Radiofrequency ablation in obstructive hypertrophic cardiomyopathy: a case report.

Background: We report endocardial radiofrequency (RF) ablation as an alternative treatment approach for a symptomatic patient with obstructive hypertrophic cardiomyopathy (oHCM), who is not suitable for surgical septal myectomy or alcohol septal ablation. Endocardial RF ablation, with detailed 3D mapping of the intrinsic conducting system, offers the possibility of reducing the risk of complete heart block rates and of effectively relieving symptoms. Case summary: We present a symptomatic 51-year-old female patient with oHCM and a maximum left ventricular outflow tract (LVOT) gradient of 148 mmHg. Because of alcohol septal ablation failure, endocardial RF ablation in combination with detailed mapping of the intrinsic conduction system and intraprocedural imaging was performed. The 6-month follow-up showed a significant improvement in exercise tolerance, no relevant dynamic LVOT obstruction with a gradient of 22 mmHg under Valsalva. Discussion: In the current case report, endocardial RF ablation persistently reduced LVOT gradients in a patient with oHCM. Pre-interventional imaging, detailed 3D mapping of the conduction system, and correlation to intracardiac and transthoracic echocardiography were key for an effective and safe ablation of a small target zone.

Left Ventricular Outflow Tract and Transcatheter Mitral Valve Replacement Obstruction and TMVR: Predictors, Evaluation, and Solutions.

In this issue of Structural Heart, high-impact presentations from Transcatheter Valve Therapies 2023 are reviewed. Dr Jaffar Khan provided updates on the current understanding of left ventricular outflow tract obstruction in the field of transcatheter mitral valve replacement, highlighting known predictors of obstruction, a generally agreed-upon strategy for preprocedure assessment, and a host of management strategies in various stages of development and study.

Titin Cardiomyopathy Associated With Refractory Ventricular Tachycardia: A Case Report.

Cardiomyopathy is defined as structural and functional myocardial abnormality not attributed to ischemic, valvular, hypertensive, or congenital cardiac causes. The main phenotypes of cardiomyopathy include hypertrophic, dilated, non-dilated left ventricular, restrictive, arrhythmogenic right ventricular, Takotsubo, and left ventricular noncompaction cardiomyopathies. A significant proportion of dilated cardiomyopathy (DCM) cases represents patients with genetic mutations, most commonly titin gene truncating variants (TTNtv). It has been shown that TTNtv mutation contributes to the development of certain types of DCM such as alcohol, chemotherapy, and peripartum. We present a case of DCM where genetic workup revealed TTNtv without other contributing factors. The course was complicated by multiple ventricular tachycardias (VTs) refractory to medical management, despite treatment with amiodarone, sotalol, dofetilide, mexiletine, and propranolol. Interestingly, endocardial mapping failed to delineate the substrate of tachycardia. This report underscores the importance of genetic testing in DCM and highlights the potential association of titin cardiomyopathy with refractory VTs, possibly of epicardial origin.

Mavacamten in real-life practice: Initial experience at a hypertrophic cardiomyopathy centre.

AIMS: In clinical trials, mavacamten reduced left ventricular outflow tract obstruction (LVOTO) and improved symptoms in patients with symptomatic obstructive hypertrophic cardiomyopathy (oHCM). We aimed to share our real-world experience with the efficacy and safety of mavacamten in this patient population. METHODS AND RESULTS: This retrospective, single-centre study included patients with symptomatic oHCM from March 2023 to November 2023. Inclusion criteria were oHCM, age >18 years, significant LVOTO (gradient >50 mmHg at rest or with Valsalva), New York Heart Association (NYHA) class ≥II despite maximally tolerated medical therapy, and left ventricular ejection fraction (LVEF) >55%. Patients were evaluated by echocardiography, NYHA class, electrocardiography and Holter monitor on each monthly visit for 3 months. A total of 31 patients were included in this study. The mean (SD) age was 58 (16.5) years, and 14 (45%) were female. Mean provoked left ventricular outflow tract gradient (LVOTG) reduced by -49.4 mmHg (P < 0.001) at 4 weeks, -59.2 mmHg (P < 0.001) at 8 weeks, and -60.8 mmHg (P < 0.001) at 12 weeks. Twenty-six of the 31 patients (83.8%) achieved an LVOTG ≤30 mmHg at Week 12. No major side effects were reported. Sixty-seven percent experienced ≥2 NYHA class improvements, LVEF remained above 55% and no dose titration was made. CONCLUSIONS: Our real-world experience aligns with established mavacamten trial outcomes. Continuous vigilance and longitudinal investigations are needed to further assess potential long-term impacts.

