Left-ventricular non-compaction and ventricular arrhythmias
Authors: Principi S , Alfieri M , Barbarossa A , Ciliberti G , Coretti F , Coraducci F , Belleggia S , Torselletti L , Paolini F , Stronati G , Dello Russo A , Guerra F 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Left ventricular non-compaction (LVNC) is a rare, although underdiagnosed, cardiomyopathy deriving from the incomplete development of myocardial tissue. Its presentations range from heart failure to embolism and arrhythmic events with the latter being the most frequent cause of death.

Purpose
To define the incidence of arrhythmic complications in LVNC and describe the interplay between systolic dysfunction and ventricular events.

Methods
This is a retrospective evaluation of a prospectively-collected database including all consecutive patients with a definitive diagnosis of LVNC followed-up at the Cardiomyopathy Clinic of our institution from October 2009 to August 2022. We conducted a follow-up analyzing the possible correlation between baseline characteristics and a composite outcome of ventricular arrhythmias (sustained VT or VF), appropriate ICD interventions and sudden cardiac death (SCD). We also extracted a sample from our population with preserved LVEF and compared global longitudinal strain (GLS) in compacted and non-compacted segments.

Results
44 patients (29 males, 65.9%) were enrolled in the study; 36 patients (81.8%) underwent a cardiac MRI and 34 (77.3%) resulted positive for Petersen criteria. 26 patients (59.1%) had positive echocardiographic criteria, while 18 patients (40.9%) were positive for both MRI and echocardiographic criteria. Five patients (11%) experienced an arrhythmic event during a median follow-up of 2 years (1 VT, 1 VF and 3 patients with appropriate ICD interventions). No clinical, ECG or lab predictors were found for arrhythmic events apart from a history of non-sustained or sustained ventricular arrhythmias, which was associated with a 36% increased risk of subsequent VT/VF episodes (RR 1.36; 95% CI 1.01-1.85; p=0.01). Notably, LVEF (which was ≤35% in 11% of the patients) was not able to significantly discriminate arrhythmic risk (50.7±13.0% vs. 50.2±7.8%; p=ns). Out of 9 patients with normal LVEF and normal GLS, the segmental LS resulted better in non-compacted cardiac segments vs. compacted ones (-20.0±4.6% vs. -17.5±4.9%; p=0.03). This was mainly due to an increase deformation of endocardial layers of non-compacted segments (-26.4±6.6% vs. -19.7±6.6%; p≤0.001), while epicardial layers were similar in compacted versus non-compacted segments.

Conclusions
LVNC represents a poorly understood condition where a mixture of genetic and molecular mechanisms create a fertile substrate for the origin of ventricular arrhythmias. Our population reflects this pattern by showing a high percentage (5.5%/year) of patients experiencing the composite outcome. GLS was higher in non-compacted segments due to an apparent hyperdeformation of endocardial layers. In our opinion, this evidence represents a valid resource and a useful weapon to distinguish LVNC from other differential diagnoses such as, for example, dilated cardiomyopathy.