HOME SUBSCRIPTIONS CURRENT ISSUE PAST ISSUES CARDIOSOURCE SEARCH HELP FEEDBACK		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (39) Citing Articles via Google Scholar Google Scholar Articles by Ommen, S. R. Articles by Nishimura, R. A. Search for Related Content PubMed PubMed Citation Articles by Ommen, S. R. Articles by Nishimura, R. A. Related Collections Related Article

CLINICAL RESEARCH: HYPERTROPHIC AND DILATED CARDIOMYOPATHY

Long-Term Effects of Surgical Septal Myectomy on Survival in Patients With Obstructive Hypertrophic Cardiomyopathy

Steve R. Ommen, MD, FACC^_*,_*, Barry J. Maron, MD, FACC^_*,, Iacopo Olivotto, MD, Martin S. Maron, MD^||, Franco Cecchi, MD, Sandro Betocchi, MD, FACC^¶, Bernard J. Gersh, MB, ChB, DPhil, FACC^_*, Michael J. Ackerman, MD, PhD, FACC^_*, Robert B. McCully, MB, ChB, FACC^_*, Joseph A. Dearani, MD, Hartzell V. Schaff, MD, FACC, Gordon K. Danielson, MD, FACC, A. Jamil Tajik, MD, FACC^_* and Rick A. Nishimura, MD, FACC^_*

^_* Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota
Cardiac Surgery, Mayo Clinic College of Medicine, Rochester, Minnesota
Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, Minneapolis, Minnesota
Regional Referral Center for Myocardial Diseases, Azienda Ospedaliera Careggi, Florence, Italy
^|| Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts-New England Medical Center, Boston, Massachusetts
^¶ Department of Clinical Medicine, Cardiovascular and Immunological Sciences, Federico II University of Naples, Naples, Italy.

Manuscript received September 30, 2004; revised manuscript received February 1, 2005, accepted February 14, 2005.

^_* Reprint requests and correspondence: Dr. Steve R. Ommen, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905. (Email: ommen.steve{at}mayo.edu).

	Abstract

Top Abstract Methods Results Discussion References

 
OBJECTIVES: This study sought to determine the impact of surgical myectomy on long-term survival in hypertrophic cardiomyopathy (HCM).

BACKGROUND: Left ventricular (LV) outflow tract obstruction in HCM increases the likelihood of heart failure and cardiovascular death. Although surgical myectomy is the primary treatment for amelioration of outflow obstruction and advanced drug-refractory heart failure symptoms, its impact on long-term survival remains unresolved.

METHODS: Total and HCM-related mortality were compared in three subgroups comprised of 1,337 consecutive HCM patients evaluated from 1983 to 2001: 1) surgical myectomy (n = 289); 2) LV outflow obstruction without operation (n = 228); and 3) nonobstructive (n = 820). Mean follow-up duration was 6 ± 6 years.

RESULTS: Including two operative deaths (procedural mortality, 0.8%), 1-, 5-, and 10-year overall survival after myectomy was 98%, 96%, and 83%, respectively, and did not differ from that of the general U.S. population matched for age and gender (p = 0.2) nor from patients with nonobstructive HCM (p = 0.8). Compared to nonoperated obstructive HCM patients, myectomy patients experienced superior survival free from all-cause mortality (98%, 96%, and 83% vs. 90%, 79%, and 61%, respectively; p < 0.001), HCM-related mortality (99%, 98%, and 95% vs. 94%, 89%, and 73%, respectively; p < 0.001), and sudden cardiac death (100%, 99%, and 99% vs. 97%, 93%, and 89%, respectively; p = 0.003). Multivariate analysis showed myectomy to have a strong, independent association with survival (hazard ratio 0.43; p < 0.001).

CONCLUSIONS: Surgical myectomy performed to relieve outflow obstruction and severe symptoms in HCM was associated with long-term survival equivalent to that of the general population, and superior to obstructive HCM without operation. In this retrospective study, septal myectomy seems to reduce mortality risk in severely symptomatic patients with obstructive HCM.

Abbreviations and Acronyms   HCM = hypertrophic cardiomyopathy   LV = left ventricle/ventricular   NYHA = New York Heart Association

Surgical septal myectomy has been performed effectively for over 40 years as the primary treatment strategy for such HCM patients of all ages, with substantial long-term hemodynamic and symptomatic benefits attributable to the operation (8–28). However, a major unresolved issue concerns whether surgical myectomy, often performed in relatively young patients, has a beneficial impact on long-term survival. A unique aspect of this study is the opportunity to compare long-term outcome in a large surgical series with that in a cohort of medically managed HCM patients, as well as the expected survival in the general population, to determine whether surgical relief of LV outflow obstruction by myectomy has clinical benefit beyond improvement in the quality of life.

