2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines.

AIM: The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy. METHODS: A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate. STRUCTURE: Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

Hypertrophic cardiomyopathy: a practical approach to guideline directed management.

Hypertrophic cardiomyopathy, one of the most common genetic cardiovascular conditions, will be encountered by nearly every health-care provider regardless of specialty. In 2020, new hypertrophic cardiomyopathy management guidelines were published, updating and evolving preceding versions. This Seminar provides a concise review and practical guide to the updated recommendations for patients with hypertrophic cardiomyopathy.

Natural language processing for identification of hypertrophic cardiomyopathy patients from cardiac magnetic resonance reports.

BACKGROUND: Cardiac magnetic resonance (CMR) imaging is important for diagnosis and risk stratification of hypertrophic cardiomyopathy (HCM) patients. However, collection of information from large numbers of CMR reports by manual review is time-consuming, error-prone and costly. Natural language processing (NLP) is an artificial intelligence method for automated extraction of information from narrative text including text in CMR reports in electronic health records (EHR). Our objective was to assess whether NLP can accurately extract diagnosis of HCM from CMR reports. METHODS: An NLP system with two tiers was developed for information extraction from narrative text in CMR reports; the first tier extracted information regarding HCM diagnosis while the second extracted categorical and numeric concepts for HCM classification. We randomly allocated 200 HCM patients with CMR reports from 2004 to 2018 into training (100 patients with 185 CMR reports) and testing sets (100 patients with 206 reports). RESULTS: NLP algorithms demonstrated very high performance compared to manual annotation. The algorithm to extract HCM diagnosis had accuracy of 0.99. The accuracy for categorical concepts included HCM morphologic subtype 0.99, systolic anterior motion of the mitral valve 0.96, mitral regurgitation 0.93, left ventricular (LV) obstruction 0.94, location of obstruction 0.92, apical pouch 0.98, LV delayed enhancement 0.93, left atrial enlargement 0.99 and right atrial enlargement 0.98. Accuracy for numeric concepts included maximal LV wall thickness 0.96, LV mass 0.99, LV mass index 0.98, LV ejection fraction 0.98 and right ventricular ejection fraction 0.99. CONCLUSIONS: NLP identified and classified HCM from CMR narrative text reports with very high performance.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines.

Aim This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use. Methods A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Structure Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

Conversion of left atrial volume to diameter for automated estimation of sudden cardiac death risk in hypertrophic cardiomyopathy.

BACKGROUND: A subset of patients with hypertrophic cardiomyopathy (HCM) is at high risk of sudden cardiac death (SCD). Practice guidelines endorse use of a risk calculator, which requires entry of left atrial (LA) diameter. However, American Society of Echocardiography (ASE) guidelines recommend the use of LA volume index (LAVI) for routine quantification of LA size. The aims of this study were to (a) develop a model to estimate LA diameter from LAVI and (b) evaluate whether substitution of measured LA diameter by estimated LA diameter derived from LAVI reclassifies HCM-SCD risk. METHODS: The study cohort was comprised of 500 randomly selected HCM patients who underwent transthoracic echocardiography (TTE). LA diameter and LAVI were measured offline using digital clips from TTE. Linear regression models were developed to estimate LA diameter from LAVI. A European Society of Cardiology endorsed equation estimated SCD risk, which was measured using LA diameter and estimated LA diameter derived from LAVI. RESULTS: The mean LAVI was 48.5 ± 18.8 mL/m2 . The derived LA diameter was 45.1 mm (SD: 5.5 mm), similar to the measured LA diameter (45.1 mm, SD: 7.1 mm). Median SCD risk at 5 years estimated by measured LA diameter was 2.22% (interquartile range (IQR): 1.39, 3.56), while median risk calculated by estimated LA diameter was 2.18% (IQR: 1.44, 3.52). 476/500 (95%) patients maintained the same risk classification regardless of whether the measured or estimated LA diameter was used. CONCLUSIONS: Substitution of measured LA diameter by estimated LA diameter in the HCM-SCD calculator did not reclassify risk.

