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LV Systolic Dysfunction in Hypertrophic Cardiomyopathy
Study Questions:
What are the prognostic markers and predictors of hypertrophic cardiomyopathy with left ventricular systolic dysfunction (HCM-LVSD)?
Methods:
Patients with HCM, enrolled in the international ShaRE (Sarcomeric Human Cardiomyopathy) Registry with at least one echocardiogram, were included. HCM phenocopies such as glycogen storage diseases were excluded. HCM-LVSD was defined as an echo with ejection fraction (EF) <50%. The primary outcome of interest was a composite of all-cause mortality, heart transplant, or left ventricular assist device (LVAD) implantation.
Results:
A total of 6,793 HCM patients between 1960 and March 2019 were analyzed. HCM-LVSD was present in 8.1% of the cohort. Patients with HCM-LVSD were younger and more likely to have sarcomeric disease compared to those with HCM without systolic dysfunction. During follow-up, 35% of HCM-LVSD patients experienced death, cardiac transplant, or LVAD implantation with a median time to event of 8.4 years. In addition, 75% of HCM-LVSD patients had New York Heart Association class III-IV symptoms, appropriate implantable cardioverter-defibrillator therapy, atrial fibrillation, and stroke.
Predictors of primary outcome included presence of multiple pathogenic or likely pathogenic sarcomeric variants, atrial fibrillation, and severe LV systolic dysfunction with EF <35% and older age. Incident HCM-LVSD on follow-up was present in 6% of the cohort with an incidence rate of 0.5% per year from initial evaluation. Predictors of developing HCM-LVSD included presence of a pathogenic/likely pathogenic sarcomeric variant (especially thin filament genes), borderline LVSD with EF 50-59% at initial visit, greater LV thickness, and late gadolinium enhancement on magnetic resonance imaging. Patients with obstructive physiology were less likely to develop LVSD. Patients who underwent myectomy or alcohol septal ablation were more likely to develop LVSD.
Conclusions:
HCM with LVSD was present in 8% of HCM patients. Presence of LVSD was associated with a high prevalence of adverse cardiovascular events and high mortality rates over a median follow-up time of 8.4 years. Patients receiving septal reduction therapy were at a higher risk of developing LVSD.
Perspective:
Results from this large, international cohort of HCM patients show that HCM-LVSD develops in 8% of patients and is associated with significant clinical implications. However, it challenges the concept of “end-stage” HCM as patients with HCM and LVSD experienced major adverse events over a considerably long time period. Furthermore, genetic substrate plays an important role in ascertaining risk for developing LVSD as well as prognosis after LVSD occurs. These findings support that both clinical features and genetic factors can help with prognostication in HCM patients. In particular, patients with HCM and LVEF 50-59% should receive close surveillance. Major limitations included possible referral bias, as all sites participating in SHaRE are high-volume HCM centers that potentially receive high-risk HCM referrals. Survival bias must also be considered, as patients had to survive until they were seen at a SHaRE site.
Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Implantable Devices, Genetic Arrhythmic Conditions, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Aortic Surgery, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Acute Heart Failure, Heart Transplant, Mechanical Circulatory Support, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound, Magnetic Resonance Imaging
Keywords: Ablation Techniques, Arrhythmias, Cardiac, Atrial Fibrillation, Cardiomyopathy, Hypertrophic, Defibrillators, Implantable, Diagnostic Imaging, Echocardiography, Genetics, Heart-Assist Devices, Heart Failure, Heart Transplantation, Magnetic Resonance Imaging, Sarcomeres, Stroke, Stroke Volume, Ventricular Dysfunction, Left
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