Right heart catheterization predictors of symptomatic improvement in patients undergoing transcatheter tricuspid valve edge-to-edge repair.

BACKGROUND: Transcatheter tricuspid valve edge-to-edge repair (TTEER) is associated with improvement in outcomes for symptomatic patients with severe tricuspid regurgitation (TR). However, reliable predictors for clinical success are not yet fully defined. This study aims to describe right heart catheterization (RHC) findings in patients referred for TTEER and identify hemodynamic characteristics of patients who experience immediate symptomatic improvement following successful TR intervention. METHODS: Patients who underwent TTEER and had a separate RHC within the preceding 6 months were included. Hemodynamic tracings from the RHC and TTEER procedures were reviewed and recorded. Clinical success was defined as a successful device implant with at least 1-grade of TR reduction and improvement in NYHA class by 1 or more grades on 30-day echocardiogram and clinical follow-up. RESULTS: Thirteen patients underwent an RHC within 6 months of TTEER procedure (median age 76 years [IQR: 73-80]). All patients were on a stable dose of loop diuretics. Baseline right atrial pressure was severely elevated (mean 19 mmHg [IQR: 9-24 mmHg]) with prominent CV waves. Median pulmonary capillary wedge pressure (PCWP) was 20 mmHg (IQR: 14-22) and 70% of patients had a mean PCWP > 15 mmHg at rest. Median PCWP CV-wave was 34 mmHg (IQR: 23-42). Higher PCWP CV-wave height (40 mmHg [IQR 33-43] versus 18 mmHg [IQR 17-31]) was associated with lower likelihood of clinical success (OR 0.83, 95% CI: 0.35-0.97, p = 0.04). CONCLUSIONS: Inclusion of invasive hemodynamics as part of pre-TTEER evaluation may allow for improved TR phenotyping and patient selection. Patients with a large left atrial CV wave on resting RHC were less likely to experience immediate symptomatic improvement despite procedural success with TTEER.

2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: 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 valvular heart disease guideline provides recommendations for clinicians to diagnose and manage valvular heart disease as well as supporting documentation to encourage their use. METHODS: A comprehensive literature search was conducted from January 1, 2010, to March 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, Cochrane, Agency for Healthcare Research and Quality Reports, and other selected database relevant to this guideline. Structure: Many recommendations from the earlier valvular heart disease guidelines have been updated with new evidence and provides newer options for diagnosis and treatment of valvular heart disease. This summary includes only the recommendations from the full guideline which focus on diagnostic work-up, the timing and choice of surgical and catheter interventions, and recommendations for medical therapy. The reader is referred to the full guideline for graphical flow charts, text, and tables with additional details about the rationale for and implementation of each recommendation, and the evidence tables detailing the data considered in developing these guidelines.

Atrial mitral regurgitation: Characteristics and outcomes of transcatheter mitral valve edge-to-edge repair.

BACKGROUND: Mitral transcatheter edge-to-edge repair (MTEER) is an established therapeutic approach for mitral regurgitation (MR). Functional mitral regurgitation originating from atrial myopathy (A-FMR) has been described. OBJECTIVES: We sought to assess the clinical, echocardiographic and hemodynamic considerations in A-FMR patients undergoing MTEER. METHODS: From 2014 to 2020, patients undergoing MTEER for degenerative MR (DMR), functional MR (FMR), and mixed MR were assessed. A-FMR was defined by the presence of MR > moderate in severity; left ventricular (LV) ejection fraction (LVEF) ≥ 50%; and severe left atrial (LA) enlargement in the absence of LV dysfunction, leaflet pathology, or LV tethering. The diagnosis of A-FMR (vs. ventricular-FMR [V-FMR]) was confirmed by three independent echocardiographers. Baseline characteristics, procedural outcomes as well as clinical and echocardiographic follow-up are reported. Device success was defined as final MR grade ≤ moderate; MR reduction ≥1 grade; and final transmitral gradient <5 mmHg. RESULTS: 306 patients underwent MTEER, including DMR (62%), FMR (19%), and mixed MR (19%). FMR cases included 37 (63.8%) V-FMR and 21 (36.2%) A-FMR. Tricuspid regurgitation (≥ moderate) was higher in A-FMR (80.1%) compared to V-FMR (54%) and DMR (42%). Device success did not significantly differ between A-FMR and V-FMR (57% vs. 73%, p = 0.34) or DMR (57% vs. 64%, p = 1.0). The A-FMR cohort was less likely to achieve ≥3 grades of MR reduction compared to V-FMR (19% vs. 54%, p = 0.01) and DMR (19% vs. 49.7%, p = 0.01). Patients with V-FMR and DMR demonstrated significant reductions in mean left atrial pressure (LAP) and peak LA V-wave, though A-FMR did not (LAP -0.24 ± 4.9, p = 0.83; peak V-wave -1.76 ± 9.1, p = 0.39). In follow-up, echocardiographic and clinical outcomes were similar. CONCLUSIONS: In patients undergoing MTEER, A-FMR represents one-third of FMR cases. A-FMR demonstrates similar procedural success but blunted acute hemodynamic responses compared with DMR and V-FMR following MTEER. Dedicated studies specifically considering A-FMR are needed to discern the optimal therapeutic approaches.

