Conduction Abnormalities and Long-Term Mortality Following Septal Myectomy in Patients With Obstructive Hypertrophic Cardiomyopathy

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases.

STRUCTURE

Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

Aim This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use. Methods A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Structure Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

Management of Subaortic Left Ventricular Outflow Tract Obstruction After Aortic Valve Replacement

BACKGROUND

Residual or new left ventricular outflow tract (LVOT) obstruction after an aortic valve replacement poses special challenges with respect to operative techniques. Our study assesses this gap.

METHODS

From January 1993 to May 2019, 18 patients underwent a septal myectomy at Mayo Clinic for subaortic obstruction after aortic valve replacement. We evaluated their demographics, clinical presentation, and echocardiograms, and the type of prior valve replacement, need for repeat replacement, and their short- and long-term outcomes. The data were analyzed using descriptive statistics.

RESULTS

All patients underwent septal myectomy for LVOT obstruction at a median interval of 7 years (interquartile range, 3-15 years) from their prior aortic valve procedure. Preoperatively, the median left ventricular outflow tract gradient was 57 mm Hg (interquartile range, 44-77 mm Hg); 10 patients (55.5%) had systolic anterior motion (SAM) of the mitral leaflets. Repeat replacement of the aortic valve at the time of myectomy was needed in 14 patients, and septal myectomy alone was performed in 4 patients. One hospital death occurred 34 days after myectomy and aortic valve replacement, and 2 patients needed permanent pacemaker placement for complete heart block.

CONCLUSIONS

Septal myectomy after aortic valve replacement may be performed with repeat replacement of the valve, if there is coexisting prosthetic dysfunction, through a normally functioning bioprosthesis or through an apical approach when visualization through the aortic prosthesis is poor. The complexity of reoperation supports a liberal approach to myectomy at the time of aortic valve replacement when there is significant subaortic septal hypertrophy.

Transapical Septal Myectomy for Hypertrophic Cardiomyopathy With Midventricular Obstruction

BACKGROUND

Midventricular obstruction (MVO) is an uncommon variant of hypertrophic cardiomyopathy (HCM). In patients receiving septal myectomy for HCM, failure to recognize the concurrent MVO in the context of basal septum thickening can lead to inadequate excision and residual gradient. In this report, we detail the operative outcomes of MVO with and without coexistent basal septal hypertrophy.

METHODS

From February 1997 through September 2018, 196 patients underwent midventricular myectomy. Medical records and follow-up databases were reviewed to obtain patient characteristics and perioperative features.

RESULTS

At baseline, 156 patients (80%) were in New York Heart Association Functional Classification III/IV. Obstruction was isolated to the midventricle in 80 patients, and 63 (79%) were treated by isolated transapical myectomy. The remaining 116 patients had intraventricular obstruction at both subaortic and midcavity levels; in 108 (93%), a combined transaortic and transapical approach was adopted to achieve complete relief of the obstruction. After septal myectomy, the resting peak instantaneous gradient decreased from a median 48 mm Hg (interquartile range [IQR], 23-77 mm Hg) preoperatively to 8 mm Hg (IQR, 0-19 mm Hg) before hospital dismissal. Median follow-up was 2.9 years (IQR, 0.7-5.0 years), and the estimated 1-, 5-, and 10-year survivals were 99%, 98%, and 90%, respectively. There were no late complications attributable to the transapical incision.

CONCLUSIONS

Transapical exposure is a safe and effective approach for relief of midventricular obstruction, and hemodynamic results are similar to those achieved by standard myectomy for subaortic obstruction. The technique can be combined with transaortic myectomy for patients with left ventricular outflow obstruction at both levels.