Symptomatic Exercise-Induced Left Ventricular Outflow Tract Obstruction without Left Ventricular 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 β-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 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.

Clinical Application of Exercise Stress Echocardiography in an Outpatient Pediatric Population

Background: Exercise stress echocardiography (ESE) is commonly employed in adults, but its applicability in pediatric populations remains to be clarified. Methods: A total of 309 consecutive children (C), with a mean age of 14.1 ± 2.6 years (range 6-17 years), underwent treadmill ESE starting in 2002. They were divided into two groups: Group I comprised 258 children, including 237 with symptoms related to exercise (such as chest pain, fatigue, lipothymia/syncope, or one aborted sudden death), 15 with electrocardiogram (ECG) abnormalities, and 6 with a positive ECG stress test showing ST changes. Group II consisted of 10 asymptomatic children whose parents requested routine screening, 11 with symptoms unrelated to exercise, 12 with a family history of sudden death, and 17 with known pathologies (including 10 with hypertrophic cardiomyopathy, 2 with aortic coarctation, and the remainder with various conditions, such as Cortriatriatum sinister, pulmonary stenosis, subaortic stenosis, bicuspid aortic valve, left ventricular hypertrophy related to arterial hypertension, and aortic switch operation). Regional wall motion abnormalities (RWMAs) and transvalvular or intraventricular (IVG) gradients were assessed using 2D and continuous-wave Doppler, respectively, in all cases. Results: The success rate was 100% (309/309). Stress-induced RWMAs were observed in two children. A significant IVG (>30 mmHg) was detected in 101 out of the 258 children (39%) in Group I, who presented with exercise-related symptoms, ECG abnormalities, or positive stress ECG. In Group I, the odds ratio (OR) of ESE reproducing the symptoms in children with IVG compared to those without IVG was 8.22 (95% CI: 4.84-13.99, p < 0.001). Conclusions: Treadmill ESE is both feasible and safe for pediatric populations. RWMAs demonstrated limited utility in our cohort of children, while IVG induced by exercise was frequently observed in symptomatic children.

Obstructive Hypertrophic Cardiomyopathy and Takotsubo Syndrome: How to Deal With Left Ventricular Ballooning?

Currently, there are 2 proposed causes of acute left ventricular ballooning. The first is the most cited hypothesis that ballooning is caused by direct catecholamine toxicity on cardiomyocytes or by microvascular ischemia. We refer to this pathogenesis as Takotsubo syndrome. More recently, a second cause has emerged: that in some patients with underlying hypertrophic cardiomyopathy, left ventricular ballooning is caused by the sudden onset of latent left ventricular outflow tract obstruction. When it becomes severe and unrelenting, severe afterload mismatch and acute supply-demand ischemia appear and result in ballooning. In the context of 2 causes, presentations might overlap and cause confusion. Knowing the pathophysiology of each mechanism and how to determine a correct diagnosis might guide treatment.

The Importance of Left Ventricular Outflow Tract and Mid-Ventricular Gradients in Stress Echocardiography: A Narrative Review

This review aims to serve as a guide for clinical practice and to appraise the current knowledge on exercise stress echocardiography in the evaluation of intraventricular obstruction in HCM, in patients with cardiac syndrome X, in athletes with symptoms related to exercise, and in patients with normal left ventricular systolic function and exercise-related unexplained tiredness. The appearance of intraventricular obstruction while exercising is considered rare, and it usually occurs in patients with hypertrophy of the left ventricle. The occurrence of intraventricular obstruction when exercising has been evidenced in patients with hypertrophic cardiomyopathy, athletes, patients with cardiac syndrome X, patients with syncope or dizziness related to exercise, and patients with dyspnea and preserved ejection fraction. The clinical significance of this observation and the exercise modality that is most likely to trigger intraventricular obstruction remains unknown. Supine exercise and lying supine after exercise are less technically demanding, but they are also less physiologically demanding than upright exercise. Importantly, in everyday life, human beings generally do not become supine after exercise, as takes place in post-exercise treadmill stress echocardiograms in most echocardiography labs. The presence of induced intraventricular obstruction might be considered when patients have exercise-related symptoms that are not understood, and to assess prognosis in hypertrophic cardiomyopathy.

