Detection of Midapical Obstruction in Hypertrophic Cardiomyopathy via Midsystolic Doppler Signal Absence
Overview
This retrospective study evaluated the prevalence and clinical correlates of a midsystolic Doppler signal void in patients with hypertrophic cardiomyopathy (HCM) and assessed whether it identifies a distinct midapical obstructive phenotype.
Background
Midapical obstruction represents a distinct anatomic and hemodynamic HCM phenotype, but standardized echocardiographic criteria for identifying it remain limited. Peak Doppler gradients may underestimate obstruction when systolic cavity obliteration causes forward flow to cease. A midsystolic Doppler signal void has therefore been proposed as a flow-based marker of midapical obstruction.
Data Highlights
The study included 606 consecutive patients with HCM.
A midsystolic Doppler signal void was present in 142 patients (23.4%).
Apical aneurysm occurred in 33.8% of patients with signal void versus 8.2% without it.
Among patients with signal void, 14.1% had midapical Doppler gradients below 30 mm Hg.
Apical aneurysm and lower absolute global longitudinal strain were independently associated with signal void.
Key Findings
Signal void was associated with pronounced midapical and papillary muscle hypertrophy, smaller indexed left ventricular end-diastolic volumes, and higher midapical Doppler gradients.
Patients with signal void had lower absolute global longitudinal strain, higher cardiac troponin I levels, and more apical aneurysms.
Peak Doppler gradients may underestimate midapical obstruction when systolic flow cessation prevents reliable gradient measurement.
Signal void identified a distinct midapical HCM phenotype not fully reflected by gradient-based assessment alone.
Longitudinal clinical outcomes were not evaluated, so diagnostic and prognostic value requires prospective validation.
Clinical Implications
A reproducible midsystolic Doppler signal void may complement conventional gradient measurements when assessing suspected midapical obstruction. Its presence may prompt targeted evaluation of ventricular morphology, myocardial deformation, and apical aneurysm, but the study does not establish that using this marker improves clinical outcomes.
Conclusion
Systolic cavity obliteration manifested as a midsystolic Doppler signal void identifies a distinct midapical HCM phenotype associated with regional hypertrophy, smaller cavity size, impaired longitudinal deformation, elevated cardiac troponin I, and a higher prevalence of apical aneurysm.
Related Resources & Content
Midsystolic Doppler Signal Void Identifies Midapical Obstruction in Hypertrophic Cardiomyopathy
Supplementary data accompanying the study
Obstruction in Hypertrophic Cardiomyopathy: Don’t Forget Midventricular Obstruction
Doppler Systolic Signal Void in Hypertrophic Cardiomyopathy: Apical Aneurysm and Severe Obstruction Without Elevated Intraventricular Velocities
Apical Aneurysms and Mid-Left Ventricular Obstruction in Hypertrophic Cardiomyopathy
Recommendations for Multimodality Cardiovascular Imaging of Patients With Hypertrophic Cardiomyopathy: An Update From the American Society of Echocardiography
A Practical Approach to Echocardiographic Imaging in Patients With Hypertrophic Cardiomyopathy
Mid-Ventricular Obstruction Is Associated With Nonsustained Ventricular Tachycardia in Patients With Hypertrophic Obstructive Cardiomyopathy
Doppler Echocardiography Underestimates the Prevalence and Magnitude of Mid-Cavity Obstruction in Patients With Symptomatic Hypertrophic Cardiomyopathy
2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary
