Survival After Myectomy for Obstructive Hypertrophic Cardiomyopathy: What Causes Late Mortality?

Sex-Associated Differences in Clinical Outcomes After Septal Reduction Therapies in Hypertrophic Cardiomyopathy

OBJECTIVE

To evaluate sex-associated differences in the short- and long-term outcomes of patients with hypertrophic cardiomyopathy (HCM) undergoing septal myectomy and alcohol septal ablation.

METHODS

This retrospective cohort study used electronic health record data from the TriNetX research database. International Classification of Diseases, Ninth Revision and Tenth Revision diagnosis and procedure codes were used to identify patients with HCM who underwent septal myectomy and alcohol septal ablation in the United States between January 2002 and March 2023. The outcomes were long-term mortality and postprocedural complications (<30 days), including death, stroke, major bleeding, and renal failure. Multivariable adjusted Cox models were used to assess the association of outcomes by sex, taking female patients as reference.

RESULTS

Of 11,680 adults (32.0% female; median age, 63 [interquartile range, 54 to 71] years), 1916 (16.4%) and 9764 (83.6%) underwent septal myectomy and alcohol septal ablation, respectively. For those who underwent septal myectomy, sex was not associated with short-term (adjusted hazard ratio [HRadj], 1.57 [0.64 to 3.87]) and long-term (HRadj, 1.05 [0.87 to 1.26]) mortality. Male patients had a higher risk of acute renal failure compared with female patients after septal myectomy (HRadj, 1.69 [1.33 to 2.15]). Of those who underwent alcohol septal ablation, male patients (HRadj, 1.07 [0.99 to 1.16]) had a similar risk of long-term mortality to that of female patients. Compared with female patients, the risk of acute renal failure was higher in male patients (HRadj, 1.23 [1.02 to 1.48]) after alcohol septal ablation.

CONCLUSION

This nationwide study found that the risk of short- and long-term mortality was similar for male and female patients undergoing septal myectomy and alcohol septal ablation for HCM. The sex-based differences in the clinical presentation should not prevent consideration of septal reduction therapies.

Impact of coronary artery disease in patients with hypertrophic cardiomyopathy

BACKGROUND

Atherosclerotic coronary artery disease (CAD) often occurs concurrently with hypertrophic cardiomyopathy (HCM). However, the influence of concomitant CAD has not been fully assessed in patients with HCM.

METHODS

Invasive or computed tomography coronary angiography was performed in 461 patients with HCM at our hospital to determine the presence and severity of CAD from March 2010 to April 2022. The primary end points were all-cause, cardiovascular, and sudden cardiac deaths. The survival of HCM patients with severe CAD was compared with that of HCM patients without severe CAD.

RESULTS

Of 461 patients with HCM, 235 had concomitant CAD. During the median (interquartile range) follow-up of 49 (31-80) months, 75 patients (16.3%) died. The 5-year survival estimates were 64.3%, 82.5%, and 86.0% for the severe, mild-to-moderate, and no-CAD groups, respectively (log-rank, p = 0.010). Regarding the absence of cardiovascular death, the 5-year survival estimates were 68.5% for patients with severe CAD, 86.4% for patients with mild-to-moderate CAD, and 90.2% for HCM patients with no CAD (log-rank, p = 0.001). In multivariate analyses, severe CAD was associated with all-cause and cardiovascular death after adjusting for age, left ventricular ejection fraction, hypertension, and atrial fibrillation.

CONCLUSIONS

This study showed a worse prognosis among HCM patients with severe CAD than among HCM patients without severe CAD. Therefore, timely recognition of severe CAD in HCM patients and appropriate treatment are important.

