disease underwent mitral valve surgery, with a plicature of the posterior leaflet. In-hospital mortality was 5%. Mitral valve regurgitation greater than mild was present in four patients (5%) at discharge. Twelve-year survival was 78 ± 22%. Cumulative incidence of rehospitalization for heart failure and rehospitalization for mitral valve disease was 10 ± 4 and 2.5 ± 2.5%, respectively. PMK implantation was 5% at discharge, with a cumulative incidence of 15 ± 7%. Freedom from cardiac reoperations was 100%.

CONCLUSION

Septal myectomy for HOCM is associated with good outcomes. Although concomitant surgery on the mitral valve to address SAM and associated regurgitation has been advocated, these procedures were needed in our practice only in patients with intrinsic mitral valve disease. Adequate myectomy addresses the underlying pathophysiology in most patients.

Treatment Strategies for Hypertrophic Cardiomyopathy: Surgical

Septal myectomy is a well-established procedure for septal reduction in patients with obstructive hypertrophic cardiomyopathy (HCM) who have not responded to medical treatment. The surgical approach is tailored to the unique pathophysiology and septal morphology of the patient. Extended transaortic myectomy is the standard procedure for patients with isolated subaortic obstruction, the most common type of HCM. However, transapical myectomy is a useful adjunct for patients with long or midventricular obstruction and is our preferred technique for ventricular enlargement in patients with severe symptomatic diastolic heart failure because of extensive apical hypertrophy. Septal myectomy provides excellent postoperative outcomes as regards symptom relief and functional improvement, and operative morbidity and mortality rates are low in experienced centers. This article summarizes our current surgical management of patients with HCM and details operative methods and outcomes.

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.

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.

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.

Primeval outcomes of thoracoscopic transmitral myectomy with anterior mitral leaflet extension for hypertrophic obstructive cardiomyopathy

BACKGROUND

The transaortic Morrow procedure is the current gold standard for hypertrophic obstructive cardiomyopathy (HOCM) patients who are resistant to maximum drug therapy. It is controversial whether concomitant mitral valve intervention is necessary. Only a few centers apply for concomitant anterior mitral leaflet extension with a bovine or autologous pericardial patch to further decrease systolic anterior motion. Our aim is to assess the primeval outcomes of thoracoscopic transmitral myectomy with anterior mitral leaflet extension (TTM-AMLE) in symptomatic HOCM patients.

METHODS

Between April 2019 and November 2020, 18 consecutive HOCM patients who underwent TTM-AMLE were enrolled in this study. Preoperative, postoperative, and follow-up outcomes were compared and statistically analyzed.

RESULTS

The mean age was (50.17 ± 6.18) years and 10 (55.56%) were males. 18 (100%) patients had mitral regurgitation preoperatively, and they all successfully underwent TTM-AMLE with a median cardiopulmonary bypass and aortic cross-clamp time of 200.0 (150.8, 232.0), and 127.5 (116.0, 149.0) min, respectively. The median length of ICU stay was 2.7 (1.4, 5.2) days. The interventricular septum thickness was significantly reduced (from 18.03 ± 3.02 mm to 11.91 ± 1.66 mm, p < .001). There was no perioperative mortality, perforation of ventricular septum, or conversion to sternotomy observed. During a median follow-up of 18 months (IQR, 5-24 months), 1 (5.56%) patient had severe mitral regurgitation due to patch detachment and received reoperation. Moderate degree of mitral regurgitation and more than 50 mmHg in left ventricular outflow tract gradient were found in 2 (11.11%), and 1 (5.56%) patients, respectively. 1 (5.56%) patient who had second-degree atrioventricular block received permanent pacemaker implantation postoperatively. Overall, the maximum left ventricular outflow tract gradient (88.50 [59.50, 112.75] mmHg vs. 10.50 [7.00, 15.50] mmHg, p = .002), left ventricular outflow tract velocity (4.70 [3.86, 5.33] m/s vs. 1.60 [1.33, 1.95] m/s, p < .001) and the degree of mitral regurgitation (6.99 ± 4.47 cm² vs. 2.22 ± 1.51 cm² , p = .001) were significantly decreased, with a significant reduction in the proportion of systolic anterior motion (94.44% vs. 16.67%, p < .001).

