European Heart Journal Advance Access originally published online on July 31, 2007
European Heart Journal 2007 28(17):2177; doi:10.1093/eurheartj/ehm299
Can septal myectomy prevent sudden cardiac death in hypertrophic obstructive cardiomyopathy?
Cardiology Department
AHEPA General Hospital
Aristotle University of Thessaloniki
Stilp. Kiriakidi 1, 54 637
Thessaloniki
Greece
Laboratory of Histology
Embryology and Anthropology
Aristotle University of Thessaloniki
Stilp. Kiriakidi 1, 54 637
Thessaloniki
Greece
Saint Lukes Hospital
Panorama, 55236
Thessaloniki
Greece
Cardiology Department
AHEPA General Hospital
Aristotle University of Thessaloniki
Stilp. Kiriakidi 1, 54 637
Thessaloniki
Greece
Laboratory of Histology
Embryology and Anthropology
Aristotle University of Thessaloniki
Stilp. Kiriakidi 1, 54 637
Thessaloniki
Greece
Cardiology Department
AHEPA General Hospital
Aristotle University of Thessaloniki
Stilp. Kiriakidi 1, 54 637
Thessaloniki
Greece
Tel: +30 2310994830 Fax: +30 2310994673 E-mail address: efthymos{at}med.auth.gr
We read with great interest the article by McLeod et al.1 reporting that surgical myectomy, classically performed to relieve left ventricular outflow tract obstruction (LVOTO) and severe symptoms in hypertrophic cardiomyopathy (HCM), is associated with a marked reduction in the frequency of appropriate implantable-cardioverter defibrillator (ICD) discharge and a reduction in the risk of sudden cardiac death (SCD). SCD is the most devastating and unpredicted of all complications in patients with HCM. Although the above study carries a very encouraging message to both clinicians and patients, the relation between LVOTO and SCD in obstructive HCM in our opinion is far more complex. There are no sufficient data to support that LVOTO serves as an independent predictor for SCD in HCM. Two major studies showed that there is a two-fold increase in relative risk of SCD due to LVOTO compared with non-obstructive patients, although, the positive predictive value of this finding is low (<10%).2,3 In the study by Maron et al.2 to which the present study refers, the likelihood of SCD was greater among patients with LVOT obstruction, however, the authors concluded that the contribution of the obstruction to risk stratification remains limited, because of the low annular rate of SCD and the low positive predictive value of the obstruction. In a recently published study,4 LVOTO during exercise echocardiography (dynamic obstruction) was identified in 70% of patients with HCM who had no LVOTO at rest. It would be very unjustified to consider all these patients as being high-risk subjects for SCD. The reduction in the frequency of ICD discharge and in SCD in patients with obstructive HCM treated by surgical myectomy seems very reasonable and it is attributed, in our opinion, not to LVOT relief, but to myectomy ‘per se’, since myectomy reduces the arrhythmogenic substrate, which is the major determinant of ventricular arrhythmias.
Irrespective of the mechanism by which surgical myectomy decreases the frequency of ICD discharge (and, therefore, the incidence of SCD), the study by McLeod et al.1 deserves a lot of credit, mainly because it shows elegantly that myectomy may alter favourably the natural history of obstructive HCM. It also generates possible clinical implications regarding the timing of surgical intervention in obstructive HCM. Should we refer such patients for myectomy at an earlier functional stage (NYHA class II), or simply on the basis of excessive hypertrophy, especially if syncopal episodes are present? Finally, a significant parameter which should be addressed is that surgical septal myectomy is a procedure performed mainly by dedicated surgeons, and, therefore, is not feasible in modern cardiothoracic centres worldwide.
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. Published online ahead of print 2007.
- Maron MS, Olivotto I, Betocchi S, Casey SA, Lesser JR, Losi MA, Cecchi F, Maron BJ. Effect of left ventricular outflow tract obstruction on clinical outcome in hypertrophic cardiomyopathy. N Engl J Med (2003) 34:295–303.
- 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] - Maron MS, Olivotto I, Zenovich AG, Link MS, Pandian NG, Kuvin JT, Nistri S, Cecchi F, Udelson JE, Maron BJ. Hypertrophic cardiomyopathy is predominantly a disease of left ventricular outflow tract obstruction. Circulation (2006) 114:2232–2239.
[Abstract/Free Full Text]
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