Takotsubo syndrome complicated by cardiogenic shock due to left ventricular outflow tract obstruction, acute mitral regurgitation, and atrial fibrillation: a case report.

Background: Although Takotsubo syndrome (TTS) is generally considered a benign disease, recent reports showed the incidence of cardiogenic shock due to left ventricular outflow tract obstruction (LVOTO), mitral regurgitation (MR), and primary pump failure was estimated to be 6-20%. Case summary: A 78-year-old woman presented with chest pain and cold sweats 2 days after surgery for lung cancer. Acute coronary syndrome was suspected based on her symptoms, electrocardiography, transthoracic echocardiography (TTE), and laboratory data; thus, emergency catheterization was performed. Normal coronaries were observed, with hyperkinesis at the base of the left ventricle and akinesis at its apex, leading to the diagnosis of the apical ballooning type of TTS. Pressure differences between the apex of the left ventricle (168/8/28 mmHg) and aorta (94/50/64 mmHg) indicated the presence of LVOTO. Two days after TTS onset, she developed cardiogenic shock (blood pressure was 54/38 mmHg). Transthoracic echocardiography showed acute MR due to systolic anterior motion of the mitral valve caused by LVOTO, which was further exacerbated by paroxysmal atrial fibrillation. Fluid resuscitation, intravenous ß-blockers, and amiodarone were administered for reduction of the pressure gradient in the left ventricular outflow, rate control, and sinus rhythm maintenance. Her condition improved along with the MR, thereby improving LVOTO and maintaining sinus rhythm. Discussion: Takotsubo syndrome should be kept in mind as a potential cause of acute MR due to LVOTO. Catheterization and multiple follow-up TTE play a major role in early detection for this condition.

Mitral Regurgitation and Left Ventricular Outflow Tract Obstruction: Confluence of Challenges for Transcatheter Treatment.

The intricate interplay between mitral regurgitation (MR) and left ventricular outflow tract (LVOT) obstruction may result in two clinical scenarios: prosthesis-related LVOT obstruction after mitral valve replacement (TMVR) and systolic anterior motion (SAM)-associated MR. This review provides a comprehensive overview of the pathophysiology, risk assessment, and transcatheter interventions for mitigating the likelihood of LVOT obstruction in patients undergoing TMVR. In addition, it extends its focus to SAM-associated MR, elucidating the different aetiological mechanisms contributing to this phenomenon, beyond hypertrophic cardiomyopathy. Transcatheter treatment options, are explored as potential therapeutic strategies, offering insights into their hemodynamic effectiveness and limitations.

Case Report: Mechanical hemolysis resulting from left ventricular outflow tract obstruction after aortic valve replacement relieved by transapical beating-heart septal myectomy.

Background: Aortic stenosis (AS) in combination with left ventricular outflow tract obstruction (LVOTO) has occasionally been reported. However, making a precise diagnosis and successfully treating this combination is challenging due to the hemodynamic interaction between the two conditions. Case summary: A 56-year-old male patient who had been diagnosed with severe AS and asymmetric left ventricular hypertrophy underwent aortic valve replacement (AVR) and a conventional septal myectomy. Immediately after the procedure, significant systolic anterior motion and mitral regurgitation developed, necessitating a surgical mitral edge-to-edge repair. Ten days after the procedure, the patient developed hematuria and LVOTO, which was confirmed by echocardiography. Because the LVOTO might have been the cause of the hematuria, the patient underwent alcohol septal ablation, but this had little effect. Three months later, a transapical beating-heart septal myectomy (TA-BSM) was performed in our hospital. Postoperatively, the LVOTO had been significantly ameliorated and the hematuria had resolved. Conclusion: For patients with AS and LVOTO due to a hypertrophic interventricular septum, inadequate amelioration of the LVOTO after AVR may lead to severe hemolytic hematuria. TA-BSM is a minimally invasive, safe, and effective surgical procedure for ameliorating LVOTO in patients with aortic valve prostheses.

