Isolated Noncompaction Of The Ventricular Myocardium

Left Ventricular Non-compaction: From Recognition to Treatment

We have gained considerable insight and understanding about the etiology, embryogenesis of the myocardium, genetic background, diagnosis and outcome of left ventricular non-compaction (LVNC) over the last 2 decades. LVNC has a distinct morphological appearance with a thickened, two-layered myocardium consisting of an epicardial compacted and a thicker endocardial non-compacted layer. These features make the recognition with non-invasive imaging modalities highly feasible.

We now recognize LVNC is a distinct phenotype of the myocardium with genetic heterogeneity. In several cases, LVNC shares a common genetic background with other forms of cardiomyopathy. Therefore, most likely it is not a distinct form of cardiomyopathy but rather a morphological expression of different diseases.

LVNC can present as an isolated condition or associated with congenital heart disease, neuromuscular disease or genetic syndromes. It may be sporadic or a familial disease, with an autosomal dominant or X-linked mode of transmission. The clinical features associated with LVNC vary from asymptomatic individuals diagnosed during screening to symptomatic patients, with the potential for heart failure, arrhythmias, thromboembolic events, and sudden cardiac death.

A comprehensive diagnostic approach includes clinical history, electrocardiogram, imaging (in many instances with more than one technique), genetic assessment, and screening of first-degree relatives. This increases the chances of instituting the most appropriate therapy. Therapy for the most part is very similar to the general heart failure population with the exception that anticoagulation is started at a lower threshold.

Arrhythmias and Left Ventricular Hypertrabeculation/Noncompaction

Arrhythmias in left ventricular hypertrabeculation/noncompaction (LVHT) comprise sustained or non-sustained ventricular tachycardia (VT) (n=135), atrial fibrillation (AF) (n=96) AV block (n=55) and QT prolongation (n=47). The prevalence differs between children and adults. In children most frequent are WPW-syndrome (n=24), AV block (n=24), VT (n=17) and bradycardia (n=15). In adults most frequent arrhythmias are VT (n=118), AF (n=95), QT prolongation (n=42) and AV block (n=31). Some arrhythmias are more frequently reported in children than in adults like WPW-syndrome (24 vs. 17 patients), second-degree AV block (4 vs. 0 patients), bradycardia (15 vs. 3 patients) and ventricular fibrillation (VF) (9 vs. 5 patients). There are nearly no pediatric cases with AF (1 vs. 95 patients). In 120 patients implantable cardioverters/defibrillators have been implanted for primary or secondary prevention of sudden cardiac death. The pathomechanisms of arrhythmias in LVHT are largely unknown, especially if patients with LVHT and neuromuscular disorders are more prone to arrhythmias than patients without. There is a need to clarify risk factors for VT or VF because 19% of LVHT patients with VT or VF have a normal systolic function and demonstration of systolic dysfunction is no reliable risk marker. Data about long-term follow- up of LVHT patients with implanted cardioverters/defibrillators are necessary since the indication for prophylactic implantation is still unclear. AF in LVHT increases the embolic risk, thus it would be useful to know which LVHT patients who have sinusrhythm at baseline are prone to develop AF in order to start early with anticoagulant therapy.