Contemporary Surgical Management of Hypertrophic Cardiomyopathy

More than half of symptomatic patients with hypertrophic cardiomyopathy (HCM) have left ventricular outflow tract (LVOT) obstruction. Septal reduction therapy by septal myectomy can dramatically relieve exertional dyspnea, chest pain, and presyncope in properly selected patients and is an important management pathway for many patients. The distribution and degree of hypertrophy in patients with obstructive HCM are variable and, as discussed in this review, can influence clinical manifestations of the disease and surgical management. Subaortic septal hypertrophy is the most common phenotype of obstructive HCM associated with LVOT obstruction, but midventricular obstruction and apical hypertrophy may occur in isolation or in conjunction with subaortic septal hypertrophy. In many comprehensive HCM centers, transaortic septal myectomy is the preferred method of septal reduction therapy for symptomatic patients with obstructive HCM. Early surgical approaches aimed at alleviating left LVOT obstruction were hampered by a lack of understanding of the anatomy and pathophysiology of obstructive HCM. With the advent of Doppler echocardiography and, more recently, cardiac magnetic resonance imaging, surgeons can precisely assess the location and degree of obstruction, left ventricular size and function, and morphology and function of the mitral valve. This review discusses the current understanding of the role of septal myectomy in the management of patients with HCM and details contemporary operative methods.

Unmet needs and future directions in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a highly treatable monogenetic disorder affecting nearly 0.2% of the population. The high burden of this disease demands suitable measures for early diagnosis and preventing as well as tackling misdiagnosis. While conventionally available therapies have been efficacious in reducing symptoms, they have not been able to change the natural history of the disease. The landscape of medical treatment is rapidly changing with advent of novel pharmacotherapies such as cardiac myosin inhibitors. Ongoing investigations in gene editing have demonstrated benefits in correcting underlying genetic mutations and this is where the future of treatment lies. Contemporary procedural techniques as alternatives to available septal reduction therapies independent of coronary vascular anatomy are also emerging. This review details the recent developments, unmet needs and future directions in diagnosis, medical and invasive treatment of HCM.

Septal Myectomy Outcomes in Children and Adolescents With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Little data exist regarding characteristics and outcomes of pediatric patients undergoing septal myectomy. We evaluated this in a large referral population.

METHODS

Septal myectomy was performed in 199 consecutive patients aged ≤18 years with obstructive hypertrophic cardiomyopathy from January 1, 1976, to June 30, 2021.

RESULTS

Median age was 13 years (interquartile range [IQR], 8-15 years). Left ventricular myectomy approaches included transaortic (163 of 198 [82%]), transapical (16 of 198 [8%]), and combined (19 of 198 [10%]). Right ventricular interventions included myectomy (13 of 199 [7%]) and patch reconstruction of the outflow tract (15 of 199 [8%]). Maximum left ventricular outflow tract gradients decreased after myectomy (prebypass: 50 mm Hg [IQR, 31-73 mm Hg] vs postbypass: 4 mm Hg [IQR, 0-9 mm Hg], P < .001), and this was sustained long-term (5 mm Hg [IQR, 5-10 mm Hg] at 10 years). Iatrogenic aortic and mitral valve injuries occurred in 13 of 199 (7%) and 1 of 199 (1%), respectively; however, all were successfully repaired. Operative mortality was 2 of 199 (1%). The cumulative incidence of redo myectomy was low, at 5.8% at 5 and 8.3% at 10 years. Redo myectomy patients had higher maximum left ventricular outflow tract gradients on echocardiography at predischarge and 1 year and were younger at the index operation (8 years [IQR, 2.5-10 years] vs 13 years [IQR, 9-16 years], P < .001). Overall survival at 10 years was 90%, relative to 47% in a previously reported pediatric nonoperative cohort.

CONCLUSIONS

Pediatric septal myectomy provides safe, effective, and durable relief of ventricular outflow tract obstruction. Iatrogenic valve injury remains a low but nonnegligible risk. Recurrent obstruction requiring redo myectomy is infrequent and can be identified early. Long-term survival in this pediatric septal myectomy cohort appears to fare better than pediatric hypertrophic cardiomyopathy cohorts managed nonoperatively.

