Imaging cardiac resynchronization therapy.

Although a prognostic benefit has been shown from cardiac resynchronization therapy, questions are often directed toward the prediction of symptomatic or functional benefit. Recent multicenter trials have shown the pitfalls of current mechanical markers of left ventricular synchrony, but these negative trial results have not marked the conclusion of efforts to predict outcome. Potential new contributors to the assessment of mechanical synchrony include echocardiographic and magnetic resonance techniques for the assessment of myocardial deformation. Nonsynchrony markers that seem promising include assessment of the location and extent of myocardial scar and imaging of the coronary venous and phrenic nerve anatomy.