Advancements in the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: A Comprehensive Review.

Hypertrophic cardiomyopathy (HCM) is characterized by excessive growth of myocardial tissue, most commonly due to genetic mutations in sarcomere proteins. This can lead to complications such as heart failure, mitral regurgitation, syncope, arrhythmias, sudden cardiac death, and myocardial ischemia. While we have come a long way in our understanding of the pathophysiology, genetics, and epidemiology of HCM, the past 10 years have seen significant advancements in diagnosis and treatment. As the body of evidence on hypertrophic cardiomyopathy continues to grow, a comprehensive review of the current literature is an invaluable resource in organizing this knowledge. By doing so, the vast progress that has been made thus far will be widely available to all experts in the field. This review provides a comprehensive analysis of the scientific literature, exploring both well-established and cutting-edge diagnostic and therapeutic options. It also presents a unique perspective by incorporating topics such as exercise testing, genetic testing, radiofrequency ablation, risk stratification, and symptomatic management in non-obstructive HCM. Lastly, this review highlights areas where current and future research is at the forefront of innovation in hypertrophic cardiomyopathy.

How to treat systolic anterior motion of the anterior mitral valve leaflet during endoscopic minimally invasive surgery.

Systolic anterior motion is characterized by the displacement of the anterior mitral leaflet towards the left ventricle outflow tract. Iatrogenic systolic anterior motion occurs after mitral valve repair as a result of mitral annuloplasty. Possible causes include excess height of a redundant posterior mitral leaflet and/or the use of an undersized ring. The condition is usually diagnosed after weaning from cardiopulmonary bypass by transoesophageal echocardiography. Apart from conservative measures, the treatment of systolic anterior motion may require the restoration of cardiopulmonary bypass and further surgical valve repair. Strategies for systolic anterior motion correction include an edge-to-edge repair or the use of a larger annuloplasty ring. In this tutorial, we present two ways of reducing posterior leaflet height as a simple option to move the leaflet coaptation more posteriorly.

Three-dimensional anatomic features of the mitral valve that predict systolic anterior motion occurring during dobutamine stress echocardiography.

BACKGROUND/AIM: Left ventricular outflow tract obstruction related to systolic anterior motion (SAM) of the mitral valve is a common complication of dobutamine stress echocardiography (DSE). However, the mechanisms underlying SAM have not been fully characterized. The objective of the present study was to use three-dimensional echocardiography to identify anatomic features of the mitral valve that predispose to SAM during DSE. METHODS: We retrospectively evaluated consecutive patients included prospectively in our database and who had undergone 3D echocardiography (including an assessment of the mitral valve) before DSE. Patients who had developed SAM during DSE (the SAM+ group) were matched 2:3 with patients who did not (the SAM- group). RESULTS: One hundred patients were included (mean age: 67 ± 10). Compared with SAM- patients (n = 60), SAM+ patients (n = 40) had a lower mitral annular area, a smaller perimeter, and a smaller diameter (p < .01 for all, except the anteroposterior diameter). The SAM+ group had also a narrower mitral-aortic angle (126 ± 12° vs. 139 ± 11° in the SAM- group; p < .01) and a higher posterior mitral leaflet length (1.4 ± .27 cm vs. 1.25 ± .29, respectively; p < .01). Furthermore, the mitral annulus was more spherical, more flexible, and more dynamic in SAM+ patients than in SAM- patients (p < .05 for all). In a multivariate analysis of anatomic variables, the mitral-aortic angle, the mitral annular area, and posterior leaflet length were independent predictors of SAM (p ≤ .01 for all). In a multivariate analysis of standard echo and hemodynamic variables, the presence of wall motion abnormalities at rest (p < .01) was an independent predictor of SAM. CONCLUSION: SAM during DSE is multifactorial. In addition to the pharmacologic effects of dobutamine on the myocardium, 3D echocardiographic features of the mitral valve (a smaller mitral annulus, a narrower mitral-aortic angle, and a longer posterior leaflet) appear to predispose to SAM.

LEOPARD syndrome with accelerated idioventricular rhythm and systolic anterior motion of the posterior mitral leaflet: a case report.