Diastolic blood pressure predicts outcomes after aortic paravalvular leak closure.

OBJECTIVES: We sought to determine hemodynamic effects of aortic paravalvular leak (PVL) and predictors of clinical outcomes after aortic PVL closure. BACKGROUND: The significance of hemodynamic alterations in PVL and relation to severity, procedural success of percutaneous closure and clinical outcomes have not been defined. METHODS: Patients undergoing percutaneous PVL closure between July 21, 2004 and September 10, 2018 were included. PVL severity was assessed by echocardiography and aortic angiography. Hemodynamics were assessed by intra-arterial pressure tracings before and after PVL closure. The primary outcome was a composite of mortality, redo aortic valve replacement (AVR) and redo PVL closure. RESULTS: One hundred and seventeen patients (mean age 70.3 ± 14.9 years, 79% surgical and 21% transcatheter prostheses) underwent PVL closure with 94% technical success. PVL was moderate or greater in 106 (91%) at baseline and 11 (11%) post-procedure. Diastolic BP for those with moderate or greater PVL was lower than for those with less PVL (50.3 ± 11.7 vs. 56.5 ± 12.4 mmHg, p < .001). Pulse pressure was similar between these groups (69.9 ± 20.3 vs. 67.4 ± 21.2 mmHg, p = .39). 35 patients (34%) had 40 events during a mean follow-up of 1.6 ± 1.9 years (23 deaths, 12 redo AVR, and five redo PVL closures). In a multivariate model, final diastolic BP <47 mmHg (HR 3.27 [1.45-7.36], p = .007) was a significant predictor of the composite endpoint. CONCLUSIONS: Diastolic BP was significantly associated with aortic PVL severity and clinical outcomes after PVL closure. In contrast, pulse pressure did not correlate with PVL severity or outcomes. These findings have implications for clinical management of patients with aortic PVL.

An unusual presentation of dyspnea following septal ablation for obstructive hypertrophic cardiomyopathy.

Residual or recurrent symptoms after septal reduction therapy are most often related to inadequate relief of left ventricular outflow gradients. We recently encountered a 71-year-old woman with hypertrophic cardiomyopathy and prior alcohol septal ablation who had a unique constellation of findings causing her symptoms. She was found to have four potential causes for her symptoms, residual midventricular obstruction, apical distribution of hypertrophy reducing end-diastolic volume, constrictive pericarditis, and marked arterial stiffness, as reflected by aortic atherosclerosis. She underwent complete pericardiectomy, transaortic septal myectomy, transapical myectomy, and replacement of a heavily calcified ascending aorta.

Aortic stenosis and the pulse contour: A true marker of severity?

The aortic pulse contour displays characteristic changes associated with the progression of aortic stenosis (AS). A diminished and delayed aortic pulse contour is indicative of significant AS, but the aortic contour may also be affected by factors including aging, hypertension and increased peripheral arterial elastance. This review describes the components of the aortic pulse contour in AS and how it can be affected by different conditions and interventions.

Alcohol septal ablation in patients with concomitant hypertrophic cardiomyopathy and aortic valvular stenosis.