Art and science of risk stratification of sudden cardiac death in hypertrophic cardiomyopathy: Current state, unknowns, and future directions

The progress in the management of hypertrophic cardiomyopathy (HCM) over the last several decades has resulted in great improvements in quality of life and overall survival for HCM patients. Yet, sudden cardiac death (SCD) due to ventricular tachyarrhythmias is among the common causes of HCM-related mortality. SCD risk stratification is a central and often challenging domain in the care of the HCM patient. Distinguishing the individuals most likely to benefit from a primary prevention implantable-cardioverter defibrillator (ICD) from those truly at a low risk of SCD in whom an ICD is not necessary is a nuanced process. Clinicians need to carefully balance the potential benefit and risks of ICDs, particularly in young patients. Because of intense investigations in diverse HCM cohorts globally, two main approaches to SCD risk stratification in HCM have emerged, one based on major SCD risk factors and one based on a mathematically derived risk score. In this overview, we discuss the current state, latest advances and remaining unknowns about established and novel markers of risk of SCD in HCM. We also review how the risk factor- and risk score-based assessments can and should be used in conjunction to enhance rather than contradict each other in facilitating informed ICD decision-making in contemporary clinical practice.

Treatment Strategies for Cardiomyopathy in Children: A Scientific Statement From the American Heart Association

This scientific statement from the American Heart Association focuses on treatment strategies and modalities for cardiomyopathy (heart muscle disease) in children and serves as a companion scientific statement for the recent statement on the classification and diagnosis of cardiomyopathy in children. We propose that the foundation of treatment of pediatric cardiomyopathies is based on these principles applied as personalized therapy for children with cardiomyopathy: (1) identification of the specific cardiac pathophysiology; (2) determination of the root cause of the cardiomyopathy so that, if applicable, cause-specific treatment can occur (precision medicine); and (3) application of therapies based on the associated clinical milieu of the patient. These clinical milieus include patients at risk for developing cardiomyopathy (cardiomyopathy phenotype negative), asymptomatic patients with cardiomyopathy (phenotype positive), patients with symptomatic cardiomyopathy, and patients with end-stage cardiomyopathy. This scientific statement focuses primarily on the most frequent phenotypes, dilated and hypertrophic, that occur in children. Other less frequent cardiomyopathies, including left ventricular noncompaction, restrictive cardiomyopathy, and arrhythmogenic cardiomyopathy, are discussed in less detail. Suggestions are based on previous clinical and investigational experience, extrapolating therapies for cardiomyopathies in adults to children and noting the problems and challenges that have arisen in this experience. These likely underscore the increasingly apparent differences in pathogenesis and even pathophysiology in childhood cardiomyopathies compared with adult disease. These differences will likely affect the utility of some adult therapy strategies. Therefore, special emphasis has been placed on cause-specific therapies in children for prevention and attenuation of their cardiomyopathy in addition to symptomatic treatments. Current investigational strategies and treatments not in wide clinical practice, including future direction for investigational management strategies, trial designs, and collaborative networks, are also discussed because they have the potential to further refine and improve the health and outcomes of children with cardiomyopathy in the future.

High-Burden Premature Atrial Contractions Predict New-Onset Atrial Fibrillation After Surgical Septal Myectomy

Although increased premature atrial contractions (PACs) reportedly predict atrial fibrillation (AF) in both general and specific (e.g., patients with stroke) populations, early postoperative AF (POAF) risk in patients with increased PAC burden who require cardiac surgery remains unclear. We examined the correlation between different preoperative PAC burdens and POAF in patients with obstructive hypertrophic cardiomyopathy (OHCM) who underwent surgical treatment. We analyzed 304 consecutively admitted patients with OHCM without previous AF who underwent isolated septal myectomy between January 2015 and December 2018. All patients underwent preoperative 24-hour Holter electrocardiogram monitoring. PACs were present in 259 patients (85.20%) and absent in 45 patients (14.80%). According to the cut-off PAC number of 100 beats/24 hours, there were 211 patients (69.41%) with low-burden PACs and 48 patients (15.79%) with high-burden PACs. AF after septal myectomy occurred in 73 patients, which consisted of 3/45 in the non-PAC group (6.67%), 47/211 in the low-PAC-burden group (22.27%), and 23/48 in the high PAC burden group (47.92%). POAF incidence was higher in both low- and high-burden patients than in patients without PAC (p <0.01). Multivariate logistic regression analyses demonstrated that high-burden PACs (p = 0.02) and age (p <0.01) but not low-burden PACs (p = 0.22) independently predicted POAF in patients with OHCM. The area under the receiver operating characteristic curve for preoperative PACs was 0.72 (95% confidence interval 0.66 to 0.79, p <0.01, sensitivity: 68.49%, specificity: 69.26%). In conclusion, POAF incidence was significantly higher in patients with preoperative high-burden PACs and can predict POAF in patients with OHCM.

