Abstract 13918: Reduced Exercise Capacity and Ventilatory Efficiency are Associated With Worse Outcome in Children With Restrictive Cardiomyopathy
Background: Pediatric restrictive cardiomyopathy (RCM) has a poor prognosis and heart transplantation (HTx) represents the only definitive treatment. Timing of listing for HTx is controversial. Little is known on predictors of outcome and some centers advocate listing at the time of diagnosis. We investigated the utility of cardiopulmonary exercise test (CPET) to risk stratify children with RCM with a view to HTx.
Patients and Methods: Between 2004 and 2012 we diagnosed 28 children (age at diagnosis 8±4.3 years, range 1-15 years; 15 males) with RCM. Family history of RCM was present in 10 patients (36%). Left ventricular (LV) end diastolic diameter Z score was -0.8±1.5, whereas the ejection fraction was 59±10%. The Z scores for left and right atrium area were +15.1± 9.3 and +9.8±7.9. Follow-up was complete for all patients and was 8±4 years since the diagnosis. In all children with adequate height a maximal CPET was performed (n= 20 patients, age at the test 14±1.8 years). HTx listing was based on worsening heart failure symptoms and increasing pulmonary vascular resistance.
Results: Survival rate at 5 years from diagnosis was 86% and event free survival (death or HTx) was 67% in the whole cohort. Of the 20 patients who had a CPET, 1 died and 8 had HTx at a follow-up of 2.6±2.8 years from the test. Peak oxygen uptake (peak VO2) was 56.8±24.4% of predicted and ventilator efficiency (VE/VCO2 slope) was 39.4±12.9. Patients with a peak VO2 ≥62% of predicted (23 vs. 67%, p=0.034) or a VE/VCO2 slope <33 (10 vs. 70%, p=0.013) had a lower event rate during follow-up.
Conclusion: Cardiopulmonary exercise test is feasible in ambulatory children with restrictive cardiomyopathy. Assessment of exercise capacity and ventilatory efficiency could be helpful to risk stratify pediatric RCM patients. Patients with better exercise capacity and with less exercise hyperventilation have a better prognosis even without HTx and no increase in pulmonary vascular resistance.
- © 2013 by American Heart Association, Inc.