Pathoanatomic Findings and Treatment During Hypertrophic Obstructive Cardiomyopathy Surgery: The Role of Mitral Valve

The Role of the Submitral Apparatus in Hypertrophic Obstructive Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease, is characterized by unexplained hypertrophy of any myocardial segment, and has a prevalence of 0.2% to 0.5% among the general population. As one of the phenotypes of hypertrophic cardiomyopathy, left ventricular outflow tract obstruction (LVOTO) is associated with high morbidity and mortality, including cardiac death. The integration of various factors, including septal hypertrophy, malformation of the mitral valve apparatus, and an anomalous mitral subvalvular apparatus, may contribute to the occurrence of LVOTO. Previous studies have thoroughly discussed the role of the mitral valve in the mechanisms of systolic anterior motion and LVOTO. Recent studies have shown the importance of determining the potential mechanism of the submitral apparatus in inducing systolic anterior motion and LVOTO. The authors review recent advances in knowledge regarding the submitral apparatus of patients with hypertrophic cardiomyopathy.

Septal Thickness Does Not Impact Outcome After Hypertrophic Obstructive Cardiomyopathy Surgery (Septal Myectomy and Subvalvular Mitral Apparatus Remodeling): A 15-Years of Experience

Background

The aim of this study was to assess the impact of septal thickness on long-term outcomes of surgical treatment for hypertrophic obstructive cardiomyopathy (HOCM) and correction of mitral subvalvular anomalies.

Methods

Sixty-six consecutive patients (58 ± 12 years, 56% female) undergoing extended septal myectomy and subvalvular mitral apparatus remodeling from 2007 to 2021 were retrospectively reviewed. Patients were divided into 2 groups according to septal thickness: moderate [< 18 mm, 29 patients (44%)] and severe [≥ 18 mm, 37 patients (56%)]. End points included survival, symptom improvement, reduction of left ventricle outflow tract (LVOT) gradient, resolution of mitral regurgitation (MR), and reoperation.

Results

The mean interventricular septal thickness was 19 ± 3 mm, 15.8 ± 0.8 mm in patients with moderate and 21.4 ± 3.2 mm in those with severe hypertrophy. Preoperative data, intraoperative variables, postoperative complication rates, pre-discharge echocardiographic and clinical parameters did not differ between the two study groups [except for procedures involving the posterior mitral leaflet (p = 0.033) and septal thickness after myectomy (p = 0.0001)]. Subvalvular apparatus remodeling (secondary chordae of mitral valve resection and papillary muscle and muscularis trabecula procedures including resection, splitting, and elongation) was invariably added to septal myectomy (100%). Four (6%) procedures involved the posterior mitral leaflets. Mitral valve replacement was carried out in two patients (3%, p = 0.4). Reoperation for persistent MR was necessary in one patient (1%, p = 0.4). Neither iatrogenic ventricular septal defect nor in-hospital mortality occurred. During follow-up (mean 4.8 ± 3.8 years), two deaths occurred. NYHA class was reduced from 2.9 ± 0.7 to 1.6 ± 0.6 (p < 0.0001), the LVOT gradient from 89.7 ± 34.5 to 16.3 ± 8.8 mmHg (p < 0.0001), mitral valve regurgitation grade from 2.5 ± 1 to 1.2 ± 0.5 (p < 0.0001), and septal thickness from 18.9 ± 3.7 to 13.9 ± 2.7 mm (p < 0.0001).

Conclusions

Regardless of septal thickness, subvalvular apparatus remodeling with concomitant septal myectomy can provide satisfactory long-term outcomes in terms of symptom improvement, LVOT obstruction relief, and MR resolution (without mitral valve replacement in most cases) in patients with HOCM.

Review of Contemporary Invasive Treatment Approaches and Critical Appraisal of Guidelines on Hypertrophic Obstructive Cardiomyopathy: State-of-the-Art Review

BACKGROUND

Hypertrophic obstructive cardiomyopathy (HOCM) is a heterogeneous disease with different clinical presentations, albeit producing similar dismal long-term outcomes if left untreated. Several approaches are available for the treatment of HOCM; e.g., alcohol septal ablation (ASA) and surgical myectomy (SM). The objectives of the current review were to (1) discuss the place of the standard invasive treatment modalities (ASA and SM) for HOCM; (2) summarize and compare novel techniques for the management of HOCM; (3) analyze current guidelines addressing HOCM management; and (4) offer suggestions for the treatment of complex HOCM presentations.