Association of physical activity with all-cause and cardiovascular mortality in 7666 adults with hypertrophic cardiomyopathy (HCM): more physical activity is better.

OBJECTIVES: Recommendations on physical activity (PA) for adults with hypertrophic cardiomyopathy (HCM) are not well established. We investigated the association of PA intensity with mortality in the general adult HCM population. METHODS: A nationwide population-based cohort of individuals with HCM who underwent health check-ups including questionnaires on PA levels were identified from the years 2009 to 2016 in the National Health Insurance Service database. Subjects who reported no PA at baseline were excluded. To estimate each individual's PA level, the PA score (PAS) was calculated based on the self-reported questionnaires, and the study population was categorised into three groups according to tertiles of PAS. The associations of PAS with all-cause and cardiovascular mortality were analysed. RESULTS: A total of 7666 participants (mean age 59.5 years, 29.9% were women) were followed up for a mean 5.3±2.0 years. All-cause and cardiovascular mortality progressively decreased from the lowest to the highest tertiles of PA intensity: 9.1% (4.7%), 8.9% (3.8%) and 6.4% (2.7%), respectively (p-for-trend=0.0144 and 0.0023, respectively). Of note, compared with the middle PA group, the highest PA group did not have an increased risk of all-cause and cardiovascular mortality (HR 0.78, (95% CI 0.63 to 0.95) and HR 0.75 (95% CI 0.54 to 1.03), respectively). All subgroup and sensitivity analyses consistently showed that all-cause and cardiovascular mortality did not increase with higher PA levels. CONCLUSIONS: Moderate-to-vigorous-intensity PA, in a middle-aged population of patients with HCM, was associated with progressive reduction of all-cause and cardiovascular mortality. The impact of vigorous-intensity PA on a younger age group requires further investigation.

Scalability of Telemedicine Services in a Large Integrated Multispecialty Health Care System During COVID-19.

Immediately before the pandemic, 300 enterprise Mayo Clinic physicians and advanced practice providers had performed a minimum of one video telemedicine consult in the preceding year. By July 15, 2020, the number of Mayo Clinic providers performing video telemedicine consults had risen to >6,500, reflecting a 2,000% increase. Through this pandemic, we have witnessed unprecedented growth in telemedicine utilization. The existing telemedicine system has proven to be scalable.

Comparison of expected and observed outcomes for septal myectomy in hypertrophic obstructive cardiomyopathy.

BACKGROUND: Septal myectomy remains the criterion standard for treatment of symptomatic, medically refractory hypertrophic cardiomyopathy (HCM). There is no specific surgical risk calculator for septal myectomy. METHODS: This study compares the outcomes of septal myectomy at a tertiary referral center with predicted outcomes of mitral valve (MV) repair and aortic valve replacement (AVR) using the Society of Thoracic Surgeons Adult Cardiac Surgery Risk Calculator (STS Calculator). A total of 298 consecutive patients with HCM underwent isolated septal myectomy from 2011 to 2014. Observed outcomes of septal myectomy were compared with the STS Calculator predicted risk of isolated MV repair and AVR predicted within this population using 1-sample tests of proportions. RESULTS: Thirty-day mortality for myectomy in this cohort was zero. STS Calculator predicted risk of mortality for MV repair was 0.7% (P = .14) and for AVR = 1.1% (P = .06). Follow-up for vital status was 6.0 ±â€¯0.7 years, at which 294 (98.7%) patients were alive. Hospital stay length was 4.9 ±â€¯1.9 days. One (0.3%) patient experienced a postoperative deep sternal wound infection, and 1 (0.3%) patient experienced a prolonged ventilated state. Postoperative atrial fibrillation occurred in 64 (21.5%) patients. During 30 days of follow-up, no patients experienced stroke, renal failure, or needed dialysis. CONCLUSIONS: Septal myectomy, performed in a tertiary referral center, had a 30-day mortality rate of 0% and low morbidity rate. There was no difference between observed myectomy mortality and STS Calculator predicted risk for AVR and MV repair. It is possible that a larger sample could reveal lower mortality than STS prediction.