	Methods

Top Abstract Methods Results Discussion References

 
Selection of patients.   The study population of 1,337 consecutive HCM patients is composed of three retrospectively identified subgroups evaluated from 1983 to 2001: 289 patients with isolated surgical ventricular septal myectomy at Mayo Clinic; 64 other patients with myectomy during this period who had additional operative procedures performed concomitantly (e.g., valve replacement, coronary artery bypass grafting) were excluded. The Mayo Clinic is a long-standing tertiary HCM center with patients referred on a national basis, and has maintained a special expertise in performing the septal myectomy operation for over 40 years. Comparison subgroups totaling 1,048 nonoperated HCM patients were included in this study: 1) 228 patients with left ventricular outflow obstruction 30 mm Hg at rest; these patients had not been recommended for myectomy largely because of insufficiently advanced symptoms or because of ongoing medical treatment for severe functional limitation; and 2) 820 patients without outflow obstruction who, by convention, were not considered candidates for surgery. These two comparison groups were assembled from three other HCM centers with large cohorts but not with specialized surgical experience in this disease (Minneapolis Heart Institute Foundation; Azienda Ospedaliera Careggi, Florence, Italy; and Federico II University of Naples, Italy). Selected clinical data from these 1,048 patients have been included in a prior report (4).

The most recent vital status was obtained for each of the 1,337 study patients by clinic visit or mailed questionnaire. This study received approval by institutional review board (or its equivalent) at each participating center.

Echocardiography.   The diagnosis of HCM was based on the presence of a hypertrophied nondilated LV in the absence of other diseases capable of producing the magnitude of the hypertrophy evident (29). Echocardiographic parameters were measured as previously described (4,29). The LV outflow tract gradient was assessed under resting (basal) conditions, using continuous wave Doppler echocardiography (4,29), at the initial evaluation in the participating institution (or just before myectomy), and also 3.2 ± 3 years after myectomy.

Surgery.   Criteria for surgical intervention at the Mayo Clinic were LV outflow obstruction 50 mm Hg at rest or with provocative maneuvers attributable to systolic anterior motion of the mitral valve, associated with New York Heart Association (NYHA) functional classes III to IV limitation (or repetitive and disabling effort-related syncope) despite maximum medical management (6,7,24). The septal myectomy operation in the present cohort was predominantly that described by Morrow et al. (8,10,11). This procedure, performed through an aortotomy, creates a rectangular trough via two parallel longitudinal incisions in the basal septum. Incisions are connected proximally below the aortic valve and extended distally just beyond the level of mitral-septal contact and subaortic obstruction, or in some patients to the base of the papillary muscles (i.e., extended myectomy).

Statistical analysis.   Data are expressed as mean ± SD. One-way analysis of variance was used to compare normally distributed data. Noncontinuous data were analyzed using chi-square tests. The p values are two-sided; p < 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 mortality and HCM-related mortality. Deaths within 30 days after myectomy were considered operative deaths and are included in both end points. The HCM mortality included sudden cardiac death (unexpected within 1 h of witnessed collapse or nocturnal), heart failure death (in context of progressive cardiac decompensation), and stroke-related death (30). Appropriate discharges from implantable defibrillators for ventricular fibrillation or sustained ventricular tachycardia (n = 8) were regarded as sudden deaths (30). Survival was censored at cardiac transplantation in 9 patients with end-stage heart failure and at the time of percutaneous septal ablation in 20 nonoperated patients with LV outflow obstruction.

Follow-up for nonoperated HCM patients began at the initial clinical evaluation at the participating institution. For myectomy patients, follow-up began on the day of operation (4.8 ± 12 months after initial evaluation). Mean follow-up duration was 6.2 ± 6 years.

To determine whether differences in survival between the myectomy and the other nonoperated HCM groups could be explained by disease-related variables other than the operation, univariate and multivariate Cox proportional hazard regression analyses were performed (Table 1). Statistically significant variables from the univariate analysis were entered stepwise into the multivariate regression model.

	Results

Top Abstract Methods Results Discussion References

 
Baseline characteristics.   Myectomy and nonoperated obstructive HCM patients were similar with respect to the initial LV outflow gradient at rest (67 vs. 68 mm Hg, respectively; p = 0.9) (Table 1). Myectomy patients were younger (45 vs. 50 years; p = 0.01) and had larger left atrial (47 vs. 45 mm; p = 0.001) and LV end-diastolic cavity dimensions (44 vs. 42 mm; p = 0.001). Because advanced symptoms refractory to pharmacologic therapy represent the standard indication for operation, myectomy patients expectedly showed more severe functional disability at study entry: 89% in NYHA functional classes III to IV compared with 15% in the nonoperated obstructive HCM group (p < 0.001).