METHODS

We searched the literature and attempted to gather the most relevant and impactful available evidence on ASA, SM, and other invasive means of treatment of HOCM. The literature search yielded thousands of results, and 103 significant publications were ultimately included.

RESULTS

We critically analyzed available guidelines and provided context in the setting of patient selection for standard and novel treatment modalities. This review offers the most comprehensive analysis to-date of available invasive treatments for HOCM. These include the standard treatments, SM and ASA, as well as novel treatments such as dual-chamber pacing and radiofrequency catheter ablation. We also account for complex pathoanatomic presentations and current guidelines to offer suggestions for tailored care of patients with HOCM. Finally, we consider promising future therapies for HOCM.

CONCLUSIONS

HOCM is a heterogeneous disease associated with poor outcomes if left untreated. Several strategies for treatment of HOCM are available but patient selection for the procedure is crucial.

Characteristics and Surgical Results of Patients with Hypertrophic Obstructive Cardiomyopathy without Intrinsic Mitral Valve Diseases Undergoing Mitral Subvalvular Procedures during Myectomy

Background

Mitral subvalvular procedures have acquired a major role during hypertrophic obstructive cardiomyopathy (HOCM) surgery. However, few studies have focused on characterizing the clinical feature of HOCM patients without intrinsic mitral valve (MV) diseases undergoing mitral subvalvular procedures in addition to myectomy. Additionally, scant data about the results of mitral subvalvular procedures during HOCM surgery are available. This single-center study aims to characterize the clinical feature and surgical results of HOCM patients without intrinsic MV diseases undergoing mitral subvalvular procedures in addition to myectomy in comparison with those receiving myectomy alone.

Methods

Among 181 eligible patients, 50 (27.6%) patients undergoing myectomy plus mitral subvalvular procedures were entered into the combined group, and the remaining 131 patients receiving myectomy alone were included in the alone group. Baseline and surgical characteristics were investigated, and surgical results were compared.

Results

Comparatively, the combined group was younger (52.9 ± 11.2 years vs. 56.8 ± 11.8 years, p=0.045) and had a better New York Heart Association (NYHA) class (p=0.034) and less septal hypertrophy (16.4 ± 2.3 mm vs. 18.5 ± 3.2 mm, p < 0.001). Septal thickness was independently associated with combined procedures in multivariable logistic regression analysis (OR = 0.887, 95% CI 0.612–0.917). No surgical death or iatrogenic septal perforation occurred in the combined group. Two (6.5%) patients in the combined group developed complete atrioventricular block and required permanent pacemaker implantation. During a median follow-up of 10 months, no deaths or reoperations were observed with the symptom of relief and NYHA class I or II in either group. Patients in the combined group as compared to the alone group had lower outflow tract gradients and a lower incidence of residual systolic anterior motion (SAM) syndrome.

Conclusions

For HOCM patients without intrinsic MV diseases who are scheduled for surgery, a less pronounced septal hypertrophy may be closely associated with myectomy with concomitant mitral subvalvular procedures instead of myectomy alone. Mitral subvalvular procedures during myectomy are safe and allow the reduction of outflow tract gradients and freedom from SAM more effectively in comparison with myectomy alone.

Cardiac magnetic resonance in hypertrophic and dilated cardiomyopathies

Cardiomyopathies are a heterogeneous entity. The progress in the field of genetics has allowed over the years to determine its origin more and more often. The classification of these pathologies has changed over the years; it has been updated with new knowledge. Imaging allows to define the phenotypic characteristics of the different forms of cardiomyopathy. Cardiac magnetic resonance (CMR) allows a morphological evaluation of the associated (and sometimes pathognomonic) cardiac findings of any form of cardiomyopathy. The tissue characterization sequences also make magnetic resonance imaging unique in its ability to detect changes in myocardial tissue. This review aims to define the features that can be highlighted by CMR in hypertrophic and dilated forms and the possible differential diagnoses. In hypertrophic forms, CMR provides: precise evaluation of wall thickness in all segments, ventricular function and size and evaluation of possible presence of areas of fibrosis as well as changes in myocardial tissue (measurement of T1 mapping and extracellular volume values). In dilated forms, cardiac resonance is the gold standard in the assessment of ventricular volumes. CMR highlights also the potential alterations of the myocardial tissue.

