Left Ventricular Dysfunction after Cardiac Resynchronization Therapy in Congenital Heart Disease Patients with a Failing Systemic Right Ventricle

BACKGROUND: Cardiac resynchronization therapy is rapidly emerging as an effective strategy for managing ventricular dysfunction and heart failure associated with congenital heart disease. Indications for therapy, optimal lead placement, and late outcomes are however lacking. METHODS: We present three patients, one with Mustard procedure and two with congenitally corrected transposition of great arteries, who developed subpulmonic ventricular dysfunction 3-6 months after biventricular pacing +/- implantable cardioverter defibrillator implantation, despite initial favorable result of resynchronization therapy. Possible factors for adverse outcome are relatively high pacing rate, unfavorable alteration of torsional contraction, and increased atrioventricular valve regurgitation due to suboptimal placement of larger diameter defibrillation leads. RESULTS: Careful evaluation of patients, particularly indications for therapy, need to be rigorous; assessment of hemodynamic response at the time of implant and appropriate programming may improve the effectiveness of cardiac resynchronization therapy (CRT) in this patient population. CONCLUSION: Our case series emphasizes the need for a registry in the absence of randomized controlled trials, in order to identify patients who benefit most from CRT, and, importantly, recognize subgroups that respond poorly.