Cardiac Myosin Inhibitors: Expanding the Horizon for Hypertrophic Cardiomyopathy Management.

OBJECTIVE: To review the current literature on the efficacy and safety of cardiac myosin inhibitors (CMIs) for the treatment of hypertrophic cardiomyopathy (HCM). DATA SOURCES: A literature search was conducted on PubMed from origin to April 2023, using the search terms "MYK-461," "mavacamten," "CK-3773274," and "aficamten." Studies were limited to English-based literature, human subjects, and clinical trials resulting in the inclusion of 13 articles. ClinicalTrials.gov was also used with the same search terms for ongoing and completed trials. STUDY SELECTION AND DATA EXTRACTION: Only phase II and III studies were included in this review except for pharmacokinetic studies that were used to describe drug properties. DATA SYNTHESIS: CMIs enable cardiac muscle relaxation by decreasing the number of myosin heads that can bind to actin and form cross-bridges. Mavacamten, the first Food and Drug Administration (FDA)-approved drug in this class, has been shown to improve hemodynamic, functional, and quality of life measures in HCM with obstruction. In addition, aficamten is likely to become the next FDA-approved CMI with promising phase II data and an ongoing phase III trial expected to release results in the next year. RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE IN COMPARISON WITH EXISTING DRUGS: CMIs provide a novel option for obstructive hypertrophic cardiomyopathy, particularly in those not suitable for septal reduction therapy. Utilization of these agents requires knowledge of drug interactions, dose titration schemes, and monitoring parameters for safety and efficacy. CONCLUSIONS: CMIs represent a new class of disease-specific drugs for treatment of HCM. Cost-effectiveness studies are needed to delineate the role of these agents in patient therapy.

Is There a Role for Alcohol Septal Ablation in Young Patients with Medically Refractory Hypertrophic Obstructive Cardiomyopathy?

Surgical myectomy is recommended for symptomatic hypertrophic obstructive cardiomyopathy (HOCM) after optimal pharmacological therapy. Percutaneous transluminal septal myocardial ablation (PTSMA) is reserved for high-risk adults. Symptomatic patients below 25 years underwent either surgery or PTSMA after heart-team discussion and informed consent. Echocardiography assessed gradients in surgical group. PTSMA group underwent invasive transseptal hemodynamic assessment, selective coronary angiography and super-selective cannulation of septal perforators using microcatheters. Contrast echocardiography through the microcatheter identified the myocardial target for PTSMA. Hemodynamic and electrocardiographic monitoring guided alcohol injection. Both groups were continued on beta-blockers. Symptoms, echocardiographic gradients and Brain natriuretic peptide (NTproBNP) measurements were assessed on follow-up. Twelve patients aged 5-23 years (11-98 kg) formed the study group. Indications for PTSMA in 8 patients included abnormal mitral valve anatomy warranting replacement (n = 3), Jehovah's witness (n = 2), severe neurodevelopmental and growth retardation (n = 1) and refusal of surgery (n = 2). PTSMA targeted first perforator (n = 5), second perforator (n = 2) and anomalous septal artery from left main trunk (n = 1). Outflow gradient reduced from 92.5 ± 19.7 to 33.1 ± 13.5 mmHg. At a median follow-up of 38 months (range 3-120 weeks), the peak instantaneous echocardiographic gradient was 32 ± 16.5 mmHg. Gradient reduced in four surgical patients from 86.5 ± 16.3 mmHg to 42 ± 14.7 mm Hg. All patients were in NYHA class I/II on follow-up. The mean NTproBNP in PTSMA group reduced from 6084 ± 3628 pg/ml to 3081 ± 2019 pg/ml; it was 1396 and 1795 pg/ml in surgery. PTSMA may be considered in medically refractory high-risk young patients. It relieves symptoms and reduces gradient. Though surgery is preferred in young patients, PTSMA may have a role in selected patients.

TGA + IVS + LVOTO: patterns of practice and outcomes.

