Significance of postprandial symptom exacerbation in hypertrophic cardiomyopathy

Unmasking Obstruction in Hypertrophic Cardiomyopathy With Postprandial Resting and Treadmill Stress Echocardiography

BACKGROUND

Latent left ventricular outflow tract obstruction (LVOTO) is an important cause of symptoms in patients with hypertrophic cardiomyopathy (HCM) but can be challenging to provoke.

OBJECTIVES AND METHODS

To examine the value of postprandial resting and stress echocardiography and utilization of invasive or enhanced drug therapies (surgical myectomy, alcohol septal ablation, disopyramide, and mavacamten) in patients with postprandial LVOTO. Consecutive HCM patients without LVOTO underwent routine and postprandial echocardiography at rest, with provocation (Valsalva and standing) and after symptom-limited treadmill stress.

RESULTS

Among 252 patients (mean age, 58 years, 39% women), postprandial LVOT gradients were higher compared with routine echocardiography at rest (median, 9.0 [0-38.0] vs 0 [0-14.0] mm Hg; P < .0001) and with provocation (18.5 [0-70.3] vs 1.5 [0-41.0] mm Hg; P < .0001). Postprandial exercise stress echocardiogram (PPXSE) gradients were higher in a subset of 44 patients who underwent both postprandial and fasting stress echocardiography (47.0 [5.3-81.0] vs 17.5 [0-46.0] mm Hg; P < .0001). In total, 49 (19.5%) patients achieved the ≥50 mm Hg threshold under routine conditions (rest/provocation); 90 (35.7%) additional patients achieved postprandial gradients ≥50 mm Hg (rest/provocation/exercise), 38 (15.1%) with PPXSE alone. A total of 71 patients were treated with 91 invasive or enhanced drug therapies, 32 (45.1%) of whom had gradients ≥50 mm Hg only after eating (rest/provocation) and 8 (11.3%) only with PPXSE, with symptom relief in the majority.

CONCLUSIONS

Postprandial echocardiography was useful at unmasking LVOTO in more than one-third of patients who did not have high gradients otherwise. Eating before echocardiography is a powerful provocative tool in the evaluation of patients with HCM.

Recommendations for Multimodality Cardiovascular Imaging of Patients with Hypertrophic Cardiomyopathy: An Update from the American Society of Echocardiography, in Collaboration with the American Society of Nuclear Cardiology, the Society for Cardiovascular Magnetic Resonance, and the Society of Cardiovascular Computed Tomography

Hypertrophic cardiomyopathy (HCM) is defined by the presence of left ventricular hypertrophy in the absence of other potentially causative cardiac, systemic, syndromic, or metabolic diseases. Symptoms can be related to a range of pathophysiologic mechanisms including left ventricular outflow tract obstruction with or without significant mitral regurgitation, diastolic dysfunction with heart failure with preserved and heart failure with reduced ejection fraction, autonomic dysfunction, ischemia, and arrhythmias. Appropriate understanding and utilization of multimodality imaging is fundamental to accurate diagnosis as well as longitudinal care of patients with HCM. Resting and stress imaging provide comprehensive and complementary information to help clarify mechanism(s) responsible for symptoms such that appropriate and timely treatment strategies may be implemented. Advanced imaging is relied upon to guide certain treatment options including septal reduction therapy and mitral valve repair. Using both clinical and imaging parameters, enhanced algorithms for sudden cardiac death risk stratification facilitate selection of HCM patients most likely to benefit from implantable cardioverter-defibrillators.

The Surgeon's View of the Left Ventricular Outflow Tract in Congenital Heart Surgery

Left ventricular outflow tract (LVOT) obstruction is a component of many forms of congenital heart disease, including hypertrophic cardiomyopathy, membranous subaortic stenosis, tunnel subaortic stenosis, and outflow tract obstruction related to atrioventricular septal defects. We have gained a particularly extensive experience with the diagnosis and treatment of hypertrophic cardiomyopathy, having performed septal myectomy in over 3,800 patients. In the setting of this review of LVOT obstruction, we use hypertrophic cardiomyopathy as a template by which other pathologies causing LVOT obstruction can be understood. We review important surgical issues in patient selection, diagnostic evaluation, interpretation of imaging, and operative management. To this end, the review focuses on obstructive hypertrophic cardiomyopathy and then broadens to discuss other pathologies causing LVOT obstruction, with important similarities and differences in their management. These other pathologies share some similar presentations and operative techniques, and at times can be confused with hypertrophic cardiomyopathy, but also have important distinctions of which the surgeon should be aware.

