Atrial Cardiomyopathy An Orphan Disease or Common Disorder?

Cardiac atria are intricate structures that first appear as localized ballooning of the outer curvature of the primary heart tube with subsequent chamber-specific differentiation and growth.1,2 During this process, the left and right atria acquire distinct molecular identities and specialized cell types that facilitate electric impulse generation and conduction. The right atrium contains the sinus node and the orifices of the superior and inferior caval veins and the coronary sinus. The left atrium has a larger body and smaller appendage than the right atrium, with sleeves of atrial myocardium extending into the pulmonary veins. The atria have key reservoir, conduit, and contractile functions, the perturbation of which can have disastrous consequences and result in thromboembolic stroke, heart failure, and death.Article see p 27 A number of factors can predispose to atrial dysfunction. The atria are exquisitely sensitive to changes in hemodynamic load, and chamber enlargement is frequently seen in conditions that impair ventricular filling or increase atrial volume such as systolic and diastolic ventricular dysfunction, valve stenosis or regurgitation, and hypertension.3 Atrial dilatation from any cause increases the propensity for tachyarrhythmias such as atrial fibrillation.4 Once arrhythmias develop, atrial systolic contraction is impaired, and further atrial dilatation can ensue. Atrial contractile dysfunction or stunning can persist even with restoration of sinus rhythm after cardioversion of atrial fibrillation and may result from effects of the procedure, as well as electric and structural remodeling of the atrial walls.5,6 The atria are frequently involved …