Cardiac resynchronization therapy in the young patient: current status and future directions.

Cardiac resynchronization therapy (CRT) in young patients with congenital cardiac disease is in its infancy and is just now beginning to be employed. The article by Moak et al.1 points out a growing problem and, potentially, a dilemma in this group of patients—when and how should CRT be employed? This article raises many pertinent questions that need to be addressed. To the present time, articles addressing the use of resynchronization therapy in children have all been retrospective studies and for the most part involved a small number of somewhat diverse patients. The largest study to date was reported by Dubin and colleagues.2 They retrospectively reviewed the records of 103 patients at multiple institutions, who had undergone placement of resynchronization devices. Unfortunately, the centers used multiple and diverse criteria for deciding when resynchronization therapy was to be employed and multiple means of assessing outcomes. Both articles provide an excellent beginning from which to develop this type of therapy in children, but should not be looked upon as providing definitive criteria for such use. The current major issues with the use of CRT in this patient population are similar to those posed in the adult population and relate to indications for resynchronization therapy, specific measures of ventricular dyssynchrony, and implant methodology as it relates to this unique group of patients. However, the answers may be very different. To date, indications for consideration of ventricular resynchronization have included advanced heart failure unresponsive to medication together with some indication for left ventricular dyssynchrony with or without a wide QRS complex. Patient symptomatology has been variable, ranging from being listed for transplantation to NYHA class I.2 Use of ejection fraction alone may not be a good indicator for CRT need. The degree of symptoms and the likelihood of patient improvement must be balanced by the risk of CRT placement,2 and quantitative indicators of a declining clinical state should be used. In all series reported to date, there has been a significant number of nonresponders. The question then arises as to the difference between responders and nonresponders. Dubin et al.2 have suggested that perhaps the nonresponders were children who had less advanced dysfunction and higher initial ejection fractions, and therefore failed to show much improvement. Better patient selection criteria hopefully will improve this.