The goal of this study is to learn more about the risk factors associated with left ventricular non-compaction (LVNC) and the predictors of adverse outcomes associated with LVNC. The main questions this study aims to answer are as follows.

• Are there any genetic mutations that impact the risk of LVNC patients developing ventricular arrhythmias?
• Does LV myocardial strain increase risk stratification in the LVNC population with or without genetic mutations?
• What are some of the determinants that cause LV dysfunction in LVNC?
• What are other risk stratifiers (ex. premature ventricular contraction (PVC) burden on Holter, non-sustained ventricular tachycardia (NSVT) on stress test) that lead to an outcome of ICD implantation?

Participants will have their medical records accessed annually for a span of ten years, either prospectively or retrospectively depending on whether they are being actively followed by physicians at the Inherited Arrhythmia Clinic or not, to evaluate LVNC progression over time. This data will be stored in a large clinical registry with the London Heart Rhythm Program at the London Health Sciences Centre, University Hospital Campus.

Left ventricular noncompaction (LVNC) is a congenital cardiomyopathy in which the left ventricle (LV) of the heart does not develop properly due to impaired myocardial compaction. In utero, cardiac muscle is initially sponge-like, eventually becoming smooth and firm through a process termed compaction. Specifically, in LVNC, impairment of compaction leads to the distal portion of the LV myocardium being thicker and more sponge-like than normal. Hypertrabeculation of the myocardium, where pieces of the heart muscle extend into the LV, result in blood-filled trabeculae and intertrabecular recesses forming within the inner endocardial wall. Collectively, this impairs the LV's ability to pump oxygenated blood throughout the body.

Although various strategies are used to manage LVNC once diagnosed, the severity of comorbidities caused by LVNC, including but not limited to atrial fibrillation, embolism, or stroke, warrant further investigation into the risk factors, etiology and management of LVNC. Furthermore, patients with a definitive diagnosis of LVNC are at an elevated risk of experiencing sudden cardiac arrest (SCA) or sudden cardiac death (SCD). However, little is known about risk stratification with regards to LVNC that can result in SCA or SCD, further highlighting the need for greater analysis of the risk factors implicated in this disease state.

Ultimately, a holistic understanding of the risk factors of LVNC and subsequent morbidities it causes is needed to help improve the diagnosis, treatment and management of patients with LVNC. Hence, the goal of this study is to evaluate the risk factors and mutations associated with cardiovascular events in patients with a confirmed diagnosis of LVNC who have preserved cardiac function.

This study aims to further investigate the risk factors associated with the onset and development of LVNC. Specifically, data will be collected from retrospective and prospective patients. The retrospective cohort consists of patients who are no longer being actively followed by physicians at the Inherited Arrhythmia Clinic at the London Health Sciences Centre, University Hospital Campus, whose data will be collected annually from their medical records from the past ten years. The prospective cohort consists of patients who are being actively followed by physicians at the Inherited Arrhythmia Clinic who, once consented and enrolled, will have their charts accessed annually for the next ten years.

Inclusion Criteria

Patients must meet the following criteria in order to be included in the study.

• Have a confirmed diagnosis of LVNC (between 2010-2020 for patients in the retrospective cohort only)
• Be over 18 years of age

Exclusion Criteria

Patients are ineligible to participate in this study if they do not meet one or more of the inclusion criterion or if they have any other cardiomyopathy aside from LVNC that is linked to a genetic mutation they carry.

Patients in this study have a confirmed diagnosis of LVNC. Specifically, those in the prospective cohort are being actively followed up by physicians at the Inherited Arrhythmia Clinic whereas those in the retrospective cohort are no longer being actively followed up.