An Interesting Case of Wolf-Parkinson-White Syndrome in a Young Patient With Sensorineural Deafness.

Wolff-Parkinson-White (WPW) syndrome is a condition associated with tachycardia due to accessory pathways in the heart, and it is one of the most common causes of tachycardia in infants and children. WPW may also be associated with mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes (MELAS syndrome) or LEOPARD syndrome (LS). We report a case of pre-excitation WPW syndrome in a 17-year-old man who was brought to the hospital by ambulance following the collapse. WPW syndrome type A was diagnosed from precordial leads. Electrocardiography (ECG) revealed a short PR interval, delta waves, and positive waves with dominant R in all pericardial leads. Blood test results showed an isolated elevated ALT level. Subsequent echocardiography was unremarkable, with an ejection fraction of 55%, apart from septal and inferior wall dyssynchrony. With regard to the past medical history, he had sensorineural deafness (SND) since childhood and had a family history of SND. Consequently, the patient was transferred to the cardiac electrophysiology department at another hospital after consultation and underwent ablation. A successful post-ablation electrocardiogram revealed the resolution of the WPW syndrome signs and post-ablation features, such as peak T waves.

Cardiogenic shock in takotsubo syndrome: etiology and treatment.

Takotsubo syndrome (TTS) can mimic acute coronary syndrome despite being a distinct disease. While typically benign, TTS can lead to serious complications like cardiogenic shock. Cardiogenic shock occurs in 1-20% of TTS cases. Various mechanisms can cause shock, including pump failure, right ventricular involvement, left ventricular outflow tract obstruction, and acute mitral regurgitation. Because treatment depends on the mechanism, early identification of the mechanism developing cardiogenic shock is essential for optimal treatment and improved outcomes in TTS patients with cardiogenic shock. This review summarizes current knowledge on causes and treatment of cardiogenic shock in patients with TTS.

The Fate of the Left Ventricular Outflow Tract Following Interrupted Aortic Arch Repair.

Objectives: To examine the probability of left ventricular outflow tract (LVOT) reintervention following interrupted aortic arch (IAA) repair in neonates with LVOT obstruction (LVOTO) risk. Methods: This retrospective multicenter study included 150 neonates who underwent IAA repair (2003-2017); 100 of 150 (67%) had isolated IAA repair (with ventricular septal defect closure) and 50 of 150 (33%) had concomitant LVOT intervention: conal muscle resection (n = 16), Ross-Konno (n = 7), and Yasui operation (n = 27: single-stage n = 8, staged n = 19). Demographic and morphologic characteristics were reviewed. Factors associated with LVOT reoperation were explored using multivariable analysis. Results: Concomitant LVOT intervention was more likely in neonates with type B IAA, bicuspid aortic valve, aberrant right subclavian artery, smaller aortic valve annulus, and ascending aorta dimensions. On follow-up, five-year freedom from LVOT reoperation was highest following Ross-Konno (100%), 77% following Yasui (mainly for neo-aortic regurgitation), 77% following isolated IAA repair (mainly for LVOTO), and 47% following IAA repair with concomitant conal resection, P = .033. While all patients had low peak LVOT gradient at time of discharge, those who had conal resection developed higher gradients on follow-up (P = .007). Ross-Konno and Yasui procedures were associated with higher right ventricular outflow tract (RVOT) reoperation. In the cohort following isolated IAA repair, aortic sinus Z score was associated with LVOT reoperation. Conclusions: Both Yasui and Ross-Konno operations effectively mitigate late LVOTO risk. The highest risk of reintervention for LVOTO was associated with conal muscle resection while the lowest risk is associated with Ross-Konno. The RVOT reoperation risk in patients who had Ross-Konno or Yasui does not seem to affect survival.