International External Validation Study of the 2014 European Society of Cardiology Guidelines on Sudden Cardiac Death Prevention in Hypertrophic Cardiomyopathy (EVIDENCE-HCM).

BACKGROUND: Identification of people with hypertrophic cardiomyopathy (HCM) who are at risk of sudden cardiac death (SCD) and require a prophylactic implantable cardioverter defibrillator is challenging. In 2014, the European Society of Cardiology proposed a new risk stratification method based on a risk prediction model (HCM Risk-SCD) that estimates the 5-year risk of SCD. The aim was to externally validate the 2014 European Society of Cardiology recommendations in a geographically diverse cohort of patients recruited from the United States, Europe, the Middle East, and Asia. METHODS: This was an observational, retrospective, longitudinal cohort study. RESULTS: The cohort consisted of 3703 patients. Seventy three (2%) patients reached the SCD end point within 5 years of follow-up (5-year incidence, 2.4% [95% confidence interval {CI}, 1.9-3.0]). The validation study revealed a calibration slope of 1.02 (95% CI, 0.93-1.12), C-index of 0.70 (95% CI, 0.68-0.72), and D-statistic of 1.17 (95% CI, 1.05-1.29). In a complete case analysis (n= 2147; 44 SCD end points at 5 years), patients with a predicted 5-year risk of <4% (n=1524; 71%) had an observed 5-year SCD incidence of 1.4% (95% CI, 0.8-2.2); patients with a predicted risk of ≥6% (n=297; 14%) had an observed SCD incidence of 8.9% (95% CI, 5.96-13.1) at 5 years. For every 13 (297/23) implantable cardioverter defibrillator implantations in patients with an estimated 5-year SCD risk ≥6%, 1 patient can potentially be saved from SCD. CONCLUSIONS: This study confirms that the HCM Risk-SCD model provides accurate prognostic information that can be used to target implantable cardioverter defibrillator therapy in patients at the highest risk of SCD.

Novel Oral Anticoagulants for Primary Stroke Prevention in Hypertrophic Cardiomyopathy Patients With Atrial Fibrillation.

Background and Purpose- Hypertrophic cardiomyopathy patients with atrial fibrillation are at increased risk of stroke, and anticoagulation is strongly recommended. However, limited data are available regarding the safety and effectiveness of non-vitamin K antagonist oral anticoagulants (NOACs) for primary prevention of stroke. Methods- Using the Korean Health Insurance Review and Assessment Service database, we identified 2397 patients with hypertrophic cardiomyopathy and nonvalvular atrial fibrillation on oral anticoagulation from 2013 to 2016 without history of ischemic stroke, intracranial hemorrhage (ICH), or gastrointestinal bleeding (992 on warfarin and 1405 on NOACs). Inverse probability of treatment weighting with propensity scores was used to balance covariates between treatment groups. Risk for ischemic stroke, ICH, gastrointestinal bleeding, death, and their composite outcome associated with NOAC use was assessed with warfarin use as the reference. Results- During a mean follow-up of 1.6 years, the incidence rates of ischemic stroke, ICH, gastrointestinal bleeding, death, and composite outcome were all significantly lower in the NOAC than in the warfarin group (stroke, 2.8 versus 5.0; ICH, 0.5 versus 1.3; gastrointestinal bleeding, 2.3 versus 3.0; death, 3.0 versus 5.1; composite, 7.5 versus 12.5 events per 100 person-years). NOACs were associated with significantly lower risks of ischemic stroke (hazard ratio [HR], 0.47; 95% CI, 0.32-0.68), ICH (HR, 0.31; 95% CI, 0.14-0.69), gastrointestinal bleeding (HR, 0.62; 95% CI, 0.40-0.96), death (HR, 0.45; 95% CI, 0.31-0.65), and the composite outcome (HR, 0.48; 95% CI, 0.38-0.61) than warfarin. The same trend was observed regardless of the NOAC dose and across various high-risk subgroups. In analysis of individual NOACs, all NOACs were associated with lower risks of ischemic stroke and composite outcome. Conclusions- NOACs showed superior effectiveness and safety versus warfarin in the primary prevention of stroke versus warfarin in real-world Asian hypertrophic cardiomyopathy with atrial fibrillation.

