NEW YORK (Reuters Health) – When a defective systemic atrioventricular valve needs to be replaced in patients who have corrected transposition of the great arteries, it should be done before systemic ventricular ejection fraction declines below 40%, a Mayo Clinic team advises.

In the introduction to their report in the Journal of the American College of Cardiology for May 17, Dr. Carole A. Warnes and colleagues in Rochester, Minnesota, explain that in congenitally corrected transposition of the great arteries, the morphologic right ventricle supports the circulation and the morphologic tricuspid valve becomes the systemic atrioventricular valve (SAVV).

In up to 70% of cases, the authors continue, the SAVV is anatomically abnormal, and severe SAVV regurgitation is associated with systemic ventricular failure.

To see if preservation of systolic function is better in the long run when SAVV replacement is done while systemic ventricular ejection fraction (SVEF) is still relatively high, the team retrospectively reviewed data on 46 patients with corrected transposition of the great arteries who underwent SAVV replacement at their institution.

The preoperative SVEF was >40% in 27 of these patients, and 17 (63%) in this subgroup still had an SVEF of at least 40% at late follow-up (ie, a year or more postop).

On the other hand, among the 19 patients with a preoperative SVEF <40%, only 2 (10.5%) had a late postop SVEF of at least 40%, the investigators found.

The rate of late postop mortality or need for cardiac transplant was 15% in the group with higher SVEF preoperatively compared with 37% among those with lower SVEF, according to the report. Apart from the SVEF, other variables associated with late mortality were a subpulmonary ventricular systolic pressure of 50 mm Hg or greater, atrial fibrillation, and New York Heart Association functional class III to IV.

“Patients with congenitally corrected transposition of the great arteries should be scrutinized for the presence of SAVV regurgitation, systemic ventricular dysfunction, and a high subpulmonary ventricular systolic pressure,” Dr. Warnes and colleagues advise. “Consideration should be given to SAVV replacement before the SVEF falls below 40% or the SPVSP rises above 50 mm Hg.”

J Am Coll Cardiol 2011;57:2008–2017.