PURPOSE: Transposition of great arteries with intact ventricular septum and left ventricular outflow tract obstruction (TGA + IVS + LVOTO) is uncommon. We reviewed operations performed in patients with TGA + IVS + LVOTO in the European Congenital Heart Surgeons Association Congenital Database (ECHSA-CD). METHODS: All 109 patients with a diagnosis of TGA + IVS + LVOTO in ECHSA-CD who underwent cardiac surgery during a 21-year period (01/2000-02/2021, inclusive) were included. Preoperative variables, operative data, and postoperative outcomes were collected. RESULTS: These 109 patients underwent 176 operations, including 37 (21.0%) arterial switch operations (ASO), 26 (14.2%) modified Blalock-Taussig-Thomas shunts (MBTTS), 11 (6.2%) Rastelli operations, and 13 (7.3%) other palliative operations (8 superior cavopulmonary anastomosis[es], 4 Fontan, and 1 other palliative procedure). Of 37 patients undergoing ASO, 22 had a concomitant procedure.There were 68 (38.6%) reoperations, including 11 pacemaker procedures and 8 conduit operations. After a systemic-to-pulmonary artery shunt, reoperations included shunt reoperation (n = 4), Rastelli (n = 4), and superior cavopulmonary anastomosis (n = 3).Overall Operative Mortality was 8.2% (9 deaths), including three following ASO, two following "Nikaidoh, Kawashima, or LV-PA conduit" procedures, and two following Rastelli. Postoperative complications occurred after 36 operations (20.4%). The most common complications were delayed sternal closure (n = 11), postoperative respiratory insufficiency requiring mechanical ventilation >7 days (n = 9), and renal failure requiring temporary dialysis (n = 8). CONCLUSION: TGA + IVS + LVOTO is rare (109 patients in ECHSA-CD over 21 years). ASO, MBTTS, and Rastelli are the most common operations performed for TGA + IVS + LVOTO. Larger international studies with long-term follow-up are needed to better define the anatomy of the LVOTO and to determine the optimal surgical strategy.

Accessory mitral valve tissue: a differential diagnosis of an obstructive mass on the left ventricular outflow tract.

Accessory mitral valve tissue is a rare congenital cardiac anomaly that is typically discovered incidentally during echocardiographic evaluation prompted by an asymptomatic murmur. This pathology has characteristic echocardiographic elements and is usually associated with other CHD. The decision to perform surgical resection depends on factors such as the degree of obstruction, presence of symptoms, presence of other CHDs, and risk of thrombosis. The researchers hereby present a case of an asymptomatic paediatric patient with accessory mitral valve tissue that produced left ventricular outflow tract obstruction.

Subendocardial stress in pre-eclampsia.

A primigravida 26-year-old woman who had developed pre-eclampsia with malignant hypertension at 30 weeks of gestation suffered acute myocardial infarction two days postpartum. Electrocardiogram demonstrated diffuse ST-segment depression suggestive of subendocardial ischemia. Echocardiography demonstrated focal asymmetric left ventricular hypertrophy, with a characteristic "basal septal bulge", and a left ventricular mid-cavitary gradient of 51 mmHg. Coronary angiography revealed normal coronary arteries and vascular flow. Peripartum acute myocardial infarction is rare and portends a high mortality. However, to date, only one case of acute myocardial infarction associated with asymmetric left ventricular hypertrophy and pre-eclampsia has been described in the literature.

Hypertensive hypertrophic obstructive cardiomyopathy crisis resolved with transvenous pacing guided by bedside echocardiography.

Cardiogenic shock due to hypertrophic obstructive cardiomyopathy (HoCM) crisis presents a clinical challenge as pharmacologic vasopressor and/or inotropic support can compromise hemodynamics and acute afterload reduction worsens left ventricular outflow tract (LVOT) obstruction. Hypertensive hypertrophic obstructive cardiomyopathy (HHoCM) is an entity mostly affecting elderly hypertensive women and could present with a clinical phenotype similar to HoCM crisis. We present a case of an 81-year-old female patient with HHoCM complicated by severe mitral regurgitation, in cardiogenic shock, in whom hemodynamic stability was restored with transvenous pacing guided by bedside echocardiography to optimize rate, left ventricle (LV) filling time, and cardiac output.

Association Between Three-Dimensional Left Ventricular Outflow Tract Area and Gradients After Myectomy in Hypertrophic Obstructive Cardiomyopathy.