CONCLUSIONS

The TTM-AMLE is a safe and effective surgical approach for selected patients with HOCM. In our series, it provides excellent relief of left ventricular outflow tract obstruction, while significantly eliminating mitral regurgitation. The early outcomes of TTM-AMLE are satisfactory, but further studies and longer follow-ups are awaited.

Surgical Management for Systolic Anterior Motion (SAM) of the Mitral Valve in Obstructive Hypertrophic Myopathy

In patients with obstructive hypertrophic cardiomyopathy, left ventricular outflow tract (LVOT) obstruction can be created by the hypertrophic interventricular septum (IVS) as well as systolic anterior motion (SAM) of the anterior mitral leaflet (AML). Sufficient septal myectomy is a fundamental surgical technique to treat LVOT obstruction, however, direct surgical management for SAM is another key aspect. Besides the hypertrophic IVS, mitral valve, subvalvular apparatus, and papillary muscle may play important role for SAM and several surgical techniques have been proposed to treat SAM in literature. In this review, each surgical technique is classified by the anatomical structure on which the surgical procedure is applied. The AML is the main surgical site and is applied with plication (vertical plication, resection–plication–release strategy), extension (the AML extension, transverse incision of the AML), sutured (edge-to-edge repair, anterior leaflet retention plasty), or traction (floating stitch, papillary muscle-to-anterior annulus stitches, paradoxical stitches, transposition of a directed chorda tendinea to the AML). Height reduction of the posterior mitral valve leaflet and papillary muscle reorientation are other techniques. We should understand theoretical aspects of each technique on correction of anatomical and functional abnormalities of the structure and should apply them under proper indication.

Review of Contemporary Invasive Treatment Approaches and Critical Appraisal of Guidelines on Hypertrophic Obstructive Cardiomyopathy: State-of-the-Art Review

BACKGROUND

Hypertrophic obstructive cardiomyopathy (HOCM) is a heterogeneous disease with different clinical presentations, albeit producing similar dismal long-term outcomes if left untreated. Several approaches are available for the treatment of HOCM; e.g., alcohol septal ablation (ASA) and surgical myectomy (SM). The objectives of the current review were to (1) discuss the place of the standard invasive treatment modalities (ASA and SM) for HOCM; (2) summarize and compare novel techniques for the management of HOCM; (3) analyze current guidelines addressing HOCM management; and (4) offer suggestions for the treatment of complex HOCM presentations.

METHODS

We searched the literature and attempted to gather the most relevant and impactful available evidence on ASA, SM, and other invasive means of treatment of HOCM. The literature search yielded thousands of results, and 103 significant publications were ultimately included.

RESULTS

We critically analyzed available guidelines and provided context in the setting of patient selection for standard and novel treatment modalities. This review offers the most comprehensive analysis to-date of available invasive treatments for HOCM. These include the standard treatments, SM and ASA, as well as novel treatments such as dual-chamber pacing and radiofrequency catheter ablation. We also account for complex pathoanatomic presentations and current guidelines to offer suggestions for tailored care of patients with HOCM. Finally, we consider promising future therapies for HOCM.

CONCLUSIONS

HOCM is a heterogeneous disease associated with poor outcomes if left untreated. Several strategies for treatment of HOCM are available but patient selection for the procedure is crucial.

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.

Comprehensive left ventricular outflow tract management beyond septal reduction to relieve obstruction

The surgical management of patients with hypertrophic obstructive cardiomyopathy can be extremely challenging. Relieving the left ventricular outflow tract obstruction in these patients is often achieved by performing a septal myectomy. However, in many instances, septal reduction alone is not enough to relieve the obstruction. Interventions on the sub-valvular apparatus, including the anomalous chordae tendineae and the abnormal papillary muscles, are often required. In this review, we summarize the embryology and the pathophysiology of the different elements that may contribute to the left ventricular outflow tract obstruction in the setting of hypertrophic obstructive cardiomyopathy. In addition, we highlight the different surgical procedures that a surgeon may adopt to relieve the left ventricular outflow tract obstruction, beyond the septal myectomy.