3-Dimensional Echocardiographic Prediction of Left Ventricular Outflow Tract Area Prior to Transcatheter Mitral Valve Replacement.

BACKGROUND: New postprocessing software facilitates 3-dimensional (3D) echocardiographic determination of mitral annular (MA) and neo-left ventricular outflow tract (neo-LVOT) dimensions in patients undergoing transcatheter mitral valve replacement (TMVR). OBJECTIVES: This study aims to test the accuracy of 3D echocardiographic analysis as compared to baseline computed tomography (CT). METHODS: A total of 105 consecutive patients who underwent TMVR at 2 tertiary care centers between October 2017 and May 2023 were retrospectively included. A virtual valve was projected in both baseline CT and 3D transesophageal echocardiography (TEE) using dedicated software. MA dimensions were measured in baseline images and neo-LVOT dimensions were measured in baseline and postprocedural images. All measurements were compared to baseline CT as a reference. The predicted neo-LVOT area was correlated with postprocedural peak LVOT gradients. RESULTS: There was no significant bias in baseline neo-LVOT prediction between both imaging modalities. TEE significantly underestimated MA area, perimeter, and medial-lateral dimension compared to CT. Both modalities significantly underestimated the actual neo-LVOT area (mean bias pre/post TEE: 25.6 mm2, limit of agreement: -92.2 mm2 to 143.3 mm2; P < 0.001; mean bias pre/post CT: 28.3 mm2, limit of agreement: -65.8 mm2 to 122.4 mm2; P = 0.046), driven by neo-LVOT underestimation in the group treated with dedicated mitral valve bioprosthesis. Both CT- and TEE-predicted-neo-LVOT areas exhibited an inverse correlation with postprocedural LVOT gradients (r2 = 0.481; P < 0.001 for TEE and r2 = 0.401; P < 0.001 for CT). CONCLUSIONS: TEE-derived analysis provides comparable results with CT-derived metrics in predicting the neo-LVOT area and peak gradient after TMVR.

Genetic variations in PTPN11 lead to a recurrent left ventricular outflow tract obstruction phenotype in childhood hypertrophic cardiomyopathy.

OBJECTIVE: Left ventricular septal myotomy provides a favorable prognosis for children with hypertrophic obstructive cardiomyopathy (HOCM). However, some children still suffer from recurrent left ventricular outflow tract obstruction (LVOTO) after surgery. Poor prognosis exists for HOCM caused by PTPN11 mutation. Therefore, the aim of this study was to determine the clinical features of recurrent obstruction in children with HOCM caused by pathogenic mutations in the PTPN11 gene. METHODS: Fifty-six children who were diagnosed with HOCM underwent septal myectomies. Whole-exome sequencing of 49 pediatric cardiomyopathy-associated genes (including PTPN11) was performed. We performed hematoxylin-eosin, Masson, and wheat germ agglutinin staining of those tissues positive and negative for PTPN11. RESULTS: Whole-exome sequencing results showed 11 children with the PTPN11 mutation (19.6%). In long-term follow-up (median 37 months, maximum 9 years), children with the PTPN11 mutation had 6 (54.5%) recurrent LVOTOs compared with other groups (P = .015) but similar survival rates (P = .514). The mean postoperative time to recurrent obstruction was 22 ± 7 months. Children with PTPN11 mutation were 9-fold more likely to experience the risk associated with recurrent obstruction (95% confidence interval, 1.77-45.81, P < .001). Hematoxylin-eosin, Masson, and wheat germ agglutinin staining also revealed more cardiomyocyte hypertrophy in tissues with the PTPN11 mutation. CONCLUSIONS: Children with PTPN11 mutation-associated hypertrophic cardiomyopathy have a greater risk of recurrent LVOTO.

Successful management of ischaemic symptoms in a patient with asymmetric septal hypertrophy: a grand round case report.

