Right Ventricle Involvement by Glycogen Storage Cardiomyopathy (PRKAG2): Standard and Advanced Echocardiography Analyses

Abstract

Background: PRKAG2 syndrome is a rare, early-onset autosomal dominant inherited disease. We aimed to describe the right ventricle (RV) echocardiographic findings using two and three-dimensional (2D and 3D) modalities including myocardial deformation indices in this cardiomyopathy. We also aimed to demonstrate whether this technique could identify changes in RV function that could distinguish any particular findings.

Methods: Thirty patients with genetically proven PRKAG2 (R302Q and H401Q), 16 (53.3%) males, mean age 39.1 ± 15.4 years, underwent complete echocardiography examination. RV-focused, 4-chamber view was acquired for 2D and 3D measurements. Student's t or Wilcoxon-Mann-Whitney tests were used to compare numerical variables between 2 groups, and p < 0.05 was considered significant.

Results: Twelve patients (40%) had a pacemaker implanted for 12.4 ± 9.9 years. RV free wall mean diastolic thickness was 7.9 ± 2.9 mm. RV 4-chamber longitudinal strain (RV4LS), including the free wall and interventricular septum, was -17.3% ± 6.7%, and RV free wall longitudinal strain (RVFWLS) was -19.1% ± 8.5%. The RVFWLS apical ratio measured 0.63 ± 0.15. Mean RV 3D ejection fraction (EF) was 42.6% ± 10.9% and below normal limits in 56.7% of patients. Positive correlation occurred between RV 3DEF, RV4LS, and RVFWLS, especially for patients without a pacemaker (p = 0.006).

Conclusion: RV involvement in PRKAG2 syndrome is frequent, occurring in different degrees. Echocardiography is a valuable tool in detecting RV myocardial abnormalities in this condition. The use of 2D RV4LS, RVFWLS, and 3DEF offers reliable indicators of RV systolic dysfunction in this rare, challenging cardiomyopathy.

Figura 1. Medida da espessura diastólica final da parede livre do ventrículo direito. Imagem bidimensional subcostal da visão de 4 câmaras. Imagem em modo M indicando a espessura da parede no final da diástole (1,3 cm). VE: ventrículo esquerdo; VD: ventrículo direito.

Figura 2. Análise bidimensional do speckle tracking do ventrículo direito a partir de uma visão de 4 câmaras em corte apical. Os valores médios de strain sistólico global e as curvas de tempo foram obtidos pelo rastreamento de uma região de interesse de 6 segmentos. Strain longitudinal de 4 câmaras do ventrículo direito mediu -9,3%. GS: strain global; VD: ventrículo direito.

Figura 3. O conjunto de dados tridimensionais foi adquirido a partir de uma visão apical de 4 câmaras com foco no VD. Em A, visão multiplanar em eixo curto para verificação das bordas endocárdicas. Em B, podemos ver o modelo 3D do VD obtido com a curva de volume. VDF: volume diastólico final; FE: fração de ejeção; VSF: volume sistólico final; VD: ventrículo direito; VS: volume sistólico.

Figure 1. Measurement of end-diastolic right ventricle free wall thickness. Subcostal 2-dimensional image of the 4-chamber view. M-mode image indicating wall thickness at end-diastole (1.3 cm). LV: left ventricle; RV: right ventricle.

Figure 2. Two-dimensional speckle tracking analysis of the right ventricle from a focused apical 4-chamber view. The global average systolic strain values and time curves are obtained by tracking of a 6-segment region of interest. Right ventricle 4-chamber longitudinal strain measured 9.3%. GS: global strain; RV: right ventricle.

Figure 3. The 3-dimensional dataset was acquired from an RV-focused apical 4-chamber view. In A, there is a multiplanar short-axis view to verify the endocardial borders. In B, we can see the RV 3-dimensional model obtained with the volume curve. EDV: end diastolic volume; EF: ejection fraction; ESV: end systolic volume; RV: right ventricle; SV: stroke volume.