Surgery for Hypertrophic Obstructive Cardiomyopathy: Comprehensive LVOT Management beyond Septal Myectomy

Hypertrophic cardiomyopathy (HCM) is a complex, underestimated, multifaceted disease frequently associated with left ventricular outflow tract (LVOT) obstruction. It is clearly demonstrated that this is due not only to septal hypertrophy but also to systolic anterior motion (SAM) of mitral valve leaflets secondary to mitral valve/subvalvular apparatus abnormalities. Surgical treatment involves performing an extended septal myectomy, eventually followed by ancillary procedures to those structures responsible for maintaining LVOT obstruction, if necessary. In this review, we describe the spectrum of possible surgical techniques beyond septal myectomy and their pathophysiologic rationale.

Influence of operator volume on early outcomes of septal myectomy for isolated hypertrophic obstructive cardiomyopathy

Background

Guidelines on the diagnosis and management of hypertrophic cardiomyopathy (HCM) recommend that septal myectomy be performed by experienced operators. However, the impact of operator volume on surgical treatment outcomes for isolated HCM has been poorly investigated.

Methods

From 2002 to 2014, 435 consecutive patients with isolated HCM undergoing myectomy at the Fuwai Hospital were retrospectively enrolled. All 29 surgeons were divided into beginner surgeons (operator volume ≤20) and experienced surgeons (operator volume >20) according to the guidelines for the diagnosis and treatment of HCM. Propensity score matching of patients in the two groups was performed.

Results

Baseline differences included advanced New York Heart Association classification and older age in the experienced surgeon group. After matching, in the beginner surgeon group (107 cases), residual obstruction (18.7% vs. 0.9%, P<0.001) was more common, and the postoperative left ventricular outflow tract pressure gradient (20.7±15.1 vs. 14.3±7.4 mmHg, P<0.001) was higher than that of the experienced surgeon group. In the experienced surgeon group (107 cases), the incidence of mitral valve replacement (1.9% vs. 11.2%, P<0.001) and permanent pacemaker implantation (1.9% vs. 3.7%, P<0.001) was significantly lower than that in the beginner surgeon group. However, there was no difference in procedural mortality (1.9% vs. 1.9%) between the two groups.

Conclusions

Operator volume is an important factor in achieving better obstruction obliteration after septal myectomy in patients with isolated HCM.

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.

Impact of sex on timing and clinical outcome of septal myectomy for obstructive hypertrophic cardiomyopathy

BACKGROUND

Sex disparities are common in hypertrophic cardiomyopathy (HCM). Previous research has shown that at time of myectomy, women are older, have greater impairment of diastolic function and more advanced cardiac remodeling. The clinical impact of these differences is unknown.

METHOD

This study included 162 HCM patients (61% men) who underwent septal myectomy. Time to treatment was calculated in relation to symptom onset and diagnosis. Pre- and post-operative echocardiographic data were collected. Sex differences were assessed at baseline and in time-to-event survival analyses for the composite endpoint of all-cause mortality, cardiac transplantation, re-intervention and aborted sudden cardiac death.

RESULTS

Women were generally older at time of myectomy (57 vs. 49 years, p < 0.01), with similar time to treatment as measured from symptom onset (2.3 [1.3-6.0] vs. 2.8 [1.1-5.3] years, p > 0.05), but a shorter time since diagnosis compared to men (2.6 [1.2-7.0] vs. 4.3 [2.4-8.3] years, p = 0.02). Mean wall thickness and left atrial diameter were the same for men and women, but were higher in women when correcting for body surface area (absolute: 20 vs. 19 mm, 48 vs 46 mm, p ≥ 0.05; corrected: 9.7 vs. 11.2 mm/m², 23.4 vs. 26.3 mm/m², p < 0.01). After 5.9 [3.0-9.1] years, 15% of men and 8% of women had reached the composite endpoint (p > 0.05).

CONCLUSION

In conclusion, although women present later in life and seem to have more advanced disease on echocardiography, time until myectomy was similar and clinical outcomes after myectomy are favourable for both men and women.