OBJECTIVE: To describe the hemodynamic and early clinical outcomes of percutaneous alcohol septal ablation in patients with concomitant dynamic left ventricular outflow tract (LVOT) obstruction and aortic valvular stenosis (AS). BACKGROUND: Alcohol septal ablation is an established method to relieve dynamic LVOT obstruction in patients with hypertrophic cardiomyopathy (HCM). However, the feasibility, safety, and efficacy of alcohol septal ablation in patients with serial obstructions from HCM and AS remain unclear. METHODS: In this case series, we describe the early outcomes of alcohol septal ablation in six patients with significant dynamic LVOT obstruction and AS. All patients had evidence of severe dynamic LVOT obstruction (resting or provoked gradient ≥50 mmHg), mild to severe AS, and NYHA class III symptoms or greater. RESULTS: Four (66.7%) patients had septal ablation performed in the setting of concomitant native valvular AS and two (33.3%) patients had TAVR performed prior to septal ablation. Successful alcohol septal ablation was performed in all patients and was associated with an immediate reduction of the dynamic LVOT gradient with a residual fixed obstruction related to AS. Four (66.7%) patients had follow-up at 1 month and of these, three (75%) had NYHA Class I-II symptoms and one (25%) Class III. CONCLUSIONS: Alcohol septal ablation is a feasible method of relieving dynamic LVOT obstruction in patients with concomitant HCM and AS. Further study is required to determine the optimal treatment approach in these patients.

Hypertrophic Obstructive Cardiomyopathy: Surgical Myectomy and Septal Ablation.

Hypertrophic cardiomyopathy is a genetic disorder characterized by marked hypertrophy of the myocardium. It is frequently accompanied by dynamic left ventricular outflow tract obstruction and symptoms of dyspnea, angina, and syncope. The initial therapy for symptomatic patients with obstruction is medical therapy with ß-blockers and calcium antagonists. However, there remain a subset of patients who have continued severe symptoms, which are unresponsive to medical therapy. These patients can be treated with septal reduction therapy, either surgical septal myectomy or alcohol septal ablation. When performed by experienced operators working in high-volume centers, septal myectomy is highly effective with a >90% relief of obstruction and improvement in symptoms. The perioperative mortality rate for isolated septal myectomy in most centers is <1%. Alcohol septal ablation is a less invasive treatment. In many patients, the hemodynamic and clinical results are comparable to that of septal myectomy. However, the results of alcohol septal ablation are dependent on the septal perforator artery supplying the area of the contact between the hypertrophied septum and the anterior leaflet of the mitral valve. There are some patients, particularly younger patients with severe hypertrophy, who do not uniformly experience complete relief of obstruction and symptoms. Both techniques of septal reduction therapy are highly operator dependent. The final decision as to which approach should be selected in any given patient is dependent up patient preference and the availability and experience of the operator and institution at which the patient is being treated.

Transcatheter aortic valve replacement for stenotic bicuspid aortic valves: Systematic review and meta analyses of observational studies.

OBJECTIVE: The aim of this study was to perform a systematic review and meta-analyses of observational studies of transcatheter aortic valve replacement (TAVR) for bicuspid aortic valve stenosis (BcAV). BACKGROUND: TAVR for BcAV stenosis has been associated with an increased incidence of paravalvular leaks, valve malposition, pacemaker placement and all-cause mortality. The conclusions drawn have been limited by small sample sizes. The use of TAVR for BcAV stenosis remains controversial. METHODS: We searched multiple databases from the inception of the databases through September 30, 2016 for studies of TAVR for BcAV stenosis. We included all observational studies with more than one patient and at least 1 month of outcomes. RESULTS: We analyzed 13 observational studies with 758 patients. Meta analyses showed device success rate of 95% [95% confidence interval (CI) 90.2% to 98.5%] and an early safety event in 16.9% [95% CI 12.2% to 22%]. At 30 days, moderate to severe paravalvular leak was seen in 12.2% [95% CI 3.1% to 24.8%] and new pacemaker implantation in 17.9% [95% CI 14.2% to 22%]. All-cause mortality was 3.7% [95% CI 2.1% to 5.6%], which should be viewed in the context of an STS PROM of 5.0%. CONCLUSIONS: This analysis suggests that TAVR for BcAV is not associated with excess mortality. The incidence of paravalvular leaks and pacemaker implant is increased compared to tricuspid aortic valve cohorts undergoing TAVR, and operators should weigh these potential complications against the clinical benefit provided by TAVR for BcAV patients at high risk for surgical valve replacement.

Cardiac resynchronization therapy in patients with end-stage hypertrophic cardiomyopathy.