QT prolongation and sudden cardiac death risk in hypertrophic cardiomyopathy.

INTRODUCTION: Risk assessment for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) remains complex. The goal of this study was to assess electrocardiogram (ECG)-derived risk factors on SCD in a large HCM population Methods: Retrospective review of adults with HCM evaluated at Mayo Clinic, Rochester, MN from 1 December 2002 to 31 December 2012 was performed. Data inclusive of ECG and 24-hour ambulatory Holter monitor were assessed. SCD events were documented by ventricular fibrillation (VF) noted on implantable cardioverter defibrillator (ICD), or appropriate VT or VF-terminating ICD shock. RESULTS: Overall, 1615 patients (mean age 53.7 ± 15.2 years; 943 males, 58.4%) were assessed, with mean follow-up 2.46 years and 110 SCD events. Via logistic regression (n = 820), the odds of SCD increased with increasing number of conventional risk factors. With one risk factor the OR was 4.88 (p < .0001; CI 2.22-10.74), two risk factors the OR was 6.922 (p < .0001; CI 2.94-16.28) and three or more risk factors, the OR was 13.997 (p < .0001; CI 5.649-34.68). Adding QTc > 450 to this logistic regression model had OR 1.722 (p = .04, CI 1.01-2.937) to predict SCD. QTc ≥ 450 was a significant predictor for death (HR 1.88, p = .021, CI 1.10-3.20). There was no correlation between sinus bradycardia, sinus tachycardia, first degree AV block, atrial fibrillation, left bundle branch block, right bundle branch block, premature atrial complexes, premature ventricular complexes, supraventricular tachycardia, PR interval, QRS interval and SCD. CONCLUSIONS: Prolonged QTc was a risk factor for SCD and death even when controlling for typical risk factors.

Women with hypertrophic cardiomyopathy have worse survival.

AIMS: Sex differences in hypertrophic cardiomyopathy (HCM) remain unclear. We sought to characterize sex differences in a large HCM referral centre population. METHODS AND RESULTS: Three thousand six hundred and seventy-three adult patients with HCM underwent evaluation between January 1975 and September 2012 with 1661 (45.2%) female. Kaplan-Meier survival curves were assessed via log-rank test. Cox proportional hazard regression analyses evaluated the relation of sex with survival. At index visit, women were older (59 ± 16 vs. 52 ± 15 years, P < 0.0001) had more symptoms [New York Heart Association (NYHA) Class III-IV 45.0% vs. 35.3%, P < 0.0001], more obstructive physiology (77.4% vs. 71.8%, P = 0.0001), more mitral regurgitation (moderate or greater in 56.1% vs. 43.9%, P < 0.0001), higher E/e' ratio (n = 1649, 20.6 vs. 15.6, P < 0.0001), higher estimated pulmonary artery systolic pressure (n = 1783, 40.8 ± 15.4 vs. 34.8 ± 10.8 mmHg, P < 0.0001), worse cardiopulmonary exercise performance (n = 1267; percent VO2 predicted 62.8 ± 20% vs. 65.8 ± 19.2%, P = 0.007), and underwent more frequent alcohol septal ablation (4.9% vs. 3.0%, P = 0.004) but similar frequency of myectomy (28% vs. 30%, P = 0.24). Median follow-up was 10.9 (IQR 7.4-16.2) years. Kaplan-Meier analysis demonstrated lower survival in women compared with men (P < 0.0001). In multivariable modelling, female sex remained independently associated with mortality (HR 1.13 [1.03-1.22], P = 0.01) when adjusted for age, NYHA Class III-IV symptoms, and cardiovascular comorbidities. CONCLUSION: Women with HCM present at more advanced age, with more symptoms, worse cardiopulmonary exercise tolerance, and different haemodynamics than men. Sex is an important determinant in HCM management as women with HCM have worse survival. Women may require more aggressive diagnostic and therapeutic approaches.