Exaggerated myocardial torsion may contribute to dynamic left ventricular outflow tract obstruction in hypertrophic cardiomyopathy

Aims

Dynamic left ventricular (LV) outflow tract obstruction (LVOTO) is associated with symptoms and increased risk of developing heart failure in hypertrophic cardiomyopathy (HCM). The association of LVOTO and LV twist mechanics has not been well studied in HCM. The aim of the study was to compare the pattern of LV twist in patients with HCM associated with asymmetrical septal hypertrophy with and without LVOTO.

Methods and results

Echocardiography (including speckle tracking) was performed in 212 patients with HCM, divided according to the absence (n = 130) or presence (n = 82) of LVOTO (defined as peak pressure gradient ≥30 mmHg either at rest and/or with Valsalva manoeuvre). Patients with LVOTO were older, had smaller LV dimensions, a higher LV ejection fraction (LVEF), a longer anterior mitral valve leaflet length, and a higher early transmitral pulsed wave to septal tissue Doppler velocity ratio (E/E'). A univariate analysis showed that peak twist was significantly higher in patients with LVOTO compared with patients without LVOTO (19.7 ± 7.3 vs. 15.7 ± 6.0, P = 0.00015). Peak twist was similarly enhanced in patients with LVOTO, manifesting only during Valsalva (19.2 ± 5.6, P = 0.007) and patients with resting LVOTO (19.9 ± 8.0, P = 0.00004) compared with patients without LVOTO (15.7 ± 6.0). A stepwise forward logistic regression analysis showed that LVEF, LV end-systolic dimension indexed to body surface area, anterior mitral valve leaflet length, E/E', and peak twist were all independently associated with LVOTO.

Conclusion

This study demonstrates that increased peak LV twist is independently associated with LVOTO in patients with HCM. Peak twist was similarly exaggerated in patients with only latent LVOTO, suggesting that it may play a contributory role to LVOTO in HCM.

Hypertrophic cardiomyopathy - phenotypic variations beyond wall thickness

Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy (LVH) in the absence of another causal disease. Several morphologic and histologic changes have been described. Given the morbidity and mortality associated with HCM, understanding these anatomic variations is key to interpreting imaging. This is especially important since many patients exhibit these associated findings in the absence of LVH and prompt early detection of these variations may lead to early diagnosis and treatment. This article describes the appearance of morphologic variations seen in HCM beyond myocardial thickening including: papillary muscle and mitral valve variants, myocardial crypts, left ventricular myocardial bands, and dystrophic calcification related to increased wall tension.

Contemporary family screening in hypertrophic cardiomyopathy: the role of cardiovascular magnetic resonance

Aims

Genetic testing in relatives of hypertrophic cardiomyopathy (HCM) patients leads to early identification of pathogenic DNA variant carriers (G+), before the onset of left ventricular hypertrophy. Routine phenotyping consists of electrocardiography (ECG) and transthoracic echocardiography (TTE). Cardiovascular magnetic resonance (CMR) has become valuable in the work-up of HCM. In this study, we investigated the value of CMR in phenotyping of G+ family members.

Methods and results

This study included 91 G+ subjects who underwent ECG, TTE and CMR, with a maximal wall thickness (MWT) <15 mm on TTE. The relative performance of TTE and CMR regarding wall thickness measurements and HCM diagnoses was assessed. HCM was defined as MWT of ≥13 mm. Logistic regression was performed to assess whether ECG and TTE parameters can predict CMR results. Most subjects (75%) had an MWT <13 mm on TTE, of which 23 (34%) were diagnosed with HCM based on CMR. MWT differences (range 1–10 mm) were often caused by an anterobasal hook-shaped thickening of the myocardium not visible on TTE. Two of 23 (9%) subjects with HCM on TTE were reclassified as no HCM on CMR. Normal ECG and TTE results almost excluded reclassifications by CMR. The prevalence of other HCM-related abnormalities on CMR was low.

Conclusion

CMR reclassified 27% of subjects. Subjects with normal ECG/TTE results were reclassified in a low number of cases, justifying screening with ECG and TTE in G+ relatives. In subjects with abnormal ECGs and/or poor TTE image quality, CMR is indicated.

