Distal Ventricular Pacing for Drug-Refractory Mid-Cavity Obstructive Hypertrophic Cardiomyopathy: A Randomized, Placebo-Controlled Trial of Personalized Pacing.

BACKGROUND: Patients with refractory, symptomatic left ventricular (LV) mid-cavity obstructive (LVMCO) hypertrophic cardiomyopathy have few therapeutic options. Right ventricular pacing is associated with modest hemodynamic and symptomatic improvement, and LV pacing pilot data suggest therapeutic potential. We hypothesized that site-specific pacing would reduce LVMCO gradients and improve symptoms. METHODS: Patients with symptomatic-drug-refractory LVMCO were recruited for a randomized, blinded trial of personalized prescription of pacing (PPoP). Multiple LV and apical right ventricular pacing sites were assessed during an invasive hemodynamic study of multisite pacing. Patient-specific pacing-site and atrioventricular delays, defining PPoP, were selected on the basis of LVMCO gradient reduction and acceptable pacing parameters. Patients were randomized to 6 months of active PPoP or backup pacing in a crossover design. The primary outcome examined invasive gradient change with best-site pacing. Secondary outcomes assessed quality of life and exercise following randomization to PPoP. RESULTS: A total of 17 patients were recruited; 16 of whom met primary end points. Baseline New York Heart Association was 3±0.6, despite optimal medical therapy. Hemodynamic effects were assessed during pacing at the right ventricular apex and at a mean of 8 LV sites. The gradients in all 16 patients fell with pacing, with maximum gradient reduction achieved via LV pacing in 14 (88%) patients and right ventricular apex in 2. The mean baseline gradient of 80±29 mm Hg fell to 31±21 mm Hg with best-site pacing, a 60% reduction (P<0.0001). One cardiac vein perforation occurred in 1 case, and 15 subjects entered crossover; 2 withdrawals occurred during crossover. Of the 13 completing crossover, 9 (69%) chose active pacing in PPoP configuration as preferred setting. PPoP was associated with improved 6-minute walking test performance (328.5±99.9 versus 285.8±105.5 m; P=0.018); other outcome measures also indicated benefit with PPoP. CONCLUSIONS: In a randomized placebo-controlled trial, PPoP reduces obstruction and improves exercise performance in severely symptomatic patients with LVMCO. REGISTRATION: URL: https://clinicaltrials.gov/study; Unique Identifier: NCT03450252.

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.

Obstruction in Hypertrophic Cardiomyopathy: Many Faces.

Hypertrophic cardiomyopathy (HCM), the most common inherited cardiomyopathy, exhibits left ventricular hypertrophy not secondary to other causes, with varied phenotypic expression. Enhanced actin-myosin interaction underlies excessive myocardial contraction, frequently resulting in dynamic obstruction within the left ventricle. Left ventricular outflow tract obstruction, occurring at rest or with provocation in 75% of HCM patients, portends adverse prognosis, contributes to symptoms, and is frequently a therapeutic target. Transthoracic echocardiography plays a crucial role in the screening, initial diagnosis, management, and risk stratification of HCM. Herein, we explore echocardiographic evaluation of HCM, emphasizing Doppler assessment for obstruction. Echocardiography informs management strategies through noninvasive hemodynamic assessment, which is frequently obtained with various provocative maneuvers. Recognition of obstructive HCM phenotypes and associated anatomical abnormalities guides therapeutic decision-making. Doppler echocardiography allows monitoring of therapeutic responses, whether it be medical therapies (including cardiac myosin inhibitor therapy) or septal reduction therapies, including surgical myectomy and alcohol septal ablation. This article discusses the hemodynamics of obstruction and practical application of Doppler assessment in HCM. In addition, it provides a visual atlas of obstruction in HCM, including high-quality figures and complementary videos that illustrate the many facets of dynamic obstruction.

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.

Invasive Management of Hypertrophic Cardiomyopathy With Clinically Important Obstruction: Catheter Intervention Is Superior.