Impact of Race and Ethnicity on Use and Outcomes of Septal Reduction Therapies for Obstructive Hypertrophic Cardiomyopathy

Background Information on impact of race and ethnicity on use and early outcomes of septal reduction therapies (SRTs) for obstructive hypertrophic obstructive cardiomyopathy are limited. Methods and Results Using the National Inpatient Sample from January 2012 through December 2019, we identified all adult admissions with a primary diagnosis of obstructive hypertrophic cardiomyopathy and those undergoing SRT. Predictors of receiving SRT and outcomes including in-hospital mortality, complications, and resource use were evaluated in racial and ethnic groups. Among a total of 18 895 adult admissions with obstructive hypertrophic cardiomyopathy, SRT was performed in 7255 (38.4%) admissions. Septal myectomy was performed in 4930 (26.1%), while alcohol septal ablation was performed in 2325 (12.3%). In adjusted analysis, Black patient (versus White patient adjusted odds ratio, 0.65 [95% CI, 0.57-0.73]; P<0.001) and Hispanic patient admissions (versus White adjusted odds ratio, 0.78 [95% CI, 0.66-0.92]; P=0.003) were less likely to receive SRT. Among admissions undergoing SRT, in-hospital mortality was significantly higher for Hispanic (adjusted odds ratio, 3.38 [95% CI, 1.81-6.30], P<0.001) and other racial and ethnic groups (adjusted odds ratio 2.02 [95% CI, 1.00-4.11]; P=0.05) compared with White patient admissions, whereas Black patient admissions had comparable mortality. Black, Hispanic, and other ethnic group patients had higher rates of SRT complications and more frequent dismissals to acute care facilities. Conclusions Among obstructive hypertrophic cardiomyopathy hospitalizations, minoritized racial groups were less likely to receive SRT. Importantly, hospitalizations of Hispanic and other ethnic patients undergoing SRT had significantly higher in-hospital mortality and complication rates. Further studies with granular echocardiographic information to assess indications for SRT are needed to better understand these differences.

Posterior Wall Thickness Associates With Survival Following Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

The left ventricular (LV) posterior wall thickness (PWT) is a predictor of sudden cardiac death in pediatric patients with hypertrophic cardiomyopathy (HCM), but the prognostic importance of PWT in adults has not been examined.

OBJECTIVES

The goal of this study was to evaluate the association of LV PWT with late survival in adult patients undergoing septal myectomy for obstructive HCM.

METHODS

This single-center study reviewed 2,418 patients who underwent transaortic septal myectomy for obstructive HCM.

RESULTS

The median preoperative PWT was 13 (IQR: 11-15) mm. Patients with PWT >13 mm tended to have systemic hypertension (55.4% vs 49.1%; P = 0.002) and a larger body mass index (median: 30.8 [IQR: 27.1-35.1] kg/m² vs 29.6 [IQR: 26.1-33.9] kg/m²; P < 0.001). Preoperatively, PWT >13 mm was associated with increased septal thickness (median: 21 [IQR: 18-24] mm vs 19 [IQR: 17-22] mm; P < 0.001), greater maximum instantaneous left ventricular outflow tract (LVOT) gradient at rest (median: 67 [IQR: 36-96] mm Hg vs 47 [IQR: 19-79] mm Hg), and increased likelihood of moderate or greater mitral valve regurgitation (54.3% vs 47.3%; P = 0.001). However, PWT was not related to the severity of limitations measured by New York Heart Association functional class (P = 0.674). After adjusting for baseline covariates, greater PWT was an independent risk factor for late mortality after septal myectomy (P = 0.003).