Prevalence and Impact of Coexistent Bicuspid Aortic Valve in Hypertrophic Cardiomyopathy.

BACKGROUND: The association between bicuspid aortic valve (BAV) and hypertrophic cardiomyopathy (HCM) has been reported but its true prevalence is unknown. This study investigated the prevalence and clinical impact of coexistent BAV in a large referral HCM population. METHODS: Retrospective analysis of 3765 echocardiograms between 2004 and 2014 in 2640 consecutive patients with HCM was performed to assess for BAV. Patients with coexistent conditions were studied. RESULTS: Twenty-three patients (0.9%) were identified with coexisting BAV and HCM. Mean age was 52±16years, 18 males (78%), 16 with NYHA functional class I/II at initial evaluation (70%). A family history of HCM was present in five patients (22%); none had a family history of BAV or aortopathy. Maximal left ventricular wall thickness was 24±6mm; the majority had either reverse curve or sigmoid septal morphology. Moderate or greater aortic valve dysfunction was present in seven patients (30%), BAV-related aortopathy in 18 patients (78%) and dynamic left ventricular outflow tract (LVOT) obstruction in nine patients (39%). Three patients had combined LVOT obstruction and aortic stenosis. Median time from diagnosis of BAV or HCM to last follow-up was 11±12.5years. At last follow-up, 22% had undergone BAV-related surgeries, 30% had septal reduction therapy (SRT), and 17% had combined SRT and BAV-related surgeries. Overall survival was 95% at 10 years. CONCLUSIONS: This study reported a 0.9% prevalence of BAV among HCM population, similar to the general population. Aortopathy and LVOT obstruction were common, necessitating cardiac interventions in over one-third of cases. Long-term survival appeared favourable.

Hemodynamic changes in systolic and diastolic function during isoproterenol challenge predicts symptomatic response to myectomy in hypertrophic cardiomyopathy with labile obstruction.

OBJECTIVES: We aimed to assess the utility of changes in systolic and diastolic function by isoproterenol challenge in predicting symptom resolution post-myectomy in selected patients with hypertrophic cardiomyopathy (HCM) and labile obstruction. BACKGROUND: In a subset of symptomatic HCM patients without resting/provocable obstruction on noninvasive assessment, isoproterenol challenge during hemodynamic catheterization may elicit labile left ventricular outflow tract (LVOT) obstruction, and demonstrate the effect of obstruction on diastolic function. These changes may determine whether patients achieve complete symptom resolution post-myectomy. METHODS: Between February 2003 and April 2009, 18 symptomatic HCM patients without LVOT obstruction on noninvasive testing underwent isoproterenol provocation and septal myectomy due to presence of provocable gradient and were followed for 4 (IQR 3-7) years. RESULTS: Thirteen (72.2%) had complete symptom resolution, while 5 (27.8%) had improved, but persistent symptoms. Those with provoked gradient >100 mm Hg or increase in left atrial pressure (LAP) with isoproterenol had symptom resolution. CONCLUSIONS: Symptomatic HCM patients without LVOT gradient on noninvasive testing may demonstrate labile obstruction with isoproterenol. With isoproterenol, patients with high LVOT gradient or increase in LAP concomitant with an increase in gradient achieved complete symptom resolution post-myectomy. Thus, improved diastolic filling as well as outflow gradient production in patients with HCM may predict symptom response to myectomy. © 2016 Wiley Periodicals, Inc.

Gain-of-function RAF1 mutations cause Noonan and LEOPARD syndromes with hypertrophic cardiomyopathy.

