Mitral Regurgitation in Patients With Hypertrophic ...

JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY ? 2016 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION PUBLISHED BY ELSEVIER

ORIGINAL INVESTIGATIONS

VOL. 68, NO. 14, 2016 ISSN 0735-1097/$36.00

Mitral Regurgitation in Patients With Hypertrophic Obstructive Cardiomyopathy

Implications for Concomitant Valve Procedures

Joon Hwa Hong, MD, PHD,a Hartzell V. Schaff, MD,a Rick A. Nishimura, MD,b Martin D. Abel, MD,c Joseph A. Dearani, MD,a Zhuo Li, MS,d Steve R. Ommen, MDb

ABSTRACT

BACKGROUND Incidence and outcome of mitral valve (MV) surgery are unknown in patients with hypertrophic obstructive cardiomyopathy (HOCM) undergoing extended transaortic septal myectomy.

OBJECTIVES This study sought to define indications and suitable operative strategy for mitral regurgitation (MR) in patients with HOCM.

METHODS A total of 2,107 septal myectomy operations performed in adults from January 1993 to May 2014 at Mayo Clinic in Rochester, Minnesota, were retrospectively reviewed. Patients with prior MV operation and apical hypertrophic cardiomyopathy were excluded. Overall, 2,004 operations were performed in 1,993 patients.

RESULTS Pre-operative MR was grade $3 (of 4) in 1,152 operations (57.5%). Systolic anterior motion of mitral leaflets caused the MR in most patients. However, intrinsic MV disease was identified pre-operatively in 99 patients, all of whom had MV surgery (with septal myectomy). In 1,905 operations, no intrinsic MV disease was identified pre-operatively; in 1,830 (96.1%), septal myectomy was performed without a direct MV procedure. For 75 patients, intrinsic MV disease discovered intraoperatively led to concomitant MV repair (86.7%) or replacement (13.3%). After isolated septal myectomy, the percentage of patients with MR grade $3 decreased from 54.3% to 1.7% (p ? 0.001) on early post-operative echocardiography. Among 174 patients with concomitant MV surgery, late survival was superior with MV repair (n ? 133 [76.4%]) versus replacement (10-year survival: 80.0% vs. 55.2%; p ? 0.002).

CONCLUSIONS In most patients with HOCM, MR related to systolic anterior motion of the MV is relieved through adequate myectomy. Concomitant MV surgery is rarely necessary unless intrinsic MV disease is present. When MV procedures are required, repair is preferred because of improved survival compared with replacement. (J Am Coll Cardiol 2016;68:1497?504) ? 2016 by the American College of Cardiology Foundation.

M itral valve (MV) leaflets have an important role in the pathophysiological process of left ventricular (LV) outflow tract obstruction in patients with hypertrophic obstructive

cardiomyopathy (HOCM). Systolic anterior motion (SAM) of the mitral apparatus and contact of the leaflets with the hypertrophied septum narrow the LV outflow, leading to dynamic pressure gradients and,

Listen to this manuscript's audio summary by JACC Editor-in-Chief Dr. Valentin Fuster.

From the aDivision of Cardiovascular Surgery, Mayo Clinic, Rochester, Minnesota; bDivision of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota; cDivision of Cardiovascular and Thoracic Anesthesia, Mayo Clinic, Rochester, Minnesota; and the dDivision of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota. Dr. Hong is now with the Department of Thoracic and Cardiovascular Surgery, Heart Research Institute, Chung-Ang University College of Medicine, Seoul, South Korea. The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Manuscript received February 25, 2016; revised manuscript received June 29, 2016, accepted July 5, 2016.

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Hong et al. Valve Procedure in Cardiomyopathy

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ABBREVIATIONS

in many patients, mitral regurgitation (MR).

AND ACRONYMS

Furthermore, studies on structural MV alter-

CPB = cardiopulmonary bypass HOCM = hypertrophic obstructive cardiomyopathy LV = left ventricle MR = mitral regurgitation MV = mitral valve SAM = systolic anterior motion

ations in HOCM have shown increased mitral leaflet length and area (1,2). However, whether MV alterations continue to contribute to MR and LV outflow tract obstruction even after adequate myectomy when mitral leaflet length and area are not corrected with concomitant surgery is unknown.

Septal myectomy is the preferred treatment of

most patients with HOCM, and many studies have

documented relief of symptoms and satisfactory late

patient survival after relief of outflow tract gradients

(3?5). Surgical management of associated MR is

controversial, and because prosthetic replacement of

the MV also relieves LV outflow tract obstruction,

some groups have advocated valve replacement with

or without septal myectomy when MR is severe (6,7).

Other surgeons have advocated plication of the

anterior leaflet or other forms of valvuloplasty to

correct associated MR caused by SAM of the MV.