Usefulness of Stress Echocardiography in Assessment of Dynamic Left Ventricular Obstructions: Case Series and Review of the Literature

Dynamic left ventricular outflow tract obstruction (DLVOTO) or midcavity obstruction in patients with structurally normal hearts is not uncommon in routine clinical practice and can cause significant symptoms mimicking coronary artery disease or heart failure. Although exercise echocardiography is the gold standard for assessing DLVOTO, dobutamine stress echocardiography (DSE) may be valuable diagnostic modality in patients who are unable to exercise or have an uninterpretable 12-lead electrocardiogram. We provide an updated overview of the relevant literature regarding prevalence, pathophysiology, clinical significance, and prognostic impact of DLVOTO and midcavity obstruction in structurally normal hearts. We also present a clinical series of 4 cases of DLVOTO and midcavity obstruction documented by DSE and discuss the value of different kinds of modern stress imaging modalities involving: (1) contrast-enhanced DSE to assess myocardial perfusion and inducible ischemia; (2) adenosine stress echocardiography to assess coronary flow reserve/microvascular dysfunction; and (3) functional imaging with deformation echocardiography to assess subclinical myocardial dysfunction in patients with structurally normal heart and without significant coronary disease. Based upon our own experiences and a critical review of the current literature, we will then present a practical guidance for management of DLVOTO and midcavity obstruction.

Distinctive Hypertrophic Cardiomyopathy Anatomy and Obstructive Physiology in Patients Admitted With Takotsubo Syndrome

Clinical spectrum of hypertrophic cardiomyopathy (HC) has been expanded to include patients with mild or no thickening of the left ventricle (LV), who nevertheless have outflow tract obstruction at rest or after exercise, due to systolic anterior motion (SAM) and ventricular septal contact, with mitral valve elongation and papillary muscles anomalies. Apical ballooning mimicking a takotsubo syndrome (TS) wall motion pattern can occur in HC with mild septal thickening when latent obstruction becomes unrelenting. To define the prevalence of anatomic abnormalities characteristic of HC in patients diagnosed with TS, we analyzed echocardiograms of 44 unselected TS patients, age 67±12 years, 95% women including studies performed before the event (n = 11, median 515 days) and after recovery of left ventricular function (n = 33, median 92 days, interquartile range = 29 to 327) and compared the findings to 60 age and sexed matched controls. Analysis of echocardiograms was blinded to event timing, and patient vs. control status. During the ballooning event, 13 patients (30%) had SAM including 9 with LV outflow obstruction, peak gradients 71±40 mmHg, as well as: ventricular septal thickening (16 ± 4 mm), elongated anterior leaflets (30 ± 3mm), and increased mitral coaptation to posterior wall distance (17 ± 5 mm), consistent with diagnosis of the HC phenotype. Compared to 31 TS patients without SAM, study patients with SAM had longer anterior leaflets (30 ± 3 vs 26 ± 4 mm, p = 0.006), thicker septum (16 ± 4 vs 12 ± 3 mm), increased coaptation to posterior wall distance (17 ± 5 vs 14 ± 4 mm, p < 0.04) and reduced distance from coaptation to septum (19 ± 5 vs 27 ± 5, p < 0.001). In the 13 patients with SAM, morphologic characteristics of HC persisted after normalization of LV function. In conclusion, a subset of patients experiencing TS events demonstrates a constellation of morphologic abnormalities characteristic of HC that persist after recovery of LV wall motion. These findings suggest that dynamic outflow obstruction may cause apical ballooning in susceptible patients.

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.

Clinical Spectrum and Management Implications of Left Ventricular Outflow Obstruction With Mild Ventricular Septal Thickness in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HC) has historically been characterized as a disease of substantial left ventricular hypertrophy, often associated with dynamic left ventricular outflow tract obstruction. However, we have recently encountered patients with subaortic obstruction and only minimal basal septal thickness, raising important management implications. Thereby, we sought to characterize the natural history and treatment strategies for this under-recognized subgroup of HC patients with dynamic obstruction. Of 1,591 consecutive patients with a HC diagnosis, 113 (7%) were identified with outflow obstruction due to elongated mitral valve leaflets producing systolic anterior motion and septal contact typical of HC (gradient, 84 ± 29 mm Hg at rest or with exercise), with maximal ventricular septal thickness ≤15 mm, including 14 patients with only 10 to 12 mm. In addition to the mechanism of outflow obstruction, other evidence supporting a HC diagnosis prominently included: positive HC family history and/or pathogenic sarcomere mutation, arrhythmic sudden death event, typical histopathology of septal muscle, and characteristic mitral valve and papillary muscle anomalies. Over 3.8 ± 3.5 years, 41 patients (36%) developed severe heart failure including 36 who have undergone myectomy associated with reconstruction of the outflow tract and mitral valve apparatus, resulting in relief of gradient without iatrogenic ventricular septal defect or mitral valve replacement. Postoperatively, all 36 patients have survived with symptom relief to New York Heart Association classes I/II. In conclusion, these observations expand the HC clinical profile and phenotype to include an under-appreciated subgroup in which disease expression includes outflow obstruction due primarily to an elongated mitral valve, associated with only minimal (or normal) ventricular septal thickness. Such HC patients can develop marked functional limitation amenable to an operative strategy that effectively relieved symptoms due to outflow obstruction, but without mitral valve replacement.