Background: PTPN11 is ubiquitously expressed and has a variety of phenotypes even in a single heart. We examined LEOPARD syndrome (LS) in a patient with PTPN11 variants through pathological, electrophysiological, and anatomical studies. Case summary: A 49-year-old man with no previous medical history was brought to our emergency department because of syncope. An electrocardiogram (ECG) revealed alternating bundle branch block, and echocardiography revealed hypertrophic cardiomyopathy-like morphology with systolic anterior motion of the posterior mitral valve. Atrioventricular block, left ventricular outflow tract (LVOT) obstruction, and ventricular tachycardia were considered the differential diagnoses; however, the treatment plan was difficult to determine. An electrophysiological study revealed the cause of the ECG abnormality to be accelerated idioventricular rhythm, and the programmed ventricular stimulation was negative. Genetic testing revealed LS with PTPN11 variant, which was speculated to be the cause of these various unique cardiac features. The cause of syncope was considered to be exacerbation of LVOT obstruction due to dehydration, and the patient was treated with oral beta-blockers. Implantable loop recorder observation for 1 year revealed no arrhythmia causing syncope, and an implantable cardioverter-defibrillator and pacemaker were deemed unnecessary for primary prevention of syncope. During 2.5 years of follow-up, the LVOT peak velocity fluctuated between 2.5 and 3.5 m/s, but the patient remained stable with no recurrent syncope. Conclusion: We confirmed that LS is distinct from other cardiomyopathies using characterization, physiological, electrophysiological, and pathological examinations. Evidence supporting a specific treatment strategy for LS is limited, and understanding the pathogenesis may help establish effective treatment strategies.

Norepinephrine and Dobutamine-Induced Dynamic Left Ventricular Outflow Tract Obstruction Caused by Systolic Anterior Motion.

This study presents a case of norepinephrine and dobutamine-induced dynamic left ventricular outflow tract obstruction (LVOTO) caused by systolic anterior motion (SAM) in a patient experiencing acute anterior myocardial infarction (MI). In a 76-year-old patient presenting with acute MI, intensive use of norepinephrine and dobutamine may lead to the development of dynamic LVOTO and SAM. The presence of hypotension and a new cardiac murmur may suggest a mechanical complication such as acute mitral regurgitation (MR) or ventricular septal rupture (VSR). The assessment of the left ventricular outflow tract (LVOT) using echocardiography plays a critical role in the diagnosis of SAM and its associated MR and dynamic LVOTO. The patient's condition was stabilized through the cessation of inotropes and the implementation of aggressive fluid resuscitation, resulting in improved hemodynamics. In conclusion, prompt identification of the underlying pathophysiological mechanisms is imperative for effectively managing this condition and preventing hemodynamic exacerbation.

Perioperative echocardiography in minimally invasive surgery for hypertrophic obstructive cardiomyopathy.

BACKGROUND: Hypertrophic obstructive cardiomyopathy (HOCM) is clinically symptomatic and prone to malignant arrhythmias and sudden cardiac death (SCD). Currently, an effective treatment is surgical resection of the hypertrophic ventricular septum to relieve the left ventricular outflow tract (LVOT) obstruction and mitral insufficiency. Our center performs an innovative, minimally invasive right infra-axillary thoracotomy for transaortic septal myectomy. Minimally invasive procedures rely more on perioperative transesophageal echocardiography (TEE). This study aimed to explore the use of echocardiography during the perioperative period of surgical intervention for HOCM. METHODS: Between August 2021 and April 2022, 27 patients with HOCM underwent cardiac surgery at our hospital. Minimally invasive transaortic septal resection (Morrow myectomy) was performed from the right axilla. The extent of myectomy and need for mitral valve repair were based on perioperative TEE assessment and surgical findings. The demographic parameters and clinical data of patients were recorded. The cardiopulmonary bypass time, aortic cross-clamp, and mechanical ventilation times were calculated. TEE was used to assess ventricular wall thickening and anatomical abnormalities of mitral regurgitation, assist in intravenous catheterization, and assess the postoperative gradients of the LVOT. RESULTS: Among the 27 patients with HOCM who underwent transaortic septal myectomy by minimally invasive right infra-axillary thoracotomy, 16 had LVOT obstruction, 2 had mid-LV obstruction, and 9 had both LVOT and mid-LV involvement. TEE provides information about the fine structure of the LV cavity and the etiology of the obstruction. In all cases, LVOT obstruction and mitral valve systolic anterior motion were resolved postoperatively, and the degree of mitral regurgitation was significantly reduced. CONCLUSION: Perioperative echocardiography provides valuable information regarding the complex etiology of LVOT obstruction during minimally invasive right infra-axillary thoracotomy for transaortic septal myectomy. It helps determine the extent of septal resection and assess the need for concomitant mitral valve repair.

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.

