Natural history of exercise function in patients with Ebstein anomaly: A serial study.
BACKGROUND
The clinical manifestations of Ebstein anomaly (EA) vary greatly; criteria for surgical intervention remain undefined. Decisions regarding surgical intervention in asymptomatic/mildly symptomatic patients would be helpfully informed by a detailed, quantitative understanding of the natural history of exercise intolerance in these patients. However, past studies of exercise function in EA have been of a cross-sectional, rather than a serial, nature. We, therefore, analyzed serial cardiopulmonary exercise (CPX) tests from patients with unrepaired EA to better appreciate the natural history of their exercise function.


METHODS
All patients with EA who had had at least 2 CPX tests, separated by at least 6 months, between November 2002 and October 2010 were identified. Patients with prior tricuspid valve surgery were excluded from the study.


RESULTS
Cardiopulmonary exercise data from 23 patients (64 CPX tests; 2.8 ± 1.0 tests/patient) were analyzed. The median time interval between the first and last CPX tests was 3.3 (range, 0.6-7.3) years. The percentage of predicted peak oxygen consumption declined slowly (1.87 ± 8.04 percentage points/y) during the follow-up period. The decline was more pronounced (3.04 ± 6.78 percentage points/y) in patients <18 years old. On multivariate modeling, only the change in oxygen pulse at peak exercise (a surrogate for forward stroke volume) and the change in peak heart rate over time emerged as statistically significant correlates of the change in percentage of predicted peak oxygen consumption.


CONCLUSION
The exercise function of patients with EA tends to deteriorate over time. This deterioration appears to be related to a progressive decline in their ability to augment their forward stroke volume and heart rate during exercise.