Effects of surgical septal myectomy on survival in patients with hypertrophic obstructive cardiomyopathy

Objective:

The purpose of this study was to determine the effects of surgical resection of muscle layer on the long-term survival of patients with hypertrophic obstructive cardiomyopathy (HOCM).

Methods:

The original study cohort consisted of 552 patients with hypertrophic cardiomyopathy (HCM), including 380 patients with HOCM and 172 patients with nonobstructive HCM. All these patients had a definite diagnosis in our center from October 1, 2009, to December 31, 2012. They were divided into three groups, viz., HOCM with myectomy group (n=194), nonoperated HOCM group (n=186), and nonobstructive HCM group (n=172). Median follow-up duration was 57.57±13.71 months, and the primary end point was a combination of mortality from all causes.

Results:

In this survival study, we compared the prognoses of patients with HOCM after myectomy, patients with nonoperated HOCM, and patients with nonobstructive HCM. Among the three groups, the myectomy group showed a lower rate of reaching the all-cause mortality with statistically indistinguishable overall survival compared with patients with nonobstructive HCM (p=0.514). Among patients with left ventricular outflow tract (LVOT) obstruction, the overall survival in the myectomy group was noticeably better than that in the nonoperated HOCM group (log-rank p<0.001). Parameters that showed a significant univariate correlation with survival included age, previous atrial fibrillation (AF), NT-proBNP, Cr, myectomy, and LV ejection fraction. When these variables were entered in the multivariate model, the only independent predictors of survival were myotomy [hazard ratio (HR): 0.109; 95% CI: 0.013–0.877, p<0.037], age (HR: 1.047; 95% CI: 1.007–1.088, p=0.021), and previous AF (HR: 2.659; 95% CI: 1.022–6.919, p=0.021).

Conclusion:

Patients with HOCM undergoing myectomy appeared to suffer from a lower risk of reaching the all-cause mortality and demonstrated statistically indistinguishable overall survival compared with patients with nonobstructive HCM. Multivariate analysis clearly demonstrated myectomy as a powerful, independent factor of survival, confirming that the differences in long-term survival recorded in this study may be due to surgical improvement in the LVOT gradient.

Anterior mitral leaflet length and mitral annulus diameter impact the echocardiographic outcome after isolated myectomy

Background

Myectomy remains the standard surgical treatment of patients with hypertrophic cardiomyopathy (HOCM). New surgical methods developed in the last decades mainly address the mitral valve and are controversial because of their conflicting assumptions. This study assesses the influence of anterior mitral valve leaflet (AML) length and the anterior-posterior diameter of the mitral annulus (MAD) on dynamic left ventricle outflow tract obstruction and mitral regurgitation (MR) after extended myectomy.

Methods

We retrospectively analysed the transthoracic echocardiograms (TTE) of 36 patients. AML length and MAD were obtained from TTE performed before the operation. The greatest maximal left ventricle outflow tract (LVOT) gradient and MR registered in follow-up were analysed. After surgery, patients were divided into two groups; those with moderate or milder MR and/or an LVOT gradient < 30 mmHg (responders), and those with more than moderate MR and/or an LVOT gradient ≥30 mmHg (non-responders).

Results

Patients in responders group had significantly longer AML: 32.3 ± 2.3 mm vs 30.0 ± 3.8 mm (p = 0.03) [parasternal long axis view – PLAX view], 25.9 ± 2.3 mm vs 23.5 ± 2.7 mm (p = 0.008) [four chamber view - 4CH view] and larger anterior-posterior mitral annulus diameter 28.1 ± 2.8 mm vs 25.4 ± 3.2 mm (p = 0.011) than those in non-responders group. Among all analysed patients longer anterior mitral leaflet was correlated with lower postoperative LVOT gradient when measured in PLAX view (p = 0.02) and lower degree of MR due to systolic anterior motion (SAM) when measured in 4CH view (p = 0.009). Greater [AML x mitral annulus] ratio correlated with lower postoperative LVOT gradient in both projections: 4CH (p = 0.025), PLAX (p = 0.012). There was significant reduction in NYHA Class after surgery (p = 0.000). There were no significant differences in NYHA class after surgery (p = 0.633) neither in NYHA class reduction (p = 0.475) between patients divided into responders and non-responders group according to echocardiographic parameters.

