Sixty-Year Evolution of Surgical Myectomy for Symptomatic Obstructive Hypertrophic Cardiomyopathy with Insights From the Historic NIH Surgical Experience to Present

Since virtually from the modern conception of hypertrophic cardiomyopathy in the early 1960s, surgical septal myectomy has been the primary “gold standard” treatment to reverse drug-refractory heart failure symptoms by permanent and complete relief of left ventricular (LV) outflow obstruction.1Ommen SR Mital S Burke MA. et al.2020 AHA/ACC Guidelines for the diagnosis and treatment of patients with hypertrophic cardiomyopathy.J Am Coll Cardiol. 2020; 76: e159-e240Crossref PubMed Scopus (258) Google Scholar,2Braunwald E Labrew E Rockoff D. Idiopathic hypertrophic subaortic stenosis. A description of the disease based upon an analysis of 64 patients.Circulation. 1964; 30: 1-217Google Scholar However, despite this long time period, myectomy studies have generally reported follow-up data over relatively short periods with few assessments of treatment outcomes across multiple management eras.3Kotkar KD Said SM Dearani JA Schaff HV. Hypertrophic obstructive cardiomyopathy: The Mayo Clinic experience.Ann Cardiothorac Surg. 2017; 6: 829-836Crossref Scopus (54) Google Scholar, 4Woo A Williams WG Choi R. et al.Clinical and echocardiographic determinants of long-term survival after surgical myectomy in obstructive hypertrophic cardiomyopathy.Circulation. 2005; 111: 2033-2041Crossref PubMed Scopus (274) Google Scholar, 5Desai MY Bhonsale A Smedira NG. et al.Predictors of long-term outcomes in symptomatic hypertrophic cardiomyopathy patients undergoing surgical relief of left ventricular outflow tract obstruction.Circulation. 2013; 128: 209-216Crossref PubMed Scopus (150) Google Scholar Therefore, in this Viewpoint we have taken the unique opportunity to compare truly long-term survival outcomes of the historic surgical myectomy series of Dr. Andrew G. Morrow at NIH Bethesda, MD [the pioneer credited with initial design and implementation of this operation6Morrow AG Brockenbrough EC. Surgical treatment of idiopathic hypertrophic subaortic stenosis: technic and hemodynamic results of subaortic ventriculotomy.Ann Surg. 1961; 154: 181-189Crossref PubMed Scopus (171) Google Scholar] with an example of more contemporary surgical results, and in the process demonstrating evolution of the myectomy operation. NIH Cohort. Over 22 years (1960-1982), Dr. Morrow performed 343 myectomy operations on patients with obstructive hypertrophic cardiomyopathy who were severely disabled by heart failure symptoms due to peak systolic pressure gradients ≥50 mmHg measured at cardiac catheterization.6Morrow AG Brockenbrough EC. Surgical treatment of idiopathic hypertrophic subaortic stenosis: technic and hemodynamic results of subaortic ventriculotomy.Ann Surg. 1961; 154: 181-189Crossref PubMed Scopus (171) Google Scholar One of the co-authors of this paper (EB) was closely involved in the selection of patients for operation,7Braunwald E Morrow AG. Obstruction to left ventricular outflow: current criteria for the selection of patients.Am J Cardiol. 1963; 12: 53-59Abstract Full Text PDF PubMed Scopus (13) Google Scholar as well as their cardiology care, representing an early example of a comprehensive “heart team” approach to complex interventional cardiovascular care. Medical records were accessible through the NIH Clinical Center. Survival status and age of death was confirmed by interrogation of the Social Security Death Index and Lexis Nexis®. Postoperative follow-up duration was 17 ± 11 years (range to 52). Fourteen patients (4%) died in the immediate postoperative period and 80 patients were lost to follow-up. Of the 249 NIH patients also comprise the study group, age at operation was 48 ± 14 years (range 8 - 76); 55% were male. Over follow-up, survival was to: ≥60 years (163; 66%); including 60-69 years (59; 24%); 70-79 (66; 27%), and ≥80 years (38; 15%). Also, 60 patients (24%) have survived 25 years and 136 (55%) ≥15 years. Survival post-myectomy from all causes was 67% (95% CI: 61,73) at 10 years; 55%, (95% CI: 48, 60) at 15 years; and 24% (95% CI: 19, 30) at 25 years. All-cause mortality rate was 3.1%/year, exceeding that expected in a general age-adjusted and gender-matched U.S. population from the same time period (SMR: 3.94 [95% CI: 3.1, 4.8]; log-rank p < 0.001) (Figure 1). Contemporary Myectomy Cohort. Of the 900 operated patients in the overall Tufts myectomy series (2003-2010; Dr. Hassan Rastegar, surgeon), 139 had a previously reported ≥10-year postoperative follow-up, presented here for comparison.8Maron MS Rastegar H Dolan N. et al.Outcomes over follow-up >10-years after surgical myectomy for symptomatic obstructive hypertrophic cardiomyopathy.Am J Cardiol. 