CONCLUSIONS

PWT is a newly identified predictor of reduced long-term survival after septal myectomy that is independent of septal thickness and severity of LVOT gradient. Future studies are warranted to investigate the mechanisms underlying the association and the potential usefulness of PWT in patient management.

Surgical treatment of hypertrophic obstructive cardiomyopathy in relatively elderly patients: Short- and long-term outcomes

OBJECTIVES

Our goal was to assess the short- and long-term outcomes of surgical treatment for hypertrophic obstructive cardiomyopathy in patients ≥65 years of age compared to patients < 65 years of age.

METHODS

Sixty-four patients aged ≥65 years, surgically treated for symptomatic hypertrophic obstructive cardiomyopathy, were compared to a control group of 125 patients <65 years.

RESULTS

Patients aged ≥65 years were less frequently male (36% vs 68%, P < 0.001) and had higher EuroSCORE II scores [1.4 (1.1-2.2) vs 0.8 (0.7-1.2), P < 0.001], lower risk of sudden death, higher pulmonary artery pressure [40 (30-50) vs 30 (30-43), P = 0.04) and more mitral annulus calcifications (44% vs 14%, P < 0.001) compared to younger patients.Hospital death was 1%, with no difference between the 2 groups (1.5% vs 0.8%, P = 0.9).Patients aged ≥65 years had more concomitant coronary bypass grafting (12% vs 5%, P = 0.05) and a higher incidence of blood transfusions (50% vs 17%, P < 0.001) and postoperative atrial fibrillation (19% vs 8%, P = 0.02).Follow-up was 98% complete [median 8.3 (5.3-12.8) years]. The 13-year survival in the group aged ≥65 was 54 (SD: 9) % vs 83 (SD: 5) % in the control group (P < 0.001), but it was comparable to that expected in the age-sex matched general national population.At 13 years, the cumulative incidence function of cardiac death in the elderly group was 19 (SD: 7)%, mostly unrelated to hypertrophic cardiomyopathy causes.At the last follow-up, 90% of patients were in New York Heart Association functional class I-II and 68% were in sinus rhythm.

CONCLUSIONS

Selected elderly symptomatic patients with hypertrophic obstructive cardiomyopathy can benefit from surgery, with low hospital mortality and morbidity, relief of symptoms and late survival comparable to that expected in the age-sex matched general population.

Post-operative management of hypertrophic obstructive cardiomyopathy

Hypertrophic obstructive cardiomyopathy patients are at increased risk of sudden cardiac arrest due to dynamic left ventricular outflow tract obstruction, myocardial ischaemia and arrhythmias. Septal myectomy remains the gold standard therapy for patients with hypertrophic obstructive cardiomyopathy (HOCM) refractory to other therapy. This review comprehensively focuses on the post-operative management and complications of HOCM patients undergoing surgical correction. Although these patients are at risk of various perioperative complications from anaesthesia and surgery due to the underlying complexity of their disease, surgical myectomy is associated with excellent long-term outcomes if carried out in experienced centers.

Preoperative left ventricular longitudinal strain predicts outcome of septal myectomy for obstructive hypertrophic cardiomyopathy

OBJECTIVE

The objective of this study was to determine the characteristics of longitudinal strain and its effect on outcomes in patients with obstructive hypertrophic cardiomyopathy (HCM) who underwent septal myectomy.

METHODS

We reviewed patients with obstructive HCM who underwent septal myectomy at our clinic from 2007 to 2016. Data of those who had strain echocardiography within 6 months before isolated myectomy were analyzed.