OBJECTIVE: Determine whether the intraoperative three-dimensional left ventricular outflow tract cross-sectional area may be inversely correlated with pressure gradients as a determinant of surgical success after septal myectomy in hypertrophic cardiomyopathy patients. DESIGN: Perioperative data were obtained by retrospective review. SETTING: Toronto General Hospital, University of Toronto, Toronto, Canada, a tertiary hospital. PARTICIPANTS: The study comprised 67 patients with hypertrophic obstructive cardiomyopathy. INTERVENTIONS: Transthoracic and intraoperative transesophageal echocardiographic assessment of pressure gradients. Transesophageal measurement of the three-dimensional left ventricular outflow tract cross-sectional area. MEASUREMENTS AND MAIN RESULTS: The smallest left ventricular outflow tract area increased on average 1.883 cm2 (98.3%) after septal myectomy. There was a significant correlation between the increase in the area and the transesophageal pressure gradients (r = -0.32; p = 0.01) after myectomy, but none with postoperative transthoracic gradients at rest (r = -0.10; p = 0.42). Postoperative transesophageal and transthoracic gradients were significantly correlated (r = 0.26; p = 0.04). The best risk factors to predict high residual gradients were preoperative transesophageal gradient >97 mmHg, postoperative transesophageal area <3.16 cm2, and moderate or more residual transesophageal mitral regurgitation (specificity 89%, 81%, and 78%, respectively). CONCLUSIONS: Three-dimensional left ventricular outflow tract area measurements with transesophageal echocardiography after myectomy correlated fairly well with postoperative transesophageal pressure gradients. Patients with residual transthoracic elevated gradients after surgery at follow-up had a smaller transesophageal area and higher transesophageal pressure gradients immediately after the procedure. However, transesophageal pressure gradients after myectomy correlated poorly with follow-up transthoracic gradients at rest.

Favorable Effects of Impella on Takotsubo Syndrome Complicated with Cardiogenic Shock.

Reportedly, approximately 9.9%-12.4% of patients with Takotsubo syndrome (TTS) are complicated with cardiogenic shock (CS) and its prognosis remains poor even with the support of conventional mechanical circulatory assist devices including intra-aortic balloon pumping and venoarterial extracorporeal membrane oxygenation. Impella, a novel percutaneous left ventricular assist device, provides strong circulatory support together with the unloading of the left ventricle, and it is theoretically a promising mechanical circulatory assist device for TTS. In this case study, we report four consecutive patients with TTS complicated with CS who were successfully resuscitated using the Impella support.

Hypertrophic Cardiomyopathy 2020.

PURPOSE OF REVIEW: To briefly review the pathophysiology and natural history of hypertrophic cardiomyopathy (HCM) and to describe the diagnosis, assessment, and contemporary management strategies. RECENT FINDINGS: HCM-related mortality remains low; however, symptoms due in large part to LVOT obstruction remain a clinical dilemma. Several medical therapies have been shown to reduce symptoms and improve functional capacity, including several recent phase 2 clinical trials involving the novel myosin modulator mavacamten. In patients with refractory symptoms, septal reduction therapy or advanced therapies remain viable options in many cases. HCM is a complex and heterogeneous disease with diverse presentations and variable anatomy and clinical outcomes. The majority of patients will remain asymptomatic or with minimal symptoms and long-term survival remains high. For symptomatic patients, a variety of medical therapies, along with septal reduction therapies, have been shown to reduce symptoms and improve functional capacity.

Isolated anterior mitral cleft.

Anterior mitral valve clefts are unusual anomalies particularly associated with endocardial cushion defects. A dysplastic subvalvular apparatus causing left ventricular outflow tract obstruction may result in diagnostic confusion. We present an isolated anterior mitral cleft associated with subvalvular dysplasia.

Hypertrophic cardiomyopathy with dynamic obstruction and high left ventricular outflow gradients associated with paradoxical apical ballooning.

BACKGROUND: Acute left ventricular (LV) apical ballooning with normal coronary angiography occurs rarely in obstructive hypertrophic cardiomyopathy (OHCM); it may be associated with severe hemodynamic instability. METHODS, RESULTS: We searched for acute LV ballooning with apical hypokinesia/akinesia in databases of two HCM treatment programs. Diagnosis of OHCM was made by conventional criteria of LV hypertrophy in the absence of a clinical cause for hypertrophy and mitral-septal contact. Among 1519 patients, we observed acute LV ballooning in 13 (0.9%), associated with dynamic left ventricular outflow tract (LVOT) obstruction and high gradients, 92 ± 37 mm Hg, 10 female (77%), age 64 ± 7 years, LVEF 31.6 ± 10%. Septal hypertrophy was mild compared to that of the rest of our HCM cohort, 15 vs 20 mm (P < 0.00001). An elongated anterior mitral leaflet or anteriorly displaced papillary muscles occurred in 77%. Course was complicated by cardiogenic shock and heart failure in 5, and refractory heart failure in 1. High-dose beta-blockade was the mainstay of therapy. Three patients required urgent surgical relief of LVOT obstruction, 2 for refractory cardiogenic shock, and one for refractory heart failure. In the three patients, surgery immediately normalized refractory severe LV dysfunction, and immediately reversed cardiogenic shock and heart failure. All have normal LV systolic function at 45-month follow-up, and all have survived. CONCLUSIONS: Acute LV apical ballooning, associated with high dynamic LVOT gradients, may punctuate the course of obstructive HCM. The syndrome is important to recognize on echocardiography because it may be associated with profound reversible LV decompensation.