Noonan and LEOPARD syndromes are developmental disorders with overlapping features, including cardiac abnormalities, short stature and facial dysmorphia. Increased RAS signaling owing to PTPN11, SOS1 and KRAS mutations causes approximately 60% of Noonan syndrome cases, and PTPN11 mutations cause 90% of LEOPARD syndrome cases. Here, we report that 18 of 231 individuals with Noonan syndrome without known mutations (corresponding to 3% of all affected individuals) and two of six individuals with LEOPARD syndrome without PTPN11 mutations have missense mutations in RAF1, which encodes a serine-threonine kinase that activates MEK1 and MEK2. Most mutations altered a motif flanking Ser259, a residue critical for autoinhibition of RAF1 through 14-3-3 binding. Of 19 subjects with a RAF1 mutation in two hotspots, 18 (or 95%) showed hypertrophic cardiomyopathy (HCM), compared with the 18% prevalence of HCM among individuals with Noonan syndrome in general. Ectopically expressed RAF1 mutants from the two HCM hotspots had increased kinase activity and enhanced ERK activation, whereas non-HCM-associated mutants were kinase impaired. Our findings further implicate increased RAS signaling in pathological cardiomyocyte hypertrophy.

Role of imaging in evaluation of sudden cardiac death risk in hypertrophic cardiomyopathy.

PURPOSE OF REVIEW: Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiomyopathy and is associated with sudden cardiac death (SCD) - an uncommon but devastating clinical outcome. This review is designed to assess the role of imaging in established risk factor assessment and its role in emerging SCD risk stratification. RECENT FINDINGS: Recent publications have highlighted the crucial role of imaging in HCM SCD risk stratification. Left ventricular hypertrophy assessment remains the key imaging determinant of risk. Data continue to emerge on the role of systolic dysfunction, apical aneurysms, left atrial enlargement and left ventricular outflow tract obstruction as markers of risk. Quantitative assessment of delayed myocardial enhancement and T1 mapping on cardiac MRI continue to evolve. SUMMARY: Recent multicenter trials have allowed multivariate SCD risk assessment in large HCM cohorts. Given aggregate risk with presence of multiple risk factors, a single parameter should not be used in isolation to determine implantable cardiac defibrillator candidacy. Use of all available imaging data, including cardiac magnetic resonance tissue characterization, allows a comprehensive approach to SCD stratification and implantable cardiac defibrillator decision-making.

Postprandial Hemodynamics in Hypertrophic Cardiomyopathy.

OBJECTIVES: Prior analysis at our institution found that patients with hypertrophic cardiomyopathy (HCM) who experience postprandial symptoms (PPS) are more likely to have resting left ventricular outflow tract (LVOT) obstruction and reduced quality of life. Our objective was to determine whether PPS in patients with HCM vs healthy subjects occur as a result of measurable hemodynamic alterations in the postprandial hemodynamic response. METHODS: We conducted a prospective cross-sectional study examining 45 patients with HCM and 10 controls who underwent fasting and postprandial 2-dimensional Doppler echocardiography. Postprandial echocardiographic measurements were obtained at symptom onset or 30 minutes after consumption of a standardized meal, whichever occurred first. RESULTS: The HCM population included 18 (40%) patients with PPS and 27 (60%) without PPS. Compared to controls, mean resting peak LVOT gradient was 23.4 ± 17.6 mmHg in HCM patients with PPS and 25.1 ± 33.1 mmHg in those without PPS (P = 0.10). The mean change in peak LVOT gradient after a meal was 0.7 ± 1.1 mmHg for controls, 5.0 ± 8.3 mmHg for HCM patients with PPS, and 1.5 ± 18.2 mmHg for HCM patients without PPS (P = 0.64). CONCLUSION: Although the ability to provoke an increased LVOT gradient with a postprandial, upright exercise study protocol was recently reported, the current study suggests that a resting, supine, postprandial protocol does not elicit evidence of LVOT obstruction. Therefore, future investigations should consider whether simply performing an upright postprandial study in HCM patients with PPS will provide evidence of dynamic LVOT or if the addition of an exercise component is necessary.