European Heart Journal Advance Access originally published online on July 31, 2007
European Heart Journal 2007 28(17):2177-2178; doi:10.1093/eurheartj/ehm300
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Can septal myectomy prevent sudden cardiac death in hypertrophic obstructive cardiomyopathy? reply
Division of Cardiovascular Diseases and
Internal Medicine
Mayo Clinic
200 First Street SW
Rochester
USA
Division of Cardiovascular Diseases and
Internal Medicine
Mayo Clinic
200 First Street SW
Rochester
USA
Division of Cardiovascular Diseases and
Internal Medicine
Mayo Clinic
200 First Street SW
Rochester
USA
Division of Cardiovascular Diseases and
Internal Medicine
Mayo Clinic
200 First Street SW
Rochester
USA
E-mail address: ommen.steve{at}mayo.edu
We would like to thank Dr Efthimiadis, and his colleagues for their interest in our study1 and their critical reflection on the relationship between surgical myectomy and implantable-cardioverter defibrillator (ICD) discharge in hypertrophic cardiomyopathy (HCM).
The surgical myectomy has been demonstrated to be the ‘gold-standard’ in therapy for those symptomatic patients with drug-refractory HCM with significant outflow tract obstruction. Although significant improvements in haemodynamics, symptoms, morbidity, and mortality have been noted,2 a relatively small amount of myocardium is removed during the myectomy procedure (typically only a few grams).3 Nevertheless, this appears to be sufficient to ameliorate the haemodynamic milieu so that left ventricle pressures and wall stress is normalized. Dr Efthimiadis correctly identifies that the relationship between outflow tract gradients, sudden death, and surgery is complex. The potential mechanisms whereby surgical relief of obstruction may ameliorate ventricular arrhythmia include decreased wall stress, decreased intraventricular pressure, improved coronary perfusion pressure, decreased myocardial oxygen demand, decreased ischaemia, decreased sympathetic drive, and likely other factors.
We also firmly agree with the statement made in our study and implied by Dr Efthimiadis that prevention of sudden death should not be considered as a primary indication for surgical myectomy. The primary indication for myectomy persists—namely, patients with severe symptoms that are refractory to pharmacologic therapy. Indeed, in the absence of symptoms, there does not appear to be any significant relationship between obstructive physiology and sudden death.4
It is important to note that this is the experience of a single centre, and provides the basis for hypothesis generation, and further study. To this effect, it will be of exceptional interest to compare these findings with those of other centres and/or procedures when more data become available. The current literature would suggest that appropriate ICD discharge rate following septal ablation is between 5 and 10% per year, notably higher than the 0.24% per year observed in our myectomy patients.5,6
Furthermore, it must be noted that the operative mortality in major HCM centres has approached almost zero over the last decade—suggesting that this surgery should be performed at these centres where outcomes have been analysed.
References
- McLeod CJ, Ommen SR, Ackerman MJ, Weivoda PL, Shen WK, Dearani JA, Schaff HV, Tajik AJ, Gersh BJ. Surgical septal myectomy decreases the risk for appropriate implantable cardioverter defibrillator discharge in obstructive hypertrophic cardiomyopathy. Eur Heart J (2007) doi:10.1093/eurheartj/ehm117.
- Ommen SR, Maron BJ, Olivotto I, Maron MS, Cecchi F, Betocchi S, Gersh BJ, Ackerman MJ, McCully RB, Dearani JA, Schaff HV, Danielson GK, Tajik AJ, Nishimura RA. Long-term effects of surgical septal myectomy on survival in patients with obstructive hypertrophic cardiomyopathy. J Am Coll Cardiol (2005) 46:470–476.
[Abstract/Free Full Text] - 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] - Elliott PM, Gimeno JR, Tome MT, Shah J, Ward D, Thaman R, Mogensen J, McKenna WJ. Left ventricular outflow tract obstruction and sudden death risk in patients with hypertrophic cardiomyopathy. Eur Heart J (2006) 27:1933–1941.
[Abstract/Free Full Text] - Burke SFCI, Spencer W III, Nielsen C, Simon R, Sturdivant J, Wharton J, Leman R, Gold M. Traditional risk factors for sudden cardiac death do not predict defibrillator shocks in patients with hypertrophic obstructive cardiomyopathy following alcohol septal ablation. Heart Rhythm (2005) 2:S283.
- Lawrenz T, Obergassel L, Lieder F, Leuner C, Strunk-Mueller C, Meyer Zu Vilsendorf D, Beer G, Kuhn H. Transcoronary ablation of septal hypertrophy does not alter ICD intervention rates in high risk patients with hypertrophic obstructive cardiomyopathy. Pacing Clin Electrophysiol (2005) 28:295–300.[CrossRef][Medline]
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