Clinical benefits of myectomy.   The surgical myectomy group experienced substantial symptomatic and hemodynamic improvement after myectomy; 255 (89%) patients were in NYHA functional classes III to IV before operation, whereas only 12 (6%) were in classes III to IV at the most recent follow-up. The mean functional class was 2.9 ± 0.7 before myectomy and 1.5 ± 0.7 at last postmyectomy follow-up (p < 0.001). The average preoperative outflow gradient at rest was 67 ± 41 mm Hg, and decreased to 3 ± 8 mm Hg postoperatively (p < 0.001). Nonfatal complications included ventricular septal defect in two patients (0.8%) and complete heart block requiring permanent pacemaker in three (1%).

Survival after myectomy.   There were 25 deaths after myectomy, including 2 related to operation (operative mortality, 0.8%); both operative deaths involved patients with NYHA functional class IV heart failure who underwent emergency myectomy at 64 and 71 years of age. Seven other deaths were probably or definitely caused by HCM (5 sudden deaths and 2 due to heart failure), and 16 were noncardiac deaths. Mean age at death was 64 ± 12 years (range, 22 to 82 years), occurring 6.8 ± 5 years (range, 0.2 to 17 years) after myectomy.

The 1-, 5-, and 10-year overall survival after myectomy was 98%, 96%, and 83%, respectively, and did not differ from the age- and gender-matched general population (98%, 95%, and 88%, respectively; log-rank p = 0.2) (Fig. 1).

View larger version (12K): [in this window] [in a new window]   Figure 1 Survival free from all-cause mortality after surgical myectomy for obstructive hypertrophic cardiomyopathy (n = 289) compared with the age- and gender-matched general U.S. white population. Log-rank, p = 0.2.

View larger version (17K): [in this window] [in a new window]   Figure 2 Survival free from all-cause mortality in three hypertrophic cardiomyopathy patient subgroups: surgical myectomy (n = 289), nonoperated with obstruction (n = 228), and nonobstructive (n = 820). Overall log-rank, p < 0.001; myectomy versus nonoperated obstructive hypertrophic cardiomyopathy, p < 0.001; myectomy versus nonobstructive hypertrophic cardiomyopathy, p = 0.8.

View larger version (19K): [in this window] [in a new window]   Figure 3 Survival free from hypertrophic cardiomyopathy-related death among patients in three hypertrophic cardiomyopathy (HCM) subgroups: surgical myectomy (n = 289), nonoperated with obstruction (n = 228), and nonobstructive (n = 820). Overall log-rank, p < 0.001; myectomy versus nonoperated obstructive hypertrophic cardiomyopathy, p < 0.001; myectomy versus nonobstructive hypertrophic cardiomyopathy, p = 0.01.

View larger version (19K): [in this window] [in a new window]   Figure 4 Survival free from sudden cardiac death among patients in three hypertrophic cardiomyopathy subgroups: surgical myectomy (n = 289), nonoperated with obstruction (n = 228), and nonobstructive (n = 820). Overall log-rank, p = 0.003; myectomy versus nonoperated obstructive hypertrophic cardiomyopathy, p = 0.003; myectomy versus nonobstructive hypertrophic cardiomyopathy, p = 0.3.

When confining the analysis to those patients 45 years old at study entry, thereby reducing the potentially confounding age-related co-morbidities such as coronary artery disease, patients treated with surgical myectomy continued to show significantly better survival than nonoperated obstructive HCM patients (overall survival HR 0.28; p < 0.001; HCM-related survival HR 0.25; p = 0.004). The 1-, 5-, and 10-year survival after myectomy was 99%, 98%, and 92%, respectively, as compared with 92%, 88%, and 75%, respectively (log-rank p = 0.006) for the nonoperated obstructive HCM patients.

	Discussion

Top Abstract Methods Results Discussion References

 
Based on over four decades of worldwide experience, and the recent American College of Cardiology-European Society of Cardiology Expert Consensus Guidelines, septal myectomy is considered the gold-standard strategy for the relief of drug-refractory symptoms in HCM patients with LV outflow obstruction (1–3,5–7). Septal myectomy, by virtue of abolishing LV outflow obstruction and mitral regurgitation and normalizing intracardiac pressures, wall stress, myocardial oxygen demand, metabolism, and coronary flow, has been shown consistently to improve both exercise capacity and quality of life (12,15,24). Because of the cumulative experience and improved myocardial protection techniques, operative mortality associated with myectomy has diminished dramatically from the initial surgical reports. At present, procedural risk is <1% to 2% at experienced centers, and, in fact, has approached zero in the most recent patients (6,17,20,22,23,27,32–36).