Spontaneous embolization of an atrial septal defect occluder device into the left ventricular outflow tract in a patient with pulmonary stenosis.

A 24-year-old man was admitted to our outpatient clinic for his routine checkup of consecutively percutaneously treated atrial septal defect (ASD) and pulmonary valvular stenosis 45 days ago. A 24 mm ASD occluder device was implanted under transthoracic echocardiographic guidance and 80 mm Hg peak-to-peak pulmonary valvular gradient decreased to 20 mm Hg gradient after pulmonary valve dilatation with 23 mm NUMED II transluminal valvuloplasty catheter balloon. Atrial septal defect (ASD) closure is now routinely performed using a percutaneous approach under echocardiographic guidance especially transthoracic echocardiography (TEE). Centrally located, ostium secundum type and less than 3.5 cm in size are considered ideal for device closure. Although there is considerable variation in size and location of the defects, TEE guidance is quite important for this proportion of ASDs. The selection of patients for percutaneous transcatheter closure of a secundum ASD requires accurate information regarding the anatomy of the defect such as its maximal diameter and the amount of circumferential tissue rims.

Value of latent outflow obstruction to predict clinical course of patients with hypertrophic cardiomyopathy.

Objective The frequency, significance and prognostic value of left ventricle obstruction (LVO) induced with provocation (latent LVO) is controversial for hypertrophic cardiomyopathy (HC) patients. This study was designed to assess the value of latent LVO in predicting the clinical course in 101 patients with HC. Methods and results Patients were followed for a mean of 82 ± 48 months (range 2 to 148 months) for clinical end points defined as a composite of cardiovascular death resuscitated cardiac arrest, appropriate defibrillator shock or hospitalization due to worsening of heart failure symptoms. Presence of LVO (hazard ratio 3.63; 95% confidence interval, 1.85 to 7.12; P = 0.0001) and log NT-proBNP levels (hazard ratio, 1.40; 95% confidence interval, 1.14 to 1.72; P = 0.001) were the independent variables associated with an increased risk of experiencing clinical end points. HC patients with latent LVO have a trend toward decreased survival when compared with HC patients without LVO (log rank P = 0.027), but better survival than patients with resting LVO (log rank P = 0.007). HC patients with NT-proBNP levels <1,000 pg/ml had also better survival. LVO and NT-proBNP levels are the major determinants of clinical end points in patients with HC. Conclusions Evaluation of patients without resting LVO to demonstrate latent obstruction is of critical importance in respect of outcome and selection of patients for septal reduction therapies, so routine provocative testing with physiological exercise and measurement of NT-proBNP is recommended in this patient population for risk stratification.

Familial hypertrophic obstructive cardiomyopathy with the GLA E66Q mutation and zebra body.

BACKGROUND: Fabry disease is caused by mutations in the α-galactosidase A (GLA) gene, which is located in X-chromosome coding for the lysosomal enzyme of GLA. Among many gene mutations, E66Q mutation is under discussion for its pathogenicity because there is no clinical report showing pathological evidence of Fabry disease with E66Q mutation. CASE PRESENTATION: A 65-year-old Japanese female was referred to our hospital for chest discomfort on effort. Transthoracic echocardiography showed severe left ventricular (LV) hypertrophy with LV outflow obstruction. Maximum LV outflow pressure gradient was 87 mmHg, and Valsalva maneuver increased the pressure gradient up to 98 mmHg. According to medical interview, one of her younger sister and a nephew died suddenly at age 42 and 36, respectively. Another younger sister also presented LV hypertrophy with outflow obstruction. Maximum LV outflow pressure gradient was 100 mmHg, and the E66Q mutation was detected similar to the case. Endomyocardial biopsy specimens presented vacuolation of cardiomyocytes, in which zebra bodies were detected by electron microscopic examination. Although the enzymatic activity of GLA was within normal range, the c. 196G>C nucleotide change, which lead to the E66Q mutation of GLA gene, was detected. We initially diagnosed her as cardiac Fabry disease based on the findings of zebra body. However, immunostaining showed few deposition of globotriaosylceramide in left ventricular myocardium, and gene mutations in the disease genes for hypertrophic cardiomyopathy (HCM), MYBPC3 and MYH6, were detected. Although the pathogenicity of the E66Q mutation cannot be ruled out, hypertrophic obstructive cardiomyopathy (HOCM) was more reasonable to explain the pathophysiology in the case. CONCLUSIONS: This is the confusable case of HOCM with Fabry disease with the GLA E66Q mutation. We have to take into consideration the possibility that some patients with the E66Q mutation may have similar histological findings of Fabry disease, and should be examed the possibility for harboring gene mutations associated with HCM.