2022; 163: 91-97Abstract Full Text Full Text PDF Scopus (7) Google Scholar Age at operation was 50±15 years (range 12 to 79); 55% male and operative mortality 0.7%. Survival post-myectomy from all causes was 91% (95% CI: 85, 96) at 10 years and 78% at 15 years (95% CI: 67, 69), with a relative mortality risk that was one-third compared to NIH patients (HR 0.3, 95% CI: 0.2, 0.5; p < 0.0001)(Figure 1) and with nearly 6-fold decrease in operative mortality (4% vs. 0.7%; p<0.01). All-cause mortality was 0.9%/year (n = 17; 12%), no different from that expected in a current age and gender-matched U.S. population (SMR: 0.81 [95% CI: 0.33, 1.29]; log-rank p =0.44) (Figure 1). These data demonstrate 2 major principles regarding myectomy for symptomatic obstructive hypertrophic cardiomyopathy. First, we have shown that the initial pioneering experience with myectomy at NIH in a very early era nevertheless provided important clinical benefit for many patients,2Braunwald E Labrew E Rockoff D. Idiopathic hypertrophic subaortic stenosis. A description of the disease based upon an analysis of 64 patients.Circulation. 1964; 30: 1-217Google Scholar,6Morrow AG Brockenbrough EC. Surgical treatment of idiopathic hypertrophic subaortic stenosis: technic and hemodynamic results of subaortic ventriculotomy.Ann Surg. 1961; 154: 181-189Crossref PubMed Scopus (171) Google Scholar including two-thirds who survived to ≥60 years (and almost 30% to ≥70) with about 25% of patients living at least 25 years after operation. Notably, the operative benefit in the Morrow series was achieved despite the numerous obstacles with open heart surgery in the early 1960s/1970s, ie., without the advantage of modern cardiac preservation techniques and the evolution of surgical strategy techniques such as extended myectomy. In addition, these Morrow outcome data reflect an unavoidable selection bias associated with the very early years of open heart surgery, in which myectomy was only performed in the most severely compromised patients.7Braunwald E Morrow AG. Obstruction to left ventricular outflow: current criteria for the selection of patients.Am J Cardiol. 1963; 12: 53-59Abstract Full Text PDF PubMed Scopus (13) Google Scholar These notable limitations related to early cardiac surgery are major reasons for the observed difference in survival between the NIH cohort and contemporary surgical cohorts such as the Tufts series.8Maron MS Rastegar H Dolan N. et al.Outcomes over follow-up >10-years after surgical myectomy for symptomatic obstructive hypertrophic cardiomyopathy.Am J Cardiol. 2022; 163: 91-97Abstract Full Text Full Text PDF Scopus (7) Google Scholar On the other hand, it is reasonable to speculate that without access to myectomy, many patients in this early NIH myectomy cohort would have experienced progressive heart failure leading to premature disability and death. Finally, given the particularly extended follow-up period for the NIH cohort, it is also reasonable to speculate that many of the deaths were likely due to non-cardiac co-morbid causes. Importantly, our comparison of the long-term outcome results in the early NIH myectomy experience to the more current myectomy outcomes underscores the evolutionary progress achieved over decades, also evident in reports from several surgical centers worldwide (prominently Mayo Clinic and Cleveland Clinic but also programs in Toronto, New York, Beijing and Northern Italy)1Ommen SR Mital S Burke MA. et al.2020 AHA/ACC Guidelines for the diagnosis and treatment of patients with hypertrophic cardiomyopathy.J Am Coll Cardiol. 2020; 76: e159-e240Crossref PubMed Scopus (258) Google Scholar, 2Braunwald E Labrew E Rockoff D. Idiopathic hypertrophic subaortic stenosis. A description of the disease based upon an analysis of 64 patients.Circulation. 