Whether the salutary hemodynamic and clinical effects of myectomy translate into enhanced long-term postoperative survival remains unresolved. Clarification of this pivotal issue has been impeded by certain insurmountable practical and ethical obstacles implicit in performing prospective, randomized trials comparing myectomy with other treatment strategies in severely symptomatic patients. These include the well-documented efficacy of myectomy for relieving symptoms, the relative infrequency with which this operation is performed (i.e., 5% of all HCM patients) (2,5,6), and the particularly long-term follow-up that would be required. It is unlikely that such trials will ever take place.

The present study provides the strongest evidence to date showing that surgical relief of obstruction may improve long-term survival. Although this study is necessarily retrospective, we have taken the unique opportunity to assess long-term outcome after septal myectomy in one of the longest-standing and continuous surgical referral programs (7,14,24). Outcomes were compared with an age- and gender-matched general U.S. population, and to recently available cohorts of nonoperated HCM patients (4). Taken together, these data afford substantial evidence of favorable (possibly enhanced) long-term survival after surgical myectomy.

Long-term survival free from HCM-related mortality after myectomy was excellent (95% at 10 years). Furthermore, the 10-year overall postoperative survival free from all-cause mortality did not differ from that of the general population, suggesting that myectomy may afford patients the opportunity to achieve normal or near-normal longevity. This observation is of particular relevance given the youthful age (mean, 45 years) of the operated patients. Notably, the comparison group of patients with LV outflow obstruction who did not undergo myectomy experienced a much less favorable outcome with greater than twice the overall mortality risk observed in myectomy patients. These data also suggest that the likelihood of sudden death was reduced after myectomy (compared with nonoperated patients); however, the events were not abolished after operation, indicating that independent risk stratification is still required for patients undergoing this procedure (2,4,6,7).

Unavoidably, rigorous matching of myectomy and nonoperated patients was not possible. Nevertheless, we regard the statistical comparisons and derived conclusions valid and clinically relevant. First, the postoperative survival of myectomy patients was indistinguishable from that of the general population. Second, the multivariate analyses clearly identified myectomy as a strong, independent determinant of survival, substantiating that the differences in long-term survival documented here are likely attributable to surgical relief of the subaortic gradient. Third, despite significantly more advanced preoperative symptoms, myectomy patients nevertheless showed long-term survival that greatly exceeded that of the less symptomatic nonoperated obstructive HCM patients. Fourth, analysis of patients 45 years old, reducing the potential for confounding age-related variables, showed nearly identical results to the primary analysis with a greater than three-fold increase in risk of mortality among obstructive HCM patients managed without surgery.

The operative results reported here represent those achieved by an experienced surgical referral center and therefore constitute a measure of the most favorable outcome that can be expected from septal myectomy (6,7,16,24). Indeed, we believe that this surgical series was most relevant to understanding the optimal benefits that can be achieved with surgical intervention in drug-refractory, severely symptomatic patients with obstructive HCM. However, it is inappropriate to extrapolate these findings to low-volume surgical centers or alternative treatment modalities such as catheter-based alcohol septal ablation, for which follow-up is comparatively brief and post-procedural outcome is incompletely defined (6,35–37). In addition to showing an impressive survival advantage for myectomy, our data also support the standard recommendation to intervene in obstructive HCM patients (with myectomy, or selectively with alternatives such as alcohol septal ablation) when refractory heart failure symptoms have progressed to NYHA functional classes III to IV (6,7,24). However, we do not regard as prudent using these data to justify or promote earlier major interventions with more lenient eligibility criteria in mildly symptomatic patients.

Survival analysis designs that include surgical patients can be problematic in part because by definition surgical patients have 100% survival up to the date of operation, and operative candidates who die while awaiting operation are not included in the analysis. The survival analysis presented in this study was judged to be the most appropriate and reliable model for these purposes. However, we had prospectively identified two additional survival analysis models. The first alternative model excluded all deaths in the nonoperated comparison HCM groups that occurred within six months of study entry. The second alternative strategy treated myectomy as a time-dependent variable with all operated and nonoperated patients having the same study entry point, i.e., the date of first evaluation at each participating center. Most importantly, both of these alternative analyses yielded substantially the same outcome results as the survival model used in the present study.

We prospectively defined cardiac events and the statistical methodology based on precedent, and our judgment that this strategy appropriately reflected the clinical scenario studied here. Nonetheless, to examine whether our event definitions unduly influenced the results, we retrospectively reanalyzed the data with implantable cardioverter-defibrillator discharge and alcohol septal ablation considered as inconsequential (non-events) and cardiac transplantation considered as a surrogate for cardiac death. With these alternative definitions, the survival results were unchanged from the principal analysis presented in the report.

In conclusion, the data presented here offer considerable evidence showing that surgical myectomy in patients with obstructive HCM not only vastly improves quality of life, but also enhances survival over that that would otherwise be expected as a consequence of longstanding LV outflow tract obstruction. In accord with contemporary consensus panel recommendations (6), the present findings support septal myectomy as the primary treatment for HCM patients with severe drug-refractory symptoms caused by LV outflow obstruction.

	References

Top Abstract Methods Results Discussion References

 

1. Wigle ED, Rakowski H, Kimball B, Wiliams WG. Hypertrophic cardiomyopathy. Clinical spectrum and treatment Circulation 1995;92:1680-1692.[Free Full Text]
2. Maron BJ. Hypertrophic cardiomyopathya systematic review. JAMA 2002;287:1308-1320.[Abstract/Free Full Text]
3. Wigle ED, Sasson Z, Henderson MA, et al. Hypertrophic cardiomyopathy. The importance of the site and the extent of hypertrophy. A review Prog Cardiovasc Dis 1985;28:1-83.[CrossRef][ISI][Medline]
4. Maron M, Olivotto I, Betocchi S, et al. Effect of left ventricular outflow tract obstruction on clinical outcome in hypertrophic cardiomyopathy N Engl J Med 2003;348:295-303.[Abstract/Free Full Text]
5. Spirito P, Seidman CE, McKenna WJ, Maron BJ. The management of hypertrophic cardiomyopathy N Engl J Med 1997;336:775-785.[Free Full Text]
6. Maron BJ, McKenna W, Danielson GK, et al. ACC/ESC clinical expert consensus document on hypertrophic cardiomyopathya report of the American College of Cardiology Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines (Committee to Develop an Expert Consensus Document on Hypertrophic Cardiomyopathy). J Am Coll Cardiol 2003;42:1687-1713.[Free Full Text]
7. Nishimura RA, Holmes Jr DR. Hypertrophic obstructive cardiomyopathy N Engl J Med 2004;350:1320-1327.[Free Full Text]
8. Morrow AG. Operative methods utilized to relieve left ventricular outflow obstruction J Thorac Cardiovasc Surg 1978;76:423-430.[Abstract]
9. Kirklin J, Ellis Jr F. Surgical relief of diffuse subvalvular aortic stenosis Circulation 1961;24:739-742.[Abstract/Free Full Text]
10. Morrow AG, Reitz BA, Epstein SE, et al. Operative treatment in hypertrophic subaortic stenosis. Techniques, and the results of pre and postoperative assessments in 83 patients Circulation 1975;52:88-102.[Abstract/Free Full Text]
11. Maron BJ, Merrill WH, Freier PA, Kent KM, Epstein SE, Morrow AG. Long-term clinical course and symptomatic status of patients after operation for hypertrophic subaortic stenosis Circulation 1978;57:1205-1213.[Abstract/Free Full Text]
12. Redwood DR, Goldstein RE, Hirshfeld J, et al. Exercise performance after septal myotomy and myectomy in patients with obstructive hypertrophic cardiomyopathy Am J Cardiol 1979;44:215-220.[CrossRef][ISI][Medline]
13. Maron BJ, Epstein SE, Morrow AG. Symptomatic status and prognosis of patients after operation for hypertrophic obstructive cardiomyopathyefficacy of ventricular septal myotomy and myectomy. Eur Heart J 1983;4:175-185.
14. Beahrs MM, Tajik AJ, Seward JB, Giuliani ER, McGoon DC. Hypertrophic obstructive cardiomyopathyten- to 21-year follow-up after partial septal myectomy. Am J Cardiol 1983;51:1160-1166.[CrossRef][ISI][Medline]
15. Cannon III RO, McIntosh CL, Schenke WH, Maron BJ, Bonow RO, Epstein SE. Effect of surgical reduction of left ventricular outflow obstruction on hemodynamics, coronary flow, and myocardial metabolism in hypertrophic cardiomyopathy Circulation 1989;79:766-775.[Abstract/Free Full Text]
16. Mohr R, Schaff HV, Danielson GK, Puga FJ, Pluth JR, Tajik AJ. The outcome of surgical treatment of hypertrophic obstructive cardiomyopathy. Experience over 15 years J Thorac Cardiovasc Surg 1989;97:666-674.[Abstract]
17. Cohn LH, Trehan H, Collins Jr JJ. Long-term follow-up of patients undergoing myotomy/myectomy for obstructive hypertrophic cardiomyopathy Am J Cardiol 1992;70:657-660.[CrossRef][ISI][Medline]
18. Schulte HD, Borisov K, Gams E, Gramsch-Zabel H, Losse B, Schwartzkopff B. Management of symptomatic hypertrophic obstructive cardiomyopathy—long-term results after surgical therapy Thorac Cardiovasc Surg 1999;47:213-218.[ISI][Medline]