RESULTS

The median age of the 857 patients studied was 55 (interquartile range [IQR], 44-63) years, and 451 (52.6%) were male. Left ventricular ejection fraction was 71% (IQR, 67%-74%), and the resting peak outflow tract gradient was 58 (IQR, 27-85) mm Hg. The median global longitudinal strain (GLS) was -14.6% (IQR, -12.0% to -17.3%). Regional longitudinal strain was nonuniform as reflected by more normal values in apical segments and more abnormal in basal segments. Moreover, GLS correlated poorly with ejection fraction and outflow tract gradient. In 64 patients who had postoperative strain echocardiography, GLS was comparable before and after septal myectomy, but regional strain was more uniform after myectomy. Over a follow-up of 8.3 (IQR, 6.5-10.3) years, when patients were equally stratified according to GLS (cutoff, -14.64%), the group with worse GLS had significantly poorer survival compared with the better GLS group (P = .002). Left ventricular ejection fraction had no association with survival.

CONCLUSIONS

Left ventricular longitudinal strain is nonuniform and might be significantly reduced in patients with obstructive HCM. Septal myectomy does not impair GLS but is associated with more uniform regional strains. Most importantly, reduced GLS preoperatively is strongly and independently associated with increased all-cause mortality after septal myectomy for obstructive HCM.

Myocardial Histopathology in Patients With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is characterized by multiple pathological features including myocyte hypertrophy, myocyte disarray, and interstitial fibrosis.

OBJECTIVES

This study sought to correlate myocardial histopathology with clinical characteristics of patients with obstructive HCM and post-operative outcomes following septal myectomy.

METHODS

The authors reviewed the pathological findings of the myocardial specimens from 1,836 patients with obstructive HCM who underwent septal myectomy from 2000 to 2016. Myocyte hypertrophy, myocyte disarray, interstitial fibrosis, and endocardial thickening were graded and analyzed.

RESULTS

The median age at operation was 54.2 years (43.5 to 64.3 years), and 1,067 (58.1%) were men. A weak negative correlation between myocyte disarray and age at surgery was identified (ρ = -0.22; p < 0.001). Myocyte hypertrophy (p < 0.001), myocyte disarray (p < 0.001), and interstitial fibrosis (p < 0.001) were positively associated with implantable cardioverter-defibrillator implantation. Interstitial fibrosis (p < 0.001) and endocardial thickening (p < 0.001) were associated with atrial fibrillation pre-operatively. In the Cox survival model, older age (p < 0.001), lower degree of myocyte hypertrophy (severe vs. mild hazard ratio: 0.41; 95% confidence interval: 0.19 to 0.86; p = 0.040), and lower degree of endocardial thickening (moderate vs. mild hazard ratio: 0.75; 95% confidence interval: 0.58 to 0.97; p = 0.019) were independently associated with worse post-myectomy survival. Among 256 patients who had genotype analysis, patients with pathogenic or likely pathogenic variants (n = 62) had a greater degree of myocyte disarray (42% vs. 15% vs. 20%; p = 0.022). Notably, 13 patients with pathogenic or likely pathogenic genetic variants of HCM had no myocyte disarray.

CONCLUSIONS

Histopathology was associated with clinical manifestations including the age of disease onset and arrhythmias. Myocyte hypertrophy and endocardial thickening were negatively associated with post-myectomy mortality.

Reversible Treatment of Pressure Overload-Induced Left Ventricular Hypertrophy through Drd5 Nucleic Acid Delivery Mediated by Functional Polyaminoglycoside

Left ventricular hypertrophy and fibrosis are major risk factors for heart failure, which require timely and effective treatment. Genetic therapy has been shown to ameliorate hypertrophic cardiac damage. In this study, it is found that in mice, the dopamine D5 receptor (D5R) expression in the left ventricle (LV) progressively decreases with worsening of transverse aortic constriction-induced left ventricular hypertrophy. Then, a reversible treatment of left ventricular hypertrophy with Drd5 nucleic acids delivered by tobramycin-based hyperbranched polyaminoglycoside (SS-HPT) is studied. The heart-specific increase in D5R expression by SS-HPT/Drd5 plasmid in the early stage of left ventricular hypertrophy attenuates cardiac hypertrophy and fibrosis by preventing oxidative and endoplasmic reticulum (ER) stress and ameliorating autophagic dysregulation. By contrast, SS-HPT/Drd5 siRNA promotes the progression of left ventricular hypertrophy and accelerates the deterioration of myocardial function into heart failure. The reduction in cardiac D5R expression and dysregulated autophagy are observed in patients with hypertrophic cardiomyopathy and heart failure. The data show a cardiac-specific beneficial effect of SS-HPT/Drd5 plasmid on myocardial remodeling and dysfunction, which may provide an effective therapy of patients with left ventricular hypertrophy and heart failure.

