The Indices of Cardiovascular Magnetic Resonance Derived Atrial Dynamics May Improve the Contemporary Risk Stratification Algorithms in Children with Hypertrophic Cardiomyopathy

Abstract

Introduction: The most efficient risk stratification algorithms are expected to deliver robust and indefectible identification of high-risk children with hypertrophic cardiomyopathy (HCM). Here we compare algorithms for risk stratification in primary prevention in HCM children and investigate whether novel indices of biatrial performance improve these algorithms.

Methods and results: The endpoints were defined as sudden cardiac death, resuscitated cardiac arrest, or appropriate implantable cardioverter-defibrillator discharge. We examined the prognostic utility of classic American College of Cardiology/American Heart Association (ACC/AHA) risk factors, the novel HCM Risk-Kids score and the combination of these with indices of biatrial dynamics. The study consisted of 55 HCM children (mean age 12.5 ± 4.6 years, 69.1% males); seven had endpoints (four deaths, three appropriate ICD discharges). A strong trend (DeLong p = 0.08) was observed towards better endpoint identification performance of the HCM Risk-Kids Model compared to the ACC/AHA strategy. Adding the atrial conduit function component significantly improved the prediction capabilities of the AHA/ACC Model (DeLong p = 0.01) and HCM Risk-Kids algorithm (DeLong p = 0.04).

Conclusions: The new HCM Risk-Kids individualised algorithm and score was capable of identifying high-risk children with very good accuracy. The inclusion of one of the atrial dynamic indices improved both risk stratification strategies.

Keywords: atrial strain; hypertrophic cardiomyopathy; outcome; risk markers.

Figure 1

The comparison of left-atrial volumetric [A—indexed maximal volume (mL/m²), B—indexed minimal volume (mL/m²) and C—indexed volume just before contraction (mL/m²)], contractile [D—total emptying fraction (%), E—conduit emptying fraction (%) and F—contractile emptying fraction (%)] and mechanical [G—total strain (%), H—conduit strain (%), I—contractile strain (%), J—total strain rate (1/s), K—conduit strain rate (1/s), L—contractile strain rate (1/s)] components between children with (red) and without (green) endpoints.

Figure 2

The comparison of right-atrial volumetric [A—indexed maximal volume (mL/m²), B—indexed minimal volume (mL/m²) and C—indexed volume just before contraction (mL/m²)], contractile [D—total emptying fraction (%), E—conduit emptying fraction (%) and F—contractile emptying fraction (%)] and mechanical [G—total strain (%), H—conduit strain (%), I—contractile strain (%), J—total strain rate (1/s), K—conduit strain rate (1/s), L—contractile strain rate (1/s)] components between children with (red) and without (blue) endpoints.

Figure 3

Comparison of receiver operating characteristic curves for baseline ACC/AHA (blue) and new Risk-Kids (green) risk stratification strategies; deLong p = 0.08.

Figure 4

Kaplan-Meier survival curves for patients with new Risk-Kids score >3.73% (green) and <3.73% (blue); log rank p < 0.01.

Figure 5

Comparison of receiver operating characteristic (ROC) curves for enriched ACC/AHA (blue) and Risk-Kids (green) Models; deLong p = ns. LAεe – Left atrial passive strain corresponding to atrial conduit function.