Aims: A dilated/end-stage phase of hypertrophic cardiomyopathy (HCM) is rare but well-recognized. The role for cardiac resynchronization therapy (CRT) in this subset of patients remains unexplored. We aimed to clarify the impact of bi-ventricular pacing CRT in dilated/end-stage HCM. Methods and results: The Mayo Clinic HCM database was interrogated to identify patients with ejection fraction (EF) <50% and CRT. Control subjects were identified in 1:1 manner. Clinical outcomes were determined. Of 2073 patients with HCM, 9 (8 male) had EF <50% and received CRT. The average age at CRT-D implant was 44.8 ± 14.8 years, an average of 17.3 ± 10.3 years after HCM diagnosis. The indication for CRT was based on New York Heart Association class ≥II symptoms (mean 2.7 ± 0.4) and EF <50% in all patients (EF 34.7 ± 7.1% at implant), with electrocardiographic evidence of abnormal ventricular conduction. At 6-month, 12-month, and long-term follow-up, EF was 39.9 ± 8.4%, 37.9 ± 9.8%, and 33.3 ± 7.6%, respectively (P > 0.05 for all). There was no difference in the combined end-point of left ventricular assist device (LVAD), cardiac transplant, or death between groups (P = 0.90). At last follow-up [mean duration 12.9 ± 8.3 (median 10.7) years], 8 (89%) in the CRT group were alive. Three and 2 patients underwent LVAD implantation and cardiac heart transplantation, respectively, 15.0 ± 10.1 years from HCM diagnosis and 2.6 ± 0.9 years from CRT implant. In the control group, 4 (44.4%) patients were alive at last follow-up [mean duration 12.0 ± 7.1 (median 12.7) years]. One patient each had LVAD and cardiac transplant. Conclusions: CRT in patients with dilated/end-stage HCM does not appear to confer a salutary effect on ventricular function. In medium-term follow-up, however, left ventricular function did not appear to deteriorate further, yet advanced heart failure therapy was common in this group.

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.

Surgery for Aortic Dilatation in Patients With Bicuspid Aortic Valves: A Statement of Clarification From the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines.

Two guidelines from the American College of Cardiology (ACC), the American Heart Association (AHA), and collaborating societies address the risk of aortic dissection in patients with bicuspid aortic valves and severe aortic enlargement: the "2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Diagnosis and Management of Patients With Thoracic Aortic Disease" (Circulation. 2010;121:e266-e369) and the "2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease" (Circulation. 2014;129:e521-e643). However, the 2 guidelines differ with regard to the recommended threshold of aortic root or ascending aortic dilatation that would justify surgical intervention in patients with bicuspid aortic valves. The ACC and AHA therefore convened a subcommittee representing members of the 2 guideline writing committees to review the evidence, reach consensus, and draft a statement of clarification for both guidelines. This statement of clarification uses the ACC/AHA revised structure for delineating the Class of Recommendation and Level of Evidence to provide recommendations that replace those contained in Section 9.2.2.1 of the thoracic aortic disease guideline and Section 5.1.3 of the valvular heart disease guideline.

Mitral valve disease--current management and future challenges.

The field of mitral valve disease diagnosis and management is rapidly changing. New understanding of disease pathology and progression, with improvements in and increased use of sophisticated imaging modalities, have led to early diagnosis and complex treatment. In primary mitral regurgitation, surgical repair is the standard of care. Treatment of asymptomatic patients with severe mitral regurgitation in valve reference centres, in which successful repair is more than 95% and surgical mortality is less than 1%, should be the expectation for the next 5 years. Transcatheter mitral valve repair with a MitraClip device is also producing good outcomes in patients with primary mitral regurgitation who are at high surgical risk. Findings from clinical trials of MitraClip versus surgery in patients of intermediate surgical risk are expected to be initiated in the next few years. In patients with secondary mitral regurgitation, mainly a disease of the left ventricle, the vision for the next 5 years is not nearly as clear. Outcomes from ongoing clinical trials will greatly inform this field. Use of transcatheter techniques, both repair and replacement, is expected to substantially expand. Mitral annular calcification is an increasing problem in elderly people, causing both mitral stenosis and regurgitation which are difficult to treat. There is anecdotal experience with use of transcatheter valves by either a catheter-based approach or as a hybrid technique with open surgery, which is being studied in early feasibility trials.

Acute invasive hemodynamic effects of percutaneous mitral paravalvular leak closure.