Anesthetic Management of Intra-aortic Balloon Pump-Induced Systolic Anterior Motion of the Mitral Valve During Coronary Artery Bypass Grafting.

The intra-aortic balloon pump (IABP) is a mechanical device that increases myocardial oxygen perfusion and indirectly increases cardiac output through afterload reduction. Since its inception, the IABP has been a mainstay of cardiac support devices, utilized as a temporizing measure in patients with or prone to developing cardiogenic shock that are awaiting definitive treatment. Systolic anterior motion (SAM) of the mitral valve is a well-described phenomenon that can precipitate hemodynamic collapse by obstructing the left ventricular outflow tract in a subset of patients with cardiac pathology, most notably hypertrophic obstructive cardiomyopathy (HOCM). This report describes the case and anesthetic management of a patient who had an IABP placed for support and later developed SAM and hemodynamic compromise after induction of general anesthesia during a coronary artery bypass surgery.

Short time effects of two radiofrequency ablation methods on hypertrophic obstructive cardiomyopathy.

BACKGROUND: Radiofrequency ablation has been applied for the treatment of hypertrophic obstructive cardiomyopathy (HOCM). The two known procedures are percutaneous intramyocardial septal radiofrequency ablation (PIMSRA) and endocardial radiofrequency septal ablation (ERSA). METHODS: This study presents a retrospective analysis of the PIMSRA and ERSA procedures in patients with drug-refractory HOCM. A total of 28 patients participated in the study, with 12 receiving PIMSRA and 16 receiving ERSA. The objective of our study was to compare the short-term effects of these two radiofrequency ablation procedures. RESULTS: At the 30-day follow-up, the PIMSRA group demonstrated a greater reduction in left ventricular outflow tract peak gradient at rest compared to the ERSA group (22.25 [16.72] mmHg versus 47.75 [21.94] mmHg) (p < .01). The values for the PIMSRA group decreased from 99.33 (32.00) mmHg to 22.25 (16.72) mmHg (p < .01), while the ERSA group decreased from 97.75 (30.24) mmHg to 47.75 (21.94) mmHg (p < .01). Only the PIMSRA group exhibited a decrease in mitral regurgitation (MR). The area of MR decreased from 10.13 (4.12) mm2 to 3.65 (2.80) mm2 in the PIMSRA group (p < .01). Additionally, the PIMSRA group experienced reductions in left atrial diameter (LAD) and left ventricular ejection fraction (LVEF)%. The values for LAD changed from 43.58 (7.53) mm to 37.08 (6.92) mm (p = .03), and the values for LVEF% decreased from 65.75 (6.12) pg/mL to 60.83 (4.06) pg/mL (p = .03). CONCLUSION: In terms of the two types of radiofrequency ablation methods used in HOCM, it has been observed that PIMSRA demonstrates a more favorable early treatment effect compared to ERSA.

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

Background: Hypertrophic cardiomyopathy (HCM) is often linked to systolic anterior motion (SAM) of the mitral valve, typically resulting in a posteriorly directed mitral regurgitation (MR) jet. An anteriorly directed MR jet suggests additional mitral valve pathology that may not be resolved by myectomy alone. Case summary: A 58-year-old construction worker with no significant medical history experienced a syncopal event and was admitted to the emergency department with acute pulmonary oedema. A systolic murmur was investigated with a trans-thoracic echocardiogram that revealed severe MR with an unusual anteriorly directed MR jet and a possible flail segment of the posterior leaflet. This finding was further characterized with a trans-oesophageal echocardiogram that revealed severe asymmetric septal hypertrophy with SAM of the mitral valve, severe mitral regurgitation into a dilated left atrium with pulmonary vein flow reversal not caused by HCM-associated SAM, and a markedly abnormal mitral valve with flail and prolapse. The patient underwent successful cardiac surgery, including mitral valve repair and septal myectomy. The patient's recovery was uneventful, allowing for a return to work within a month post-surgery. Discussion: The anteriorly directed MR jet served as a red flag, leading to the discovery of an independent mitral valve pathology that required surgical intervention beyond the expected treatment for SAM-associated HCM. This case highlights the complexity of assessing MR in patients with HCM and underscores the importance of characterizing MR jet direction in diagnosing additional mitral valve diseases.

Cardiac Arrest During the Medical Management of Left Ventricular Outflow Tract Obstruction Following the Transcatheter Aortic Valve Implantation.