Background: Hypertrophic cardiomyopathy (HCM) is a genetic heart disease that can lead to heart failure, atrial fibrillation, and ischaemic symptoms. Managing patients with HCM and ischaemic symptoms is challenging, and several treatment options have been proposed. Case summary: A 30-year-old male patient presented with severe chest pain that had been ongoing for more than 30 min at rest. He was diagnosed with HCM and had periodic chest pain since the age of 14. He underwent two separate ethyl alcohol ablations of the first septal branches of the left anterior descending and posterior descending arteries, which relieved his symptoms. Discussion: This case report highlights the challenges in managing patients with HCM and ischaemic symptoms. In this patient, the use of ethyl alcohol ablation was effective in reducing left ventricular outflow tract obstruction and improving symptoms. Ethyl alcohol ablation is a minimally invasive procedure that has been shown to be effective in symptomatic patients with HCM. Overall, this case report emphasizes the importance of individualized treatment for patients with HCM and the potential benefits of alcohol ablation in this population.

Molecular Pathways and Animal Models of Hypoplastic Left Heart Syndrome.

Hypoplastic left heart syndrome (HLHS) is a severe congenital heart disease (CHD) with underdevelopment of left-sided heart structures. While previously uniformly fatal, surgical advances now provide highly effective palliation that allows most HLHS patients to survive their critical CHD. Nevertheless, there remains high morbidity and mortality with high risk of heart failure. As hemodynamic compromise from restricted aortic blood flow has been suggested to underlie the poor LV growth, this suggests the possibility of prenatal fetal intervention to recover LV growth. As such interventions have yielded ambiguous results, the optimization of therapy will require more mechanistic insights into the developmental etiology for HLHS. Clinical studies have shown high heritability for HLHS, with an oligogenic etiology indicated in conjunction with genetic heterogeneity. This is corroborated with the recent recovery of mutant mice with HLHS. With availability-induced pluripotent stem cell (iPSC)-derived cardiomyocytes from HLHS mice and patients, new insights have emerged into the cellular and molecular etiology for the LV hypoplasia in HLHS. Cell proliferation defects were observed in conjunction with metaphase arrest and the disturbance of Hippo-YAP signaling. The left-sided restriction of the ventricular hypoplasia may result from epigenetic perturbation of pathways regulating left-right patterning. These findings suggest new avenues for fetal interventions with therapies using existing drugs that target the Hippo-YAP pathway and/or modulate epigenetic regulation.

Mitral Geometry on the Mechanism of Left Ventricular Outflow Tract Obstruction in Hypertrophic Cardiomyopathy.

OBJECTIVE: The mechanism of left ventricular outflow tract obstruction (LVOTO) is complex in hypertrophic cardiomyopathy (HCM). We aimed to evaluate the impact of mitral valve geometry on LVOTO by echocardiography. MATERIALS AND METHODS: The study population comprised 177 consecutive patients with HCM. Morphological findings of left ventricular hypertrophy and LVOTO-related abnormalities were assessed by comprehensive transthoracic echocardiography. Aortomitral angle, mitral leaflet length, and coaptation height were measured and analyzed at rest. Multivariable stepwise forward logistic regression analysis was performed to identify geometric predictors of LVOTO. RESULTS: One hundred thirty-seven patients had an LVOT gradient ≥30 mm Hg. Multivariable logistic regression showed that aortomitral angle (odds ratio [OR], 0.89; 95% CI, 0.83-0.95, P < .001), coaptation height (OR, 1.96; 95% CI, 1.41-2.72, P < .001), and accessory mitral valve chordae tendineae (OR, 13.1; 95% CI, 4.32-39.95; P < .001) were independently associated with LVOTO. Receiver operating characteristic analysis showed that the area under the curve of mitral coaptation height was higher (area under the curve = 0.815) than the other 2 indicators (P < .05). CONCLUSION: Mitral coaptation height, aortomitral angle, and accessory mitral valve chordae tendineae were important predictors of SAM and LVOTO in HCM independent of septal hypertrophy.

