Glycogen storage cardiomyopathy (PRKAG2): diagnostic findings of standard and advanced echocardiography techniques

Aims: Describe the findings obtained using standard echocardiography (Echo) and deformation indices (2D and 3D speckle tracking strain) in patients (Pts) with PRKAG2 cardiomyopathy. Seek to identify any peculiar characteristics and possible strain patterns that may distinguish this condition from other causes of left ventricular hypertrophy (LVH).

Methods and results: Thirty Pts with genetically proven PRKAG2 (R302Q and H401Q), 16 (53.3%) male, mean age 39.1± 15.4 years old, were examined using standard, speckle tracking (STE), and 3D Echo. Pacemaker (PM) had been implanted in 12 (40%) Pts with a mean age of 38.1 ± 13 years. Hypertrophy was found in varying degrees in 18 (86%) Pts. Seven Pts (24%) presented 3D ejection fraction (EF) below normal limits. Diastolic function was abnormal in 17 (63%) Pts. Global longitudinal strain (GLS) on 2D measured -16.4% ± 5.3%. GLS measured -13.2% ± 4.8%, global radial strain 40.8% ± 13.8%, global circumferential strain (GCS) -16.1% ± 4.4%, and global area strain -26.1% ± 6.7% by 3D Echo offline analyses. Pts with PM presented lower EF and GCS compared with those without PM. EF/GLS measured 3.65 ± 1.00. In the bull's eye map, a strain pattern similar to stripes in 18 (60%) Pts was identified, which might be a differentiating signal among LVH.

Conclusion: Echocardiography is a valuable tool in detecting diffuse and focal myocardial abnormalities in PRKAG2 cardiomyopathy. The deformation indices are especially revealing because they may help distinguish this rare infiltrative disease, thereby favouring early diagnosis, enhanced treatment, and improved outcome.