19. McIntosh CL, Maron BJ. Current operative treatment of obstructive hypertrophic cardiomyopathy Circulation 1988;78:487-495.[Free Full Text]
20. ten Berg JM, Suttorp MJ, Knaepen PJ, Ernst SM, Vermeulen FE, Jaarsma W. Hypertrophic obstructive cardiomyopathy. Initial results and long-term follow-up after Morrow septal myectomy Circulation 1994;90:1781-1785.[Abstract/Free Full Text]
21. Heric B, Lytle BW, Miller DP, Rosenkranz ER, Lever HM, Cosgrove DM. Surgical management of hypertrophic obstructive cardiomyopathy. Early and late results J Thorac Cardiovasc Surg 1995;110:195-206.[Abstract/Free Full Text]
22. Theodoro DA, Danielson GK, Feldt RH, Anderson BJ. Hypertrophic obstructive cardiomyopathy in pediatric patientsresults of surgical treatment. J Thorac Cardiovasc Surg 1996;112:1589-1597.[Abstract/Free Full Text]
23. Schoendube FA, Klues HG, Reith S, Flachskampf FA, Hanrath P, Messmer BJ. Long-term clinical and echocardiographic follow-up after surgical correction of hypertrophic obstructive cardiomyopathy with extended myectomy and reconstruction of the subvalvular mitral apparatus Circulation 1995;92:II122-II127.
24. McCully RB, Nishimura RA, Tajik AJ, Schaff HV, Danielson GK. Extent of clinical improvement after surgical treatment of hypertrophic obstructive cardiomyopathy Circulation 1996;94:467-471.[Abstract/Free Full Text]
25. Williams WG, Wigle ED, Rakowski H, Smallhorn J, LeBlanc J, Trusler GA. Results of surgery for hypertrophic obstructive cardiomyopathy Circulation 1987;76:V104-V108.
26. Schönbeck MH, Brunner-La Rocca HP, Vogt PR, et al. Long-term follow-up in hypertrophic obstructive cardiomyopathy after septal myectomy Ann Thorac Surg 1998;65:1207-1214.[Abstract/Free Full Text]
27. Merrill WH, Friesinger GC, Graham Jr. TP, et al. Long-lasting improvement after septal myectomy for hypertrophic obstructive cardiomyopathy Ann Thorac Surg 2000;69:1732-1735discussion 1735–6.[Abstract/Free Full Text]
28. Robbins RC, Stinson EB. Long-term results of left ventricular myotomy and myectomy for obstructive hypertrophic cardiomyopathy J Thorac Cardiovasc Surg 1996;111:586-594.[Abstract/Free Full Text]
29. Klues HG, Schiffers A, Maron BJ. Phenotypic spectrum and patterns of left ventricular hypertrophy in hypertrophic cardiomyopathymorphologic observations and significance as assessed by two-dimensional echocardiography in 600 patients. J Am Coll Cardiol 1995;26:1699-1708.[Abstract]
30. Maron BJ, Olivotto I, Spirito P, et al. Epidemiology of hypertrophic cardiomyopathy-related deathrevisited in a large non-referral-based patient population. Circulation 2000;102:858-864.[Abstract/Free Full Text]
31. Therneau T, Offord J. Expected Survival Based on Hazard Rates (update)Rochester, MN: Section of Biostatistics, Mayo Clinic; 1999. pp. 1-26.
32. van der Lee C, Kofflard MJ, van Herwerden LA, Vletter W, ten Cate FJ. Sustained improvement after combined anterior mitral leaflet extension and myectomy in hypertrophic obstructive cardiomyopathy Circulation 2003;108:2088-2092.[Abstract/Free Full Text]
33. Ommen SR, Thomson HL, Nishimura RA, Tajik AJ, Schaff HV, Danielson GK. Clinical predictors and consequences of atrial fibrillation after surgical myectomy for obstructive hypertrophic cardiomyopathy Am J Cardiol 2002;89:242-244.[CrossRef][ISI][Medline]
34. Ommen SR, Park SH, Click RL, Freeman WK, Schaff HV, Tajik AJ. Impact of intraoperative transesophageal echocardiography in the surgical management of hypertrophic cardiomyopathy Am J Cardiol 2002;90:1022-1024.[CrossRef][ISI][Medline]
35. Nagueh SF, Ommen SR, Lakkis NM, et al. Comparison of ethanol septal reduction therapy with surgical myectomy for the treatment of hypertrophic obstructive cardiomyopathy J Am Coll Cardiol 2001;38:1701-1706.[Abstract/Free Full Text]
36. Qin JX, Shiota T, Lever HM, et al. Outcome of patients with hypertrophic obstructive cardiomyopathy after percutaneous transluminal septal myocardial ablation and septal myectomy surgery J Am Coll Cardiol 2001;38:1994-2000.[Abstract/Free Full Text]
37. Firoozi S, Elliott PM, Sharma S, et al. Septal myotomy-myectomy and transcoronary septal alcohol ablation in hypertrophic obstructive cardiomyopathy. A comparison of clinical, haemodynamic and exercise outcomes Eur Heart J 2002;23:1617-1624.[Abstract/Free Full Text]