Prognostic significance of anterior mitral valve leaflet length in individuals with a hypertrophic cardiomyopathy gene mutation without hypertrophic changes

Purpose

Previous studies suggest that anterior mitral valve leaflet (AMVL) elongation is a primary phenotypic feature in hypertrophic cardiomyopathy (HCM). Our aim was to assess AMVL length in individuals with HCM gene mutations and in healthy controls and to identify predictors of the development of HCM during follow-up.

Methods

A total of 133 HCM mutation carriers and 135 controls underwent cardiac examination including electro- and echocardiography. AMVL length was measured in the parasternal long axis and apical three chamber view during diastole. Univariate and multivariable cox proportional hazard regression analyses were performed to identify predictors of HCM.

Results

There were no significant differences between HCM mutation carriers and controls regarding age and sex. In the parasternal long axis view, AMVL length was similar in mutation carriers and controls (24 ± 4 vs 24 ± 4 mm, p = 0.8). In the apical three chamber view, AMVL were shorter in mutation carriers (29 ± 4 vs 30 ± 4 mm, p = 0.02). When averaged for both views, AMVL length was similar in mutation carriers and controls (27 ± 3 vs 27 ± 3 mm, p = 0.2). During 5.8 ± 3.0 years follow-up, 13 (14%) HCM mutation carriers developed HCM. Pathological Q wave (hazard ratio 9.89, p = 0.004), E/e′ ratio (hazard ratio 2.52, p = 0.001), and maximal wall thickness (hazard ratio 2.15, p = 0.001) were independent predictors of HCM. AMVL length was not predictive of the development of HCM.

Conclusions

AMVL length is similar in HCM mutation carriers and controls. AMVL length is not predictive of the development of HCM, in contrast to pathological Q wave, E/e′ ratio, and maximal wall thickness.

Effect of aortic regurgitant jet direction on mitral valve leaflet remodeling: a real-time three-dimensional transesophageal echocardiography study

Chronic aortic regurgitation (AR) induces mitral valve (MV) leaflet enlargement, although, its mechanism still remains unclear. This study aimed to clarify the influence of AR jet directions on the MV apparatus in patients with chronic AR. This study included 69 consecutive patients with severe chronic AR and 17 controls who underwent three-dimensional (3D) transesophageal echocardiography (TEE). The anterior mitral leaflet (AML), posterior mitral leaflet (PML) and MV annulus areas were measured at mid-diastole. All AR patients were classified into the posterior (Group A, n = 38) or non-posterior (Group B, n = 31) group based on the AR jet directions. Both two groups revealed the increased total leaflet areas compared with the controls. No significant differences in the left ventricular volumes, PML or MV annulus area were observed between Group A and B; however, Group A had the larger AML area and greater AML/PML area ratio than Group B (both P < 0.01). The multivariate analysis indicated that the posterior AR jet was independently associated with the AML/PML area (P < 0.01). 3D TEE depicted geometric differences in the MV apparatus between the different types of AR jet directions. These results may be helpful in understanding the mechanism of MV leaflet remodeling in chronic AR.

