Predictors of Long-Term Outcomes in Symptomatic Hypertrophic Obstructive Cardiomyopathy Patients Undergoing Surgical Relief of Left Ventricular Outflow Tract Obstruction

Abstract

The study population is part of an ongoing institutional review boardapproved registry of HCM patients at a single tertiary care center (Cleveland Clinic, Ohio), with the initial visit between January 1997Background-We report the predictors of long-term outcomes of symptomatic hypertrophic cardiomyopathy patients undergoing surgical relief of left ventricular outflow tract obstruction. Methods and Results-We studied 699 consecutive patients who have hypertrophic cardiomyopathy with severe symptomatic left ventricular outflow tract obstruction (47±11 years, 63% male) intractable to maximal medical therapy, who were referred to a tertiary hospital between January 1997 and December 2007 for the surgical relief of left ventricular outflow tract obstruction. We excluded patients <18 years of age, those with an ejection fraction <50%, those with hypertensive heart disease of the elderly, and those with more than mild aortic or mitral stenosis. Clinical, echocardiographic, and Holter data were recorded. A composite end point of death, appropriate internal cardioverter defibrillator discharges, resuscitated from sudden death, documented stroke, and admission for congestive heart failure was recorded. During a mean follow-up of 6.2±3 years, 86 patients (12%) met the composite end point with 30-day, 1-year, and 2-year event rates of 0.7%, 2.8%, and 4.7%, respectively. The hard event rate (death, defibrillator discharge, and resuscitated from sudden death) at 30 days, 1 year, and 2 years was 0%, 1.5%, and 3%, respectively. Stepwise multivariable analysis identified residual postoperative atrial fibrillation (hazard ratio, 2.12; confidence interval, 1. The degree of left ventricular (LV) hypertrophy in the study population was deemed significantly out of proportion to the duration and degree of hypertension; this decided after a thorough clinical evaluation by experienced physicians. We excluded the following patients:(1) patients <18 years and >65 years of age, (2) those with hypertensive heart disease of the elderly and concomitant LVOT obstruction, 13-16 (3) those with an ejection fraction <50%, and (4) those with the presence of more than mild aortic or mitral stenosis on the initial echocardiogram. Patients with hypertensive heart disease and concomitant LVOT obstruction were defined as those >65 years of age with a long-standing history of hypertension and characteristic sigmoid-shaped basal septal hypertrophy identified on echocardiography. These patients were excluded because they have a different pathophysiological and genetic profile from the typical HCM patients.13-16 Additionally, we eliminated the potentially confounding effects of end-stage disease (manifesting as depressed LV function) on outcomes by excluding such patients. Clinical DataDemographic, clinical (including standard and HCM-related risk factors, detailed family history, and examination), medication use (including antiarrhythmics and anticoagulation), and electrocardiographic data obtained at the time of the initial and follow-up visits were recor...

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“…In addition, optimal hemodynamic results and sustained clinical improvement to New York Heart Association class I or II have been documented in >90% of patients over long-term follow-up (5,7,10). The exceedingly low operative mortality and major long-term benefits of transaortic surgical myectomy (with extended survival equivalent to patients with non-obstructive HCM and similar to the age and gender matched general population) is now well documented for high volume centers (1,5,7,10).…”

“…Obstruction to LV outflow obstruction is associated with mitral valve regurgitation, disabling heart failure symptoms and increased cardiovascular mortality (3,4). For almost 50 years, transaortic septal myectomy has represented the standard surgical approach for the treatment of patients with obstructive HCM and severe symptoms refractory to medical treatment (1,(5)(6)(7).…”

“…During the last 20 years, a decrease in operative mortality due to improved surgical techniques and myocardial protection has reduced the hospital mortality for isolated septal myectomy to <1% at HCM Centers of Excellence (5,7,10). In addition, optimal hemodynamic results and sustained clinical improvement to New York Heart Association class I or II have been documented in >90% of patients over long-term follow-up (5,7,10).…”

“…As there is a direct relation between volume of myectomies performed and surgical outcomes, optimal results cannot be expected from surgeons with a low-volume exposure to symptomatic patients with obstructive HCM (1,15,16). Therefore, the best results have been obtained by those few surgeons in the world with extensive myectomy experience and a small number of referral centers in North America and Europe (5,7,11,(17)(18)(19)(20). This represents an important obstacle to bringing septal myectomy to the HCM population.…”

“…Patients with obstructive HCM often have mitral valve abnormalities, including papillary muscle displacement within the LV cavity, fibrotic and retracted secondary mitral valve chordae and markedly elongated mitral valve leaflets that can contribute to outflow obstruction (11,17,(31)(32)(33). In such patients, septal myectomy is often associated with mitral valve repair (7,11,32,34). A number of novel valve repair techniques have been developed that reduce the contribution of the mitral valve apparatus to outflow obstruction.…”