Conclusions

Patients with a longer AML and a greater diameter of the mitral annulus are less likely to have mitral regurgitation due to residual SAM and increased LVOT gradient after an extended myectomy. Division of patients according to echocardiographic criteria into responders and non-responders was not in concordance with clinical improvement.

Trial registration

Retrospective study. Approved by ethics committee (IK-NPIA-0021-21/1763/19) at 16.01.2019.

Alcohol septal ablation: in which patients and why?

At present, surgical septal myectomy is regarded as the "gold standard" treatment for most patients with obstructive hypertrophic cardiomyopathy (HCM) and drug-refractory symptoms. However, the best results are obtained by those surgeons who have extensive experience with this operation at a small number of referral centers. In the mid-1990s, percutaneous alcohol septal ablation was introduced as an alternative to myectomy to reduce LV outflow gradient and heart failure symptoms in patients with obstructive HCM. However, certain features of alcohol ablation limit its applicability to carefully selected patients. Because this procedure involves the injection of 1-4 mL of 96% ethanol into a septal perforator of the left anterior coronary artery to produce a myocardial infarction (with septal thinning, outflow tract widening and gradient reduction), alcohol ablation is limited by the size and distribution of the septal perforator branches. In addition, rich blood supply from other septal branches not occluded by the balloon and from the posterior descending coronary artery may restrict myocardial ischemia to portions of the septum that do not contribute to outflow obstruction. Septal hypertrophy may be either mild or particularly marked, and abnormalities of mitral valve apparatus may also play a major role in outflow obstruction. When such features are present, alcohol-induced septal thinning is unlikely to significantly reduce the gradient. In addition, persisting uncertainties regarding the risk for ventricular tachyarrhythmias after alcohol ablation suggest this procedure should be limited to patients of advanced age, patients at unacceptable operative risk due to comorbidities, or those with strong aversion to surgery. Further progress in the treatment for patients with obstructive HCM and severe refractory symptoms will come from assuring proper patient selection for alcohol septal ablation, as well as increasing the number of surgeons and centers experienced in performing septal myectomy.

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.

Long-term benefit of myectomy and anterior mitral leaflet extension in obstructive hypertrophic cardiomyopathy

Severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HC) may benefit from surgical myectomy. In patients with enlarged mitral leaflets and mitral regurgitation, myectomy can be combined with anterior mitral leaflet extension (AMLE) to stiffen the midsegment of the leaflet. The aim of this study was to evaluate the long-term results of myectomy combined with AMLE in patients with obstructive HC. This prospective, observational, single-center cohort study included 98 patients (49 ± 14 years, 37% female) who underwent myectomy combined with AMLE from 1991 to 2012. End points included all-cause mortality and change in clinical and echocardiographic characteristics. Mortality was compared with age- and gender-matched patients with nonobstructive HC and subjects from the general population. Long-term follow-up was 8.3 ± 6.1 years. There was no operative mortality, and New York Heart Association class was reduced from 2.8 ± 0.5 to 1.3 ± 0.5 (p <0.001), left ventricular outflow tract gradient from 93 ± 25 to 9 ± 8 mm Hg (p <0.001), mitral valve regurgitation from grade 2.0 ± 0.9 to 0.5 ± 0.8 (p <0.001), and systolic anterior motion of the mitral valve from grade 2.4 ± 0.9 to 0.1 ± 0.3 (p <0.001). The 1-, 5-, 10-, and 15-year cumulative survival rates were 98%, 92%, 86%, and 83%, respectively, and did not differ from the general population (99%, 97%, 92%, and 85%, respectively, p = 0.3) or patients with nonobstructive HC (98%, 97%, 88%, and 83%, respectively, p = 0.8). In conclusion, in selected patients with obstructive HC, myectomy combined with AMLE is a low-risk surgical procedure. It results in long-term symptom relief and survival similar to the general population.

Myectomy and mitral repair through the left atrium in hypertrophic obstructive cardiomyopathy: the preferred approach for contemporary surgical candidates?