Hypertrophic cardiomyopathy is a common inherited cardiac condition where the myocardium progressively thickens in the absence of abnormal loading conditions. Left ventricular hypertrophy often leads to outflow tract obstruction, and this confers significant mortality and morbidity implications. Septal reduction therapies aim to relieve the obstruction in an attempt to reduce the burden of symptoms and potentially improve prognosis. However, both surgical and catheter-based approaches to septal reduction carry risks. At present, international guidelines and expert consensus statements suggest surgical myomectomy is the gold-standard treatment. In this point-counterpoint review, we discuss why in our opinion this recommendation should be reconsidered. We hope to cover the history of catheter based septal reduction therapies and the significant advances made over the last two decades. We also hope to show why we believe the current evidence shows catheter-based alcohol septal ablation is superior to surgical myomectomy.

Mitral valve remodeling in the development of obstructive hypertrophic cardiomyopathy.

Approximately 2/3 of patients with hypertrophic cardiomyopathy (HCM) have significant left ventricular outflow tract obstruction (LVOTO), which is caused by the interaction mitral valve apparatus and the hypertrophied septum. The contribution of mitral valve remodeling to the development of obstruction over time has never been described. We analyzed retrospectively 40 patients with HCM and no baseline obstruction followed up for a median of 2179 days. At follow up, 13 patients developed significant LVOTO. Patients who developed LVOTO had longer posterior leaflets and longer anterior leaflet residual length.

Pulmonary artery sarcoma: an unexpected settler in the right ventricular outflow tract.

Pulmonary artery sarcoma (PAS) is a sporadic malignant tumor that mainly originates from the pulmonary arteries. However, PAS may also involve the right ventricular outflow tract (RVOT) and lead to obstruction, syncope, or sudden death. Early diagnosis and complete surgical resection are essential to prolong survival and improve the quality of life of patients with PAS. Herein, we report a case of a young female patient admitted for pulmonary malignancy and acute pulmonary embolism. The patient had a mass in the RVOT, which was detected by transthoracic echocardiography. Computed tomography and magnetic resonance imaging revealed the invasion depth and extent of the lesions. Surgical resection improved hemodynamics, while pathological and immunohistochemical tests confirmed the diagnosis of a pulmonary artery sarcoma. Local recurrence was detected in the adjacent tissues about two months after the surgery. Given the potential risk of reoperation, the patient was suggested to undergo conservative treatment.

Left ventricular outflow tract obstruction caused by a congenital accessory mitral valve leaflet and treated by open-heart surgery in a young dog.

A 3-month-old Shetland sheepdog presented with a loud ejection murmur and exercise intolerance. Echocardiography revealed an accessory mitral valve leaflet, characterised by a valve-like structure separate from the mitral valve seen in the subaortic region of the ventricular septum. The left ventricular outflow tract was partially obstructed with a pressure gradient of 12 mmHg. Accessory mitral valve leaflet resection and mitral valvuloplasty were performed during open-heart surgery. Histology performed on the membrane-like structures were indicative of fibrous connective tissues. Postoperative echocardiography confirmed removal of the valve-like structure with resolution of the left ventricular outflow tract obstruction. The pressure gradient was decreased to 4.6 mmHg. The dog was in good condition and no further treatment was required 5 months after surgery. Both cardiac troponin I and NT-proBNP were markedly decreased. In this dog, surgical resection combined with mitral valve plasty resolved the left ventricular outflow tract obstruction and the clinical signs.

Tissue tracking of segmental strain as a predictor of provoked dynamic left ventricular outflow tract obstruction.