This article has been cited by other articles:

				T. Le Tourneau, S. Susen, C. Caron, A. Millaire, S. Marechaux, A.-S. Polge, A. Vincentelli, F. Mouquet, P.-V. Ennezat, N. Lamblin, et al. Functional Impairment of Von Willebrand Factor in Hypertrophic Cardiomyopathy: Relation to Rest and Exercise Obstruction Circulation, October 7, 2008; 118(15): 1550 - 1557. [Abstract] [Full Text] [PDF]

				R. T Murphy Bringing the obstruction back into hypertrophic cardiomyopathy Heart, October 1, 2008; 94(10): 1249 - 1250. [Full Text] [PDF]

				D H Kwon, R M Setser, M Thamilarasan, Z V Popovic, N G Smedira, P Schoenhagen, M J Garcia, H M Lever, and M Y Desai Abnormal papillary muscle morphology is independently associated with increased left ventricular outflow tract obstruction in hypertrophic cardiomyopathy Heart, October 1, 2008; 94(10): 1295 - 1301. [Abstract] [Full Text] [PDF]

				S R Ommen, P M Shah, and A J Tajik Left ventricular outflow tract obstruction in hypertrophic cardiomyopathy: past, present and future Heart, October 1, 2008; 94(10): 1276 - 1281. [Full Text] [PDF]

				D. H. Kwon, S. R. Kapadia, E. M. Tuzcu, C. M. Halley, E. Z. Gorodeski, R. J. Curtin, M. Thamilarasan, N. G. Smedira, B. W. Lytle, H. M. Lever, et al. Long-Term Outcomes in High-Risk Symptomatic Patients With Hypertrophic Cardiomyopathy Undergoing Alcohol Septal Ablation J. Am. Coll. Cardiol. Intv., August 1, 2008; 1(4): 432 - 438. [Abstract] [Full Text] [PDF]

				P. Sorajja, U. Valeti, R. A. Nishimura, S. R. Ommen, C. S. Rihal, B. J. Gersh, D. O. Hodge, H. V. Schaff, and D. R. Holmes Jr Outcome of Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy Circulation, July 8, 2008; 118(2): 131 - 139. [Abstract] [Full Text] [PDF]

				P. Ferrazzi, M. Triggiani, and A. Iacovoni Debating About a Registry to Define the Best Invasive Treatment for Obstructive Hypertrophic Cardiomyopathy: Should It Also Include Obstructive Patients Medically Treated? J. Am. Coll. Cardiol., March 25, 2008; 51(12): 1233 - 1234. [Full Text] [PDF]

				I. Olivotto, S. R. Ommen, M. S. Maron, F. Cecchi, and B. J. Maron Reply J. Am. Coll. Cardiol., March 25, 2008; 51(12): 1234 - 1235. [Full Text] [PDF]

				A. J. Mittnacht, M. Fanshawe, and S. Konstadt Anesthetic Considerations in the Patient With Valvular Heart Disease Undergoing Noncardiac Surgery Seminars in Cardiothoracic and Vascular Anesthesia, March 1, 2008; 12(1): 33 - 59. [Abstract] [PDF]

				M. A. Fifer and G. J. Vlahakes Management of Symptoms in Hypertrophic Cardiomyopathy Circulation, January 22, 2008; 117(3): 429 - 439. [Full Text] [PDF]

				N. G. Smedira, B. W. Lytle, H. M. Lever, J. Rajeswaran, G. Krishnaswamy, R. K. Kaple, D. O.W. Dolney, and E. H. Blackstone Current Effectiveness and Risks of Isolated Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy Ann. Thorac. Surg., January 1, 2008; 85(1): 127 - 133. [Abstract] [Full Text] [PDF]

				R. F. Padera Jr. and F. J. Schoen Pathology of Cardiac Surgery Card. Surg. Adult, January 1, 2008; 3(2008): 111 - 178. [Full Text]

				M. Enriquez-Sarano, V. T. Nkomo, and H. Michelena Principles and Practice of Echocardiography in Cardiac Surgery Card. Surg. Adult, January 1, 2008; 3(2008): 315 - 348. [Full Text]

				M. W. Hansen and N. Merchant MRI of Hypertrophic Cardiomyopathy: Part 2, Differential Diagnosis, Risk Stratification, and Posttreatment MRI Appearances Am. J. Roentgenol., December 1, 2007; 189(6): 1344 - 1352. [Abstract] [Full Text] [PDF]