The evolution of basal septal hypertrophy: From benign and age-related normal variant to potentially obstructive and symptomatic cardiomyopathy

Localized thickening of the basal portion of the ventricular septum or basal septal hypertrophy (BSH) has been identified both at autopsy and by imaging studies for decades; despite numerous investigations, there is no consensus on the significance of this finding and a remarkable lack of consistency in terminology. This paper summarizes the scientific literature on the topic, focusing on recent echocardiographic findings. A case description illustrating some of the complex issues involved in measurement and diagnosis and differentiation from sigmoidal hypertrophic cardiomyopathy (HCM) is presented. Criteria are proposed for diagnosing pathologic BSH which include the following: (1) Exertional symptoms compatible with left ventricular outflow tract obstruction (LVOTO) such as dyspnea, near-syncope, and chest discomfort; (2) Documented LVOTO gradient demonstrated at peak bicycle or post-treadmill exercise >30 mm Hg; and (3) Symptomatic improvement with β-blocker (or other negative inotropic) therapy (preferably accompanied by documentation of reduction of exercise-induced LVOT).

Anomalous Papillary Muscle Insertion Causing Dynamic Left Ventricular Outflow Tract Obstruction without Hypertrophic Obstructive Cardiomyopathy

Anomalous papillary muscle insertion directly into the surface of the mitral valve leaflet is rare, especially in a subject without apparent evidence of hypertrophic cardiomyopathy. We present a case of this isolated congenital malformation producing two hemodynamic sequelae of dynamic left ventricular outflow tract obstruction and severe mitral regurgitation.

Drug Therapy for Hypertrophic Cardiomypathy: Physiology and Practice

HCM is the most common inherited heart condition occurring in 1:500 individuals in the general population. Left ventricular outflow obstruction at rest or after provocation occurs in 2/3 of HCM patients and is a frequent cause of limiting symptoms. Pharmacologic therapy is the first-line treatment for obstruction, and should be aggressively pursued before application of invasive therapy. Beta-blockade is given first, and up-titrated to decrease resting heart rate to between 50 and 60 beats per minute. However, beta-blockade is not expected to decrease resting gradients; its effect rests on decreasing the rise in gradient that accompanies exercise. For patients who fail beta-blockade the addition of oral disopyramide in adequate dose often will decrease resting gradients and offer meaningful relief of symptoms. Disopyramide vagolytic side effects, if they occur, can be greatly mitigated by simultaneous administration of oral pyridostigmine. This combination allows adequate dosing of disopyramide to achieve therapeutic goals. Verapamil utility in obstructive HCM with high resting gradients is limited by its vasodilating effects that can, infrequently, worsen gradient and symptoms. As such, we tend to avoid it in patients with high gradients and limiting heart failure symptoms. In a head-to-head comparison of intravenous drug administration in individual obstructive HCM patients the relative efficacy for lowering gradient was disopyramide > beta-blockade > verapamil. Severe symptoms in non-obstructive HCM are caused by fibrosis or severe myocyte disarray, and often by very small LV chamber size. Severe symptoms caused by these anatomic and histologic abnormalities, in the absence of obstruction, are less amenable to current pharmacotherapy. New pharmacotherapeutic approaches to HCM are on the horizon, that are to be evaluated in formal therapeutic trials.

Misconceptions and Facts About Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy is the most common genetic heart disease. Once considered relentless, untreatable, and deadly, it has become a highly treatable disease with contemporary management. Hypertrophic cardiomyopathy is one of cardiology's "great masqueraders." Mistakes and delays in diagnosis abound. Hypertrophic cardiomyopathy commonly "masquerades" as asthma, anxiety, mitral prolapse, and coronary artery disease. However, once properly diagnosed, patients with hypertrophic cardiomyopathy can be effectively managed to improve both symptoms and survival. This review highlights some of the misconceptions about hypertrophic cardiomyopathy. Providers at all levels should have awareness of hypertrophic cardiomyopathy to promptly diagnose and properly manage these individuals.

Diverse geometric changes related to dynamic left ventricular outflow tract obstruction without overt hypertrophic cardiomyopathy

BACKGROUND

Dynamic left ventricular (LV) outflow tract (LVOT) obstruction (DLVOTO) is not infrequently observed in older individuals without overt hypertrophic cardiomyopathy (HCM). We sought to investigate associated geometric changes and then evaluate their clinical characteristics.

METHODS

A total of 168 patients with DLVOTO, which was defined as a trans-LVOT peak pressure gradient (PG) higher than 30 mmHg at rest or provoked by Valsalva maneuver (latent LVOTO) without fixed stenosis, were studied. Patients with classical HCM, acute myocardial infarction, stress induced cardiomyopathy or unstable hemodynamics which potentially induce transient-DLVOTO were excluded.