Systolic anterior motion of the mitral valve and left ventricular outflow tract obstruction are complications following transcatheter aortic valve implantation and can lead to hemodynamic collapse. Medical management for those complications is usually centered on a reduction in left ventricular contractility with negative inotropes. An 88-year-old woman underwent transcatheter aortic valve implantation for severe aortic stenosis. Hemodynamic collapse and exacerbation of mitral regurgitation occurred immediately after valve implantation. For suspected left ventricular outflow tract obstruction, medical management centered on negative inotropes was performed. Hemodynamics and left ventricular outflow tract obstruction improved over time; however, the oxygen supply-demand imbalance progressed. On postoperative day 5, the patient suddenly went into pulseless electrical activity. Cardiopulmonary resuscitation was performed for three minutes, resulting in the return of spontaneous circulation. Subsequent refractory hypotension and oxygen supply-demand imbalance improved with continuous infusion of adrenaline, dobutamine, and phenylephrine. Her hemodynamics remained stable after she was weaned off the pressor infusions, and negative inotropes were not required again. In summary, the cause of cardiac arrest was possibly due to excessive negative inotropic effects even though the effects contributed to improvement of left ventricular outflow tract obstruction. Anesthesiologists and intensivists should recognize the risk of cardiac arrest induced by negative inotropic effects and use negative inotropes with rigorous hemodynamic monitoring, even when left ventricular outflow tract obstruction is treated effectively.

Mitral regurgitation mechanisms related to systolic anterior motion in hypertrophic cardiomyopathy.

Background: Systolic anterior motion (SAM) of the mitral valve can result in mitral regurgitation (MR) and adverse outcomes in patients with obstructive hypertrophic cardiomyopathy (HCM). However, the mechanism and characteristics of MR severity mediated by SAM are unresolved. This study aimed to elucidate the anatomic and hemodynamic associations of MR and the impact of septal myectomy on changes in MR severity in patients with HCM. Methods: We retrospectively reviewed patients who underwent septal myectomy with SAM and interpretable imaging between 2017-2022. Significant MR was defined as moderate or more MR. The mitral valve, papillary muscle, and left ventricular geometry were quantitatively evaluated via echocardiography and cardiac computed tomography. Results: Out of 34 patients, two groups were identified: those with preoperative significant MR (n=16) and those without significant MR (n=18). Patients with significant preoperative MR exhibited worse heart failure symptoms at baseline than those without. Following myectomy, these patients showed higher residual left ventricular outflow tract (LVOT) gradients at rest and with provocative measures than those without preoperative MR. Multivariate regression analysis revealed a significant association between the tenting area and MR severity. Additionally, the chordal cutting procedure alleviated the tenting area [2.1 (1.8-2.6) vs. 1.4 (1.2-1.6) cm2] compared to those without it. Conclusions: Our preliminary data suggested that chordal cutting with septal myectomy was associated with an improvement in the tenting area, contributing to MR severity. This procedure may serve as an effective therapy for patients with SAM and significant MR.

PlasmaBlade-assisted surgical septal myectomy: technique and our experience.

Background: The pulsed-electron avalanche knife (PEAK) PlasmaBlade provides an atraumatic, scalpel-like cutting precision and electrocautery-like hemostasis. PlasmaBlade operates near body temperature, and its long, thin, and malleable tip can overcome the limitations of a surgical knife. In this study, we aimed to evaluate our clinical experience and histopathological outcomes of septal myectomy using PlasmaBlade. Methods: Electronic medical records were reviewed for preoperative, operative, and follow-up data of the patients who underwent septal myectomy using PEAK PlasmaBlade at our institute between January 2019 and December 2022. Histopathology of the myectomy specimens was reviewed for the depth of muscle necrosis and compared with the left atrial appendage (LAA) specimen. Results: Twenty-nine patients underwent septal myectomy using the PEAK PlasmaBlade. No mortality was reported. The mean age was 60.6 ± 12.5 years, and 58.6% of patients were male. Peak left ventricular outflow tract (LVOT) gradients were 40.5 ± 34.9 mmHg at rest and 56.5 ± 34.9 mmHg after provocation. Concomitant procedures performed were LAA ligation in 20 (69.0%), aortic valve replacement in 5 (17.2%), and coronary artery bypass grafting in 3 (10.3%) patients. Postoperative complications were complete heart block in one (3.4%) and ventricular septal defect in two (6.9%) patients. Both the ventricular septal defects were identified intraoperatively and repaired. Histopathology of myectomy specimens demonstrated cautery artifact limited to <50 µm depth compared to >1,000 µm with conventional electrocautery. At a mean follow-up of 8.4 ± 10.3 months, the mean LVOT gradient was 4.4 ± 5.8 mmHg at rest and 9.5 ± 3.3 mmHg after provocation. All patients were alive and in New York Heart Association class I/II. No patient developed complications or required reintervention or reoperation. Conclusion: Adequate septal myectomy can be precisely and safely performed using the PEAK PlasmaBlade with minimal collateral damage.