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.

Unplanned Thirty-Day Readmission After Alcohol Septal Ablation for Hypertrophic Cardiomyopathy (From the Nationwide Readmission Database)

Alcohol septal ablation (ASA) is indicated for symptomatic hypertrophic cardiomyopathy (HC) patients. We sought to analyze the incidence of the 30-day readmission rate, predictors, causes of readmission, and incremental healthcare resource (cost and length of stay) utilization after ASA. Nationwide Readmission Database from 2010 January to 2015 September was queried to identify 30-day unplanned readmission after ASA for HC by using the International Classification of Disease, 9th Revision, Clinical Modification. Those readmitted were similar in terms of age and sex but had higher burden of co-morbidities compared with those not readmitted within 30-days. The 30-day unplanned readmission rate was 10.4% (511/4,932) after ASA. Readmissions lead to an additional mean hospitalization cost of 8,433 US dollars and mean of 4.9 days of length of stay. Predictors of 30-day unplanned readmission were liver disease (adjusted odds ratio [aOR] 2.62, 95% confidence interval [CI] 1.22 to 5.59), renal failure (aOR 2.30, 95%CI 1.52 to 3.50), previous myocardial infarction (aOR 1.97, 95%CI 1.16 to 3.33), previous pacemaker (aOR 1.50, 95%CI 1.09 to 2.08), atrial fibrillation (aOR 1.43, 95%CI 1.08 to 1.89), Medicaid (aOR 1.74, 95%CI 1.12 to 2.68), and weekend admission (aOR 1.75, 95%CI 1.12 to 2.75). Common reasons for readmissions were atrial fibrillation (12.6%), acute on chronic systolic heart failure (12.6%), paroxysmal ventricular tachycardia (6.4%), atrioventricular block (4.9%), and HC (3.0%). Unplanned readmissions after ASA occur in patients with higher burden of co-morbidities and are mainly caused by cardiac etiologies.

Hypertrophic Cardiomyopathy With Left Ventricular Systolic Dysfunction: Insights From the SHaRe Registry

BACKGROUND

The term "end stage" has been used to describe hypertrophic cardiomyopathy (HCM) with left ventricular systolic dysfunction (LVSD), defined as occurring when left ventricular ejection fraction is <50%. The prognosis of HCM-LVSD has reportedly been poor, but because of its relative rarity, the natural history remains incompletely characterized.

METHODS

Data from 11 high-volume HCM specialty centers making up the international SHaRe Registry (Sarcomeric Human Cardiomyopathy Registry) were used to describe the natural history of patients with HCM-LVSD. Cox proportional hazards models were used to identify predictors of prognosis and incident development.

RESULTS

From a cohort of 6793 patients with HCM, 553 (8%) met the criteria for HCM-LVSD. Overall, 75% of patients with HCM-LVSD experienced clinically relevant events, and 35% met the composite outcome (all-cause death [n=128], cardiac transplantation [n=55], or left ventricular assist device implantation [n=9]). After recognition of HCM-LVSD, the median time to composite outcome was 8.4 years. However, there was substantial individual variation in natural history. Significant predictors of the composite outcome included the presence of multiple pathogenic/likely pathogenic sarcomeric variants (hazard ratio [HR], 5.6 [95% CI, 2.3-13.5]), atrial fibrillation (HR, 2.6 [95% CI, 1.7-3.5]), and left ventricular ejection fraction <35% (HR, 2.0 [95% CI, 1.3-2.8]). The incidence of new HCM-LVSD was ≈7.5% over 15 years. Significant predictors of developing incident HCM-LVSD included greater left ventricular cavity size (HR, 1.1 [95% CI, 1.0-1.3] and wall thickness (HR, 1.3 [95% CI, 1.1-1.4]), left ventricular ejection fraction of 50% to 60% (HR, 1.8 [95% CI, 1.2, 2.8]-2.8 [95% CI, 1.8-4.2]) at baseline evaluation, the presence of late gadolinium enhancement on cardiac magnetic resonance imaging (HR, 2.3 [95% CI, 1.0-4.9]), and the presence of a pathogenic/likely pathogenic sarcomeric variant, particularly in thin filament genes (HR, 1.5 [95% CI, 1.0-2.1] and 2.5 [95% CI, 1.2-5.1], respectively).

