Relationship Between Left Ventricular Mass, Wall Thickness, and Survival After Subaortic Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy

Feb 25, 2011
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Authors:
Brown ML, Schaff HV, Dearani JA, Zhuo L, Nishimura RA, Ommen SR.
Citation:
J Thorac Cardiovasc Surg 2011;141:439-443.
Summary By:
Anna M. Booher, MD

Study Questions:

Following septal myectomy, do measures of left ventricular (LV) wall thickness (WT) and LV mass impact late survival in patients with hypertrophic cardiomyopathy (HCM)?

Methods:

This was a retrospective review of 416 patients with HCM who underwent surgical myectomy and had adequate postoperative echocardiograms within 30 days of surgery. Late survival was compared to age- and gender-matched controls. Univariate and multivariate analyses were performed.

Results:

Mean age was 50 ± 15 years and 58% were male. Preoperative measures of LVWT and LV mass are as follows: septal WT = 19.4 ± 5.6 mm, posterior WT = 14.0 ± 3.3 mm, maximal WT = 19.5 ± 5.6 mm, LV mass index = 162.5 ± 55.8 g/m2, and LV ejection fraction (LVEF) was 72% ± 6%. All patients underwent successful myectomy. Concomitant or pre-existing implantable cardioverter-defibrillator placement occurred in 17% of patients. Postoperatively, septal WT = 15.9 ± 4.9 mm, posterior WT = 13.1 ± 2.9 mm, maximal WT was 16.3 ± 14.7 mm, LV mass index = 134.7 ± 45.9 g/m2, and LVEF was 66 ± 7%. Late survival at 1, 5, and 10 years was 99%, 97%, and 85%, respectively, with a mean follow-up duration of 3.6 ± 3.2 years and similar to age- and gender-matched controls (p = 0.45). Older age, presence of coronary artery disease, and lower preoperative LVEF were associated with mortality on univariate analysis. On multivariate analysis, only the presence of coronary artery disease was associated with late mortality. LV mass and LVWT were not associated with survival following myectomy.

Conclusions:

In this cohort of patients with HCM, post-myectomy survival was not associated with echocardiographic measures of LVWT or LV mass. Late survival was similar to age- and gender- matched controls.

Perspective:

Prior studies on the natural history of HCM have evaluated patients not treated surgically and have suggested that marked LVWT (>30 mm) is associated with worse survival and increased risk of sudden cardiac death and heart failure. Additionally, prior retrospective studies have shown that survival is better in certain HCM patients managed with surgical myectomy. In this cohort of surgically managed patients, postoperative survival was similar to controls, but not related to changes in LVWT or LV mass. Therefore, the mechanism of postoperative survival remains unclear. Prospective evaluation of medically versus surgically treated HCM patients is warranted in order to clarify the survival benefits of surgical myectomy.

Keywords: Coronary Artery Disease, Follow-Up Studies, Ventricular Function, Left, Cardiomyopathy, Hypertrophic, Heart Failure, Heart Ventricles, Death, Sudden, Cardiac, Echocardiography


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