Reversibility systolic anterior motion of the mitral valve after aortic valve replacement for severe aortic stenosis.

Key Clinical Message: Patients with aortic valve replacement (AVR) for severe aortic stenosis (AS) will cause reversibility systolic anterior motion (SAM). This may occur because of afterload reduction caused by the relief of the AS and the prolonged anterior mitral valve. It is important to evaluate the mechanism of SAM by intraoperative real-time transesophageal echocardiography (TEE). Abstract: This case video describes the presentation and successful treatment of a 58-year-old man who experienced post-AVR SAM with dynamic (left ventricle outflow tract) LVOT obstruction. This case highlights the fact that patients with AVR for severe AS may cause reversible SAM. This may occur because of afterload reduction caused by the relief of the AS combined with the prolonged anterior mitral valve. It is important to evaluate the mechanism of SAM by intraoperative real-time TEE and then make the surgical decision.

Posterior Papillary Muscle Suspension for Treating Systolic Anterior Motion in Hypertrophic Obstructive Cardiomyopathy.

Systolic anterior motion of the anterior mitral leaflet can persist after ventricular septal myectomy for obstructive hypertrophic cardiomyopathy, resulting in residual pressure gradients and mitral regurgitation. However, additional procedures for systolic anterior motion involving mitral valve leaflet suturing and resection may lead to future valve disease. Therefore, we adopted posterior papillary muscle suspension, a subvalvular procedure for functional mitral regurgitation, to treat systolic anterior motion without directly intervening in the mitral valve leaflets. Papillary muscle suspension toward the posterior mitral annulus moved the papillary muscles away from the interventricular septum and successfully eliminated the systolic anterior motion and midventricular pressure gradient. In terms of avoiding direct mitral interventions, this procedure is a viable option for systolic anterior motion, especially in cases of very mild mitral regurgitation.

Management of the mitral valve in thoracoscopic trans-mitral myectomy for hypertrophic obstructive cardiomyopathy.

Objective: This study aimed to compare clinical outcomes of different mitral valve (MV) management methods in thoracoscopic transmitral myectomy (TTM) and guide surgeons' decision making for hypertrophic obstructive cardiomyopathy (HOCM). Methods: Seventy-three consecutive patients (41 females; mean age, 53.7 ± 13.6 years) with HOCM who underwent TTM between January 2019 and October 2022 were enrolled and divided into 3 groups according to MV surgical strategy. Clinical outcomes were analyzed and compared among the groups. Results: None of the patients experienced postoperative residual left ventricular outflow tract obstruction. Percentages of patients with mitral regurgitation (MR) grade ≥3+ (57.5% vs 1.4%) and systolic anterior motion (95.9% vs 2.7%) were significantly decreased postoperatively (P < .001 for both). The preoperative anterior mitral leaflet length was longer in patients in the anterior mitral leaflet direct reattachment group (median, 2.9 cm [interquartile range (IQR), 2.7-3.3 cm] vs 2.7 [IQR, 2.4-2.9 cm]; P = .018), but the postoperative coaptation length was shorter (mean, 8.3 ± 2.1 mm vs 11.1 ± 3.8 mm; P = .038). After a median echocardiography follow-up of 11.8 months, the left ventricular outflow tract gradient (LVOTG) and mitral regurgitation grades remained significantly improved in all 3 groups (P < .05 for all). Conclusions: Total TTM in selected patients is safe and effective, and all 3 MV management strategies can significantly reduce the LVOTG while improving MR. Mitral valvuloplasty is the preferred initial management strategy over valve replacement except in the scenario of irreparable intrinsic MV disease and valvuloplasty failure.

Spontaneously Resolved Systolic Anterior Motion of Native Mitral Valve Leaflet After Transcatheter Mitral Valve Replacement.

Systolic anterior motion of a mitral leaflet can occur by various mechanisms and it is one of the causes of left ventricular outflow tract obstruction after transcatheter mitral valve replacement. We present a case of systolic anterior motion that resolved spontaneously as the anterior mitral leaflet adhered to the prosthesis. (Level of Difficulty: Intermediate.).