BACKGROUND: Left ventricular outflow tract obstruction (LVOTO) is commonly observed in patients with hypertrophic cardiomyopathy (HCM) or left ventricular hypertrophy (LVH). Some patients develop LVOTO provoked by physical exertion, and hence termed dynamic LVOTO (DLVOTO). However, its precise prevalence and mechanism are still unclear. AIM: Two-dimensional speckle tracking echocardiography (2D STE) seems to be helpful for the detection of early LV structural abnormalities. This study aimed to examine the possible role of segmental as well as global longitudinal strain in identifying DLVOTO non-HCM patients as detected by dobutamine stress echocardiography (DSE). METHODS AND RESULTS: Two hundred and fifty patients without structural heart disease had undergone conventional transthoracic echocardiography, 2D STE, and DSE. All patients with non-ischemic evidence were divided into two groups according to the DSE results; DLVOTO (+) and DLVOTO (-). Among 250 patients, 50 patients (36%) had shown DLVOTO after DSE (15 males, 35 females; mean age 55±7years). They were compared with 90 non -LVOTO obstruction patients (43 males, 47 females; mean age 57±6years). Based on multivariate logistic regression analysis, the independent predictors of provoked DLVOTO during DSE were resting basal septal longitudinal strain BS-LS average (p < 0.001), resting LA reservoir strain (p < 0.001), and systolic LVOT diameter (p = 0.03). Resting BS-LS average with cut-off - 17.5% was recognized as a critical indicator of DLVOTO, with sensitivity 78%, and specificity 95% (better than systolic LVOT diameter of sensitivity 76%, and specificity 15% and resting LA reservoir strain which showed poor AUC at ROC curve 0.007). CONCLUSION: We demonstrate that provoked LVOTO during DSE in non HCM symptomatic patients is directly correlated to resting regional LS, where the increased BS-LS of ≥ -17.5% was a key determinant of LVOT gradient provocation. Assessment of baseline BS-LS average might be a bedside simple tool for detection of patients with DLVOTO not able to do DSE.

Opposing forces of cardiogenic shock: left ventricular outflow obstruction, severe mitral regurgitation, and left ventricular dysfunction in Takotsubo cardiomyopathy.

Rates of stress (Takotsubo) cardiomyopathy have increased during the coronavirus pandemic due to social stressors, even in patients who are not infected with the virus. At times, Takotsubo cardiomyopathy (TC) may present as cardiogenic shock. Herein, we present a case during the pandemic of shock from TC secondary to left ventricular outflow tract obstruction (LVOTO), mitral regurgitation (MR), and left ventricular (LV) dysfunction. The contrasting management strategy of LVOTO, MR, and LV failure was cause for clinical challenge, and we highlight the balance of treating these opposing forces.

An Unusual Case of Left Ventricular Outflow Tract Obstruction after Aortic Valve Replacement.

Surgical valve replacement improves the symptoms and prognosis of patients with valvular heart diseases. Aortic regurgitation elicits volume overload that causes enlargement of the left ventricle (LV), while the LV size often shrinks to near normal after aortic valve replacement (AVR), which is referred to as "reverse remodeling". We experienced a case in which LV outflow tract (LVOT) obstruction became apparent after AVR, resulting in worsening of heart failure. A 65-year-old man who had undergone surgical AVR for aortic valve regurgitation 15 months previously exhibited dyspnea on effort accompanied with severe LVOT obstruction. With double pressure catheters, we directly recorded an augmented pressure gradient in the LVOT and rapid relief of the obstruction by intravenous administration of the anti-arrhythmic drug cibenzoline. Since the considerable LV hypertrophy had been indicated by an electrocardiogram and echocardiography before AVR, we suspected that dilation of the LV chamber due to aortic valve regurgitation could have masked the subclinical LVOT obstruction, which became clinically evident after LV size reduction due to reverse remodeling after AVR.

Surgical Repair of Secondary Subaortic Stenosis in Congenital Heart Disease Without Initial Subaortic Obstruction.

