Review article on Noncompaction of Left Ventricle ( LVNC) DEFINITION — LVNC is a rare disorder, classified as a primary genetic cardiomyopathy by the American Heart Association .
LVNC is characterized by the following features:
· An altered myocardial wall with prominent trabeculae and deep intertrabecular recesses resulting in thickened myocardium with two layers consisting of compacted and noncompacted myocardium .
· Continuity between the left ventricular cavity and the deep intratrabecular recesses, which are filled with blood from the ventricular cavity without evidence of communication to the epicardial coronary artery system.
· LVNC may be due to intrauterine arrest of compaction of the loose interwoven meshwork that makes up the fetal myocardial primordium.
GENETICS — LVNC can be either sporadic or familial. Rarely LVNC can occur as a transient phenomenon during myocarditis . 12 to 50 percent of LVNC had a family history .
CLINICAL MANIFESTATIONS — The major clinical manifestations of LVNC are heart failure, atrial and ventricular arrhythmias, and thromboembolic events, including stroke..
At diagnosis, the clinical manifestations included:
· Dyspnea
· New York Heart Association class III or IV heart failure
· Chest pain
· Chronic atrial fibrillation
The electrocardiogram is usually abnormal , but there are no characteristic changes . The abnormalities that can be seen include left or right bundle branch block, fascicular block, atrial fibrillation, and ventricular tachycardia.
DIAGNOSIS — The diagnosis of LVNC is usually established by echocardiography.
Echocardiography —Criteria for diagnosis:
· A thickened left ventricular wall consisting of two layers: a thin compacted epicardial layer; and a markedly thickened endocardial layer with numerous prominent trabeculations and deep recesses with a maximum ratio of noncompacted to compacted myocardium > 2:1 at end-systole in the parasternal short-axis view .
· - Color Doppler evidence of flow within the deep intertrabecular recesses.
· - Prominent trabecular meshwork in the LV apex or midventricular segments of the inferior and lateral wall.
All three echocardiographic criteria were required for diagnosis. The criteria are assessed in the parasternal short-axis view at base, mid and apical levels.Other nonspecific findings that can be seen on echocardiography include reduced global left ventricular systolic function, diastolic dysfunction, left ventricular thrombi, and abnormal papillary muscle structure .
PROGNOSIS — LVNC is associated with high rates of morbidity and mortality in adults. Patients with or without atrial fibrillation are at high risk for arterial thromboembolism .Atrial and ventricular arrhythmias are common causes of morbidity and mortality .
MANAGEMENT — Data on treatment of LVNC are limited, and there is no specific therapy for LVNC. Medical management varies with the clinical manifestations, left ventricular ejection fraction (LVEF), the presence or absence of arrhythmias, and perceived risk of thromboembolism. SUMMARY on Management:
· For patients with LVNC with reduced LVEF and HF( Heart failure), use standard medical therapy for HF due to systolic dysfunction.
· For patients with LVNC with reduced LVEF without HF, use standard medical therapy for asymptomatic systolic dysfunction.
· Patients with LVNC and atrial fibrillation who meet standard criteria for anticoagulation should be anticoagulated according to standard guidelines.
· We recommend anticoagulation with warfarin in patients with LVNC without atrial fibrillation with LVEF <40 percent .
· For all patients with LVNC, we suggest annual Holter monitoring to detect asymptomatic arrhythmias.
· Patients with LVNC should receive ICD (implantable cardioverter-defibrillator) therapy according to standard indications for secondary and primary prevention of SCA( Sudden cardiac arrest).
· - Patients with LVNC who survive an episode of sustained ventricular tachycardia or SCA should receive implantable cardioverter-defibrillator (ICD) therapy for secondary prevention of SCA(Sudden cardiac arrest).
· - Patients with LVNC with an LVEF ≤35 percent and NYHA class II to III HF should receive ICD therapy for primary prevention of SCA.
· Until further data are available, we suggest implantable cardioverter-defibrillator (ICD) therapy for primary prevention of SCD if one or more of the following features are present: syncope, non-sustained ventricular tachycardia, severe left ventricular dysfunction (LVEF ≤35 percent) OR family history of SCA. .
· Patients with LVNC who have end-stage heart failure are candidates for cardiac transplantation evaluation.