1964; 30: 1-217Google Scholar, 3Kotkar KD Said SM Dearani JA Schaff HV. Hypertrophic obstructive cardiomyopathy: The Mayo Clinic experience.Ann Cardiothorac Surg. 2017; 6: 829-836Crossref Scopus (54) Google Scholar, 4Woo A Williams WG Choi R. et al.Clinical and echocardiographic determinants of long-term survival after surgical myectomy in obstructive hypertrophic cardiomyopathy.Circulation. 2005; 111: 2033-2041Crossref PubMed Scopus (274) Google Scholar, 5Desai MY Bhonsale A Smedira NG. et al.Predictors of long-term outcomes in symptomatic hypertrophic cardiomyopathy patients undergoing surgical relief of left ventricular outflow tract obstruction.Circulation. 2013; 128: 209-216Crossref PubMed Scopus (150) Google Scholar,7Braunwald E Morrow AG. Obstruction to left ventricular outflow: current criteria for the selection of patients.Am J Cardiol. 1963; 12: 53-59Abstract Full Text PDF PubMed Scopus (13) Google Scholar, 8Maron MS Rastegar H Dolan N. et al.Outcomes over follow-up >10-years after surgical myectomy for symptomatic obstructive hypertrophic cardiomyopathy.Am J Cardiol. 2022; 163: 91-97Abstract Full Text Full Text PDF Scopus (7) Google Scholar, 9Maron BJ Dearani JA Ommen SR. et al.Low operative mortality achieved with surgical septal myectomy: Role of dedicated hypertrophic cardiomyopathy centers in the management of dynamic subaortic obstruction.J Am Coll Cardiol. 2015; 66: 1307-1308Crossref PubMed Scopus (133) Google Scholar, 10Ferrazzi P Spirito P Iacovoni A. et al.Transaortic chordal cutting: mitral valve repair for obstructive hypertrophic cardiomyopathy.J Am Coll Cardiol. 2015; 66: 1687-1696Crossref PubMed Scopus (126) Google Scholar reporting 3-fold less late mortality, heart failure reversal in the vast majority, and nearly 10-fold improved operative risk (now 0.5%). Indeed, current expectation for long-term post-myectomy survival is equivalent to that of an age-matched general U.S. population, based on reports from dedicated hypertrophic cardiomyopathy programs.1Ommen SR Mital S Burke MA. et al.2020 AHA/ACC Guidelines for the diagnosis and treatment of patients with hypertrophic cardiomyopathy.J Am Coll Cardiol. 2020; 76: e159-e240Crossref PubMed Scopus (258) Google Scholar, 2Braunwald E Labrew E Rockoff D. Idiopathic hypertrophic subaortic stenosis. A description of the disease based upon an analysis of 64 patients.Circulation. 1964; 30: 1-217Google Scholar, 3Kotkar KD Said SM Dearani JA Schaff HV. Hypertrophic obstructive cardiomyopathy: The Mayo Clinic experience.Ann Cardiothorac Surg. 2017; 6: 829-836Crossref Scopus (54) Google Scholar, 4Woo A Williams WG Choi R. et al.Clinical and echocardiographic determinants of long-term survival after surgical myectomy in obstructive hypertrophic cardiomyopathy.Circulation. 2005; 111: 2033-2041Crossref PubMed Scopus (274) Google Scholar, 5Desai MY Bhonsale A Smedira NG. et al.Predictors of long-term outcomes in symptomatic hypertrophic cardiomyopathy patients undergoing surgical relief of left ventricular outflow tract obstruction.Circulation. 2013; 128: 209-216Crossref PubMed Scopus (150) Google Scholar,8Maron MS Rastegar H Dolan N. et al.Outcomes over follow-up >10-years after surgical myectomy for symptomatic obstructive hypertrophic cardiomyopathy.Am J Cardiol. 2022; 163: 91-97Abstract Full Text Full Text PDF Scopus (7) Google Scholar, 9Maron BJ Dearani JA Ommen SR. et al.Low operative mortality achieved with surgical septal myectomy: Role of dedicated hypertrophic cardiomyopathy centers in the management of dynamic subaortic obstruction.J Am Coll Cardiol. 2015; 66: 1307-1308Crossref PubMed Scopus (133) Google Scholar, 10Ferrazzi P Spirito P Iacovoni A. et al.Transaortic chordal cutting: mitral valve repair for obstructive hypertrophic cardiomyopathy.J Am Coll Cardiol. 2015; 66: 1687-1696Crossref PubMed Scopus (126) Google Scholar Maturation of surgical septal myectomy over 60 years with enhanced operator expertise has resulted in a low risk:high benefit option for severely symptomatic patients with obstructive hypertrophic cardiomyopathy when performed in experienced centers.1Ommen SR Mital S Burke MA. et al.2020 AHA/ACC Guidelines for the diagnosis and treatment of patients with hypertrophic cardiomyopathy.J Am Coll Cardiol. 2020; 76: e159-e240Crossref PubMed Scopus (258) Google Scholar The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.