OBJECTIVE

Patients with hypertrophic obstructive cardiomyopathy due to diffuse hypertrophy extending to or below the papillary muscles are poor candidates for alcohol septal ablation and suboptimal candidates for transaortic septal myectomy. In addition, the outflow obstruction is often aggravated by an abnormal mitral valve and subvalvular apparatus.

METHODS

We performed transatrial myectomy in 12 patients with diffuse hypertrophy, who were highly symptomatic despite maximal medical therapy. All had at least moderate mitral regurgitation and systolic anterior motion. The anterior mitral leaflet (AML) was detached from commissure to commissure, allowing an easy myectomy through this AML toward the base of the anterior papillary muscle, with mobility fully restored. The abnormal chordae from the septum to the anterior papillary muscle and AML were divided. The continuity of this AML was restored with augmentation using an autologous pericardial patch. The height of the posterior mitral leaflet was reduced and the repair completed using an oversized annuloplasty ring.

RESULTS

The peak intraventricular gradients decreased spectacularly from 98.8 ± 6.29 to 19.2 ± 13.4 mm Hg (P < .001), and the systolic anterior motion and mitral regurgitation disappeared. One patient died of left ventricular diastolic dysfunction. All other patients left the hospital in New York Heart Association class I or II.

CONCLUSIONS

We believe that this technique is preferable for patients with hypertrophic obstructive cardiomyopathy and diffuse hypertrophy extending to the midportion of the left ventricle or beyond. It results in disappearance of outflow tract gradients and allows correction of the mitral valve abnormality.

Surgical treatment of functional mitral regurgitation

Incidence of functional mitral regurgitation (FMR) is increasing due to aging and better survival after acute myocardial infarction, the most frequent cause of FMR. At the basis of FMR there is a displacement of one of both papillary muscle(s) and/or annular enlargement, which can be primitive or, more often, secondary. There is general agreement that its natural history is unfavorable, as witnessed by a considerable body of evidences. However, even if there is no clear evidence that surgical treatment of FMR changes consistently the outcome of patients with this disease, at least in terms of survival, there are some studies which show that function improves, as well as the global quality of life. The guidelines reflect this uncertainty, providing no clear indications, even in the gradation of severity of the FMR. Surgical techniques are variable and are mainly addressed to the annulus (restrictive annuloplasty), which is only a part of the anatomic problem related to FMR. Insertion of a prosthesis inside the native valve is appearing more and more a valuable option rather than a bail out procedure. On the other side, techniques addressed to modify the position of the papillary muscles appear to be still under investigation and not yet in the armamentarium of surgical treatment of FMR. Even after many years, rules are not established and results are fluctuating, but how and when to treat FMR is becoming more and more a topic of interest in cardiac surgery.

A contemporary European experience with surgical septal myectomy in hypertrophic cardiomyopathy

Aims

The recent American College of Cardiology and American Heart Association Guidelines on hypertrophic cardiomyopathy (HCM) have confirmed surgical myectomy as the gold standard for non-pharmacological treatment of obstructive HCM. However, during the last 15 years, an extensive use of alcohol septal ablation has led to the virtual extinction of myectomy programmes in several European countries. Therefore, many HCM candidates for myectomy in Europe cannot be offered the option of this procedure. The purpose of our study is to report the difficulties and results in developing a myectomy programme for HCM in a centre without previous experience with this procedure.

Methods and results

The clinical course is reported of 124 consecutive patients with obstructive HCM and heart failure symptoms who underwent myectomy at a single European centre between 1996 and 2010. The median follow-up was 20.3 months (inter-quartile range: 3.9–40.6 months). No patients were lost to follow-up. A cumulative incidence of HCM-related death after myectomy was 0.8, 3.3, and 11.2% at 1, 5, and 10 years, respectively, including one operative death (procedural mortality 0.8%). The left ventricular (LV) outflow gradient decreased from 95 ± 36 mmHg before surgery to 12 ± 6 mmHg at most recent evaluation (P < 0.001), with none of the patients having a significant residual LV outflow gradient. Of the 97 patients in New York Heart Association functional class III–IV before surgery, 93 (96%) were in class I–II at most recent evaluation (P < 0.001).

Conclusion

Our results show that the development of a myectomy programme at a centre without previous experience with this procedure is feasible and can lead to highly favourable clinical results.