Giant Blood Cyst of the Mitral Valve in a Disseminated Tuberculosis Patient.

Cardiac blood cysts are rare with most cases stemming from the pediatric population. The few case reports in adults have not generated clear guidelines regarding management. The finding of a cardiac mass engenders a broad differential including primary cardiac benign tumors, malignant tumors both primary and metastatic, as well as infectious processes in addition to blood cysts. The clinical context, imaging results, and potential for complications must be taken into account when making diagnostic and treatment decisions. We present, to our knowledge, the first case of a giant cardiac blood cyst resected in an adult with a history of tuberculosis.

Dynamic LVOT Obstruction and Aortic Stenosis in the Same Patient: A Case of Challenging Doppler Hemodynamics.

We present a patient with both dynamic left ventricular outflow tract obstruction and valvular aortic stenosis. The aortic valve was calcified, and velocities and gradients measured by continuous-wave Doppler met standard criteria for severe aortic stenosis. The increased subvalvular velocities invalidated assumptions of the simplified Bernoulli equation; correction using the longer form of the Bernoulli equation suggested a lower but still significant gradient. The complex shape of the subvalvular spectral Doppler envelope indicated supranormal systolic function and dynamic left ventricular outflow obstruction. Left heart catheterization with an end-hole catheter was required to determine the subvalvular and valvular components of the obstruction.

Oral Everolimus for Treatment of a Giant Left Ventricular Rhabdomyoma in a Neonate-Rapid Tumor Regression Documented by Real Time 3D Echocardiography.

The presented case reports on successful treatment with everolimus in a neonate with left ventricular giant rhabdomyoma. The authors used a different dosage regime compared to literature and documented rapid tumor regression by 3D echocardiography.

Sitting maneuver to uncover latent left ventricular outflow tract obstruction in patients without hypertrophic cardiomyopathy.

BACKGROUND: Left ventricular outflow tract obstruction [LVOTO; pressure gradient (PG) ≥30 mmHg] is observed in some patients without hypertrophic cardiomyopathy (HCM), and it may develop especially in older patients without HCM (non-HCM). The aim of this study is to investigate if the Valsalva or an upright sitting maneuver can unveil latent LVOTO in patients with non-HCM. METHODS: A total of 33 non-HCM patients with a late peaking or dagger-shaped pulsed Doppler waveform of the LVOT and PG <30 mmHg were included. The Doppler flow velocity of the LVOT was measured at rest, after the Valsalva and a sitting maneuver. Peak PG of ≥30 mmHg after either maneuver was defined as latent LVOTO. The angle between the left ventricular septum and the aorta in the parasternal long-axis view and the apical three-chamber view was measured. RESULTS: Twenty (61 %) of the 33 patients (mean age 74 ±â€¯9 years) were diagnosed with latent LVOTO. Of these, five (25 %) patients were diagnosed after both the Valsalva and sitting maneuver, and 15 (75 %) were diagnosed only after the sitting maneuver. The latent LVOTO group had a significantly smaller angle than the no-LVOTO group between the ventricular septum and the aorta in the parasternal long axis views (107 ±â€¯8° vs. 117 ±â€¯8°, p < 0.01). CONCLUSION: The sitting maneuver is better than the Valsalva maneuver in unveiling latent LVOTO in older, non-HCM patients.

Computer-Assisted Transcatheter Mitral Valve Implantation for Valve-in-Valve Procedures.

Transcatheter mitral valve-in-valve is an alternative to high-risk reoperation on a failing bioprosthesis. It entails specific challenges such as left ventricular outflow tract obstruction. We propose a patient-specific augmented imaging based on preoperative planning to assist the procedure. Valve-in-valve simulation was performed to represent the optimal level of implantation and the neo-left ventricular outflow tract. These data were combined with intraoperative images through a real-time 3D/2D registration tool. All data were collected retrospectively on one case (pre and per-procedure imaging). We present for the first time an intraoperative guidance tool in transcatheter mitral valve-in-valve procedure.