For over 50 years, surgical septal myectomy has been the preferred treatment for drug-refractory heart failure symptoms in obstructive hypertrophic cardiomyopathy (HCM). However, given the relatively youthful adult ages at which HCM surgery is usually performed, it is informative to evaluate longer-term results of myectomy after ≥10 years. We identified 139 consecutive obstructive HCM patients (50 ± 15 years of age; 55% men) who underwent surgical myectomy, 2003 to 2010 at Tufts HCM Center and followed 11.3 ± 2.7 years (range to 17). Operative mortality was low (0.6%) and left ventricular (LV) outflow gradients at rest were reduced from 56 ± 40 mm Hg preoperatively to 1 ± 7 mm Hg postoperatively, durable over the study period, with no patient requiring reoperation for the residual gradient. Over follow-up, 129 of 139 patients (93%) were alive ≥10 years after myectomy, including 17 patients ≥15 years. Of 118 patients with complete long-term clinical follow-up data, 109 (92%) experienced clinical improvement to New York Heart Association classes I or II. In 9 patients (8%) refractory class III/IV symptoms reoccurred 6.6 ± 3.9 years postoperatively, including 4 who ultimately underwent a heart transplant. After myectomy, there were 2 late HCM-related deaths, but none suddenly; notably 6 patients (12%) with prophylactic implantable cardioverter-defibrillators experienced appropriate therapy terminating ventricular tachycardia/ventricular fibrillation after myectomy. Survival following myectomy was 91% at 10 years (95% confidence interval: 85, 96%) not different from the age- and gender-matched general United States population (log-rank p = 0.64). In conclusion, myectomy provides permanent abolition of outflow gradients with reversal of heart failure and highly favorable long-term survival, representing a low-risk:high-benefit option when performed in experienced HCM centers. Myectomy did not protect absolutely against arrhythmic sudden death events, underscoring the importance of risk stratification in operative patients.
For >50 years, surgical ventricular septal myectomy, has been the gold standard treatment for drug-refractory heart failure symptoms in patients with obstructive hypertrophic cardiomyopathy (HCM). By abolishing the outflow gradient and associated mitral regurgitation, myectomy provides the opportunity to reverse heart failure and significantly improve quality of life. Although relatively long-term follow-up data are available in some studies, , results in other reports are based on shorter postoperative periods of observation, , particularly relevant given the young adult age at which surgery is usually performed. Tufts HCM center has been 1 of the most active North American centers performing myectomy over the last 2 decades, and supported by detailed individual patient follow-up data important for deriving a comprehensive understanding of the extended impact of surgery on patient outcome. , Therefore, we have evaluated the results of myectomy in patients ≥10 years postoperative in a cohort with a single operating surgeon.
Methods
The Tufts myectomy program was established 17 years ago primarily to serve New England and the populous northeastern United States corridor, but also receives surgical referrals from other regions of the country, with Dr. Hassan Rastegar as the senior operating surgeon. , The initial myectomy was performed in 2003 and up to March 2021 over 900 patients have undergone the septal myectomy operation. All patients in this study agreed to undergo surgery, accept its inherent risks to relieve their heart failure symptoms (usually equivalent to New York Heart Association [NYHA] functional Class III to IV) refractory to optimal medical management which had therefore become an obstacle to an acceptable quality of life with an outflow tract gradient ≥50 mm Hg because of mitral valve ventricular septal contact. , Patients were presented with the risks and benefits of all available treatment options, including myectomy and percutaneous alcohol septal ablation, in the context of shared decision-making, and with consideration for their cardiac anatomy and personal preferences.
In the present analysis, we have selected for specific analysis the subset of 139 consecutive obstructive highly symptomatic HCM patients (operated 2003 to 2010) with the longest period of postoperative follow-up of at least 10 years (mean 11.3 ± 2.7 years). One patient who died within 30 days of surgery, a 45-year-old man with an operative course complicated by cardiogenic shock, was excluded from the study group.
Comprehensive clinical data was obtained in 118 survivors ≥10 years obtained as of December 2020 by hospital or clinic visit and/or referring physician. In the 11 patients without such clinical follow-up data, survival status was confirmed by the Social Security Death Index.
As is our practice, before initiation of cardiopulmonary bypass, intraoperative transesophageal echocardiography (TEE) was reviewed to assess the extent and distribution of ventricular septal thickening, inspect morphology of the mitral valve and submitral structures including papillary muscles (and ascertain the degree of mitral regurgitation).
Through a transverse aortotomy, a wide and deep muscular resection and trough was started 1 cm below the nadir of the right coronary cusp and right-left commissure and extended distally to the mid-ventricle at the level of the papillary muscle heads well beyond the site of mitral-septal contact. Abnormal intraventricular muscle bundles and accessory chordal connections were judged to contribute to outflow tract impedance and were resected. In 2 patients with anomalous anterolateral papillary muscle insertion directly into anterior mitral leaflet (in the absence of chordae tendineae) adjunctive surgical debulking of the papillary muscle was performed.
To ensure complete relief of subaortic obstruction, 8 patients (6%) required mitral valve repair with plication of anterior mitral leaflets. Mitral ring annuloplasty was performed in 3 patients with severe mitral regurgitation because of intrinsic degenerative valvular disease. At the time of myectomy, concurrent procedures were performed in 15 patients, coronary artery bypass grafting in 12, and subaortic membrane resection in 3. In association with myectomy, a bi-atrial Cox-Maze III or IV procedure with removal of the left atrial appendage was performed in selected patients with a history of symptomatic paroxysmal atrial fibrillation (AF).