OBJECTIVES: The aim of this study was to demonstrate the physiologic effects of percutaneous mitral paravalvular leak (PVL) closure through pre- and post-closure left and right heart catheterization. BACKGROUND: Mitral PVL represents a significant source of morbidity and mortality following mitral valve repair and replacement. Although percutaneous PVL closure is an effective treatment with improvements in symptoms and mortality, data regarding the acute hemodynamic effects of such closure are lacking. METHODS: Consecutive patients with clinically significant heart failure and/or hemolysis attributed to mitral PVL underwent percutaneous mitral PVL closure with pre- and post-procedural right and left heart catheterization. Hemodynamic measurements of cardiovascular function obtained in this manner were compared and stratified according to pre- and post-procedural echocardiographic severity of PVL. RESULTS: Twenty-four patients (age 68 ± 9.4 years, 75% male) underwent percutaneous mitral PVL closure. Significant improvements were found in left atrial pressure (LAP) (mean LAP lowered from 21 ± 4 to 19 ± 3 mm Hg, P = 0.005), pulmonary artery pressure (PAP) (mean PAP lowered from 36 ± 11 to 33 ± 9, P = 0.04), and cardiac index (increased from 2.8 ± 0.8 to 3.0 ± 0.7 L/min/m2 , P = 0.01). Left atrial v-wave reduction of 20% was associated with ≤ mild residual PVL by transesophageal echocardiography (P = 0.09). CONCLUSIONS: Percutaneous mitral PVL closure is associated with significant reductions in LAP and PAP and an increase in cardiac index. These hemodynamic effects underlie the clinical benefits of PVL closure and may be a useful tool for intraprocedural guidance. © 2017 Wiley Periodicals, Inc.

Grade I diastolic dysfunction and elevated left ventricular end-diastolic pressure: Mitral Doppler inflow, pulmonary vein atrial reversal, and the M-mode mitral B-bump.

Grade I diastolic dysfunction (DD) is generally associated with a normal mean left atrial pressure (LAP) and normal left ventricular end-diastolic pressure (LVEDP). The first hemodynamic alteration seen in DD, however, is the development of an elevated LVEDP with a persistent normal LAP. This is manifested by echocardiography as a continued mitral pulsed wave (PW) E/A <0.8 (Grade I DD), but with evidence of an elevated LVEDP. Such findings include alterations in PV flow, mitral PW inflow response to Valsalva maneuver, and also the presence of a B-bump on the mitral M-mode tracing. When assessing diastolic function, it may be clinically helpful to assess for this early hemodynamic manifestation of DD.

Robotic Mitral Valve Repair for Simple and Complex Degenerative Disease: Midterm Clinical and Echocardiographic Quality Outcomes.

BACKGROUND: Severe primary (degenerative) mitral regurgitation (MR) is repaired with durable results when simple single-scallop disease is addressed. The midterm quality outcomes of minimally invasive repair for complex disease are unknown, however. METHODS AND RESULTS: From January 2008 to January 2015, 487 patients (56±11 years, 360 men, ejection fraction 65±6%, 98.8% complete follow-up) underwent robotic mitral valve repair for severe nonischemic degenerative MR. Simple pathology was addressed in 289 of 487 (59%) patients, and complex repair (all others) was performed in 198 of 487 (41%). Four patients died during follow-up with a 5-year survival rate 99.5% (99.4% simple; 99.5% complex; hazard ratio, 0.48; 95% confidence interval, 0.05-4.59); and New York Heart Association functional class I/II was documented in 97.9% (477/487). Eight patients had recurrence of moderate-to-severe MR (4 simple, 4 complex), with a 5-year freedom from MR of 94.6% (96.2% simple; 92.7%, complex; P=0.67; hazard ratio, 1.36; 95% confidence interval, 0.34-5.43). Seven patients (2 simple, 5 complex), underwent mitral reoperation, with a 5-year freedom from reoperation of 97.7% (99.1% simple; 95.7% complex; P=0.13; hazard ratio, 3.35; 95% confidence interval, 0.65-17.32). CONCLUSIONS: At a large tertiary care referral center, midterm quality outcomes after robotic correction of degenerative MR are excellent, with very high survival, infrequent complications, and a low likelihood of MR recurrence, regardless of mitral valve repair complexity. Awareness of these improvements in outcome is important to inform contemporary decisions regarding high-quality alternatives to conventional and percutaneous mitral repair.

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.