Left ventricular outflow tract obstruction/hypertrophic cardiomyopathy/takotsubo syndrome: A new hypothesis of takotsubo syndrome pathophysiology.

The pathophysiology of TTS is still elusive. This viewpoint proposes that TTS is an acute coronary syndrome, engendered by an ASNS/catecholamine-induced LVOTO, which results in an enhanced wall stress and afterload-based supply/demand mismatch, culminating in a segmental myocardial ischemic injury state, in susceptible individuals. Such individuals are felt to be particularly women with chronic hypertension, known or latent HCM, or non-HCM segmental myocardial hypertrophy, and certain structural abnormalities involving the LV and the MV apparatus. Recommendations are provided to explore further this hypothesis, while maintaining our focus on all other advanced TTS pathophysiology hypotheses for all patients, or those who do not experience LVOTO, men, the young, and patients with reverse, mid-ventricular, or right ventricular TTS, in whom more prolonged hyperadrenergic stimulation and/or larger amounts of blood-ridden catecholamines, segmental particularities of cardiac innervation and/or density of α-, and ß-adrenergic receptors, pheochromocytoma, neurological chronic or acute comorbidities/catastrophies, coronary epicardial/microvascular vasospasm, and CMD.

Association of left ventricular outflow tract size with arch morphology in interrupted aortic arch.

OBJECTIVES: Left ventricular outflow tract obstruction (LVOTO) is a major cause of morbidity and mortality in infants with interrupted aortic arch (IAA). Left Ventricular Outflow Tract (LVOT) development may be flow-mediated, thus IAA morphology may influence LVOT diameter and subsequent reintervention. We investigated the association of IAA morphology [type and presence of aortic arch aberrancy (AAb)] with LVOT diameter and reintervention. METHODS: All surgical patients with IAA (2001-2022) were reviewed at a single institution. We compared IAA-A versus IAA-B; IAA with aortic AAb versus none; IAA-B with aberrant subclavian (AAbS) artery versus others. Primary outcomes included LVOT diameter (mm), LVOTO at discharge (≥50 mmHg), and LVOT reintervention. RESULTS: Seventy-seven infants (mean age 10 ± 19 days) were followed for 7.6 (5.5-9.7) years. Perioperative mortality was 3.9% (3/77) and long-term mortality was 5.2% (4/77). Out of 51 IAA-B (66%) and 22 IAA-A (31%) patients, 30% (n = 22) had AAb. Smaller LVOT diameter was associated with IAA-B [IAA-A: 5.40 (4.68-5.80), IAA-B: 4.60 (3.92-5.50), P = 0.007], AAb [AAb: 4.00 (3.70-5.04) versus none: 5.15 (4.30-5.68), P = 0.006], and combined IAA-B + AAbS [IAA-B + AAbS: 4.00 (3.70-5.02) versus other: 5.00 (4.30-5.68), P = 0.002]. The likelihood of LVOTO was higher among AAb [N = 6 (25%) vs N = 1 (2%), P = 0.004] and IAA-B + AAbS [N = 1 (2%) vs N = 6 (30%), P = 0.002]. Time-to-event analysis showed a signal towards increased LVOT reintervention in IAA-B + AAbS (P = 0.11). CONCLUSIONS: IAA-B and AAb are associated with small LVOT diameter and early LVOTO, especially in combination. This may reflect lower flow in the proximal arch during development. Most reinterventions occur in IAA-B + AAbS, hence these patients should be carefully considered for LVOT intervention at the time of initial repair.

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.

Unmasking Severe Systolic Anterior Motion With Left Ventricular Outflow Tract Obstruction Following Mitral Valve Repair.

A 38-year-old male with a history of myxomatous mitral valve disease post-repair presented with recurrent dyspnea during exertion. Initial evaluation showed mild systolic anterior motion and mitral regurgitation, but medical management was unsuccessful. The patient underwent reoperation; intraoperative transesophageal echocardiogram with provocation unmasked severe systolic anterior motion and torrential mitral regurgitation.