CONCLUSIONS

HCM-LVSD affects ≈8% of patients with HCM. Although the natural history of HCM-LVSD was variable, 75% of patients experienced adverse events, including 35% experiencing a death equivalent an estimated median time of 8.4 years after developing systolic dysfunction. In addition to clinical features, genetic substrate appears to play a role in both prognosis (multiple sarcomeric variants) and the risk for incident development of HCM-LVSD (thin filament variants).

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 ± 0.7 years, at which 294 (98.7%) patients were alive. Hospital stay length was 4.9 ± 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.

Septal Myectomy and Concomitant Coronary Artery Bypass Grafting for Patients With Hypertrophic Cardiomyopathy and Coronary Artery Disease

Severe coronary artery disease is associated with disproportionately increased risks of death in patients with hypertrophic cardiomyopathy. There is a paucity of data on the long-term effect of coronary revascularization at the time of myectomy. Between January 1, 1961, and October 31, 2017, 2913 adult patients underwent transaortic septal myectomy at Mayo Clinic. Concomitant coronary artery bypass grafting (CABG) was performed in 246 (8.4%). We compared baseline characteristics of patients who underwent septal myectomy with and without CABG and assessed the effect of surgical revascularization on the risk of all-cause mortality. Patients who underwent concomitant CABG were older (median [interquartile range], 66.3 [59.8-72.1] years vs 54.4 [43.5-64.8] years; P<.0001) and more likely to be male (63.0% vs 54.2%; P=.008) than those who did not undergo coronary revascularization at operation. There was no significant difference in preoperative left ventricular outflow tract gradients (55 [25-81] mm Hg vs 58 [25-88] mm Hg; P=.116). Overall operative mortality (≤30 days after surgery) was 1.0% and higher in patients who underwent concomitant CABG (2.2% vs 0.8%; P=.048). In multivariable analysis (n=2641), factors independently associated with mortality included concomitant CABG (hazard ratio [95% CI], 1.89 [1.39-2.58]; P<.0001), older age at operation (per interquartile range increase, 2.79 [1.95-3.98]; P<.0001), atrial fibrillation (1.46 [1.11-1.92]; P=.006), diabetes (1.45 [1.04-2.04]; P=.031), higher body mass index (change from 0.95 to 0.5 quantile, 1.95 [1.46-2.59]; P<.0001), and surgery performed earlier in the study period (2.02 [1.31-3.11]; P=.001). In conclusion, obstructive coronary artery disease severe enough to prompt concomitant CABG at the time of septal myectomy is an important risk factor for late mortality.

Targeted Medical Therapies for Hypertrophic Cardiomyopathy

PURPOSE OF REVIEW

The management of hypertrophic cardiomyopathy (HCM) has changed considerably over the years, although molecular therapies targeting core mechanisms of the disease are still lacking. This review provides an overview of the contemporary medical approach to patients with HCM, and of promising novel developments hopefully soon to enter the clinical arena.

RECENT FINDINGS

Our perception of therapeutic targets for medical therapy in HCM is rapidly evolving. Novel approaches include myocardial metabolic modulation, late sodium current inhibition, and allosteric myosin inhibition, actively pursued to reduce and hopefully prevent the development of severe HCM phenotypes, improve symptom control, and preserve patients from disease-related complications. Clinical management of patients with HCM should be guided by in-depth knowledge of the complex mechanisms at the energetic, metabolic, and electrophysiologic level. Until new experimental therapies become available, tailored management of modifiable disease manifestations should be pursued, including lifestyle counseling and prevention of comorbidities.