Minimally Invasive Surgery for Hypertrophic Obstructive Cardiomyopathy With Mitral Regurgitation

BACKGROUND

To summarize the safety and effect of minimally invasive surgery for hypertrophic obstructive cardiomyopathy (HOCM) with significant mitral regurgitation through a single transaortic approach via right minithoracotomy.

METHODS

From 2008 to 2017, 51 HOCM patients with significant mitral regurgitation underwent minimally invasive surgery via right minithoracotomy. Preoperative peak left ventricular outflow tract pressure gradient (LVOTPG) was 96.53 ± 28.72 mm Hg. Preoperative average interventricular septum thickness was 24.31 ± 3.52 mm. All patients had significant mitral regurgitation with systolic anterior motion phenomenon. An oblique incision was made on the anterior wall of ascending aorta or aortic root. Modified Morrow procedure and edge-to-edge mitral valvuloplasty were performed through the single transaortic approach via right minithoracotomy.

RESULTS

All patients successfully underwent the minimally invasive surgery through the single transaortic approach via right minithoracotomy. At discharge, postoperative peak LVOTPG (18.16 ± 6.41 mm Hg) and interventricular septum thickness (14.33 ± 1.99 mm) were significantly decreased compared with preoperative values (P < .05). All patients had no or trivial mitral regurgitation. The average peak mitral valve pressure gradient was 3.39 ± 1.82 mm Hg. Systolic anterior motion phenomenon disappeared in all patients. During follow-up, peak LVOTPG was 19.27 ± 6.10 mm Hg; average interventricular septum thickness was 14.67 ± 1.87 mm. All patients had no or trivial mitral regurgitation. Average peak mitral valve pressure gradient was 3.04 ± 1.52 mm Hg. No systolic anterior motion phenomenon occurred.

CONCLUSIONS

Minimally invasive surgery of modified Morrow procedure and edge-to-edge mitral valvuloplasty through a single transaortic approach via right minithoracotomy could be safely and effectively applied for patients with HOCM and significant mitral regurgitation, which could also effectively eliminate systolic anterior motion phenomenon and without mitral valve stenosis.

Neurological complications after cardiac surgery: a retrospective case-control study of risk factors and outcome

Background

To evaluate incidence, risk factors, and outcomes of postoperative neurological complications in patients undergoing cardiac surgery.

Methods

A total of 2121 patients underwent cardiac surgery between August, 2008 and December, 2013; 91/2121 (4.3%) underwent brain computed tomography (70/91, 77%) or magnetic resonance imaging (21/91, 23%) scan because of major stroke (37/2121, 1.7%) and a spectrum of transient neurological episodes as well as transient ischemic attacks and delirium /psychosis/seizures (54/2121, 2.5%). The mean age was 65.3 ± 12.1 years and 60 (65.9%) were male. Variables were compared among study- and matched-patients (n = 113) without neurological deficits.

Results

A total of 37/2121 (1.7%) patients had imaging evidence of stroke. Radiological examinations were done 5.72 ± 3.6 days after surgery. Patients with and without imaging evidence of stroke had longer intensive care unit length of stay (LOS) (13.8 ± 14.7 and 12.9 ± 15 days vs. 5.7 ± 12.1 days, respectively (p < 0.001) and hospital LOS (53 ± 72.8 and 35.5 ± 29.8 days vs. 18.4 ± 29.2 days, respectively (p < 0.001) than the control group. The hospital mortality of patients with and without imaging evidence of stroke was higher than the control group (7/37 patients [19%], and 12/54 patients [22%] vs. 4/115 patients [3%], respectively (p < 0.001). Multivariate analysis showed that bilateral internal carotid artery stenosis of any grade (p < .001), and re-do operations (p = .013) increased the risk of postoperative neurological complications.

Conclusions

Neurological complications after cardiac surgery increase hospitalization and mortality even in patients without radiologic evidence of stroke. Bilateral internal carotid artery stenosis of any grade, suggesting a diffuse patient propensity toward atherosclerosis, and re-do operations increase the risk of postoperative neurological complications.