RESULTS

Their mean age was 71 ± 11 years and 98 (58%) patients were women. Patients were classified as pure sigmoid septum (n = 14) if they have basal septal bulging but diastolic thickness less than 15 mm, sigmoid septum with basal septal hypertrophy for a thickness ≥15 mm (n = 85), prominent papillary muscle (PM) (n = 20) defined by visually large PMs which occluded the LV cavity during systole or 1/2 LVESD, or as having a small LV cavity with concentric remodelling or hypertrophy (n = 49). The prominent PM group was younger, had a higher S' and lower E/e' than other groups. In all groups, a higher peak trans-LVOT PG was related (p < 0.10) to higher E/e', systolic blood pressure, relative wall thickness, and pulmonary arterial systolic pressure. In multivariate analysis, resting trans-LVOT PG correlated to pulmonary arterial pressure (ß = 0.226, p = 0.019) after adjustment for systolic blood pressure, relative wall thickness, and E/e'.

CONCLUSIONS

DLVOTO develops from various reasons, and patients with prominent PMs have distinct characteristics. We suggest to use DLVOTO-relieving medication might reduce pulmonary pressure in this group of patients.

Cardiogenic shock accompanied by dynamic left ventricular outflow tract obstruction and myocardial bridging after transient complete atrioventricular block mimicking ST-elevation myocardial infarction: a case report

Background

Dynamic left ventricular outflow tract obstruction with or without mitral regurgitation is typically observed in hypertrophic cardiomyopathy, but is also occasionally seen without left ventricular hypertrophy. In this report, we present a case of cardiogenic shock that mimics ST-elevation myocardial infarction, due to dynamic left ventricular outflow tract obstruction with transient mitral regurgitation and myocardial bridging after transient complete atrioventricular block.

Case presentation

A 65-year-old man with hypertension presented himself at the emergency department with syncope after chest pain. His initial electrocardiography showed inferior ST elevation with profound precordial ST depression and transient complete atrioventricular block. Due to sustained hypotension, an intra-aortic balloon pump was applied. His coronary angiography revealed almost normal right coronary artery and left circumflex artery and only a severe myocardial bridge in the mid-segment of his left anterior descending artery. Instead, severe mitral regurgitation was found without regional wall motion abnormality both in the left ventriculography and the portable echocardiography. However the severe mitral regurgitation completely disappeared in follow up echocardiography the day after. The pressure gradient across the left ventricular outflow tract was measured at 8.95 mmHg during the resting state, and was increased to 38.95 mmHg during the Valsalva state.

Conclusions

The patient presented with a case of cardiogenic shock that mimicked ST-elevation myocardial infarction due to dynamic left ventricular outflow tract obstruction combined with myocardial bridging in the mid-left anterior descending artery.

Treatment of obstructive hypertrophic cardiomyopathy symptoms and gradient resistant to first-line therapy with β-blockade or verapamil

BACKGROUND

There is controversy about preferred methods to relieve obstruction in hypertrophic cardiomyopathy patients still symptomatic after β-blockade or verapamil.

METHODS AND RESULTS

Of 737 patients prospectively registered at our institution, 299 (41%) required further therapy for obstruction for limiting symptoms, rest gradient 61 ± 45, provoked gradient 115 ± 49 mm Hg, and followed up for 4.8 years. Disopyramide was added in 221 (74%) patients and pharmacological control of symptoms was achieved in 141 (64%) patients. Overall, 138 (46%) patients had surgical relief of obstruction (91% myectomy) and 6 (2%) alcohol septal ablation. At follow-up, resting gradients in the 299 patients had decreased from 61 ± 44 to 10 ± 25 mm Hg (P<0.0001); New York Heart Association class decreased from 2.7 ± 0.7 to 1.8 ± 0.5 (P<0.0001). Kaplan-Meier survival at 10 years in the 299 advanced-care patients was 88% and did not differ from nonobstructed patients (P=0.28). Only 1 patient had sudden death, a low annual rate of 0.06%/y. Kaplan-Meier survival at 10 years in the advanced-care patients did not differ from that expected in a matched cohort of the US population (P=0.90).

CONCLUSIONS

Patients with obstruction and symptoms resistant to initial pharmacological therapy with β-blockade or verapamil may realize meaningful symptom relief and low mortality through stepped management, adding disopyramide in appropriately selected patients, and when needed, by surgical myectomy.