Phenotyping Left Ventricular Obstruction With Postprandial Re-Test Echocardiography in Hypertrophic Cardiomyopathy

Dynamic left ventricular (LV) obstruction has important clinical and therapeutic implications in patients with hypertrophic cardiomyopathy (HC). Although absent at rest, LV obstruction may be elicited using varying stressors. Meal-related hemodynamic changes may favor LV obstruction and support postprandial (PP) symptoms in HC patients. The aim of this study was to evaluate PP-LV obstruction inducibility in HC patients in comparison with fasting Valsalva maneuver and exercise test. Ninety-two HC patients without LV obstruction underwent at-rest Transthoracic Echocardiography (TTE) during Valsalva maneuver and exercise test under fasting condition followed by at-rest re-test PP-TTE 30 to 60 minutes after a standardized midday meal. LV obstruction was noted and classified as being related to systolic anterior motion (SAM) of the mitral valve (SAM-related) and/or non-SAM-related (mid-cavity or apical), and intraventricular gradient was measured. At-rest re-test PP-TTE showed significant intraventricular gradient (>30 mm Hg) in 68 patients (60 SAM-related, 8 non-SAM related, 30 combined) with a higher prevalence (74%) of HC phenotype re-classified as obstructive compared with the fasting Valsalva maneuver (23%) or exercise test (33%) (p < 0.001). At multivariate analysis, a clinical history of PP symptoms and mitral anterior leaflet length and/or LV outflow ratio >2 were independently correlated with PP-TTE obstruction. In conclusion, PP TTE re-test is a simple and effective approach to unmask latent LV dynamic obstruction in daily clinical practice over fasting Valsalva maneuver or exercise test. PP clinical phenotype refinement may be relevant in targeting and evaluating HC therapy.

Dynamic obstruction in hypertrophic cardiomyopathy

PURPOSE OF REVIEW

The present article reviews the recent advances in the echocardiographic assessment of left ventricular outflow tract (LVOT) obstruction in hypertrophic cardiomyopathy (HCM). In particular, it highlights the role of novel imaging techniques in promoting our understanding of the pathophysiology of obstruction and discusses the prognostic value of information obtained from exercise echocardiography and the emerging role of image-guidance technologies for interventional relief of obstruction.

RECENT FINDINGS

The advent of novel echocardiography technologies, such as vector flow mapping, continues to expand our understanding of the exact mechanism of systolic anterior motion leading to dynamic LVOT obstruction by providing new insights into the interaction between pathologic mitral geometry and the left ventricular flow field. New studies provide evidence for the prognostic value of exercise echocardiography in the assessment of patients with HCM. Myocardial contrast perfusion imaging can delineate the anatomy of septal perforator arteries and identify the downstream septal perfusion bed, which is critical for safely guiding the procedure of alcohol septal ablation.

SUMMARY

Echocardiography represents a versatile, continuously evolving, and easily repeatable technique, allowing truly dynamic imaging studies, and is therefore most appropriate to evaluate a dynamic disease condition such as LVOT obstruction in HCM. It provides profound insights into the pathophysiology of LVOT obstruction, information on its clinical impact, and guidance for its relief by interventional strategies.

Relation Between Temperature Extremes and Symptom Exacerbation in Patients With Hypertrophic Cardiomyopathy

Warm temperatures induce peripheral vasodilation, decrease afterload, and may concurrently increase the left ventricular outflow tract (LVOT) gradient. We aimed to assess the impact of subjective ambient temperature on hypertrophic cardiomyopathy (HC) symptoms and determine whether they were associated with LVOT gradient, patient quality of life (QOL), and risk of sudden cardiac death (SCD). We identified consecutive patients with HC presenting to a tertiary referral center. Of the 173 patients in the study, 143 (83%) had HC symptoms, with ambient temperature change worsening symptoms for 72 patients (50%). Symptom exacerbation occurred only with heat for 57 (79%), whereas symptoms were exacerbated with cold only or with cold and heat equally for 15 (21%). Patients affected by any temperature exacerbation more commonly were women (p = 0.009), had a lower QOL (p = 0.04), had a family history of HC (p = 0.007), or underwent myectomy (p = 0.01). A greater proportion of patients with heat-only exacerbation had a family history of HC (p = 0.005) and SCD (p = 0.05). The presence of an LVOT gradient either at rest or with provocation was similar in all groups. In conclusion, although no appreciable difference in LVOT gradients were observed between patient groups, approximately half of the patients with HC reporting symptoms at baseline noted worsening of symptoms with temperature changes, with >75% describing heat-induced symptom exacerbation. Furthermore, affected patients more frequently were women, underwent surgical intervention and device implantation, and had an overall lower QOL.