SEE PAGE 1505

When the MV is intrinsically abnormal in HOCM, valve repair or replacement may be necessary (8). However, adequate septal myectomy relieves outflow tract gradients, SAM of the MV, and MR in many patients (9). Nevertheless, several reports have described adjunctive techniques of mitral valvuloplasty aimed at eliminating SAM of the MV (10?13). Thus, the controversy regarding the optimal surgical strategy for patients with HOCM and significant MR related to SAM of the leaflets continues.

The aims of the present study were to determine: 1) how frequently additional procedures are necessary in patients who have SAM-related MR and what is the outcome of septal myectomy alone in such patients; 2) what MV problems require direct repair or replacement in addition to septal myectomy; and 3) when direct MV procedures are necessary, what are the outcomes of valve repair versus valve replacement.

METHODS

PATIENT SELECTION. From January 1993 to May 2014, a total of 2,107 operations for septal myectomy were performed in adult patients (age $18 years) with HOCM at Mayo Clinic's campus in Rochester, Minnesota. In the present study, 103 patients were excluded from analysis because of nonobstructive physiological characteristics (n ? 88) (14) or previous MV surgery (n ? 15). The Mayo Clinic Institutional Review Board approved the study protocol.

PATIENT CHARACTERISTICS. Analysis included 2,004 operations in 1,993 patients (56% men; age at surgery: 53.6 ? 14.4 years [mean ? SD]). Before myectomy, MR severity determined by transthoracic Doppler echocardiography was grade 20 mm Hg with provocation, significant residual SAM, or MR with a greater than mild degree of severity. We resumed CPB for additional myectomy when the patient had SAM of the MV and residual LV outflow tract obstruction detected through direct measurement and transesophageal echocardiography, with or without MR and regardless of its grade. If the patient had MR grade $3 without SAM of the MV and without LV outflow tract obstruction, CPB was resumed and additional procedures were directed in MV surgery.

DATA COLLECTION. Data on pre-operative patient status, operative record, post-operative MR, and survival were obtained from our prospective clinical database as well as from electronic medical records. Post-operative transthoracic echocardiography was performed on all patients before hospital discharge. Vital status was determined through the Mayo Clinic registration database, which collates information

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from multiple sources, including correspondence from family and physicians and Accurint, an institutionally approved, Web-based resource and location service. Accurint is a subsidiary of Seisint, Inc. (Boca Raton, Florida), a private information management company that provides access to Social Security death data and a number of other data sources.

STATISTICAL ANALYSIS. Categorical values are reported as frequency (percentage); continuous variables are reported appropriately as mean ? SD or median (range). Categorical values were compared among the patients who had MV surgery with 1 or 2 periods of CPB using chi-square test or Fisher exact test. Continuous variables were compared with 2-sample Student t test or Wilcoxon rank sum test where appropriate.

Kaplan-Meier method was used to draw survival curves and calculate 5- and 10-year survival estimates. Cox regression models were used to determine univariate and multivariate predictors of overall mortality rate. The multivariate model considered univariately significant variables (p < 0.05), and model selection was made with the stepwise method (backward and forward methods resulted in the same

model). All statistical tests were 2-sided with a level

set at 0.05 for significance.

RESULTS

CONCOMITANT MV SURGERY. Of 2,004 operations, intrinsic MV disease was identified pre-operatively in 99 operations, and each of these patients had MV surgery in conjunction with transaortic septal myectomy. Among the 1,905 operations without pre-operative diagnosis of intrinsic MV disease, concomitant MV surgery was performed with myectomy in 75 patients. Thus, 174 patients (99 with and 75 without preoperative diagnosis of intrinsic MV disease) underwent transaortic septal myectomy and concomitant MV surgery. Table 1 lists pre-operative general characteristics, intraoperative data, and postoperative results. Table 2 summarizes the intrinsic MV diseases identified in 99 patients before surgery, including chordal rupture, MV prolapse, rheumatic MV disease, healed or acute infective endocarditis, MV mass, and leaflet cleft.

All patients had transaortic myectomy. In the 99 patients with intrinsic MV disease identified preoperatively, 68 (68.7%) had MV repair and 31 (31.3%) had MV replacement. Among the other 75 patients who had mitral surgery (3.9% of 1,905 without a preoperative diagnosis of associated MV disease), structural valve abnormalities were discovered through

TABLE 1 Clinical Characteristics of 174 Patients Who Underwent Myectomy and Concomitant Mitral Valve Surgery

Pre-operative variable Age, yrs Male Body surface area, m2 Smoking history Diabetes mellitus Automated implantable cardioverter-defibrillator Heart failure New York Heart Association functional class I?II III?IV Medication Beta-blocker Calcium-channel blocker Mitral regurgitation grade ................
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