				C. J. McLeod, S. R. Ommen, M. J. Ackerman, P. L. Weivoda, W. K. Shen, J. A. Dearani, H. V. Schaff, A. J. Tajik, and B. J. Gersh Surgical septal myectomy decreases the risk for appropriate implantable cardioverter defibrillator discharge in obstructive hypertrophic cardiomyopathy Eur. Heart J., November 1, 2007; 28(21): 2583 - 2588. [Abstract] [Full Text] [PDF]

				S. Ommen, C. McLeod, M. Ackerman, and B. Gersh Can septal myectomy prevent sudden cardiac death in hypertrophic obstructive cardiomyopathy? reply Eur. Heart J., September 1, 2007; 28(17): 2177 - 2178. [Full Text] [PDF]

				I. Olivotto, S. R. Ommen, M. S. Maron, F. Cecchi, and B. J. Maron Surgical Myectomy Versus Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy: Will There Ever Be a Randomized Trial? J. Am. Coll. Cardiol., August 28, 2007; 50(9): 831 - 834. [Abstract] [Full Text] [PDF]

				B. J. Maron Surgical Myectomy Remains the Primary Treatment Option for Severely Symptomatic Patients With Obstructive Hypertrophic Cardiomyopathy Circulation, July 10, 2007; 116(2): 196 - 206. [Full Text] [PDF]

				M. A. Fifer Most Fully Informed Patients Choose Septal Ablation Over Septal Myectomy Circulation, July 10, 2007; 116(2): 207 - 216. [Full Text] [PDF]

				I. Barac, S. Upadya, R. Pilchik, G. Winson, M. Passick, F. A. Chaudhry, and M. V. Sherrid Effect of Obstruction on Longitudinal Left Ventricular Shortening in Hypertrophic Cardiomyopathy J. Am. Coll. Cardiol., March 20, 2007; 49(11): 1203 - 1211. [Abstract] [Full Text] [PDF]

				U. S. Valeti, R. A. Nishimura, D. R. Holmes, P. A. Araoz, J. F. Glockner, J. F. Breen, S. R. Ommen, B. J. Gersh, A. J. Tajik, C. S. Rihal, et al. Comparison of Surgical Septal Myectomy and Alcohol Septal Ablation With Cardiac Magnetic Resonance Imaging in Patients With Hypertrophic Obstructive Cardiomyopathy J. Am. Coll. Cardiol., January 23, 2007; 49(3): 350 - 357. [Abstract] [Full Text] [PDF]

				M. S. Maron, I. Olivotto, A. G. Zenovich, M. S. Link, N. G. Pandian, J. T. Kuvin, S. Nistri, F. Cecchi, J. E. Udelson, and B. J. Maron Hypertrophic Cardiomyopathy Is Predominantly a Disease of Left Ventricular Outflow Tract Obstruction Circulation, November 21, 2006; 114(21): 2232 - 2239. [Abstract] [Full Text] [PDF]

				R. M. Suri, J. A. Dearani, H. V. Schaff, G. K. Danielson, and F. J. Puga Long-term results of the Konno procedure for complex left ventricular outflow tract obstruction. J. Thorac. Cardiovasc. Surg., November 1, 2006; 132(5): 1064 - 1071. [Abstract] [Full Text] [PDF]

				C. J Knight Alcohol septal ablation for obstructive hypertrophic cardiomyopathy. Heart, September 1, 2006; 92(9): 1339 - 1344. [Full Text] [PDF]

				P. M. Elliott, J. R. Gimeno, M. T. Tome, J. Shah, D. Ward, R. Thaman, J. Mogensen, and W. J. McKenna Left ventricular outflow tract obstruction and sudden death risk in patients with hypertrophic cardiomyopathy Eur. Heart J., August 2, 2006; 27(16): 1933 - 1941. [Abstract] [Full Text] [PDF]

				P. Spirito and C. Autore Management of hypertrophic cardiomyopathy. BMJ, May 27, 2006; 332(7552): 1251 - 1255. [Full Text] [PDF]

				A. N. DeMaria, O. Ben-Yehuda, D. Berman, G. K. Feld, G. S. Ginsburg, B. H. Greenberg, W. Y.W. Lew, D. Sahn, and S. Tsimikas Highlights of the Year in JACC 2005 J. Am. Coll. Cardiol., January 3, 2006; 47(1): 184 - 202. [Full Text] [PDF]

H. Watkins and W. J. McKenna The Prognostic Impact of Septal Myectomy in Obstructive Hypertrophic Cardiomyopathy J. Am. Coll. Cardiol., August 2, 2005; 46(3): 477 - 479. [Full Text] [PDF]