BACKGROUND: Secondary subaortic stenosis (SSS) is a rare heart disease of the left ventricular outflow tract (LVOT). It usually occurs after cardiovascular correction with or without initial left ventricular outflow tract obstruction (LVOTO). Because most patients with SSS are asymptomatic, many do not realize the need for reoperation until the obstruction worsens. Few studies suggest the characteristics and reasons of SSS without initial SAS. We conducted a retrospective study to describe the characteristics and surgical outcomes of these patients. METHODS: In this study, we examined a single-center retrospective cohort of SSS patients without initial SAS undergoing resection from 2010 to 2019. Patients are defined as secondary subaortic obstruction requiring surgery after cardiovascular correction. Demographics, perioperative findings, and clinical data were analyzed. RESULTS: Twenty-three patients had undergone secondary cardiac surgery for SSS without initial SAS during 10 years in our center. The median age at operation was 7.3 (4.0-13.5) years. In this study, the most commonly associated cardiac lesions were ventricular septal defect (VSD), atrioventricular septal defect (AVSD), patent ductus arteriosus (PDA), and coarctation arch hypoplasia (COA). The surgical techniques included membranous resection of five patients, fibromuscular resection of 17 patients, and reconstruction of the intraventricular baffle of one patient. The results of surgery in these patients are satisfied. The average LVOT gradient at the last follow up was 14.9 (7.8-26.2) mmHg. There was no operative mortality. Two patients had postoperative complications. The median follow-up period was 2.9 (1.1-4.3) years with one late death. Two patients (8.7%) had recurrence of stenosis. CONCLUSIONS: Secondary subaortic stenosis is an uncommon heart disease. The reason is related to several causes, including missed diagnosis, unnoticed abnormalities of LVOT, and further changes of geometric morphology by intracardiac surgery. The results of surgery in these patients are satisfied. However, the recurrence of stenosis is still frequent.

Impact of Body Mass Index on Outcome of Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy.

BACKGROUND: Obesity is highly prevalent in patients with obstructive hypertrophic cardiomyopathy (HCM). In this study, we investigated the impact of body mass index (BMI) in patients undergoing septal myectomy (SM) for obstructive HCM. METHODS: We reviewed 2746 patients who underwent transaortic SM for obstructive HCM from February 1993 through September 2018. Patients were stratified into 3 groups based on BMI (normal weight, <25 kg/m2; overweight, 25 to <30 kg/m2; and obese, ≥30 kg/m2). RESULTS: Preoperatively, the median left ventricular outflow tract gradient was 58 mm Hg, and there was no difference in gradients across BMI strata (P = .35). The percentage of obese patients with moderate or greater mitral valve regurgitation was lower (45.8%) compared with normal weight (52.9%) and overweight (55.4%) patients (P < .001). However, patients with a higher BMI were more likely to have New York Heart Association Functional Classification III/IV limitation at presentation (P < .001). After myectomy, anteroseptal thickness (P = .115) and left ventricular outflow tract gradient (P = .210) did not differ between groups. There were 14 (0.5%) deaths within 30 days postoperatively, and the risk was similar across BMI strata (P = .448). Model-estimated changes in average BMI at 10 years postprocedure showed stratum-specific increases ranging from 0.60 to 1.56 kg/m2. During a median follow-up of 7.2 years (interquartile range, 3.2-13.3 years), a higher BMI was associated with reduced survival after adjusting for baseline covariates (P = .001). CONCLUSIONS: SM is safe and effective in HCM patients with obesity, but the risk of late death increased with increasing BMI. Attention to risk factor management through weight loss may improve late results after SM.

Plasma metabolomic profiling of hypertrophic cardiomyopathy patients before and after surgical myectomy suggests postoperative improvement in metabolic function.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a common inherited heart disorder complicated by left ventricle outflow tract (LVOT) obstruction, which can be treated with surgical myectomy. To date, no reliable biomarkers for LVOT obstruction exist. We hypothesized that metabolomic biomarkers for LVOT obstruction may be detectable in plasma from HCM patients. METHODS: We conducted metabolomic profiling on plasma samples of 18 HCM patients before and after surgical myectomy, using a commercially available metabolomics platform. RESULTS: We found that 215 metabolites were altered in the postoperative state (p-value < 0.05). 12 of these metabolites were notably significant after adjusting for multiple comparisons (q-value < 0.05), including bilirubin, PFOS, PFOA, 3,5-dichloro-2,6-dihydroxybenzoic acid, 2-hydroxylaurate, trigonelline and 6 unidentified compounds, which support improved organ metabolic function and increased lean soft tissue mass. CONCLUSIONS: These findings suggest improved organ metabolic function after surgical relief of LVOT obstruction in HCM and further underscore the beneficial systemic effects of surgical myectomy.