Decisions to implant a primary prevention implantable cardioverter-defibrillator (ICD) in 56 patients after or before myectomy was based on the presence of ≥1 conventional sudden death risk marker, in accord with 2020 American Heart Association/American college of Cardiology (AHA/ACC) management guidelines for HCM. Defibrillator discharges were considered appropriate therapy when triggered by ventricular fibrillation or rapid ventricular tachycardia, documented by stored electrographic data.
Continuous and categorical data are expressed as mean (±SD) or n (%). Comparisons of characteristics between groups were made with unpaired Student t test, one-way ANOVA, chi-square tests, or Fisher’s exact test where appropriate. A p value <0.05 was considered statistically significant.
The survival analysis model used proportional hazards regression methodology. Kaplan-Meier survival curves were compared using log-rank statistics. End points were all-cause and HCM-related mortality (sudden cardiac death, heart failure death, or stroke death related to embolic stroke secondary to atrial fibrillation).
For comparison with myectomy patients, the expected survival curve for the general population was generated from the United States Health Statistics, based on all-cause mortality. Each myectomy patient was matched to the United States population by age, gender, and year of operation.
Results
Clinical and demographic characteristics of the overall study population of 139 patients are summarized in Table 1 . Over the follow-up period, a total of 129 patients (93%) survived ≥10 years from the time of surgery, including 10 to 14 years in 112 patients and ≥15 years in 17 patients (range to 17 years).( Figure 1 ) Of these 129 long-term myectomy survivors, 118 had detailed current clinical follow-up for which 109 (92%) experienced sustained improvement in limiting heart failure symptoms to NYHA classes I or II at 11.3 ± 2.7 years postoperatively, including 64 (54%) who were asymptomatic in class I at last follow-up ( Figures 1 and 2 ).
| Variable | 139 HCM PatientsUndergoing Myectomy ≥10 y Before |
|---|---|
| Male | 77 (55%) |
| Age at HCM diagnosis (years) | 44±16 |
| Age at Myectomy (years) | 50±15 |
| Age <30 y at time of surgery | 12 (9%) |
| Age ≥60 y at time of surgery | 37 (26%) |
| Age at Last Follow-Up, (years) | 60±15 |
| Age 60–69 at last follow-up | 31 (22%) |
| Age 70–79 at last follow-up | 31 (22%) |
| Age ≥80 at last follow-up | 11 (8%) |
| LVOT resting gradient, (mm Hg) | 56±40 |
| LVOT resting gradient≥50 mm Hg | 85 (61%) |
| Maximum LV Thickness, (mm) | 21±5.3 |
| Maximum LV Thickness≤15 mm | 10 (7%) |
| Maximum LV Thickness≥30 mm | 10 (7%) |
| LV ejection fraction, (%) | 66±4 |
| Left Atrial Dimension, (mm) | 42±6 |
| LVED (mm) | 42±6 |
| CMR studies | 58 (42%) |
| Presence of LGE | 28 (48%) |
| If present, degree of LGE (%) | 3.4±2.7 |
| If present, LGE≥15% of LV | 0 |
| Family history of HCM | 47 (34%) |
| Family history HCM-related sudden death | 15 (11%) |
| NSVT on ambulatory monitor | 13 (9%) |
| Unexplained syncope, | 17 (12%) |
| NYHA functional classification: | |
| I | 0 |
| II | 2 * (1.4%) |
| III | 136 (98%) |
| IV | 1 (0.7%) |
| Atrial fibrillation | 24 (17%) |
| Previous alcohol septal ablation | 3 (2%) |
| No. patients with ICDs before myectomy | 25 (18%) |
| Appropriate ICD interventions | 3 (2%) |
| Resuscitated cardiac arrest | 0 |
| Drug Therapy before to myectomy: | |
| β-blockers | 108 (78%) |
| Calcium channel blockers | 52 (37%) |
| Disopyramide | 15 (11%) |
| Genetic Testing performed: | 32 |
| Pathogenic/likely pathogenic gene identified, n (%) | 15 (47%) |
| MYBPC3 | 9 |
| MYH7 | 3 |
| TNNT2 | 2 |
| TNNI3 | 1 |
| Most recent echocardiography | |
| Time from myectomy, (years) | 8.2±2.8 |
| LVOT gradient, (mm Hg) | 1.2±7 |
| LVOT resting gradient≥50 mm Hg, | 0 |
| LV ejection fraction, (%) | 58±9 |
| LV ejection fraction<50%, | 9 (7.6%) |
| Left Atrial Dimension, (mm) | 43±7 |
| Left ventricular end-diastolic dimension | 45±8 |
| NYHA functional class at most recent follow-up ‡ | |
| I | 64 (54%) |
| II | 45 (38%) |
| III/IV | 9 (8%) |
| New onset AF after myectomy | 22 of 110 (20%) |
| Recurrent AF after Maze procedure at myectomy | 11 of 23 (48%) |
| Time from Maze to recurrent AF | 4.2 (1.3, 5.6) |
| Stroke | 4 of 137 (3%) |
| Time from myectomy to stroke | 5.9±3.8 |
| Appropriate ICD intervention for VT/VF after myectomy | 6 |
| Out of hospital cardiac arrest | 0 |
| Need for repeat cardiac intervention | 9 |
| Time from myectomy, (years) | 8.8±3.6 |
| Mitral valve replacement | 3 |
| Aortic valve replacement | 6 † |
| Cardiac transplant | 4 (3%) |
| Death | 17 (12%) |
| Non-HCM related | 15 |
| HCM related | 2 |
| HF death | 1 |
| Stroke death | 1 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
